Cultivating, Oversowing, and Topdressing Hill-country Pastures of Northern Raglan

New Zealand Journal of Agriculture, Volume 87, Issue 3, 15 September 1953, Page 240

Cultivating, Oversowing, and Topdressing Hill-country Pastures of Northern Raglan

By

J. E. BELL,

Fields Superintendent, Department of Agriculture. Auckland, and

H. McM. BULL, Instructor in Agriculture, Department of Agriculture, Hamilton THE hills of the northern portion of Raglan County are typical of several million acres of the better class hill country throughout the North Island that have been grassed after bush. Varying in contour from rolling to steep and with soils derived from limestone, sedimentary rocks, and volcanic showers they have confronted the farmer with many diverse problems of control.

FARMERS on the limestone coastal belt —Te Akau, Waimai, Waikaretu, running north to the Waikato Heads —were able to maintain fair production in spite of price fluctuations and lack of fertilisers. Its natural fertility held on through good or adverse years limited only by a drying out tendency in summer and a lack of

permanent water in some areas. In contrast the clay areas derived from sedimentary rocks further inland by reason of steep broken hills and valleys and a strong tendency to revert to fern and second growth proved both difficult and expensive to handle. Indeed, if aerial topdressing had not eventuated, large areas of this country

would have reverted to fern with a consequent loss of production of wool and meat. Ploughable Land 1 The improvement of hill country involves the introduction of better kinds of grasses and clovers and the raising of fertility by topdressing and liming so that these grasses and clovers will establish and grow. The pasture of the poor hills comprises much browntop, danthonia, sweet vernal, and inferior clovers, and these. need to be replaced by better grasses and clovers. Much of the land is ploughable and the most speedy and most certain method of improvement is to plough or giant disc such areas in early winter to allow weathering, and then to grow a crop of chou moellier, kale, or swedes preparatory to grassing. On rush-infested limestone areas two successive crops' are often taken to ensure a more effective smother of the natural regrowth. Such winter-fed crops are extremely useful. They enable the pasture to be spelled in May and June so that there is a long enough growth for the cattle to do well in late winter. A mixed crop' can be grown, about Jib. of chou moellier and fib. of swedes per acre with 3cwt. of serpentine superphosphate and up to 1 ton of lime being sown. Chou moellier will stand many diseases that may destroy the swede crop and is a

Hill-country Pastures of Northern Raglan

safeguard, particularly after crops of the turnip family. However, to do well chou moellier requires liberal dressings of both lime and phosphates. Therefore on areas not previously cropped, particularly, in the raw initial , breaking-in stages, swedes are better. The seed is better drilled, although it may be sown broadcast immediately after mixing with the fertiliser. After the crop is eaten off, the area can be reploughed or disced, limed at J ton per acre, and prepared for another crop. Soft turnips at lib. or rape with 2|lb. of seed and 3cwt. of serpentine superphosphate are popular. Rape, provided it ripens properly, will prove useful in topping off , stores and ,in flushing ewes before tupping. After the crop is removed, the area can be lightly disced, well harrowed, and sown to pasture. Consolidation is vital and when use of a roller is not practical sheep should be herded on to the area before sowing. On very light fluffy soils or ridges liable to blow or scour excellent results have been achieved from broadcasting seed in the remnants of a cron, thus allowing the stock to trample it in when cleaning up a paddock. The following seed mixture should be sown in March: lb. Certified perennial ryegrass ... ... .. 25 Certified white clover . . 2 Certified red clover .. 3 Certified cocksfoot . . 4 Paspalum .. .. .. 4 Crested dogstail . . 3 Mixed Mt. Barker and ‘ Tallarook subterranean clover . . .. ' . . 3 441 b. per acre

The heavier soils should be limed at 1 ton per acre before sowing and phosphate applied at 3cwt. per acre on both light and heavy soils. The area should be moderately grazed with sheep throughout winter and given an- ‘ other dressing of 3cwt. of phosphate in early spring. After that annual dressings of phosphate at 3cwt. per acre plus lime every 2 years at lOcwt. or every 4 years at . 1 ton, particularly on the heavier soils, will be required. Land Not Ploughable Lana ,NOT riougnaoie On non-ploughable areas or those which will not be ploughed for some time careful examination should be

made of the pasture to see what species are present and what require introduction. White clover is the most important and should be introduced if it is not' present. Lotus major should be introduced in wet areas and very shady faces that are neglected by stock, and subterranean clover should be introduced on dry sunny faces if not already present. The introduction of clover by surface sowing is fairly uncertain and the introduction of grasses is more difficult still. . ' Subtelre?n .3 clover i.-x more easily established than white clover or Lotus major. However, an attempt should be made to introduce clovers not present and if none of the three

species is there, one at least must be introduced if the pastures are to be improved by topdressing and liming, This improvement is best carried out by concentrating on one field at a time, and if operations are begun on one field each year, slow but fairly certain progress can be made. From trials carried out in Raglan and Kawhia Counties it would appear that the strike of clovers is more certain after dry summers. The pasture is then well eaten down and the seed reaches the soil and is not caught in the foliage. The close mat formed by browntop is particularly difficult to penetrate; therefore the pasture on which the clover is to be established should be well eaten out that summer by concentrating on it cattle and then sheep. The seed is more certain to establish if sown when autumn rains

have set in, usually by late March, Sometimes a dry period may follow the sowing and strike of the seed, but this risk is better than delaying sowing until the winter months. The strike may be materially assisted by running sheep in the area to tramp the seed in. Certified white clover seed should be used at 21b. per acre, a mixture of Tallarook and Mt. Barker subterranean clover at 31b., and Lotus major at lib. On areas liable to continuous close grazing Tallarook subterranean clover has proved superior to Mt. Barker probably because it comes into flower some weeks later, when there is more feed about. Under the same conditions Kentish white clover has proven much superior to Certified white clover because it has lower fertility requirements and because its

prostrate nature assists it to survive hard grazing. The object should be, however, not to treat the pasture in this manner. Sheep are particularly hard on young seedlings either pulling them on or chewing’ them off below the crowns. Therefore the block should be spelled or very lightly grazed in April, May, and June, when the young seedlings are coming through and again in November-December, when they are reseeding. Complete control with cattle for 12 months would be ideal. Although the November-Decem-ber spelling coincides with a strong growth of fern, the value derived from a prolific growth of young .seedlings more than compensates for the temporary roughage which can be controlled with cattle the following winter.

Before a programme of oversowing on the harder hill country is embarked on some understanding of the fertility requirements of the various clovers is essential. White clover should not be sown until the fertility level is built up. On heavy soils liming is essential to obtain results from serpentine superphosphate or other superphosphate combinations. On light soils though application of lime is advisable, serpentine superphosphate or other superphosphate compounds will give worthwhile results without lime.. The blower is about the only means of applying lime and it can also be used to sow North African phosphate and basic slag. The blower does not spread the fertiliser or lime evenly, but by using all points of vantage and favourable wind currents, it will get the material on and give some kind of cover. Serpentine superphosphate can be sown satisfactorily by air and the seed can be mixed with this fertiliser just before sowing. At least 3cwt. of phosphate should be applied per acre with the seed. The following autumn it should receive another dressing of fertiliser and if the seed strike has not been satisfactory, another sowing of seed. Subsequent dressings of fertiliser and lime can be made according to finance available, but at least 2c wt. of phosphate every year or 4cwt. every 2 years should be applied, 2cwt. every year being - preferable. Lime should be applied up to an optimum of about 1 ton every 4 years on the heavier soils. The value of molybdenum in this country is now under investigation and its use may ultimately assist in bringing in certain areas more rapidly and with smaller dressings of lime than at present appear necessary. Farmers are, however, advised to consult the local Instructor in Agriculture before applying molybdenum on all but small trial areas. Rates of application should in no case exceed 2|oz. of sodium molybdate per acre. If one block at a time is concentrated on. the established clovers are well fed and thrive ' and in time. the better grasses, ryegrass and crested

dogstail, will come in on their own. Obviously on very steep areas the building up process will take longer, as the surface is cut up by sheep Hacks to form a succession of steps. The grazing animal forages on the upright faces and the dung, and urine are dropped on the steps or stock tracks, On these upright faces moss and danthonia persist through free drainage

and the non-return of nutrients from the animal. However, even these difficu areas will succumb in time to per management' Cocksfoot will j ncrease jf the grazing is lax enough; .. . . und * continuous cattle that is, If under continuous cattle grazing, it these pastures are as well treated as lowland : pastures and clovers are present, there should be

nothing to stop hill country of this district eventually carrying 3 sheep and cattle to the acre. Once the clovers establish in the first year the block can be grazed more severely, but improvements will not be readily attained unless the pasture is permitted to grow and is not constantly subjected to hard grazing. Secondary Burns Areas of second growth, manuka, and other scrub can be cut and burnt and seed sown on the burn. If the scrub is heavy, it can be cut about November ready for burning and sowing in autumn. Light scrub is better left for cutting until later and about 6 weeks before burning. If the scrub is cut too soon, it will lose its leaves, a clean burn will not be obtained, and there will be less ash for the seed-bed. Generally, areas of light scrub which will dry out easily are better fired as late as possible to catch the autumn rains. The burn will not be subjected to the baking effects of the sun and the tender seedlings will have more chance to survive. The burnt area should be limed and topdressed as for oversowing to enable the grass sward to thicken up and cover the ground to prevent manuka and other weeds re-establishing. The pasture mixture would be approximately as follows, although more seed could be sown with advantage:— lb. Certified perennial ryegrass ... 8 Crested dogstail .. . . '. . 3 Cocksfoot (on good burns) . . 4 Browntop (where fertility ;is not high) .. ...... 3 Danthonia pilosa (where not present) .. .. .. ' .. 2 Certified white clover .. .. 2 Mt. Barker and Tallarook . subterranean clover .. .. .. 3 Lotus major . . . . .... I

Cocksfoot is possibly better omitted when the ash is sparse. If the area is to be well treated, browntop and danthonia may be omitted and the ryegrass increased. Danthonia may also be omitted if it is already present and the fire has not been intense. As in all sowings the purity and germination, of the seed should be ascertained and allowances made for poor germination and low purity., The new burn should be treated as a new pasture and not grazed hard in the following winter. Often only patches of fields are burnt and sown and sheep congregate on these patches, eating the newly sown pasture close to the ground, thus not giving it a chance. Fields containing new burns, however small, should be grazed with cattle for the first 12 months and the whole of the remainder of the area should be oversown where needed and well topdressed to encourage stock to graze the block more evenly. If the strike, is poor, the area should be permitted to seed in the following summer to thicken the sward. In . a burn two bad errors must be avoided. Standing scrub which intensifies the growth of seedlings should not be fired nor should fern be set off in winter or spring. Regrowth in late spring will be almost uncontrollable, it will smother all growth underneath it, and will have no “body” to carry , a fire for a year or two to come. General Improvement Though it is desirable to concentrate on small areas at a time, the over-all management of a farm should not be sacrificed. Old fences must be kept in good repair if blocks are to be handled successfully, new . subdivisions must be erected to keep pace with pasture improvement, and oversowing where needed, and topdressing must be done.. All these general

improvements must not be allowed to lapse in favour of a too intensive programme of development in one particular area. When the area is being chosen land should be selected which will give the quickest return for the money expended. If it is ploughable, an obvious choice is the easiest and most compact area that can be found. If it is not ploughable, an area with the most promising pasture carrying the least fern and scrub and with a warm sunny aspect should be chosen. Some of the soils in this district are so acid that they will not respond well to serpentine superphosphate and are therefore slow to improve with aerial topdressing. On these soils basic slag and North African phosphate are worth consideration if the financial position permits, particularly should liming not be feasible. ■ There are, however, areas of soil which are usually brown and of a lighter texture and these usually do not need so much lime. Here, fair results can be secured with serpentine superphosphate, even though better results may be obtained from basic slag, North African phosphate, or serpentine superphosphate and lime. Before money is spent on aerial topdressing farmers should put down small trials here and there, in which possible alternatives to serpentine superphosphate are tried. Thus they could try out 4cwt. of serpentine superphosphate versus 2|cwt. of basic slag or North African phosphate or 2cwt. of serpentine superphosphate and Bcwt. of lime, or at comparable rates at which these materials can be bought, carted, and applied by aeroplane or blower. In studying the results it is well to keep in mind the better distribution and ease of application by air. However, it is not worth distributing by. air materials which will not result in a worthwhile improvement of the sward.