Effect of green manuring and zinc fertilization on productivity and nutrient uptake in Basmati rice (Oryza sativa)-wheat (Triticum aestivum) cropping system

Field experiments were conducted during kharif and rabi of 2008–09 and 2009–10 for two consecutive years at New Delhi; to study the effect of summer green manuring crops in conjunction with zinc (Zn) fertilization on productivity and nutrient uptake of Basmati rice (Oryza sativa L.) - wheat [Triticum aestivum (L.) emend. Fiori & Paol] cropping sequence. Among the summer green manuring crops, dhaincha (Sesbania aculeata) Pers accumulated significantly higher dry matter (7.41 t/ha) and N (180.5 kg/ha) than mungbean [Vigna radiata (L.) Wilczek]. Significantly higher grain yield (3.64 t/ha), N and Zn uptake of Basmati rice recorded when it was grown after incorporation of Sesbania aculeata as compared with cowpea [Vigna unguiculata (L.) Walp], mungbean [Vigna radiata (L.) Wilczek] and summer fallow. Application of 2.0% zinc-enriched urea (ZEU) ‘ZnSO₄.H₂O’ recorded the highest grain yield (3.79 t/ha) of Basmati rice as compared to remaining treatments closely followed by 2.0% ZEU (ZnO). The highest N (159.7 kg/ha) and Zn (3085.3 g/ha) uptake in Basmati rice was recorded with 2.0% ZEU (ZnSO₄.H₂O) followed by 2.0% ZEU (ZnO) and 0.2% foliar spray of ZnSO₄.H₂O. Wheat recorded significantly higher grain yield (3.09 and 3.20 t/ha), N and Zn uptake due to residual effect of summer green manuring crops and Zn fertilization. Significantly higher available nutrients (NPK and Zn) in soil after harvest of Basmati rice was recorded with Sesbania aculeata green manuring and 2.0% ZEU (ZnSO₄.H₂O) Zn fertilization treatment under Basmati rice-wheat cropping system. The highest productivity of Basmati rice-wheat cropping system was recorded after incorporation of Sesbania aculeata and application of 2.0% ZEU (ZnSO₄.H₂O).