Recent Research Work

New Zealand Journal of Agriculture, Volume 94, Issue 6, 15 June 1957, Page 551

Recent Research Work

SULPHUR

THIRTEEN pasture topdressing trials in which sulphur has been ■ included have been conducted in the Hororata-Rakaia Gorge area during 1955 and 1956. These trials have covered five main soil types, Kakahu, Kowhai, Ruapuna, Mayfield, and Lismore. The trials were laid down mainly on native tussock which had received little or no treatment with superphosphate and lime.

LOCATION OF TRIALS

THE trial areas are situated 50 to 60 miles

from the coast. Altitudes range from 800 ft. to 1600 ft. with the Lismore and Mayfield types

at the lower altitude, Ruapuna intermediate, and Kowhai and Kakahu at the higher altitude. Rainfall varies from about 28in. per annum on the Lismore soil type to about 32in. on the Mayfield, rising to 40in. on the Kakahu soil type.

KAKAHU SOILS

Excellent responses have been received from the applications of sulphur and molybdenum on the Kakahu soil. Phosphate alone (in the form of double superphosphate) gave no response even though the phosphate soil test was low, but when it was applied with sulphur the response was better than to sulphur alone. Indications are that this series will respond well to lime. Elemental sulphur gave a fairly quick response in trials on this soil type, whereas on some other soils the response has been very slow, in some cases up to 2 years before reaching a maximum.

KOWHAI SOILS

Soils of the Kowhai series are of more recent

origin than the Kakahu series and consist mainly of terrace country adjacent to and overlooking

the Rakaia River. The rainfall is slightly lower than on the Kakahu series. They are less acid than the Kakahu soils and usually have a high phosphate soil test. Trials on these Kowhai soils indicate that they are particularly sulphur responsive, but only slightly responsive to lime. Good molybdenum responses have also been obtained on most of the trials. The three trials on this soil type which have been down longest all show that excellent clover establishment can be obtained by oversowing and topdressing with superphosphate plus molybdenum. On two of the trials gypsum gave excellent results, especially when applied with molybdenum, whereas elemental sulphur was slow acting by comparison.

RUAPUNA SOILS

Of the four trials on the Ruapuna soils, three have produced excellent responses to sulphur (two to elemental sulphur and one to superphosphate), while the other has not been down

long enough to produce results. One of these trials on lucerne and cocksfoot did not indicate a response to elemental sulphur until after the first year.

MAYFIELD SOILS

On trials laid down on the Mayfield soils

excellent responses were obtained from superphosphate plus molybdenum, superphosphate

plus lime, and superphosphate alone, the response to superphosphate plus molybdenum being equal to that of superphosphate plus lime. Gypsum plus molybdenum has responded well, but elemental sulphur has been much slower acting. An interesting feature on one trial is that when applied with both lime and superphosphate, molybdenum appears to have a depressing effect. A slight depressing effect also occurred where molybdenum was applied without sulphur and phosphate.

LISMORE SOILS

The trials on the Lismore series seem to show

that best results will be obtained from the application of lime plus sulphur plus phosphorus; in other words superphosphate plus lime.

Molybdenum should be used with caution and not without advice from the Department of Agriculture.

OVERSOWING CLOVERS

All the trials on the tussock country of

the Kakahu, Kowhai, and Mayfield series were oversown with red clover, white

clover, and alsike, all of which established

and grew well in spite of an abnormally dry season. Best results were obtained from oversowing and topdressing in late winter, one of the best trials being laid down on snow in late July. So far no clover inoculation problems have been encountered, as clovers have established readily without being inoculated.

FURTHER t TRIALS 1

Excellent responses have been obtained so far,

but further investigation is necessary, particularly with regard to rates of application of

sulphur, phosphorus, and lime.

Trials have also been extended to include the tussock covered Tekapo, Pukaki, Tekoa, and Cass soil types, which occur at the same levels as or higher than Kakahu soils.

Results of the new trials, which include minor-element trials, rate of topdressing trials, the use of hydrated lime and sulphate of ammonia, and plant-introduction trials (with the grassland sod-seeder and grassland tips on a standard drill), should be available soon and will be published in a future issue of the “Journal”.

—R. L. BENNETTS