Comparison of conventional and recommended water and nitrogen practices on spinach growth and water and nitrogen usage

The recommended water (by balance method) and nitrogen (by KNS system) practices were compared with conventional practices on spinach growth in field experiment. The results showed that there were no significant differences in spinach recommended and conventional N practices. However, the spinach in the recommended water treatments to control soil moisture in the ranges of 50%～80% and 60%～90% of plant extractable soil water could significantly increased compared to conventional water treatment. In consequence,in recommended water and nitrogen practices, nitrogen and water input amounts were reduced by 73.6% and 39.2%,respectively, of conventional inputs with similar spinach yield, and the residue of inorganic nitrogen in the soil surface layer of recommended water treatment was much lower than that in conventional water treatment. Optimum water strategy could solve the conflict between high yield and environmental protection.