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Fertilization with suitable amendment in acidic soil is crucial to achieve long-term high crop yield without deteriorating soil health in intensive cropping system. We studied the chemical and biological properties of soil, soybean, and wheat yield after 47 years of long-term fertilization in an acidic Alfisol. Treatments were: unfertilized (control); recommended N dose (N); recommended N and P (NP); recommended N, P and K (NPK); NPK + hand weeding (NPK + HW); NPK + 10 Mg ha−1 farmyard manure (NPK + FYM) and NPK + 0.40 Mg ha−1 lime (NPK + lime). Long-term application of NPK + FYM significantly enhanced the soil cation exchange capacity (CEC), organic carbon, available NPK and microbial functions compared to NPK. Application of NPK + lime increased soil pH, dehydrogenase activity (DHA) and bacterial population by 15.7%, 38.8% and 145% respectively, over NPK. Continuous inorganic-P fertilizer application leads to substantial build-up of available-P in soil. Fertilization of FYM/lime with NPK recorded higher crops yield compared to NPK. Soil DHA, bacterial population and CEC were most influencing factors governing grain yield. Overall, long-term application of NPK with FYM/lime improved soil health and crop yield, but rate of inorganic-P input should be curtailed in an Alfisol. [ABSTRACT FROM AUTHOR]

Although the 13C (13Carbon) natural abundance method is used to study soil C dynamics, scanty information is available on long‐term fertilization effects on soil C sequestration rates along with δ13C in surface (0–30 cm) and deep (30–90 cm) soil layers and their relationships with crop productivities in subtropics. Hence, soil aggregation, δ13C in bulk soils and aggregates, C pools, and sequestration rates were studied in an Indian Alfisol under a 43‐year old wheat (Triticum aestivum L.)‐based cropping system. Treatments were as follows: no mineral fertilizer and no manure (unfertilized control), 100% recommended dose of nitrogen (N), 100% N and 100% recommended phosphorus (NP), 100% N, 100% P, and 100% recommended potassium (NPK), NPK + lime (NPKL), 150% recommended NPK (1.5NPK), and NPK + farmyard manure at 10 Mg ha−1 (NPKF). Plots with NPKF contained 50% higher soil organic C than NPKL in surface soil (0–15‐cm layer). In the 0–90‐cm profile, soil organic C accumulation and sequestration rates in NPKF were ~0.15 and 0.11 Mg ha−1 yr−1 higher than NPKL plots, respectively. The NPKF plots had higher glomalin‐related soil protein and greater recalcitrant C than NPKL, 1.5NPK, and NPK in surface soil. The NPKF plots had higher δ13C values within bulk soils and their aggregates than NPKL and NPK. There were significant correlations between deep soil C sequestration rates with mean crop productivities and δ13C with deep soil C sequestration rates. Overall, NPKF application had the largest surface and deep soil C sequestration with highest crop productivity and hence is recommended. [ABSTRACT FROM AUTHOR]

The aim of this study was to understand impacts of long-term (43 years) fertilization on soil aggregation, N accumulation rates and δ15N in surface and deep layers in an Alfisol. Soil samples from seven treatments were analysed for N stocks, aggregate-associated N in 0-30 cm and the changes in δ15N in 0-90 cm depths. The treatments were: unfertilized control (control); recommended N dose (N); recommended N and phosphorus doses (NP); recommended N, P and potassium doses (NPK); 150% of recommended N, P and K doses (150% NPK); NPK + 10 Mg FYM ha−1 (NPK + FYM) and NPK + 0.4 Mg lime ha−1 (NPK + L). Results revealed that plots under NPK + FYM had ~39% higher total N concentrations than NPK + L in 0-30 cm soil layers. In NPK + L, macro-aggregates had 35 and 11% and microaggregates had 20 and 9% lower δ15N values than NPK + FYM in 0-15 and 15-30 cm soil layers, respectively. However, plots receiving NPK + FYM had ~39% greater deep soil (30-90 cm) N accumulation than NPK + L. These results would help understanding N supplying capacity by long-term fertilization and assist devising N management strategies in sub-tropical acidic Alfisols. [ABSTRACT FROM AUTHOR]