Effects of irrigation techniques on 15N-urea utilization by tomato in greenhouse

Effects of drip irrigation and furrow irrigation on the utilization of urea-N in greenhouse tomato were studied by using 15N isotope technique. The results showed that fertilizer utilization efficiency of 15N were 11.5% for drip irrigation and 7.4% for furrow irrigation treatments. The amounts of 15N were taken up by the aboveground part of tomato plant of drip irrigation treatment increased by 56.3% compared to the furrow irrigation treatment. No distinct effects of irrigation techniques on the distribution ratios of 15N among the fruits, stems and leaves could be found. The residual amounts of 15N in soil depth of 0-100 cm was 143.1 kg/hm2 and 133.0 kg/hm2, accounting for 63.6% and 59.1% of the total applied nitrogen fertilizer for the drip irrigation and the furrow irrigation treatments, respectively. In the 0-20 cm top soil, the amounts of 15N of both treatments which were 79.9 kg/hm2 and 97.3 kg/hm2, being greater than these in other layers, accounted for 60.1% and 68.0% of the amount in 0-100 cm layer, respectively. The loss rates of N were 75.5 kg/hm2 and 56.0 kg/hm2 for furrow irrigation and drip irrigation, and occupied 33.5% and 24.9% of the total applied N fertilizer, respectively. (authors)