Abstract

A two year field study was conducted on a permanent layout to investigate the effect of crop residues (CR) incorporation and P application (0, 40, 80, 120kg P₂O₅ ha^-1) on rehabilitation of saline soil (ECe=4.59 dS m-1; pH=8.38; CaCO3=3.21%; Extractable P=4.07mg kg^-1; sandy clay loam) during 2011-12. The experiment was laid out according to split plot design with three replications. Planting of direct seeded rice (DSR) with and without crop residue incorporation @2ton ha^-1 were placed in main plots and P application was in sub plots. Data on productive tillers, panicle length, paddy/grain and straw yields was collected. Soil was sampled (0-15cm) before initiation and after the harvest of last crop. On an average of two years, maximum productive tillers (18), panicle length (33), paddy yield (3.26t ha^-1) and was produced with P application @ 80kg P₂O₅ ha^-1 along with CR incorporation. Similarly in case of wheat grown after DSR, maximum tillers (17), spike length (17), grain panicle^-1 (66) and grain yield (3.56t ha^-1) were produced with P application @80kg P₂O₅ ha^-1 along with CR incorporation. Although, the growth and yield contributing parameters with this treatment (80kg P₂O₅ ha^-1+CR) performed statistically equal to 120kg P₂O₅ ha^-1 without CR incorporation during both the years, but on an average of two years, grain yield of DSR and wheat was significantly superior (22 and 24% respectively) than that of higher P rate (120kg ha^-1) without CR. Overall, continuous two year CR incorporation further increased (17%) paddy yields during the follow up year of crop harvest. Higher concentration of P, K and Ca2+ in both DSR and wheat plant tissues was found where 80kg P₂O₅ ha^-1 was applied along with CR incorporation or 120kg P₂O₅ ha^-1 alone while Na²⁺ and Mg²⁺ concentration decreased with CR incorporation and increasing P rate. The soil salinity was decreased and fertility was improved significantly after two years of study.

Keywords: Slightly saline soil; Direct seeded rice; Crop residues incorporation; P application; Growth and yield; Ionic concentration; P use efficiency

Abbreviations: CR: Crop Residues; ECe: Electrical Conductivity of Extract: pH; Negative log of Hydrogen Ion; CaCO3: Calcium Carbonate; P: Phosphorus; mg kg^-1: milligram per kilogram; kg P₂O₅ ha^-1: Kilogram Phosphate per hectare; DSR: Direct Seeded Rice; cm: Centimeter; t ha^-1: ton per hectare; K: Potash; Na²⁺ and Mg²⁺: Sodium and Magnesium; PUE: Phosphorus Use Efficiency; SOP: Sulfate of Potash; SAR: Sodium Adsorption Ratio; SOM: Soil Organic Matter; TPU: Total P Uptake; LSD: Least Significant Difference; CO₂: Carbon di Oxide