The effect of wet season land treatment and nitrogen fertilizer on safflower, linseed, and wheat in the Ord River valley. 2. Safflower and linseed

Abstract

Gila safflower and RR 204 linseed were grown under irrigation at Kimberley Research Station in the 1964 dry season after 6-months and 18-months clean and weedy fallows. Four levels of nitrogen fertilizer, as ammonium sulphate and as urea, were superimposed. Seed yield responses to nitrogen fertilizer up to 80 lb N an acre (safflower) and 160 lb N an acre (linseed) were obtained after weedy fallows, but after 18 months clean fallow neither crop showed a significant response to nitrogen fertilizer up to 160 lb N an acre. Ammonium sulphate was more effective than urea at equivalent rates of nitrogen per acre. The amount of nitrate-nitrogen in the top three feet of soil shortly before planting was related to the total nitrogen yield of linseed at maturity, which, in turn, was closely related to seed yield. Increases in seed yield of linseed with clean fallowing and nitrogen fertilizer were largely the result of increases in bolls per plant and 100-seed weight.