Viable alternatives to the rice-wheat cropping system in Punjab.

摘要

On-farm experiments conducted on alluvial soils of Punjab with diverse crop rotations of different water requirement showed that at Nawanshahar, mean yield of wheat was similar for rice-wheat system (RWS; 4.0 Mg/ha) and maize-wheat system (MWS; 4.3 Mg/ha). Mean yield of maize was also similar in the MWS (4.4 Mg/ha) and maize-rapeseed system (MRS; 4.4 Mg/ha). Although output in gross returns (GR) and return on variable expenses (ROVE) were higher for RWS in Nawanshahar district, substituting maize for rice in the monsoon season is preferred because of savings in water. In Faridkot district, the monetary returns were higher for the cotton-wheat system (CWS), which makes judicious use of groundwater as compared to the non-traditional RWS. Soil organic carbon (SOC) concentration at Nawanshahar increased from a mean initial level of 0.44% to 0.50% when both rice and wheat residues were burned; 0.51% when rice straw was incorporated but wheat straw was removed; and 0.57% when both rice and wheat straw were incorporated. At Faridkot site, the SOC concentration increased from a mean initial level of 0.39% to 0.49% when both rice and wheat straw were incorporated. The positive effect of straw incorporation on soil quality was more pronounced in the light-textured soil (sandy loam) at Faridkot than in loamy soil at Nawanshahar. Soil bulk density at the Faridkot site decreased from 1.65 Mg/m3 to 1.58 Mg/m3, and water infiltration rate increased from 6.1 mm/hr to 7.6 mm/hr. Straw incorporation increased soil organic carbon pool at the Faridkot site by 1 Mg/ha in 0-15 cm depth across a two year period. Comparative economics of residue incorporation in RWS across three years showed that, although the GR (Rs/ha) was the same in straw-burned and straw-incorporated treatments, the improvements in soil quality that the straw incorporation brings about for sustainable agriculture in the long-run offset any advantage of burning straw and gave higher net returns and benefit-cost ratio (BCR) in the short-term. Efficient on-farm water management using fertigation technology was demonstrated in a farmer's field for production of vegetables throughout the year. Diversified agriculture in the form of agroforestry and fish culture as alternative land-use options were also demonstrated in farmers' fields. Agroforestry interventions involving poplar trees with a range of intercrops were found to be useful cyclic interventions in the land-use and management strategy for sustainable agriculture in the intensively cultivated alluvial soils of Punjab.