LINCOLN RESEARCH DIARY

Press, 27 April 1984, Page 16

LINCOLN RESEARCH DIARY

Sulphur Sulphur came to prominence in the 19505, particularly in hill and high country development. Recent research at Lincoln has shown new aspects of sulphur responses in two very different situations on dry hill country and on irrigated plains land. Dry hills may have a reasonable phosphate status but a deficiency in sulphur. New fertiliser formulation, such as sulphur super extra, provides more sulphur for plant growth. The success of using this fertiliser at a low application rate was shown this year on a dry hills site near Waikari. Growth of sub-cover in spring was about 800 kg dry matter per hectare without fertiliser but with 55kg per ha of sulphur super there was a three-fold increase in production. This result suggested a requirement for sulphur rather than phosphate as D.A.P. (phosphate and nitrogen nutrients) gave only a slight advantage over no fertiliser and the sulphate of ammonia (a nitrogen and sulphur nutrients source) also gave a threefold increase in yield. The good response of annual legumes to these sulphur fertilisers reflects good growing conditions this

year. The continued interest will be in fertiliser residual effect which may be limited on these dry hills by the dry weather. On the plains, superphosphate generally meets both sulphur and phosphate needs but the use of spray irrigation seems in some circumstances to leach the sulphur. Likely effects of sulphur shortage on white clover seed production were queried by local farm advisory officers and Peter Clifford, of Grasslands Division, responded with a trial comparing the use of gypsum with superphosphate and a no fertiliser control. Both fertilisers caused similar increase in growth and seed yield indicated that the effect was due to sulphur rather than phosphate. The 50 per cent increase in seed yield came mainly from an increase in seed size indicating improved photosynthetic activity from improved nutrition. This is a first instance of a limiting nutrient influencing clover seed production, albeit on a farmm which produces the greatest quantity of white clover seed in Canterbury. Inca gold I was intrigued recently to discover that the yam as we know it, is regatded as one of the “forgmten

crops of the Incas” and is known outside New Zealand only in the high Andes. How the yam or more correctly the “oca” got to New Zealand is unknown, but interestingly the small pink tuber we grow here is of a rather superior kind, and some Americans believe that it has the potential to become a common vegetable in North America during the next 20 years. The oca is one of the oxalis family hence its slightly acid taste. It is still a stable food of the Bolivian Indians but unknown to the Western world except in New Zealand. One can’t help but wonder if there is a major overseas market for this vegetable. As with other crops such as kiwifruit, tamarillos, passionfruit and cherimoya, New Zealanders have lead the way in developing the crop to a stage where it is likely to be commercially viable. It may be that in discovering the potato, the Spanish conquistadors left behind a vegetable which could do for the New Zealand vegetable industry, what the kiwifruit has done for the fruit industry. —Howard Bezar