Barley Yield and Nitrogen Derived by Plants from Mineral and Organic Fertilizers with Application of 15N Stable Isotope.

Abstract

A field experiment was carried out with constructed drip irrigation system on sandy soil to recognize the most proper nitrogen fertilization strategy that could be more benefits for barley production taking into consideration the economical and environmental impacts. Barley crop was significantly positively affected by nitrogen fertilizer rates and organic compost. Grain yield (45%) and shoot (11%), root (36%) dry weight were relatively increased with increasing N fertilizer rate. Plants fully fertilized with organic compost showed relative higher grain yield than those either received 100% or 50% N-mineral fertilizer which accounted for 37%. In this case, shoot and root dry matter yield were nearly closed to those of 50% N-fertilizer, but to some extent lower than those of 100% N-fertilized treatment. Plants treated with fully organic compost achieved N uptake by grains nearly closed to those obtained with high N fertilizer rate (70 kg N fed -1 ). Combined treatment of organic plus mineral-N did not reflect significant differences than those of plants fertilized with half N fertilizer dose. Portion of nitrogen derived from fertilizer (Ndff) and absolute value reflected higher values and percentage at rate of 100% fertilizer than those induced by 50% N rate. Ndff by grain, shoot and root of combined treatment were nearly closed to those achieved by 50% mineral-N rate. More nitrogen was derived from organic compost and still higher in grain than shoot and root systems. Nitrogen added at half dose combined with organic compost was efficiently used by grain and root recording values nearly closed to those recorded with plants treated by half mineral-N rate.