Effect of residue retention and phosphatic fertilizer on soil nutrients and crop yield under conservation agriculture in maize-wheat cropping system

A conservation agriculture (CA)-based study was started during the year 2013 to assess the effect of crop residue (CR) retention and phosphorus (P) fertilization over soil fertility. The experiment was laid out as split-plot design comprising of various CR retention rates viz. No CR, 2 t CR ha⁻¹, 4 t CR ha⁻¹ and 6 t CR ha⁻¹ as main-plot and P-fertilizer doses viz. No P fertilizer, 50% recommended dose of phosphorus (RDP), 100% RDP, 150% RDP and 50% RDP + arbuscular mycorrhiza (AM) + phosphate solubilizing bacteria (PSB) as sub-plots. After completion of five cropping cycles, soil samples were collected for the analysis. Results indicated that soil chemical properties (pH, EC) and nutrients (organic C, available N, P and K) were significantly influenced by both CR retention and P-fertilization. These properties were recorded highest under 6 t CR ha⁻¹ that was at par with 4 t CR ha⁻¹ except for available nitrogen (N) that was highest in case of 4 t CR ha⁻¹. Furthermore, P-fertilizer treatment 50% RDP+ AM + PSB was found to be at par with 100% RDP. Hence, CR retention @ 4 t ha⁻¹ and P-fertilizer supplemented with AM and PSB was found to be beneficial in reducing the P-fertilizer rate and maintenance of soil fertility under CA based cropping system.