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Soil quality degradation associated with resources scarcity is the major concern for the sustainability of conventional rice-wheat system in South Asia. Replacement of conventional management practices with conservation agriculture (CA) is required to improve soil quality. A field experiment was conducted to assess the effect of CA on soil physical (bulk density, penetration resistance, infiltration) and chemical (N, P, K, S, micronutrients) properties after 4 years in North-West India. There were four scenarios (Sc) namely conventional rice-wheat cropping system (Sc1); partial CA-based rice-wheat-mungbean system (RWMS) (Sc2); CA-based RWMS (Sc3); and CA-based maize-wheat-mungbean (Sc4) system. Sc2 (1.52 Mg m−3) showed significantly lower soil bulk density (BD). In Sc3 and Sc4, soil penetration resistance (SPR) was reduced and infiltration was improved compared to Sc1. Soil organic C was significantly higher in Sc4 than Sc1. Available N was 33% and 68% higher at 0-15 cm depth in Sc3 and Sc4, respectively, than Sc1. DTPA extractable Zn and Mn were significantly higher under Sc3 and Sc4 compared to Sc1. Omission study showed 30% saving in N and 50% in K in wheat after four years. Therefore, CA improved soil properties and nutrient availability and have potential to reduce external fertilizer inputs in long run. [ABSTRACT FROM AUTHOR]

A field experiment was initiated at the Central Soil Salinity Research Institute, Karnal from 1994 to 2003 on the use of nitrogen, phosphorus and potassium separately and in combination with organic manure (green manuring and farm yard manure) in rice-wheat cropping system to assess their impact on soil fertility, yield of rice and wheat and economic return of the crops. On the basis of 10 years data, application of recommended doses of NPK (120+26+42 kg ha-1) with green manuring or farm yard manure (FYM) increased significantly over the recommended dose of NPK. The mean yield of rice was 5.44, 6.38 and 6.25 t ha-1 at the application of the recommended doses of NPK alone and its combination with green manuring and FYM, respectively during 1994-2003. Addition of organic manure has increased rice yield by 16 per cent as compared to the recommended doses of NPK alone. The maximum yield of rice was obtained with green manuring treatment. Half doses of recommended NPK (60+13+21 kg ha-1) with green manuring or FYM were yielded more or less equal to that of yield obtained by recommended doses of NPK. The green manure or FYM has increased N, P, K, organic carbon and micronutrients in the soil significantly and reduced soil pH which ultimately benefited soil productivity and crop yields. [ABSTRACT FROM AUTHOR]

Soil quality degradation associated with resources scarcity is the major concern for the sustainability of conventional rice-wheat system in South Asia. Replacement of conventional management practices with conservation agriculture (CA) is required to improve soil quality. A field experiment was conducted to assess the effect of CA on soil physical (bulk density, penetration resistance, infiltration) and chemical (N, P, K, S, micronutrients) properties after 4 years in North-West India. There were four scenarios (Sc) namely conventional rice-wheat cropping system (Sc1); partial CA-based rice-wheat-mungbean system (RWMS) (Sc2); CA-based RWMS (Sc3); and CA-based maize-wheat-mungbean (Sc4) system. Sc2 (1.52 Mg m -3 ) showed significantly lower soil bulk density (BD). In Sc3 and Sc4, soil penetration resistance (SPR) was reduced and infiltration was improved compared to Sc1. Soil organic C was significantly higher in Sc4 than Sc1. Available N was 33% and 68% higher at 0-15 cm depth in Sc3 and Sc4, respectively, than Sc1. DTPA extractable Zn and Mn were significantly higher under Sc3 and Sc4 compared to Sc1. Omission study showed 30% saving in N and 50% in K in wheat after four years. Therefore, CA improved soil properties and nutrient availability and have potential to reduce external fertilizer inputs in long run.