استفاده از روش ايزوتوپي ازت - 15 در بررسي كارايي سطوح مختلف اوره تحت سيستم كود- آبياري قطره اي و مقايسه آن با روش شياري در گياه گوجه فرنگي

Use of 15N Methodology to Assess Urea Use Efficiency under Different Nitrogen Levels in Fertigation System and Comparison with Furrow Irrigation on Tomato

In order to determine a suitable level of nitrogen fertilizer for simultaneous increasing the nitrogen fertilizer use efficiency and the yield production under the trickle fertigation system in comparison with the furrow irrigation, an experimental design was conducted in a randomized complete block (RGB) with five treatments and four replications in plots of 3 5 square meters area. The treatments of N0 , N1 , N2 and N3 received 0, 100, 150 and 200 mgN/lit, respectively under the trickle fertigation , and for the treatment of Ns the amount of fertilizer were equal to Nz but under the furrow irrigation system. Fertilization and irrigation were performed by means of two fertigator pumps ( one for urea and the other for ammonium phosphate and potassium sulfate ) . In order to determine the nitrogen fertilizer use efficiency, six plants in the middle of each plot received 15n labeled urea (isotopic form of 14N) through plastic containers. Irrigation schedule and soil moisture monitoring were performed by means of a neutron gauge . The results showed that in spite of increasing the nitrogen levels in the fertigation system, the nitrogen fertilizer use efficiency decreases. In this respect , the treatment of Ni could absorb % 54 of nitrogen fertilizer which indicated that the highest fertilizer use efficiency under the current design condition and the final nitrogen fertilizer use efficiency for N2 and N3 treatments are %39 and %31, respectively. In addition, the traditional treatment (Ns), with %83 losses of nitrogen had the lowest rate of fertilizer use efficiency.