Articles | Plant, Soil and Environment | Agricultural Journals

Yield sustainability issues are always related to soil quality, its assessment is very vital. Thus, a long-term experiment (after 31^st cycle) was targeted to recognise the soil indicators related to the system productivity of rice-wheat. To achieve the objective, system productivity was calculated and it was observed that treatments supplemented with organic residues were more productive (11.6–12.2 t ha⁻¹). Soil qualities under each of the treatments were assessed by integrating the sensitive physical, chemical and biological parameters. All the soil parameters were improved under the treatments supplemented with organic residues. The soil quality index (SQI) was 0.26 for control (T1) and 0.59–0.63 for the integrated treatments (T6, T8 and T10). The SQI was highly correlated (R²=0.928) with the system yield. The soil factors like electrical conductivity, available phosphorus, soil organic carbon, porosity, microbial biomass carbon and dehydrogenase activity are identified as the key variables affecting the yield of the rice-wheat cropping system under long-term fertilizer trial.

A field experiment was conducted to investigate the influence of long-term application of organic manures on aggregate stability, associated carbon concentrations and carbon pools as an important soil-quality parameter under a scented rice-potato-onion cropping system in silt-loam textured soil in Eastern Bihar, India (subtropical climatic condition). Five treatments were used: 1) nitrogen, phosphorus and potassium (NPK) – 100% recommended dose of NPK; 2) NPK+FYM (farmyard manure) – 50%NPK+50% N as FYM; 3) FYM+VC (vermicompost)+ NC (neem cake) – different organic sources each equivalent to 1/3 of the recommended N (FYM +VC +NC); 4) FYM+VC+NC+PSB (phosphate-solubilizing bacteria – different organic sources each equivalent to 1/3 of the recommended N (FYM +VC+NC)+biofertilizers containing N and P carriers (PSB) and 5) FYM+BFN+BM+PSB – 50% N as FYM + biofertilizer for N +Bone meal to substitute P requirement of crops + PSB. The aggregate size distribution (>250 μm) at different soil depths is higher in treatment FYM+VC+NC+PSB and is at par with FYM+VC+NC, followed by FYM+BFN+BM+PSB and NPK+FYM, and the lowest in treatment receiving 100% NPK. The mean carbon concentration in each soil fraction was higher in soil depth 0–10 cm, followed by 10–20 cm and 20–30 cm. The trend of mean weight diameter (MWD) in different treatments was FYM+VC+NC+PSB ≥ FYM+VC+NC > NPK+FYM > FYM+BFN+BM+PSB > NPK. The trend of carbon concentrations in different treatments was FYM+VC+NC+PSB ≥ FYM+VC+NC > FYM+BFN+BM+PSB ≥ NPK+FYM > NPK. Non-labile pool of carbon forms the major portion (60.14%) of the total soil organic carbon (SOC) irrespective of all depths. Bulk density (BD) has a significant role in stabilizing soil aggregates as well as increasing the SOC content in soil. SOC was negatively correlated with BD (r = −0.870, p = 0.05), MWD (r = −0.911, p = 0.01) and geometric mean diameter (GMD) (r = −0.958, p = 0.05) irrespective of depth. This study took further steps toward understanding the enhancing of aggregate stability on organic manures addition for soil quality improvement.