Long-term effect of manures and fertilizers on sorghum (Sorghum bicolor), pulse productivity and soil nutrient status in canal command

A long-term experiment with 10 treatments comprising manure and fertilizer alone and in combination was conducted for 17 years in a Vertisol (Calciustert) under irrigated conditions. The treatments were incorporated only to winter (rabi) season crop, i.e. sorghum (Sorghum bicolor) and rainy (kharif) season pulses (soybean (Glycine max L. Merr) and greengram (Vigna radiata var. radiata) were grown on residual manure and fertilizer. The treatment that received 10 tonnes/ha farmyard manure+ 100 % recommended dose of fertilizers recorded highest sorghum yield and it was on par with that of 100 % recommended dose of fertilizers during most of the years. Application of higher doses of farmyard manure (10 tonnes/ha) along with fertilizer (50 or 100 %) increased grain yield significantly over only manure incorporation. Fertilizer (at 50 or 100% recommended dose of fertilizers) have to be applied along with manure (at 5 or 10 tonnes/ha) for realizing the higher and sustained sorghum grain yield. Application of manure alone even at 10 tonnes/ha would not be sufficient to realize the higher yields. Sorghum grain yield was not influenced (not reduced) by withholding K application. The differences in sorghum (ranged between 0.97 and 0.23 tonnes/ha) yields between various treatments involving manure narrowed in the last few years compared to the initial years of experimentation. Soybean yield in the 10 tonnes/ha farmyard manure applied plots were significantly higher (the difference between these 2 treatments ranged from 0.27 to 1.05 tonnes/ha) than in recommended dose of fertilizers in all the years. The economic optimum fertilizer dose for sorghum crop was 121:72:70 kg/ha N, P2O5 and K2O. The build-up of available N, P and K in soils with application of manure was observed compared to 50 % recommended dose of fertilizers. The nutrient status further increased when fertilizers (either at 50 or 100 % recommended dose of fertilizers) were applied along with the manure.