Effect of integrated use of farmyard manure and chemical fertilizers on soil physical properties and productivity of soybean

The effect of sole application of inorganic fertilizers (NPK) (N:P:K:: 30:26:25 kg ha(-1)) and combined application of farmyard manure (FYM) @ 4 Mg ha(-1) and inorganic fertilizers (NPK + FYM) vis-a-vis non-application of fertilizers and manures (control) on changes in soil physical properties and plant growth characteristics of soybean (cv. JS 335) was studied in a deep Vertisol at the Indian Institute of Soil Science, Bhopal during the year 2001-2004. The results indicated that conjunctive use of recommended dose of fertilizer and farmyard manure (NPK + FYM) resulted in significant (P < 0.05) decrease of bulk density (9.3%), soil penetration resistance (42.6%) and increase in hydraulic conductivity (95.8%) and mean weight diameter of the water stable aggregates (13.8%) and soil organic carbon content (45.2%) compared to control. Among the aggregates, in macro-aggregate fraction (250-500 mu m and 500-1000 mu m size fraction) and in large macro-aggregate fraction (>2000 mu m) maximum soil organic carbon concentration was recorded under NPK + FYM. The root mass of soybean was mostly (98%) confined to 15 cm soil depth. Combined application of NPK and FYM recorded significantly higher (P < 0.05) root length density and root mass density of soybean in the 0-15 cm soil layer at flowering stage over NPK (28 and 65%) and control (63 and 175%). The root length density of soybean was significantly negatively correlated with the penetration resistance (r = 0.98, P < 0.05). Application of FYM @ 4 Mg ha(-1) with NPK significantly (P < 0.05) improved the biomass partitioning towards pod over NPK and control. The grain yield, water use efficiency and nitrogen use efficiency of soybean under NPK + FYM were significantly (P < 0.05) higher than NPK and control. The total above ground biomass and the leaf area index at R8 stage could account for respectively, 89 and 63% variation in grain yield of soybean. Therefore in every crop season, integrated use of farmyard manure at 4 Mg ha(-1) and recommended dose of chemical fertilizers may be practised in Vertisols for improving soil physical environment and achieving higher soybean productivity through efficient utilization of water and nutrients. (C) 2010 Elsevier B.V. All rights reserved.