EFFECT OF AMMONIUM-CHLORIDE, AMMONIUM-SULFATE, AND SODIUM-NITRATE ON TAKE-ALL AND GRAIN-YIELD OF WHEAT GROWN ON SOILS IN SOUTH-WESTERN AUSTRALIA

Five field experiments are described which measured the effect of three sources of nitrogen (N) fertilizer, applied at 45 kg N/ha, on the incidence of take-all and grain yield of wheat. The N fertilizers were ammonium sulphate, ammonium chloride, and sodium nitrate. Compared with the Nil N treatment, ammonium-nitrogen fertilizer, either as ammonium sulphate (ASdr) or ammonium chloride (ACdr) drilled with the seed, lowered the severity of take-all Sodium nitrate topdressed (SNtd) to the soil surface reduced the severity of take-all in three of five experiments, while ammonium sulphate topdressed (Astd) reduced the severity in four of the five experiments. Ammonium sulphate and ammonium chloride drilled with the seed were equally effective in reducing the severity of take-all in three of the five experiments. However, ACdr was more effective than ASdr in reducing the severity of take-all in one experiment whereas ASdr was more effective than ACdr in another experiment. In these two experiments (I and 5), the effects of the reduction in take-all severity between the ASdr and ACdr treatments did not affect grain yield. The results suggest that grain yield losses from take-all are most severe where wheat plants are deficient in N. Chloride containing fertilizers are, unlikely to control take-all disease of wheat on soils of southwestern Australia.