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There are limited reports about the impacts of long-term rice wheat cropping system (RWCS) on soil properties and nutrient stocks under smallholder farmer's conditions in developing counties. The study was carried out in RWCS in Haryana (10 districts) of North-West India in order to map out some soil properties and assess their variability within the area. From the study area, a total of 150 surface soil samples (15 samples each district) were collected using Global Positioning System (GPS) after harvest of wheat crop. Then, soil properties, that is, pH, electrical conductivity (EC), soil organic carbon (SOC), carbonate content, cation exchange capacity (CEC), salinity content (Na+, K+, Ca2+ + Mg2+) soil available nutrients (NPK, Fe & Zn), and micronutrient fractions were measured in the laboratory. All soil properties significantly changed under RWCS, except for bulk density, SOC, and SAR variables. The SOC stock varied significantly among the majority of RWCS in north-western India but was not significantly different in total nitrogen (TN) stocks. After log-transformation of data, classical statistics were used to describe the soil properties, and one-way analysis of variance. The PCA chosen soil properties explained 81.37% of the soil quality variability among the RWCS. Such soil properties and nutrient stock variability among the RWCS suggested the introduction of suitable management practices that sustain the soil system of the RWCS with poor properties and nutrients. On the basis of the linear function, soil chemical properties (44.65%) contributed more to soil quality index (SQI) than physical ones. [ABSTRACT FROM AUTHOR]

Eight integrated crop management (ICM) practices were evaluated for six years consecutively, which are ICM1&2: 'business-as-usual' (conventional transplanted rice fb flatbed wheat), ICM3&4: conventional direct seeded rice (DSR) fb furrow irrigated raised-bed wheat without residues, ICM5&6: conservation agriculture (CA)-based zero-tilled (ZT) DSR fb ZT wheat with the wheat and rice residues and ICM7&8: CA-based ZTDSR fb ZT wheat with the wheat, mungbean and rice residues. ICM7-8 produced 9.6–16.4% and 9.4–9.9% greater system rice equivalent yield (REY) than the ICM1-4 and ICM5-6, respectively. Residue-retained CA-based ICM5-8 had 23.2% and 58.5% greater N and P balance, respectively, than the residue removed (ICM1-4); subsequently, negative K balance (–53 to –115.5 kg ha−1) was recorded in ICM1-4. ICM5-8 consumed ~60-78% of total energy and produced the highest energy output (Eo) in rice (11.5–12.6%)/wheat (7.3–13%) than ICM1-4. In contrast, ICM1-4 had a greater energy use efficiency (EUE) compared to ICM5-8 due to lesser energy input (EI) through indirect renewable sources. At a soil depth of 0.0–0.45 m, the ICM5-8 contributed 7.9% and 20.2% greater active and passive OC pools over the ICM1-4. Thus, CA-based ICM in rice-wheat rotation (RWR) could be a possible substitute for the positive nutrient balance, system yields and energy and carbon dynamics. [ABSTRACT FROM AUTHOR]