Effect of ammonium sulphate and farmyard manure on the yield of paddy and on soil

1. The results of an experiment to study the effect of continuous application of ammonium sulphate, with and without f.y.m. in an alluvium clay soil for a period of 10 years on the yield of paddy and soil, have been reviewed. 2. The grain yield was increased significantly by ammonium sulphate in all the years except in the last two. The increases in straw yield were significant in all years. On consolidating the results, it was found that both the grain and straw yields were significantly increased by the effect of ammonium sulphate. The grain yield was not increased by the effect of f.y.m., but the straw yield was increased by this significantly at 5% level. 3. The straw:grain ratio increased with the increasing doses of nitrogen. 4. The maximum grain yield was obtained by the combination of ammonium sulphate at the rate of 30 lb. N plus f.y.m. at 100 md. per acre. This combination was significantly better than f.y.m. alone, but was not significantly better than ammonium sulphate at 30 lb. N. On economical consideration at the prevailing market price level, the dose 30 lb. N of ammonium sulphate applied alone is the most suitable. 5. No deleterious effect on the yield of paddy or change in the composition, hardness and percentage aggregation in soil have been observed after a 10-year period of continuous application of ammonium sulphate in the same paddy soil.