Impact of Thirty-Four Years of Fertilization and Manuring on Soil Nutrients Availability, Yield and Quality of Crops in Indo-Gangetic Plains

Dryland rainfed agriculture needs an appropriate fertilization strategy to achieve sustainable yield with good soil health. This study was aimed at assessing the impact of long-term fertilization on soil available nutrients, its enzymatic activities, and yield and quality of crops. Depth-wise soil samples were collected from a 34-year-old long-term fertilizer experiment (LTFE) with a rainfed rice-lentil cropping system. Treatments used for comparison were: control, 100% NPK (recommended NPK), 50% NPK, 50% FYM (50% of recommended nitrogen from farmyard manure), 100% FYM, and 50% NPK + FYM. Collected samples were analyzed for the physico-chemical and biological properties of soils along with the quality and yield of crops harvested. Among the treatments, 50%NPK + FYM showed the highest activities of dehydrogenase (DHA) (72.7%), alkaline phosphatase (ALKP) (48%), arylsulphatase (ASP) (92.8%) and urease (URE) (112%) compared with the control at the surface layer. It (NPK + FYM) also enhanced soil macro- (available N, P, K and S) and micro-nutrients (available Zn, Cu, Fe, Mn and B). The use of FYM either alone or in combination with inorganic fertilizer, had significant impacts on uptake of macro- and micro-nutrients by grains and straw of rice. Conjoint use of FYM and inorganic fertilizer also improved grain yield of rice (2038 kg ha-1) and lentil (965 kg ha-1), values of sustainable yield index (SYI), and quality of rice in terms of enrichment of N, P and K (1.34%, 0.37% and 0.24%) in grains. Results also revealed an improved agronomic efficiency (AE) and apparent recovery efficiency (ARE) of N (38.8%), P (33.7%) and K (91.4%) with FYM. With the exception of control, there was a positive apparent N and P balance shown in all the treatments, whereas negative apparent K balance in all except the FYM-treated plots. Application of NPK with FYM improves soil physico-chemical and biological properties, crop productivity and also its quality. It also ensures a steady supply of N, P and K to crops enhancing their use efficiencies. A balanced and conjoint application of inorganic fertilizer and FYM to rainfed rice-lentil cropping system is recommended for upkeeping soil health, improving crop productivity and its quality under Indo-Gangetic Plains.