Volume 78 1969 > Volume 78, No. 1 > Sweet potatoes and Maori terraces in the Wellington area, by J. W. Macnab, p 83 - 111
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SWEET POTATOES AND MAORI TERRACES IN THE WELLINGTON AREA

Indigenous food supplies in New Zealand were not unlimited. Plentiful supplies of fish and shellfish from fresh water and the sea were a main item in the diet but in its natural state New Zealand was sparsely endowed with edible plants. Buck lists twenty-seven food plants but some of these were only varieties of the same species and the selection was very poor. 1 Of carbohydrate storing plants only the bracken fern (Pteridium esculentum) was in abundant supply and this became the chief vegetable food of the Maori. 2 However, the proportion of starch to vegetable matter in the bracken rhizomes was not high, preparation was tedious and although desirable varieties were recognised, selected and encouraged, it did not become ennobled to form the basis of a permanent agricultural system.

In New Zealand the crops introduced were tropical in origin and limited in the climatic tolerance. Few were suited to the temperate climate of New Zealand and only a few plants survived the introduction: taro (Alocasia antiquorum), yam (Dioscorea sp.), ti pore (Cordyline terminalis), the gourd (Lagenaria siceraria) and the sweet potato or kumara (Ipomoea batatas). As Lewthwaite has recorded: “Among these the hitherto humble kumara assumed the dominant position, displacing taro from its pivotal role.” 3 It was, however, still less important than bracken fern but nevertheless it was a preferred food and great efforts were made to cultivate it, efforts which in turn led to profound modifications of the environment.

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There is no dispute today that the sweet potato (Ipomoea batatas) is of South American origin. If Vavilov's theory of plant origins is accepted, then Yen's study of sources and numbers of varieties indicates a Peruvian centre for the domestication of sweet potato. 4 It is generally believed that sweet potato was carried by man into the Pacific as not only is it usually reproduced vegetatively and dispersal by seeds was therefore unlikely, but also the Quechua name “kumara” was carried with the plant to places as far apart as Easter Island and New Zealand and recognisable variations of the name are found on Tahiti, umara; Hawaii, uala; and Rarotonga, kuara. However, this linguistic connection has recently been questioned by Donald Brand of the University of Texas. 5

The sweet potato was a difficult plant to store and even more difficult to transport any distance by sea. Oviedo writing about 1525 A.D. regarding the carriage of this plant from the New World stated: “. . . when the batatas are well cured they have often been carried to Spain when the ships happened to make a quick passage, but more often they are lost on the voyage.” 6 Merrill whose knowledge of Pacific plants was encyclopedic, agreed with this point and wrote: “ . . . as its keeping qualities are limited it must have been introduced as a growing plant, in soil.” 7 That this method was adopted is suggested in the Horouta legend by the description of the cliff falling with the plants. 8

However, if roots had been well cured and a quick voyage had been made, kumara could have been introduced into New Zealand as tubers and not by the growing plant. Root planting was the sowing method adopted in New Zealand as the stem propagation of the tropics so well described by Handy 9 was not suited to the cool temperate climate encountered. In New Zealand the cultivation cycle had to be changed from one of continuous year-round growth, cropping and replanting of the terminal shoots of the vines, to one with a seasonal rhythm of planting, growth, harvest and storage. As storage was such a difficult and elaborate technique, Yen suggested that the sweet potato was introduced during a period of mild climate when year-round growth was possible, and storage practices were developed later. 10 That there was a mild climatic phase at the beginning of the millennium when kumara was introduced into New Zealand is by no means certain and the temperature differences that are postulated are so minor that annual variations often exceed them. Yen's hypothesis must certainly be regarded as unproven and indeed may not be necessary.

A change in the method of planting from the tropical one of using the terminal part of the vine and successive plantings with year-round growth, to a storage phase and the planting of the whole tubers in the following spring, was necessitated by New Zealand conditions. This was a major change to make and an urgent one, for it had to be made in the - 85 first year or seed stock would have to be obtained anew. However, the Maoris would be quick to realise that year-round growth was not possible as any vines planted after harvest would be killed by the first frost. The tubers from that year's harvest would already be stored for future use, and however primitive the storage during that first winter, enough must have survived to provide seed tubers for the next spring planting. After the second harvest, one can be sure that much more careful treatment would have been given. That the need for care was recognised is proved by the elaborate rituals and taboos that grew up around the cultivation, harvesting and storage of the crop.

Areas with favourable climate and suitable light soils were not extensive. Kumara was probably restricted at first to coastal locations in the Auckland Peninsula, the Coromandel Peninsula and in the Bay of Plenty with outliers in Poverty Bay on the East Coast and perhaps as far south as Taranaki on the West Coast. The thermal region near Rotorua was one of the few interior areas where kumara would flourish. Colenso recorded that the thermal regions of New Zealand with their artificially mild climate and light pumice soils were popular. “I remember when at Rotorua Lakes, nearly forty-five years ago (1835) visiting a very large kumara plantation (that neighbourhood being a principal and noted one of all New Zealand for its fine prolific kumara crops, said to be owing to the extra warmth of its heated volcanic soil).” 11

Walsh recorded that the kumara required dry sites and should not be exposed to the cold southerly winds or to the spring and autumn frosts. He states: “The heaviest crops are obtained on the sand and shingle terraces above high water mark and on the low river-flats; but as the former are limited in extent and the latter are more exposed to frosts—besides taking a good while to dry up after the winter rains—advantage was taken of well-drained sheltered spots on higher ground for the earlier plantings, though the work of cultivation was attended by much harder labour.” 12

Early Maori settlements were often located on coastal shingle bars near the mouths of rivers. In those locations, food from stream, sea, forest and fern was available and to the gathering and hunting some permanent agriculture based on sweet potato could be added. In these favoured areas, land selection, land breaking and cultivation techniques were developed which in turn were to permit further advance on to land originally marginal for kumara cultivation. At first, only the most favoured sites could be used but the Maori wedded his knowledge of the environment to his knowledge of the behaviour of the sweet potato in that environment and the cultivation of the kumara passed from being an art, to a science and eventually a ritual.

THE CULTIVATION OF THE KUMARA

The number of varieties of sweet potato which were cultivated in New Zealand has never been accurately determined because after the initial European contacts, other crops more suited to the temperate climate - 86 quickly replaced it as the staple. Colenso identified thirty-two varieties in the northern districts of the Bay of Islands, Hokianga and Kaitaia. 13 Five of these varieties were cultivated in Hawke's Bay and on the East Coast and there were a further sixteen varieties grown in that area. Thus Colenso recorded forty-eight different varieties and he considered that his lists were by no means exhaustive. In all the lists, the variety called parakaraka, one with a red skin and flesh, was said to be the oldest.

The variety of sweet potato which gave its name to the whole species in Polynesia is identified by Towle as cjumara, the Quechua name for the starchy variety. 14 It is probable that the Maoris only had sweet potatoes descended from original starchy varieties. Yen states: “In all areas of its distribution the plant is in a similar state of evolution.” 15 Whilst this statement is accepted, Sauer's statement is also attractive. Sauer wrote that “it may also be noted that these Maori forms seem to have been starchy and coarse-fibred, like the cumara (sic) of the Andean Yungas, and suggest a derivation from an older, and now nearly extinguished American form.” 16 After Yen's work, one cannot suggest that the Maori varieties were, in an evolutionary sense, more primitive but they were starchy like the Quechua variety named cjumara and they were not so palatable as later introductions. Certainly the Maoris took the earliest opportunity in the early nineteenth century of obtaining more palatable and larger varieties from the American whalers as Berridge 17 and Walsh 18 have recorded. The two most important obtained at this early contact were merikana named after the Americans and waina named after its long vines.

Somatic variation is very common in sweet potatoes and even today breeders have to select and re-select to keep their stocks true to type. 19 Consequently even though the sweet potato did not set seed in New Zealand making genetic variation impossible, somatic variations almost certainly occurred and the large number of varieties distinguished by the Maori could have arisen from a single introduction. Original varieties of Maori kumara still exist. In the 1940s, Enid Tapsell recorded four varieties in North Auckland. One taroamakoe was claimed by the Arawa tribe to be the original variety brought to New Zealand. It was a small, finger-like, dry tuber with few eyes, which could be eaten raw, dried or steam cooked. 20 Yen collected Maori varieties in the years 1955 and 1958 mostly in the Auckland and Bay of Plenty areas, which are in the climatically favoured parts of Northern New Zealand. From ninety-seven collections, he found that there were only four Maori varieties and four introduced varieties, one of which had five or six forms. The chief characteristic of the Maori varieties was the bush habit of the plant. The vines were short to medium in length usually less than five feet long. - 87 The tubers were white, smooth, long and cylindrical but variable five to six per plant. They were firm textured, only slightly sweet, dry and mealy and stored exceptionally well. Propagation was by planting roots. 21 This collection did not include the red kumara which Colenso recorded as being the oldest.

The range of variation in the Maori types was small. Each variety recognised by the Maoris probably gave some slight advantage in its particular environment but the differences were not great. As the varieties were similar, this meant that the plant was only suited to a narrow range of environmental conditions and in general the environment had to be suited to the plant, not the plant variety chosen for a particular environment. This necessitated extensive and permanent modifications to the soil and to the terrain when the kumara was grown under more difficult conditions.

The sites of Northern New Zealand naturally suited for kumara cultivation were those with mild climate and ash or sandy soil. Generally these were not heavily forested, for over much of the northern area there had been successive showers of volcanic ash and the forest had been destroyed. Large areas were covered with manuka (Leptosporum scoparium) or bracken fern. Manuka, a tough hard wood when dry, was easily cut with a slanting downward blow when growing. Its bushy foliage and arm-thick trunks burnt readily with a fierce heat even while green. Clearings might have been made with fire alone, in which case, after a few months, any remaining dead trunks were easily pushed over as the roots rotted quickly. With a vigorous pull the dead manuka could then be removed from the ground, piled into heaps, perhaps around any standing trees, and burned.

The ashes of this plant made good fertiliser. Miller and others examined the production of plant nutrients on an area where manuka stood eight to ten feet high. When the manuka was burned, the amounts of plant nutrients in ash per acre in terms of common fertilisers were equivalent to 100 lbs of superphosphate, 980 lbs of calcium carbonate, 180 lbs of magnesium carbonate and 330 lbs of potassium sulphate. These large quantities of nutrients formerly immobilised in the manuka community were released to the soil in a form easily assimilated by the cultivated plants. The amounts were comparable with applications of commercial fertiliser currently being applied by farmers. 22

The bracken covered areas were more difficult to clear but with these areas there was secondary advantage. The bracken rhizomes, rich in carbohydrate, were the main staple food and clearing could be associated with food collecting. Walsh claimed that the autumn season was the one preferred for clearing because the bracken rhizomes were then at their best for food, 23 but in contrast, Colenso claims that the spring and early summer were the best times for collecting fern roots. 24

New land would probably be dug over at the time of clearing since if - 88 fern roots were left in the ground they would grow again in the spring and compete with the sweet potato. The principal cultivation implement used was the heavy ko, an eight to ten foot long digging stick. A footrest was attached about a foot from the end of the ko and in appearance it looked very much like a child's stilt. When breaking in new land or when digging the ground for fern root, several men standing in a row worked together, digging in the ko in unison and then heaving over a long sod of earth in one unified movement. 25

Best described the subsequent cultivation which was carried out in early spring:

In preparing the soil for planting a different method was adopted. The soil was not turned over; it was not even all dug. The sweet potato was planted in little mounds, and these were spaced in a very regular manner. Only at these spots where the seed tubers were to be planted was the soil dug. To prepare such a spot the digger thrust his ko into the ground three times, and, by pressing the shaft down loosened the soil by means of the upward movement of the point. Thus the spade (ko) was used as a lever is, and not as we manipulate a spade. The three thrusts of the spade were made on different parts of the circumference of the small area where the mound was to be formed ∴ The performance loosened the soil, broke it up and raised it; the next operation was the pulverising of the clods, which was done with a wooden club, after which the soil was further worked and loosened, roots, etc., were cast aside, and the finely worked soil formed into small mounds ready to receive the seed tubers. 26

These little round hills called tupuke, were about nine inches high and twenty to twenty-four inches in diameter and set quite close together. Colenso described this pattern, when commenting on “the extreme regularity of their planting, the kumara generally being set about two feet apart in true quincunx order, with no deviation from a straight line when viewed in any direction.” 27

The creation of mounds was the most important feature of the sweet potato cultivation for they were more productive if grown in this micro-topographical feature. Handy recorded that the ancient Hawaiians planted sweet potatoes in mounds. 28 Large mounds, almost hillocks, twelve or more feet across are presently used in New Guinea 29 and large mounds found in Taranaki and the East Wairarapa coast may have been made for this crop. The use of mounds was associated with the need of the plant for adequate root aeration and good drainage. The tubers were susceptible to rotting if conditions were too wet though Walsh noted that it was an advantage to have a hard bottom below the cultivated area because if tillage was too loose, the roots of the kumara - 89 would be inclined to run, with the resultant tubers small and of poor quality. 30

Special treatment of tubers was necessary in order to ensure sprouting. Shallow pits previously warmed by fire were hollowed out, lined with dry fern, then layers of tubers, more fern and finally earth and left three weeks or more. Then the soil was carefully loosened and the tubers divided into two or three pieces before carrying to planting ground. . . . The young shoots were hardened off enough to move. Care had to be taken that they were not dislodged from their ‘eye’ sockets in the process of transferring from hot bed to plot. 31

Walsh recorded that the seed consisted “of tubers which were too small to be eaten. If these were not sufficient, they were supplemented by the heads . . . the end containing the eyes . . . of the larger ones broken off for the purpose.” 32 Sweet potatoes first produce sprouts (slips) at the apical end with other sprouts subsequently developing over the whole tuber. These slips alone are used by commercial growers today but they were not used by the Maori.

Many writers who have recorded the Maori methods of cultivating the sweet potato have commented on the need for warm humid conditions during the planting season. Tapsell recorded that “planting time was usually November (late spring), or when weather signs and conditions were favourable to the young plants. When a marangai came in from the sea, and the sun was obscured and the air damp with sea mist, was the most propitious time to plant.” 33 Walsh wrote: “When a ‘mackerel sky” showed an exact picture of a kumara-plot extending across the heavens the Maoris knew that the atua were busy at their planting above, and that they themselves ought to be doing the same below.” 34 This is perhaps the best record of all of the type of weather required by the Maori for planting and of his ability as a weather forecaster. The signs recorded here still form part of the local weather lore. The “mackerel sky” is an easily recognisable weather phenomenon. These high clouds are the first indications that a warm front is approaching. In New Zealand the rain belt of the warm front is usually one to three days behind the appearance of the “mackerel sky”. This warmth and moisture would provide ideal conditions for the growth of the new plants.

Planting was recognised as being important, so important in fact that it assumed religious significance. It was considered essential that the whole plot be planted in one day. All men, women and children, from chief to slave, participated and both workers and plot were tapu from the commencement of work until completion. The tubers were placed one to each hill, about two or three inches below the surface with the sprout end raised and pointing towards the north. 35 Best's version of the planting practices differed slightly. He said that the seed tubers were - 90 placed in the little mounds with the sprouted end to the east and as the planting season advanced, the tubers were faced a little further to the north so as to “follow the sun”. 36

In New Zealand in pre-European days, diseases or weeds or pests were few, so tending the crop was not an onerous task. The soil was kept loose around the plant in the early stages of growth and later in the summer the plants were given one weeding by a party made tapu for the occasion.

The one danger was that the plant would waste its energy on other than main tuber production. Trailing vines were checked and adventitious roots spreading downwards from nodes in contact with the ground were pulled loose as small useless tubers might develop on these and the strength of the main tubers consequently be diminished. The bush habit of the Maori varieties helped to prevent this dissipation of energy. The Maori kumara has grown for its roots and the vegetative parts of the plant had no secondary value as vegetable or fodder.

Of the few pests, the only significant one was the large larva of one of the largest moths. Some years they appeared on the plants almost like a swarm of locusts. If this happened, they were picked off by hand, carried away and burned, otherwise they would have rapidly devoured the leaves of the young kumara. With no browsing animals in Maori New Zealand, fences were not necessary to keep out stock. However, fences were used for shelter against the windy conditions which prevailed in even the mildest parts of the country.

The greatest danger was not disease, poor season or pest but man himself. It was considered good strategy in war to destroy the crops of the enemy; consequently fields were often placed in concealed positions. Small separate fields scattered throughout the area might be overlooked by the raiding party.

The high standard of agriculture reached was impressive. The unspoiled Maori was a very fine farmer and this is best summarised by the description of Nicholas, who as early as 1814 stated:

. . . the nice precision that was observed in setting the plants and the careful exactness in clearing out the weeds, the neatness of the fences, with the convenience of the stiles and pathways might all have done credit to the most careful cultivator in England. 37

Harvesting the crop was a simpler operation than planting but required equal care. As kumara from the previous season would be exhausted 38 or in short supply by this time, the practice arose of taking the largest tubers from the mounds before they had all grown to a large size. Early harvesting was possible with sweet potatoes as this crop, being tropical in origin, did not come to a definite maturity but continued growing. The largest potatoes were taken from the mounds with as little disturbance of the plant as possible. In the process, the earth was loosened around the plant and hilled up again. At this time too, any withered leaves, weak sprouts or adventitious roots were removed. Nothing was left that might rot and infect the other growing roots.

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The tubers from the early harvest were given special treatment. They were half dried in the sun on clean matting, turned every day and protected carefully from rain and dew. When dry, this kao was stored. This practice was very similar to one observed by the writer in Japan. Best recorded that the sun-dried tubers were steamed after drying. 39 Kao was a prized food, eaten raw, or soaked or mixed with water into a kind of porridge. This thin porridge, warmed with hot stones, was the only hot drink available to the Maori and it provided an excellent food for invalids.

The digging of the main crop came later, always before the first frost, but it was delayed as long as possible in order to reap the largest harvest. Sweet potatoes suffered injury at temperatures below 50°F and were badly damaged at temperatures below 40°F. Warm, sunny harvest days were essential as the tubers had to be kept dry to guard against mould. Great care was necessary when lifting them from the ground in order to avoid bruising and cutting. Damaged roots were placed to one side for early use. Small roots were selected for next season's seed and the remaining larger ones would be eaten later. The finest tubers were placed in newly made flax baskets for carrying to the store. It was considered proper to carry the baskets on the back only, and the harvest scene must have been reminiscent of that witnessed recently in Japan.

Current recommendations are that sweet potatoes should be cured for ten to fourteen days at a temperature of 80° to 85°F with a relative humidity of 85 to 90 percent, and then stored at temperatures that do not fall below 50°F with a relative humidity of 80 to 85 percent. In contrast non-cured sweet potatoes stored for four to four and a half months at a constant temperature of 50°F suffer almost 100 percent decay. The loss is somewhat less at 55°F and still less in storage at 60°. 40

It is difficult to determine whether the Maoris cured their sweet potatoes. Berridge writing in 1913 about European experiments with storage methods offers some indirect evidence that they did:

Many methods have been tried for storing sweet potatoes such as packing in dry sand, putting in clamp, sorting in shed, etc., but experience teaches that storing in ruas as the Maoris call their underground pits, is the most successful. If properly handled, the potatoes can be kept in this manner until the next crop is ready to dig. The kumeras must be dried thoroughly, and the pits opened and ventilated every five days until the sweating period is over. This generally takes about a month, and even afterwards the pits should be ventilated occasionally. The tubers should be kept from direct contact with the bottom and sides of the pit by a layer of dry fern. It is advisable before using a rua again to clean out all fern and rubbish, and burn sulphur. This will kill all wood lice and insects, and help to destroy germs of decay and fungus. 41

If this is a description of the Maori curing and storing method, then their practices might well have met present-day recommendations. The - 92 ventilation would keep the humidity down to the required level and water would not accumulate at the bottom of the rua because of drains. With the sweating there would be increase in heat and temperatures would rise in the storage chambers. When the ruas were closed, the temperatures inside must have been sufficiently high to preserve the crop.

The risk of loss from diseased tubers was lessened by having numerous small storage places. If disease broke out in one store, it could only affect the potatoes stored within it. The stores were often shallow as the baskets of potatoes were not piled one upon the other but given their own bed on the fern on the floor or sloping sides. Previously used ruas were often abandoned in order to avoid new tubers being contaminated by last year's diseases. Thus the number of abandoned ruas which can be observed in one place today bears little relationship to the number of ruas used in any one year and no relationship at all to the area under cultivation at any given time although attempts have been made to correlate the two.

The growing season was not long for a crop which had originated in the tropics. John Butler noted on Saturday, 11th October, 1823:

In the afternoon I went to Tabooatahi, about three miles distant, to see the natives and to converse with them. I found them busy in working their ground for koomeras. I told them I was glad to see them so usefully employed. I then told them that the morrow would be Sunday, a sacred day, and that they must not work, but go to Tatee, the missionary station, to hear prayer, singing, and preaching in New Zealand language. They replied that the seed time was almost over, and they wanted to finish planting their potatoes.

On Monday, 24th March, 1823, he recorded the previous harvest:

We were much gratified on beholding a great increase of land cultivated with corn, taro, potatoes at this part of Wymattee; we passed through several fields of Indian corn which looked remarkably well, but we were prevented taking anything more than a general survey on account of the sweet potato being tabooed. This being harvest time, everyone was busily engaged, some on making houses to receive produce, and some on making baskets for the purpose of carrying it to their storehouses, or presenting it for sale. 42

This eye-witness account gives the growing season in North Auckland as about five months long. Many coastal areas in New Zealand, particularly in the North Island and in the northern part of the South Island normally had a growing season of this length but infrequent, early frosts must have provided a hazard to the kumara crop in these cooler parts of New Zealand, and only land with favourable micro-climatological conditions could have been utilised without fear of crop loss.

AGRICULTURAL EXPANSION AND ITS PROBLEMS

A continuing problem for the Maori was the finding of additional areas suitable for the cultivation of sweet potatoes. Climate was a restricting factor since in many areas of New Zealand the growing season was - 93 too short. With soil, it played a major role in limiting the selection of new sites.

The type of soil preferred by the Maori has been described by Taylor:

The yellow-brown loams formed from fine volcanic dust (such as occurs in the Waikato, at the west and east ends of the Bay of Plenty, and in western Taranaki) are good cropping and gardening soils. They are well drained, hold moisture well, have very friable top soils and subsoils, and do not become sticky when wet. The yellow-brown pumice soils are coarse, having in most places a sandy gravelly topsoil and with coarse sands and gravel below, but because of the pumiceous nature of the soil particles they do not dry out as rapidly as their texture suggests. Where they thin out over the yellow-brown loams, as they do near the Tauranga and Maketu, they form an almost perfect kumara soil from the physical point of view, and may possibly have been a model guiding the Maori in his ultimate extensive reconstruction of soils elsewhere. Unfortunately, much of the pumice land is so elevated that frosts would rule out the cultivation of the greater part of it. 43

The advance inland was certainly not a single probing movement but an advance from a number of settled areas. Choice of new sites depended not on agricultural criteria alone, but also on all other elements which affected the lives and livelihood of the people. Problems of water, of food from stream, bracken and forest, and of defence had to be solved and these occupied the minds of the Maori pioneers as much as the difficulty of finding suitable agricultural land.

Discovery and utilisation of the ash-covered thermal regions of the Rotorua area was relatively simple. Elsewhere, the success of inland settlement where soil conditions were not so suitable depended on the development of specialised techniques. The building of artificial hillocks was one way of by-passing the natural soils, many of which were heavy sticky clays, the least suitable of all soils for sweet potato cultivation. The recent alluvial soils of the river valleys were lighter in texture than the clay-covered hills and were chosen in preference but even these soils needed modification before use. The changes wrought in the alluvial soils were some of the most extensive achieved by a people who had only stone and wooden tools. The need must have been pressing indeed.

Alluvial soils were modified in two ways, one organic and one physical. Organic changes in a Waimea soil, in the Nelson area, are described by Rigg and Bruce as follows:

An examination of the soil revealed the fact that it contained considerable quantities of charcoal, which could be separated to some extent by the simple immersion of the soil in water. The charcoal was noticed in several areas of the Maori gravel soil, and occurred, not only in the top 9 in., which may be regarded as the true top-soil, but was found to the full depth of 12 in. to 16 in. which constitutes the whole layer of the prepared soil. The dark appearance of Maori gravel soil results, in fact, principally from the presence of charcoal, - 94 which apparently was introduced from the very beginning in the preparation of the land for their crops . . . The presence of charcoal throughout the whole depth of Maori gravel soil suggests that very large quantities of wood must have been burnt on the soil. It is well-known that wood ashes contain considerable amounts of both phosphates and potash salts. Analyses of teatree (manuka) and bracken ash made in the laboratory, show that they contain about 1.1 percent of phosphoric acid and from 8 percent to 17 percent potash. The ash of these plants is alkaline, and contains carbonate of lime, which would remedy soil acidity. It is not enough to assume that the Maoris simply burnt, from time to time, the vegetation growing in situ on their soil. This would not account for the large increase in either the available phosphoric acid or that soluble in hydrochloric acid. The increase can only be explained by a long continued policy of burning wood, or more probably scrub, taken from the other lands in the vicinity . . . The Moutere Hills flank the whole of the land used by the Maoris. Nowhere are the hills more than one mile from their fields. Teatree or Manuka (Letosporum scoparium) flourishes on almost every part of the hills, and if cut, rapidly establishes itself. It seems probable that this was the source of the wood used for burning on their soil. It is difficult to give any estimate of the total wood which was burnt on the land during the Maori occupation. The accumulations of the present day represent a portion only of the quantities of plant food which must have been introduced by the Maoris. Large quantities of potash would quickly leach out of such a loose textured soil, and the crops of both Maoris and Europeans must have removed very large amounts of both potash and phosphoric acid. On the richer portions of the Maori gravel lands, several hundred tons of vegetable matter must have been burnt on each acre. 44

Following the Rigg and Bruce paper, an editorial note stated that Taranaki Maoris prepared compost for use in the cultivation of the kumara.

It was the custom of these people in by-gone times, after a flood in a river, or a storm at sea, for the experts in agriculture . . . to examine most carefully the deposit of sand and silt thrown up or left by storm and flood. If suitable, material was gathered in baskets and taken to a suitable spot where it was mixed with vegetable matter, gathered in by other bands of workers. This consisted mainly of the succulent ground-fern called Mouku (Asplenium bulbiferum), which grew in abundance throughout the neighbouring forests, and the leaves and tender branches of certain shrubs of the coprosma family . . . the taupata, karamu, raurakau . . . and probably leaves of other trees and shrubs in a lesser degree. 45

In 1923, an old compost heap prepared by the Maoris on the banks of a stream about seventeen miles south-west of New Plymouth, was - 95 analysed. A superficial examination of a mixed sample taken from several parts of the compost heap showed that it contained uniformly coarse sandy particles. The sand was dark in colour, due to the presence of charcoal and magnetic ironsand. Pieces of charcoal could be picked out by hand, while ten to twelve percent of ironsand particles could be separated easily by use of a magnet. This compost was compared with the Maori soil of the Waimea Plains as shown in Table 1.

TABLE 1
COMPARISON OF COMPOSITION OF NEW PLYMOUTH COMPOST WITH THAT OF WAIMEA MAORI SOIL
  New Plymouth Compost% Waimea Maori Soil%
Moisture 1.0 1.6
Organic Matter 2.5 6.4
Fine Gravel 4.5 14.5
Coarse Sand 68.5 38.9
Fine Sand 19.9 17.2
Coarse Silt 1.8 10.0
Fine Silt 0.6 8.4
Clay 0.3 2.6
  99.1 99.6
Nitrogen .147 .078
Loss on Ignition 2.5 6.4

Available Plant Food

Phosphoric Acid P2O5 .094 .042
Potash K2O .01 .019

Plant Food Soluble in Strong Hydrochloric Acid

Phosphoric Acid P2O5 .11 .16
Potash K2O .25 .6
Lime CaO 3.1 -
Magnesia MgO .5 -
Lime Requirement Fig. .05 .11

The most striking feature was the very high content of available phosphoric acid in the compost, a quantity seven times greater than that normally present in local soils. The potash content was low for it was rapidly leached by water, but it was estimated that when the compost was originally prepared, the potash content would not have been less than five percent. 46

Taylor stated that “there has been some conjecture as to how the Maori supplied enough nitrogen to these gravelly soils to get a worthwhile crop. The problem, however, may not have been too difficult. First, the slow fire method of carbonization would produce much charred material and soot-absorbent material from which the nitrogen is not completely lost, as it is in ashes. Secondly, soil nitrogen would build up during a fallow under native vegetation. Thirdly, successive slow fires producing additional charred material would partially sterilise the topmost layer of the soil causing a flush of available nitrogen. This combination of practices could well provide the answer.” 47

The physical structure of the soil was also extensively modified. Colenso wrote: - 96

For the kumara . . . a dry and light sandy soil, or rather a gravelly soil, was selected; and if it were not naturally, it would be sure to become such, as every year they laboriously carried on to it many weary backloads of fine gravel obtained from pits or river beds in the neighbourhood. 48

Elsdon Best recorded a similar practice:

The ground was covered with a thick layer, sometimes six inches thick, of fine gravel. The work of carrying that gravel on the back from a gravel pit was a laborious one. We see fields whereon hundreds of tons of such gravel have been spread. The writer has seen pits in which a good-sized house might be built that were formed by gravel seeking cultivators . . . The cold and stiff soils of parts of the Waikato district called for much labour in sand treatment and in many places pumice sand was so used. In course of time this treatment would break up heavy soils and render them much more suitable for the cultivation of the sweet potato. 49

Large areas of soil were modified by the Maori. Rigg and Bruce estimated that the total area of Maori gravel soil in the part of the Waimea district examined by them was more than one thousand acres. In its natural state, the topmost layer of soil was a loam some eighteen inches thick. Underneath the loam was fine sand ten to thirty inches thick, and underlying that, several feet of coarse sand and gravel. The Maoris dug pits into the two lower layers and after picking out the largest stones, spread the remaining gravelly sand on the surface to a depth of ten to sixteen inches. 50 Thus, the manufactured soil, the topmost layer of which contained a large percentage of fine gravel and coarse sand was physically similar to the natural volcanic soils which the Maoris used. Taylor estimated that there were about 5,000 acres of these made soils on the mid-Waikato plain. He records that “in Waipa County the most frequent soil profile is nine to ten inches of black fine gravelly soil with much charcoal throughout, resting on an older soil . . . They are adjacent to pits dug to the stratified sands and gravels below.” 51 Thus, manufactured soils with a lightened texture had been developed artificially to meet the needs of the crop.

The soils developed by the Maori are physically almost perfect sweet potato soils and are similar to those sought for sweet potato growing in North Carolina where it is recommended that “soils with sands, loamy sands, or sandy loamy surface textures and pH of 5.8 to 6.2 are best suited to growing high yields of good quality sweet potato” 52 The Maori soils too had been enriched with nitrogen, phosphate and potash and these are the fertilisers applied commercially today. The Maori had developed techniques which met the physical and nutritional requirements of the kumara. Wherever suitable conditions prevailed, these techniques were applied, but in the Wellington culture area, where conditions were difficult, additional techniques had to be developed

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FIGURE 1
Illustration.
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A STUDY OF A PARTICULAR SITE ON WHITIREIA PENINSULA

Porirua Harbour is a two-armed inlet occupying a shallow down-warped depression which runs parallel to the coast (Figure 1). The southern arm of the harbour is sheltered behind Whitireia Peninsula. This hilly peninsula some 300 feet at its highest, is cliffed on its western seaward margin. It is steepened on its eastern inner margin, and has gentle north-facing slopes. The harbour entrance is narrow and at an oblique angle to the open sea so little of the inner water is exposed. The harbour waters are shallow, only deep enough to take small craft. They are used today by fishing craft and pleasure vessels.

In the Wellington area kumara agriculture was not easily adopted. Best has written: “Inferior soils and high lying districts would permit of only small crops being produced; herein the kumara was little more than an occasional luxury. The Wellington district may be included in this class, for it is on the fortieth parallel, which is far south for the kumara.” 53 However, only the sweet potato was available as a cultigen. Its cultivation was attempted and it was successful.

Wakefield on a journey north in the early 1840s, described some sweet potato fields in an area less than ten miles distant from the Whitireia Peninsula. This was near the present township of Paekakariki where the long sandy beach of the west coast meets the cliffed rocky shore. Wakefield said about the area:

The beach was shingly and studded with rocks . . . At one spot we passed through a natural arch in a spur of rock which jutted into the sea. I had to get on to E Puke's shoulders; and he seized a favourable time to run through the passage as the surf occasionally rolled breast high into it. A little further on, some neat plantations of the kumara, or sweet potato, betrayed the neighbourhood of a settlement. They extended about thirty yards up the face of the hill, in terraces formed by logs of wood laid horizontally, and supported by large pegs. The terraces were covered with sand from off the beach, which the natives assured me was the best soil for the growth of the kumera. In storms, these plantations must be covered with salt spray and swept by the north-west wind; but on this day a hot sun shone upon the bank, and I was told that such a position was esteemed highly productive. 54

Wakefield was not surprised to see sweet potatoes and they must therefore have been common in his experience. His comments about aspect, terracing and sandy soils are also relevant.

On the gentle north-facing slopes of Whitireia Peninsula, numerous flights of terraces may still be observed. These terraces were first recorded in 1926. 55 The numerous terraces could have been habitation sites but the local Maoris did not consider that they were when early ethnologists recorded the settlements of the area. The local settlements were mainly located near the water's edge on the inner harbour. The origin of these - 99 terraces was attributed by Morgan to marine action 56 but that hypothesis is destroyed by an examination of the soils. It was suggested to the writer that they were remnants of fields on which Irish potatoes had been cultivated by the Maori. But Colenso wrote: “As the potato loves a virgin, or a strongly manured soil, the Maoris chose rather to prepare fresh ground every year, generally by felling and burning on the outskirts of forests.” 57 Irish potatoes were a crop suited to temperate New Zealand and there was no need to go to elaborate lengths in order to prepare slope or ground for its cultivation. In addition, early European writers noted Irish potatoes growing on the alluvial flats in the Wellington area. For example, Brees, describing Makaenuku Pa in the Hutt Valley, wrote: “This Pa has been built and extensive potato grounds around it cleared entirely within the memory of the present settlers. It was occupied by the Porerua and some other troublesome natives who acknowledged Ruaperaha and Rangihaeata as their chiefs.” 58 Best had the flight on Whitireia Peninsula recorded as artificial terraces on a map of the Wellington District and Ongley stated that Best considered that they were made by the Maoris for kumara cultivation. 59

The Choosing of a Site for Cultivation

Near Porirua Harbour, sites suitable for the cultivation of sweet potato were not numerous. Land adjacent to the harbour had been drowned and the bay heads were very shallow. The shallow waters were an excellent habitat for shellfish which provided part at least of the permanent food supply. Large shellfish middens can be found today alongside parts of the harbour road. At low tide the bay heads became mudflats unoccupied by other than wild-fowl which also provided food. Behind the bayhead mudflats were alluvial lowlands recently emerged, ill-drained and swampy, ideal habitat for the fresh water eel beloved by the Maori, but less than suitable for Maori agriculture. The alluvial lowlands higher upstream were not much better, as the valleys were narrow and shaded throughout much of the day. Cold air drainage from the steep enclosing hills was considerable and these areas were heavily frosted in winter and winters lingered long. Damp mists too hung in the valley. Alluvial lowlands were also under the disadvantage of possible flooding. Volcanic soils were absent and the alluvial soils of the lowlands around the Porirua Harbour were cold, damp, and difficult to work. The building of mounds in this area might have overcome the drainage problems but would not have offset the climatic disadvantages and the Maori searched elsewhere for cultivation sites. Choice of site bore a direct relationship to the technological developments of the people. People with primitive stone and wooden implements could practise permanent agriculture but they would prefer areas with light soils. These soils were often found in hilly areas.

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The Maoris chose the north-facing headland of Whitireia Peninsula as their site for cultivation. This hilly site provided many advantages over the level areas. The varied terrain, with its different slopes and aspects, offered a large number of choices. Micro-climatological conditions may well have proved the greatest attraction.

The slopes had in general a northerly aspect. Not only did they face the sun but their orientation gave them protection from the wind. The flight of terraces examined in detail (Site N 160/28) had a north-easterly aspect which served to shelter it from both the southerly and westerly winds, the two coldest winds on this part of the coast. The terraces angled back from the sea and the erection of a brush wind-break along the cliff edge would have given the whole flight some protection, though it is probable that each terrace not only had its own surrounding wind-break but transverse ones as well. Such wind-breaks were often noted by early European visitors. Walsh quoting Cook recorded that plantations were “fenced in, generally with reeds, which were placed so closely together that there was scarcely room for even a mouse to creep between. This was done to shelter the crop from the strong winds which blew in the early summer; and in exposed situations additional breakwinds formed of fern or tea-tree (manuka) fronds stuck in the ground were set up in lines across the plantation.” 60 This was a site where wind-breaks would not only be desirable but essential as personal experience when surveying the terraces confirmed. Insolation was high on this coast and cloudiness was not common. The Maori windbreaks could have provided, during daylight hours, conditions not much inferior to those of a European glasshouse.

Aspect was the main element influencing the desirable micro-climatological conditions and may have been more important to the Maori than level land. An extensive area of flat land at the head of the terraces was examined for evidence of cultivation but no traces were found, which supported the contention that aspect was more attractive than slope was deterrent. On this coast, frosts were not hard or common while in addition, the natural slope provided good drainage for cold air. This would lessen the danger from an unusually early frost and the growing season would in consequence be long with little risk. With 40 in. to 45 in. of rainfall, well distributed throughout the year, and with considerable quantities of dew, there was adequate water available for the plants.

The natural vegetation also proved attractive. The broad-leafed ever-green trees and manuka scrub would soon be cleared from the site and their ashes would provide fertiliser. Adjacent to the terraces, the colder south-facing slopes were covered with vegetation. If these were also cleared, the first plant to reappear in the cycle would be the rapid-growing manuka, thus providing a permanent supply of the Maori's favourite fertiliser. The manuka-covered slopes may well have been essential for the permanent utilisation of the terraces and the relationship that was established between forest and field was as intimate as that still observed in parts of Upland Japan.

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The site had advantages for communications. If the flight which was surveyed belonged to Porirua Pa, as it does today, workers could easily and quickly have made their way on foot to the fields, a distance of only one and a half miles. From the fields, too, there was a commanding view of the sea approaches and the workers would have had some protection from a sea attack. The land approaches behind them were guarded by the village itself.

The site had additional advantages for transport. A steep but easily negotiated path led down to the sea and a straight rock-walled channel wide enough for a canoe, sliced through the wave-cut rock platform almost to a stony beach at the foot of the path. A natural landing and loading stage was provided. At harvest time, the baskets full of the heavy kumara would not have to be carried overland to the village but only down the steep path to the waiting canoes. There they would be loaded for transportation to the village on the inner harbour. Thus much of the hardest labour, so detested in similar areas in Japan today, would have been avoided. No storage pits have been found near the fields and they may not have been used. If we are prepared to give credence to the hypothesis that cultivation methods, soils and slopes were altered as cultivation of the kumaras was shifted south, we must also accept the possibility that storage methods were also changed. Storage pits which were satisfactory when dug in the light volcanics of the Auckland peninsula may have become water-logged and cold in the Wellington clays. Indeed storage at all times may have been more difficult than cultivation as it is in temperate lands today.

If ruas were not satisfactory, other substitutes were at hand. The small, well insulated, low-doored, easily closed houses, used for sleeping (whare-puni) would have been suitable. These have characteristics similar to the old storage places of North Carolina except that those buildings were based on the module of the pine log whilst the Maori sleeping rooms were based on the module of the raupo reed. Japanese methods could also have been used. There the storage places were still underground but the pits were made inside the earth-floored entrance rooms of the houses.

The Natural Environment

The natural slope of the land was in the order of 10°. The underlying rock was greywacke, a very fine hard sandstone possibly metamorphosed, overlain by a moderately leached yellow-brown weathered drift of grey-wacke. The soil which had developed was a moderately leached yellow-brown earth though some soil profiles show characteristics of the yellow-grey earths. The top three inches of the A horizon was a dark greyish-brown silt loam, a friable soil with a weakly developed fine granular structure encompassing some fine nutty structures. The mechanical analysis showed 36 percent to be sand 0.2 mm. to 0.02 mm. in size, 39 percent to be silt 0.02 mm. to 0.002 mm. in size and 25 percent to be clay less than 0.002 mm. in size. A second A horizon from three to nine inches in depth was a greyish brown silt loam, firm in texture with weakly developed fine nutty structures and a few fine yellowish-brown mottles. - 102 It was composed of 43 percent sand, 33 percent silt and 24 percent clay. The B horizon, nine to twenty-four inches, was a brownish-yellow clay loam, very firm in texture, with a medium prismatic structure breaking to a coarse blocky form. It had weakly developed coarse nutty structures and its mechanical analysis showed 30 percent sand, 29 percent silt and 41 percent clay. The lower B horizon, twenty-four to forty-eight inches, was a white and yellowish-brown mottled clay with 20 percent sand, 23 percent silt and 57 percent clay. The soil was naturally rich in phosphorus and potassium acid. The pH of the soil was 5.6 in the top three inches and 6.0 in the layer below, an ideal fertility and acidity for the sweet potato.

The Maori must have regretted the absence of underlying layers of gravel which he had used so effectively in the alluvial areas. Nevertheless, the soil had possibilities. It was less heavy in texture than the sticky clays so common in New Zealand but in its natural state it contained too much clay and silt for a good garden soil as it would tend to pack down and seal with cultivation. However, this was the best soil available and for the foregoing reasons, this site was selected for cultivation.

FIGURE 2
Soil profiles of section across terrace. Numbers and arrows indicate location of profiles described in text.
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FIGURE 3
Reeds on rear of terraces indicate presence of water.
The Developed Soil

Dr N. Taylor, former head of the New Zealand Soil Survey, made a survey of the soils on the terraces for the writer. When the initial survey was made with soil augur, the augur turned easily through the upper layers of the soil to a depth of about one foot. The layers had been modified by tillage and although they had not been worked for decades, the physical modifications were still apparent. The soil extracted by augur broke up easily, had a silty-sandy texture and had excellent water retention qualities, as it was damp and moist. Dr Taylor considered it a good garden soil and even though it had not been touched for many years it could have been dug over and planted to crops without any new or additional treatment.

It was not advisable to dig a section across the terraces as this would have concentrated the water flow and caused erosion. Fortunately a typical section across a terrace was discovered where part of a terrace near to the sea cliff had slumped away. The A horizon (see Figure 2) showed a distinct black colour when it was cut with a spade. Burnt vegetation had been incorporated into the soil and although this was generally fine, some small pieces of charcoal were dug out. Soil profiles are summarised as follows:

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TABLE 2
SOIL PROFILES OF SECTION ACROSS TERRACE

1. 0 ft mark

sA 2″ very dark grey-grey brown (10YR 3/1-3/2) turfy sandy silt loam; somewhat tough, many dead roots, soil between friable with weak fine crumb structure; many bleached grains. Boundary distinct.
A 7#x2033; very dark greyish brown (10YR 3/2) fine sandy silt loam, friable (slightly firm); very weak fine prismatic structure (to medium and fine nut in places with slightly darker coatings) breaking to fine crumb, pockets of cast granules, many fine grass roots; diffuse boundary. (The presence of fine granules throughout this horizon is evident from weathered face.)
B1 5″ dark greyish brown (2.5Y 4/2) light fine sandy loam with abundant medium worm mottles (10YR 3/2) and with few faint mottles slightly redder; friable (slightly firm); very weak fine prismatic structure breaking to medium blocky; some fine roots. Boundary distinct.
B2 On light yellowish brown 2.5Y 6/4 (wet 5/4) silty clay loam; horizon compact; peds firm; coarse blocky breaking to moderately developed medium and fine blocky structure, peds coated. (10YR 5/4).

2. 3 ft mark

sA 2″
A 6″
B1 4″

3. 8 ft mark

sA 2″
A 7″
B1 2″

4. 12 ft mark

sA 2″
A 7″
B1 5″

5. 19 ft mark

A 6″ brown-dark brown (10YR 4/3-3/3) fine sandy silt loam; very friable; strongly developed fine crumb structure with weak fine to medium pseudonuts and some cast granules; diffuse boundary.
?AB 2″ light olive brown (2.5Y 5/4) heavier sandy silt loam with many fine indistinct worm mottles; slightly firm to friable; moderately developed medium and fine blocky structure; roots few; boundary distinct.
B1 5″ dark greyish brown (2.5Y 4/2) light fine sandy loam with abundant medium worm mottles (10YR 3/2) and with few faint mottles slightly redder; friable (slightly firm); very weak fine prismatic structure breaking to medium blocky; some fine roots. Boundary distinct.
B2 On light yellowish brown 2.5Y 6/4 (wet 5/4) silty clay loam; horizon compact; peds firm; coarse blocky breaking to moderately developed medium and fine blocky structure, peds coated. (10YR 5/4.)

6. 26 ft mark

A 5″ Brown.
  5″ Grey.

Physical modifications of the soil had not been great. The gravel mulch developed on the alluvial lowlands was not used to any great extent although Dr Taylor noted in a weathered face the presence of fine gravels in the A horizon and numerous small weathered pebbles were taken from the soil samples. The gravel mulch may not have been necessary for if evidence from other countries such as China is accepted, the gravel mulch may have been a water retention device to keep the soil cool and prevent evaporation, not, as is commonly believed, a device to permit free drainage of the soil. 61 These terraces certainly did not require additional water retention devices as the fields were levelled and drainage was therefore checked. The reeds on the back portions parti- - 105 cularly indicated the presence of ample water and small cultivation mounds may have provided sufficient drainage.

During the construction of the fields, the Maori must have conscientiously spread as much of the A horizon over the new surface as possible in order to make the sand, present in the A horizon, available to the sweet potato. Some additional sand may have been laboriously carried up the hill from the beach but here there were not the large quantities used in other locations.

These soils had been modified organically by using plant ash as fertiliser. This carbon-darkened soil absorbed heat more quickly, so lengthening the growing season. In Japan the writer discovered that the farmers who grew sweet potatoes there considered that the tubers stored better if the plants were fertilised with wood ash. As storage was so difficult in temperate New Zealand this may have been a further reason for the Maoris using wood ash.

FIGURE 4
Broad view of terraces.
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The Terraces

On Whitireia Peninsula, soil modifications alone were not sufficient to ensure successful cultivation of the kumara. Major alterations had to be made to the terrain. The natural slope had to be completely modified and a flight of step-like terraces was constructed (Figure 4). There were particular factors pertaining to the slope of Whitireia Peninsula which made it attractive for cultivation and once chosen, additional pressures induced the Maori to drastically alter the terrain.

Sweet potato plants grow best in well-aerated mounds or ridges. The Maori constructed small mounds, not ridges, for his tools restricted his manipulation of the soil to this form. Ridges can be made with hoe or plough but not easily with digging sticks. The Maori's main implement was the ko, an oversized digging stick with a footrest, which could be used only for making holes. By levering the ko backwards in a hole, a small amount of soil could be lifted and by making three holes close together in a triangle a mound could be raised. Unlike the spade, the ko did not permit the individual Maori to turn a sod so any form of complete tillage was difficult. The implement was even less suitable for making ridges and furrows. The furrow is the product of the hoe or the hoe's offspring, the plough, and in this class of implement the Maori had developed only a short angled stick, the timo, which at best could only scratch the surface. Therefore the Maori could not cultivate the land in continuous rows and contour cultivation was not possible even if the concept had occurred to him.

Mounds were difficult to make on a slope and if so constructed would be inherently unstable. Instability would be increased by weeding and by the removal of the adventitious roots which naturally anchor the sweet potato canopy to the ground. Consequently the Maori would require level land on which to raise his mounds.

Soil erosion exerted an even greater pressure to create level land. Gully erosion is the product of moving water. If the slope permitted free flow and there were no infiltration, the force exerted by water moving down a slope is not the product of mass times velocity but mass times velocity squared. Thus, if either mass or velocity increases, the force rises rapidly. Long slopes provide large water collecting areas and permit great velocity to be reached. The force of moving water is consequently greatest at the foot of slopes and there the evidence of gully erosion may first be observed. The alteration of a long slope into a series of steps and short slopes by terracing decreased both mass and velocity and was therefore one of the most effective ways of preventing gully erosion. The Maori had been utilising volcanic ash soils in the north and under heavy rain these soils were notoriously prone to erosion. Slumps, scars and gullies must have been obvious on the youthful terrain. The Maori must not only have been aware of the danger of accelerated erosion but also have seen the cause and discovered the cure. His cure was the development of full terraces.

Terrace Construction

Three major types of terraces can be identified in different parts of the - 107 world. These are cut and fill terraces, walled terraces, and irrigated terraces. These three main types have numerous sub-types and hybrid forms developed for special purposes in different environments but only the first type is relevant here although the second type was used by the Maori in the neighbourhood.

Cut and Fill Terraces

On Whitireia Peninsula, cut and fill terraces were constructed. In an evolutionary sense they can be considered the most primitive. They are made by the moving of soil and its deposition lower down a slope. They may be accidental or deliberate creations.

The most simple kind is the lynchet terrace, developed when cultivation on a slope accelerates the movement of soil downhill until it is checked by a balk. The zone of soil accumulation is termed the positive lynchet and the zone of soil removal the negative lynchet. In Thailand, personal observation showed that even shifting cultivators sometimes moved trees across the slope to check soil movement and created this type of terrace. The reduction in grade may initially be only a few degrees less than the original slope but if this gives some advantage, cultivation can be continued and eventually the cultivated area will be completely levelled.

The cut and fill terraces on Whitireia Peninsula were deliberately created. The material was excavated from the inner margin of the terrace and deposited on the outer edge. It was a work of considerable magnitude as is shown in Figure 4.

It is suggested here that the construction of each flight of terraces was a single major effort of short duration by a whole tribal group. “In Maori communities, mutual help was a fundamental expression of blood kinship as well as human kindness . . . The general tasks requiring a number of people were accomplished by community co-operation without thought of pay.” 62 By one large effort, they could construct sufficient terraces in one season for a family. The large labour force might be available only in the winter but each year further terraces could be constructed. Once the terraces had been created, the level fields could easily be worked by a family group and this was the usual pattern as Buck has described. “There was community co-operation in labour where required, but there was individual ownership of the plots and the resulting crops.” 63 Thus a labour surplus used at one season could permanently lessen labour demands at another season. The terraces became a permanent capital asset which with an annual input of labour could continue indefinitely to give returns.

Group labour had many advantages. The ko as an individual implement was relatively ineffective but when used by a team was more efficient. Men would stand in a line across a slope, dig in their ko and heave back in unison and a sod would be broken out. This action would be repeated and as the scarp increased in depth a specialised ko with higher footrest would be used until the requisite bank had been created. Subsequent - 108 development of the terrace would be a levelling operation and the ko would be used for loosening earth but sticks, wooden scoops (koko), wooden picks (timo) and hands would scratch and scrape. Flax baskets would be used for carrying the spoil and the whole operation would be extremely labour intensive with men, women and children assisting.

Unified construction had other advantages for with all terraces being made at one time, the fill would not damage lower surfaces. If construction was piecemeal, with each terrace being made separately and work commencing at the lowest part of slope, on construction of the higher terraces at a later date, damage would result from spilled over debris. If they were constructed piecemeal from the top down, the creation of the next lowest terrace would undermine the toe of the spoil forming the outer face of the higher terrace and render that face unstable.

Terraces on Whitireia Peninsula were even and the slopes between them were of similar grade and regularity. It is therefore considered that the whole flight of terraces was constructed simultaneously. It was a major effort, for the largest terrace was over two hundred feet long and averaged more than twelve feet in width, and in this one flight forty-two terraces were mapped. But this construction feat was well within the capacity of a whole tribal group.

The magnitude of the effort expended precludes another possibility. These terraces were not constructed after Irish potatoes were introduced, since it would not then have been worth the effort to laboriously construct terraces for kumara cultivation. There were easier ways of obtaining food then available, not least the cultivation of temperate crops on the fertile alluvial lowlands.

Advantages and Disadvantages of Terraces

Cut and fill terraces were simple to construct and if vegetation were permitted to cover the banks, maintenance was easy. The terraces checked soil erosion almost completely and even with little or no maintenance, a very long existence was assured as the almost perfect terraces on the Whitireia Peninsula prove today.

Individual attention was necessary for each kumara plant and each plant was precious in the eyes of the cultivator. This was horticulture, not field crop farming. A levelled terrace enabled attention to be given much more easily to each plant. Special conditions had been created so that this favoured kumara plant could be cherished. Mounds would permit adequate drainage but the terraces checked run-off and the water would percolate into the soil. As they were in part cut into the slope, unweathered parent rock would be close to the surface and water would tend to remain on top of it, percolating only slowly into the ground. In a dry summer this water immediately beneath the cultivation mounds would make the difference between a good yield or a bad one.

There was some loss in the usable surface as the original slope had a greater area than the newly-levelled terraces. This loss would not have concerned the Maori, even if he were aware of it, for favourable sites on the Whitireia Peninsula were relatively plentiful. The small size of the - 109 individual terrace did not create difficulties to a people without draught animals or machines. Small size and close proximity may well have been advantageous as the walls of each pocket protected the terraces from the cold southerly wind.

Two Theories Applied to Maori Terraces

It has been claimed by some writers that terracing is an independent invention, a discovery made more than once by different people in different parts of the world. Others believe that terracing has been diffused, the technique having spread from a single place where it originated. Spencer and Hale consider that “the basic concepts of terracing owe their origins to a relatively few regional developments” 64 and from these few cultural hearths the techniques were spread to many parts of the world including New Zealand. In answer, Wright with experience in South America wrote: “Surely there can be little doubt that the concept of terracing has been of independent origin in different regions?” 65

It is now generally agreed that agriculture originated and developed separately in the New World and the Old World. Terracing occurred in both areas and must therefore have been invented at least twice. It is also difficult to conceive how knowledge of terracing techniques could persist through any period of non-utilisation. The diffusion theory is therefore not probable. More applicable to New Zealand is Wright's hypothesis that the technological advance arose through the stress of warfare when a part of the population “isolated on some high defensive position began by artificially steepening the slopes for defensive reasons and finished by using the narrow ledges so formed for the growing of essential crops.” 66 Terracing, unlike a plant species which must have genetic links to a single place of origin, is free to develop wherever the need arises. The need arose and the Maori independently created terraces.

If agricultural terraces were first made in this locality they would have had an effect on other parts of New Zealand. There are many terraces in the Wellington area, particularly along the south-west and east Wairarapa coasts but these have not yet been investigated and at this stage it is not possible to suggest where terracing was first developed. Further developments in this area may have been checked by new cultural influences. Europeans arrived bringing with them not only new techniques but, more importantly, new staple crops such as wheat and Irish potatoes which were better suited to temperate New Zealand than the tropical crop, sweet potato, and terraces were not required for their cultivation. This new cultivation was carried out on alluvial land close to village and pa and cultivation on the terraces may then have been quickly abandoned.

CONCLUSION

The cultural and physical elements present on Whitireia Peninsula were different from anywhere else on earth but despite this, there were some elements namely slope, vegetation cover, climate and tilled surface, com- - 110 monly duplicated in other places. Unmodified, the slopes could not long be cultivated for it is universally true that this leads to destruction by accelerated soil erosion. Cultivation and complete vegetation cover were incompatible. Climate is beyond man's control even today and climatically the only place in this area suitable for cultivation of the kumara were north-facing slopes. Unmodified, the slopes could not be used and the only possible change was to the angle of slope. Maori technology imposed limitations, the solution to which was the permanent levelling of the land by the creation of cut and fill terraces. With this development the Maori had achieved all the advantages of the plain yet retained all the benefits of a sunny hillside. The requirements of the kumara were paramount but its needs were satisfied on the terraced slopes of Whitireia Peninsula.

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1   Buck 1950:86.
2   Shawcross 1967:330-352.
3   Lewthwaite 1966:17.
4   Yen 1963:95.
5   Personal communication of a paper presented at a Symposium at Sante Fe.
6   Gray and Trumball 1883:247-248.
7   Merrill 1954:220.
8   Turei 1912:153-161.
9   Handy 1940:145.
10   Yen 1961:343.
11   Colenso 1880:10.
12   Walsh 1902:13.
13   Colenso 1880:34.
14   Towle 1961:78.
15   Yen 1963:110.
16   Sauer 1963:510.
17   Berridge 1913:415.
18   Walsh 1902:13.
19   Personal communication, Pope 1967.
20   Tapsell 1947:329.
21   Yen 1963:32-33.
22   Miller, Stout, Lee 1955:299 and 312.
23   Walsh 1902:14.
24   Colenso 1880:21.
25   Best 1924:366.
26   Best 1924:366
27   Colenso 1880:9.
28   Handy 1940:146.
29   Howlett 1967:62.
30   Walsh 1902:16.
31   Tapsell 1947:329.
32   Walsh 1902:18.
33   Tapsell 1947:328.
34   Walsh 1902:17.
35   Walsh 1902:19.
36   Best 1924:376.
37   Nicholas 1817:252.
38   Colenso 1880:23.
39   Best 1924:374.
40   Lutz 1958:2.
41   Berridge 1913:417.
42   Barton 1927:299.
43   Taylor 1958:73.
44   Rigg and Bruce 1923:88-90.
45   Journal of the Polynesian Society 1923:93
46   Bishop 1924:317-320.
47   Taylor 1958:78.
48   Colenso 1880:8.
49   Best 1924:356-374.
50   Rigg and Bruce 1923:92.
51   Taylor 1958:77.
52   Covington 1959:12.
53   Best 1924:356.
54   Wakefield 1906:225-226.
55   Ongley 1931:282.
56   Ongley 1931:282.
57   Colenso 1880:11.
58   Brees 1847:30.
59   Ongley 1931:282.
60   Walsh 1902:19.
61   Rigg and Bruce 1923:85.
62   Buck 1950:375.
63   Buck 1950:376.
64   Spencer and Hale 1961:31 and Fig. 5.
65   Wright 1962:100.
66   Wright 1962:100.