Recent Research Work

New Zealand Journal of Agriculture, Volume 87, Issue 1, 15 July 1953, Page 73

Recent Research Work

HILL-COUNTRY PASTURES

The . improvement of grazing pastures of hill country , in higherrainfall districts depends primarily on the pasture species present, particularly the clovers, the soil fertility, and the management of the sward. Soil-fertility investigations in hill country have received new importance with the rapid increase in aerial topdressing and consequently the means whereby the findings of fertiliser investigations can be translated into farming practice. The large numbers of trials of this type on hill country are giving results of more direct application than was at first thought possible.

TUSSOCK COUNTRY

WORK has been continued over the last year in the tussock and depleted country of the South Island, and approximately 20 trials are in progress. It has been found that legumes can

often be established, particularly if the fertility is raised by topdressing, on all but the most arid and depleted country. Legumes appear to establish best in the shelter of tussock, with the aid of spelling and topdressing with superphosphate, but, if necessary, they can often be introduced without spelling. The most productive legumes are lucerne, alsike, and broad red clover, and, when fertility has been increased, white clover. Subterranean clover is also useful, the Tallarook variety being better than Mt. Barker. Several trials have investigated the possibilities of using zig-zag clover, but the usefulness of this species has not yet been determined. The grasses which are most successful in these conditions are cocksfoot and tall oat grass, but tall fescue, sweet vernal, Phalaris tuberosa, and crested dogstail are quite promising. Of the native grasses blue wheat grass and plume grass are very good. All grasses seem to establish best in the open. Of other species yarrow and sheep’s burnet are valuable. The establishment of both grasses and legumes is aided by topdressing and protection from rabbits. Several seed-production trials were laid down last year to obtain bulk supplies of seed for tussock grassland investigations, and grazing and palatability trials are also being carried out.

LEGUMES

The introduction of legumes with phosphate is the first step to improvement on many cloverdeficient swards and subterranean clover is

apparently the most suitable clover for this initial stage, more especially on soils subject to drying out in summer. Tallarook subterranean clover has been . found in most cases to be more persistent than Mt. Barker. A possible explanation lies in the fact that the Tallarook strain, being later to . come into full leaf production than Mt. Barker, is not so severely defoliated by grazing, as there is usually more alternative feed available at that time. It is also more prostrate in growth habit and this. gives some protection from over-grazing. On the moister, more fertile soils white clover is the more productive plant, though subterranean clover is often better in the initial stages of fertility building, as its fertility, requirements appear to be lower than those of white clover. In highrainfall districts or on shady slopes Lotus major is a most valuable legume. Red clover, especially Montgomery red clover, has been successfully introduced in a number of trials. It seems to do better on shady slopes, but is often not as persistent as the other legumes mentioned.. Trial results indicate that in most districts better establishment of Montgomery red clover and subterranean clover is

Heading photograph by National Publicity Studios.

obtained by autumn sowing, though a better initial strike may be secured in spring. In all cases, especially with subterranean clover, the summer grazing management in the first year after sowing must be sufficiently lax to allow reseeding.

SEED-BED

Comparisons of different types of seed-bed preparation indicate that although establishment is better with surface cultivation, it is quite

possible to obtain good clover swards without the aid of cultivation. The best type of sward on which to oversow appears to differ in different localities. On soils subject to severe drying out or wind erosion some surface litter is almost essential, but on the other hand establishment is usually poor on close turfs where it is difficult for the sown seed to reach the soil surface and where young germinating seedlings are subject to severe competition from established plants. The number of failures from trial oversowings is a disturbing feature. Some of these can, perhaps, be attributed to stock concentration on the trial area to the detriment of establishing plants, but there is definite evidence that much mortality of young seedlings is caused by birds, various insects, and slugs.

PELLETING CLOVER SEED

Over the past 4 years a large number of field trials has been laid down in various districts to investigate the effect of pelleting clover seed with fertiliser and other substances.

Pelleting aims primarily at benefiting the seedling or established plant by placing fertiliser in the immediate vicinity of the seed at the time of sowing, in which position it should do the most good. It seems reasonable to hope that if the fertiliser is so placed, a smaller quantity would give a result similar to a broadcast application at the usual rate. However, the results of most of the trials show that use of the types of pellets developed to date does not show any advantage over the broadcasting of seed and fertiliser at the usual rates.

—F. H. THORNTON and S. MACLEAN * ❖ *. * ■

FERTILISERS

THE rate at which superphosphate should be applied to improve hill country which has received little or no phosphatic topdressing

is also being studied. A few trials of this type have been recently laid down in the South Island to study rates of application of double superphosphate applied by aeroplane. In the North Island superphosphate or serpentine superphosphate at 3 to 4cwt. per acre has proved superior to lighter rates of application. In most cases good lime responses have also been obtained and a new series of trials incorporates comparisons of rates of lime as well as kinds of phosphates. Many trace element trials are giving particularly important results on hill country, much of which is responding to a few ounces of molybdenum per acre (a practical and economic dressing in association with phosphatic fertiliser) on land which it was previously thought needed heavy lime dressings which were quite impracticable to apply. It is important to stress, however, that the basic need for practically all hill country is phosphatic fertiliser, and molybdenum is no substitute for phosphates.

P. B. LYNCH