SUBTERRANEAN CLOVER AS A FERTILITY BUILDER

New Zealand Journal of Agriculture, Volume 78, Issue 5, 16 May 1949, Page 489

SUBTERRANEAN CLOVER AS A FERTILITY BUILDER

Use on Steward Settlement, North Otago

By

A. J. COUGHLAN,

Fields Instructor, Department of Agriculture,

Oamaru.

SOIL fertility and carrying capacity have been increased during recent years over much of the lighter and higher elevated areas of the Steward Settlement on the south bank of the Waitaki River and extending from the mouth to the vicinity of Aitchesons railway station. The soil is of the stony silt loam type overlying the old bed of the Waitaki River, which forms the northern boundary between North Otago and South Canterbury. As the average rainfall is in the vicinity of 20in. per annum, and is not well distributed, the area is subject to long dry spells in summer. This area would appear to be about the southern limit of successful general use of subterranean clover on account of excessive ground frosts and short growing period.

THE Steward Settlement, of approximately 23,000 acres, was formerly known as the Waitaki Plains Estate. It was surveyed and opened for selection in 1906. The contour is uneven and broken by old river terraces and the soil is very thin in places. The original cover of shrub and silver tussock and fescue tussock provided sparse herbage for grazing animals. Before its subdivision the country provided wool and store sheep, but as time went on the grazing policy was modified by the introduction of forage crops for sheep. The main crops grown were turnips and rape, with oats for chaff and grain. Basis of Nitrogen Supply Under closer settlement the policy of farm management is to secure higher-

producing pastures, which necessitates building up the fertility of the soil to allow the higher-fertility-demanding grasses and clovers to subsist. The surest and most economical method to secure this is through the employment of the subterranean clover plant as the basis of nitrogen supply. Clovers are essential in good grazing pastures, supplying nitrogen to the grasses, increasing the mineral content of the herbage, and building up the organic content of the soil; fertility is thereby improved, and subterranean clover is outstanding in this respect. It has the capacity to grow well on light soil and builds up fertility to such an extent that in a relatively short time ryegrass and other high-producing pasture plants will thrive where previously they would not persist.

Introduction on Settlement

Subterranean clover was introduced on the settlement in 1931 by Mr. F. R. Saunders, who originally came from Australia and had seen the plant growing on similar country there. He x included Jib. of this clover in a mixture he used to lay down a 32-acre pasture. The seed established well, but owing to the very light seeding it took a long time to thicken up.' However, he was encouraged by the result and increased the area sown year by year. Mr. Saunders found by his own experience, together with experience gained through co-operative field trials laid down on his property by the Department of Agriculture, that by increasing the seeding rate from Jib. to 5 to 61b. per acre and at the same time applying carbonate of lime and superphosphate, at the rate of 1 ton and lewt. respectively per acre, a rapid establishment was secured and the carrying capacity very much increased. Neighbouring farmers became interested and observed the results closely. Experimental trials embodying the Mt. Barker, Tallarook, Dwalganup, and Marlborough strains were laid down on the settlement by the Department of Agriculture in 1937 and were under experimental observation until 1941. It was found that all strains established well in the early stages of the trial. Mt. Barker gave the earliest feed, while the Tallarook strain, which is 2 to 3 weeks later, provided much more feed in late spring and was superior to the Marlborough and Dwalganup strains. The Dwalganup strain did not show good results and its use is not recommended on this type of country. All strains showed a marked response to applications of superphosphate and lime.

' However, it is only in the last 4 to 5 years that the real value of subterranean clover has become apparent to the .general 1 farming community, and it is now becoming general practice to include 31b. of subterranean clover in the pasture mixture or to establish 1 a subterranean clover pasture by drilling in about 5 to 61b. of seed with the turnip crop sown in December. . •

With subterranean clover established and fertility built up, perennial ryegrass, cocksfoot, crested dogstail, and Montgomery red clover and white clover are able to

persist, and consequently areas which previously carried only i to 1 sheep per acre are now able to carry 2 to 3 sheep per acre.

Characteristics of Plant

Subterranean clover (Trifolium subterraneum) is a low-growing annual producing a dense growth from the crown. In the spring it develops long runners, which spread over the surface of the ground. Flower heads are produced at intervals along the runners, and when ripe they turn down, burying the seeds in the ground. It is from this characteristic that the plant derives its name. Each flower head possesses three or four florets, each of which produces a single seed. When the seed has ripened in December to early January the plant dies off, leaving no green feed for the dry part of the autumn.

The green herbage is palatable and nutritious and cattle and sheep thrive on it, though it is advisable to provide some dry feed to balance this protein-rich clover when it is in a succulent state. In its dried-off state it forms a natural hay which has considerable feeding value and dry stock do well on it during summer and autumn.

Special Care in First Year

As the plant is an annual, it is dependent on reseeding for its existence. Special grazing management is required in the first year to allow it to reseed, and stock should not be allowed to graze on it during the flowering stage. After its first year of establishment this precaution is not necessary.

If seed is sown in December with the turnip crop, as is the general practice on the settlement, the plant establishes itself well and makes good growth without flowering; it provides feed right through the winter and comes away with a great burst of growth in the spring, to set seed in midsummer.

If seed is sown in the spring, the plant flowers in the following autumn and often dies before the seed is mature.

Fitting in with Farm Practice

Subterranean clover provides little feed in the form of green herbage from December till the seeds germinate after autumn rains supply sufficient moisture. In a mild autumn , with sufficient rains the young plants establish well and supply feed right through the winter and provide a rush of growth in the spring, but when a dry autumn is experienced the young plants fail to get a good hold before

frosts occur and consequently suffer damage from frost lift. A week of heavy frosts may destroy a large number of plants, and consequently the clover will provide little or no feed till the end of August or September.

Where there has been surplus growth during spring and summer the dried-off herbage will be available for sheep, whose feed demands are not great at this time. It may, however, still be necessary to grow forage crops such as rape, turnips, greenfeed oats, barley, or Italian or short-rotation ryegrass to cater for this period.

A stand of lucerne fits in well with subterranean clover, as it provides grazing in summer in addition to hay for winter. New Zealand Green Globe turnips sown in December with subterranean clover provide : for late winter until the main subterranean pasture is sufficiently well advanced to provide grazing for stock. A mixture of cocksfoot and Montgomery red clover and. white clover supplies feed when the subterranean clover goes off; These paddocks should be lightly grazed in spring and early summer, when the subterranean clover is being grazed, and this spell enables these pastures to be reserved for midsummer use.

Methods of Establishment

The method'Usually adopted in the establishment of a subterranean clover pasture is to sow down with the turnip crop in December. The subterranean clover seed is mixed with superphosphate or reverted superphosphate at the rate of 51b. to 61b. per acre. Because of the possibility of injury to seed, reverted superphosphate is recommended. Sowing with turnips in December has proved very satisfactory, because the clover then shows no tendency to flower and die as is the case if sown in the spring. The trampling incidental to feeding off of the turnips tends to prevent frost lift.

Farmers have found that the best establishments are obtained by shallow drilling of the seed with lcwt. of superphosphate or reverted superphosphate per acre. This is well accomplished when the seed is sown with the turnip crop, but if sown with greenfeed oats or barley, which also has proved successful, it is a good plan to drill the oats, harrow and roll, and then cross-drill the ' subterranean clover, taking special care to avoid burying the seed too deep. Usually half the superphosphate may be sown with the oats and the other half with the subterranean clover seed. Superphosphate does not appear to harm the germination of the subterranean clover seed. In all cases it is advisable to topdress with 1 ton per acre of carbonate of lime before sowing.

The feeding off of the crop tends to give the young clover plants a good firm hold. The area must remain ungrazed or very lightly stocked during November and December to allow setting of the seed. Restraint in grazing is not necessary in subsequent years, as there will always be a reserve of “hard” seed in the ground, and there will' also be some seed setting even under normal grazing.

Subterranean clover may be sown under a cereal crop for grain, provided this is done not later than March. Later sowings may result, in frost lift of the clover. During the maturing and ripening of the cereal crop the clover plants are free to develop and set a considerable quantity of seed. It is also possible to establish subterranean clover by surface introduction by surface working the ground with the one-way discs or by grubbing and drilling the seed in with superphosphate and lime or ' reverted superphosphate not later than March to allow the young plants to get a good root hold before winter frosts occur. . Broadcasting of the seed is satisfactory on a well-prepared seed-bed under ideal conditions, provided the land has received an initial dressing of lime and superphosphate, but drilling usually gives more reliable results and after the first year’s seeding the spaces between the drills are filled in. Subterranean clover in pasture mixtures is most successfully established in early autumn on land which has had. a summer fallow after a greenfeed crop. The soil is then in good heart, and the clover plant may obtain a good root hold before winter; the plants then get away well as soon as the ground warms up in spring.

Superphosphate and Lime Essential

To maintain subterranean pasture on the light land of the settlement it is most essential to apply both lime and superphosphate together. The response to superphosphate alone is often disappointing and there is clear evidence that for good results the two should be used in conjunction. One ton of carbonate of lime and lcwt. of superphosphate should be the initial application, and after this lOcwt. of lime and lcwt. of superphosphate in alternate years will maintain the pasture.

Water Supply

This country has always been at. a very great disadvantage through Raving no natural water supply. The present supply is taken from the Waitaki River, the intake to the race being situated near Black Point. The race is controlled by the Waitaki County Council and was designed to supply domestic and stock needs and the Waitaki Farmers’ freezing works at Pukeuri.

If irrigation were properly established on the Steward Settlement, there would not be the same need for the use of subterranean clover as- a soil builder. Irrigation would place the farmer in the position of being able to sow down his pastures with the better strains of grasses and clovers and enable him to increase the carrying capacity and maintain a high standard of soil fertility. Under the present dry-farming conditions subterranean clover is the most valuable pasture species and its. use should be extended.

I SUBTERRANEAN CLOVER 1 ON STEWARD SETTLEMENT

The surest and most economical method of securing higher-pro-ducing pastures on the stony silt loam under conditions of low annual rainfall unevenly distributed is by using subterranean clover as the basis of nitrogen supply to build up fertility.. It is now general to include 31b. of subterranean clover in the pasture mixture or to drill 5 to 61b. of seed with turnips sown in December. With subterranean clover established, high-fertility - demanding grasses are able to persist, and areas which previously carried only 4 to 1 sheep per acre now carry 2 to 3.

I ' COLOUR AND VARIETY IN THE MIXED FLOWER BORDER LiiaMaMiiaaKMMaaißaHnMvinMMrtttnaaßnMHHnHmNMaiiaMMnKaMHannMiMMMMMMnnaßaManMMMitMMKWl

The yellow and purple markings of Lilium auralutn make vivid splashes in the , border, and a cascade of unusual colour can be achieved in late spring with the salmon-pink flowers of alpine phlox. The flowers of Viburnum carlesii are very fragrant and the pink manuka makes a fine show in October. Bougainvillea is an attractive climber to cover a fence or wall, but is not hardy everywhere.