Effect of irrigation and nitrogen on yield, water use eficiency and nutrient balance in rice (Oryza sativa)- based cropping system

Abstract

An experiment was conducted at ICAR- RCER, Patna during 2001-02 to 2003-04 to study the effect of irrigation and nitrogen on yield, water-use efficiency and nutrient balance in rice ( Oryza sativa L.)- based cropping system. Application of optimum level of irrigation and nitrogen fertilization increased the rice-equivalent yield by 8.40, 6.38 and 6.90 % over the sub-optimum level in both the cropping systems. Among cropping systems, total water-use efficiency was higher in rice-lentil (Lens culinaris Medius)-greengram (Vigna radiata L.Wilczek), followed by rice-wheat (Triticum aestivum L. emend. Fiori & Paol.)-greengram. However, total water- use efficiency was more at optimum level of irrigation during first year, whereas during second and third year reverse was the case. There was a negative balance in nitrogen and phosphorus in both the cropping systems as well as levels of irrigation and nitrogen. Among the cropping system, maximum negative balance (-564 kg N/ha) was recorded in rice-wheat -greengram, followed by rice-lentil- greengram (-350 kg N/ha). Available phosphorus balance was also negative in both the cropping systems, levels of irrigation and nitrogen. Maximum available phosphorus balance was recorded in cereal dominated cropping system (-244 kg P/ha), followed by pulse dominated cropping system (-238 kg P/ha). There was a positive balance in potassium in both the cropping systems and levels of irrigation and nitrogen.