Integrated phosphorus management in maize-chickpea rotation in moderately-alkaline Inceptisol in Kanpur, India: An agronomic and economic evaluation

Abstract

Worldwide, input-intensive modern agriculture is accountable for incessant depletion of non-renewable phosphorus (P) reserve. This, in turn, has generated a renewed interest on efficient use of fertilizer P in field crop production, which is equally important for enhancing profitability and mitigating environmental challenges associated with fertilizer P application. In tropical soils, the productivity of field crops is mostly constrained by low availability of P in soil. Given the context, a field experiment was carried out on a moderately-alkaline Inceptisol (pH ˜8.2) for five years to assess the effect of six system-based inorganic fertilizer P treatments (kg P2O5 ha−1) in maize (M)-chickpea (C) rotation [M0-C0, M0-C40, M30-C0, M30-C40, M60-C0, M60-C40], two manure treatments [no farmyard manure (FYM), FYM at 5 t ha−1] and two phosphate solublizing bacteria (PSB) treatments [no treatment, PSB seed treatment in chickpea] on crop performance, system productivity, economics and production sustainability. A strong integrated effect of FYM and fertilizer P was observed on growth and productivity of both the component crops. However, the effect of PSB was marginal. Notably, the treatment M30-C0+FYM had a similar maize yield to that of M60-C40-FYM; and, chickpea grain yield was comparable in the treatments M60-C0+FYM ± PSB and M60-C40-FYM ± PSB, indicating a strong positive effect of FYM in alkaline soil, which was primarily attributed to increased soil available-P. At the end of five-year rotation, soil available-P in absolute control treatment M0-C0-FYM-PSB was depleted by 53%, where an increase of 56% in available-P was observed in the treatment M60-C40+FYM + PSB. In both the component crops, strong correlations (p < 0.01) between grain yields and soil available-P were observed. Residual effect of fertilizer P was observed in the subsequent crop, being higher in chickpea. The scale of residual advantage of fertilizer P was decreased with increase in current fertilizer P rate. Irrespective of FYM and PSB treatments, order of fertilizer P treatments for chickpea equivalent yield (CEY) was M60-C40 > M30-C40 > M0-C40 ≥ M60-C0 > M30-C0 > M0-C0 (p < 0.05). The treatment M60-C40+FYM + PSB led to 18% higher CEY over the treatment M60-C40-FYM-PSB, which in turns fetched additional net returns of INR 14,853. Thus, integrated application of FYM (5 t ha−1) and fertilizer P treatment M30-C40 could be recommended for higher crop productivity and economic return from maize-chickpea rotation in tropical moderately-alkaline soil.