Effect of Tank Silt Amendment, Integrated Nutrient Management, and Biofertilizers on Agronomic Productivity of Semi‐Arid Alfisols

The harsh climate, land degradation, and poor resources are the principal causes of low productivity in the rainfed areas. A field experiment was conducted during the rainy and winter seasons of 2010–2015 (6 years) on maize‐horsegram cropping sequence to study the effect of soil amendment with tank silt, integrated use of chemical fertilizers and organic manure, and biofertilizers application on productivity, profitability, and changes in soil properties in degraded Alfisols of southern India. A total of 12 treatments were applied viz., T1 = Control, T2 = Recommended dose of fertilizer (RDF), T3 = 75% RDF + Phosphate solubilizing bacteria (PSB) + Azotobacter (AZ), T4 = 75% RDF + Farm yard manure (FYM) @ 5 Mg ha−1, T5 = 75% RDF + FYM @ 5 Mg ha−1 + PSB + AZ, T6 = 75% RDF + Tank Silt 30 Mg ha−1 (Once in 3 years), T7 = 75% RDF + Tank Silt 30 Mg ha−1 + PSB + AZ, T8 = 50% RDF + PSB + AZ, T9 = 50% RDF + FYM @ 5 Mg ha−1, T10 = 50% RDF + FYM @ 5 Mg ha−1 + PSB + AZ, T11 = 50% RDF + Tank Silt 30 Mg ha−1, T12 = 50% RDF + Tank Silt 30 Mg ha−1+ PSB + AZ. Significantly higher system yield (Mg ha−1) was observed in 75% RDF + tank silt + PSB + AZ (5.5) and 75% RDF + FYM + PSB + AZ (5.4) treatments compared to control and RDF. The performance of the maize crop during the rainy season, especially in the years with a higher number of dry spells, was better in the tank silt applied plots compared to the plots without tank silt application. The average maize yields under 75% RDF + tank silt + PSB + AZ were higher than the treatments 75% RDF + PSB + AZ and 75% RDF + FYM + PSB + AZ by 17.5% and 4.4%, respectively. Significantly higher uptake of N (100.9 kg ha−1), P (32.0 kg ha−1), and K (119.8 kg ha−1) in maize was found in 75% RDF + tank silt + PSB + AZ. Higher crop response ratio (CRR) was recorded in 50% RDF + tank silt with biofertilizers treatment (31.19 kg yield kg−1 nutrient applied). Higher partial factor productivity for NPK (PFPf) was observed in 50% RDF + tank silt with or without biofertilizers treatments (40.7 kg yield kg−1 fertilizer nutrients applied). Significantly higher gross return (₹49,535 ha−1), net return (₹32,519 ha−1) and B:C ratio (2.91) were observed in 75% RDF + FYM + PSB + AZ, which were very closely followed by 75% RDF + tank silt + PSB + AZ with ₹49,478 ha−1, ₹32,212 ha−1 and 2.87, respectively. Addition of tank silt once in 3 years not only increased the soil available N, P, K contents (with maximum contents of 163, 19.9, and 173 kg ha−1, respectively) under 50% RDF + tank silt with or without biofertilizers, but also increased their availability to plants, which was reflected in nutrient uptake by maize. Thus, tank silt soil amendment can be a viable option to improve system productivity in light‐textured poor soils of semiarid tropics.