Fate of Soil Residual Fertilizer-15N as Affected by Different Drip Irrigation Regimes

Soil residual N is a potential factor threatening the environment, but it also an fertilizer resource. Few studies have evaluated fate of soil under agronomic practice. The objective this study was to investigate distribution and its possible influencing factors with different irrigation regimes. Under three situations created by previous season using 15N labeled urea, we employed lettuce as plant material lower limits drip including 75% (DR1), 65% (DR2), 55% (DR3) accounting for field water capacity experimental treatments. A furrow treatment (FI) same regime DR2 used control. Results showed that 2.1–4.8% from absorbed succeeding lettuce, 78.0–84.4% still remained in 0–80 cm soil, 10.9–20.0% unaccounted for. After harvest lettuces, mainly existed mineral form. Moreover, reuse efficiency for15N positively correlated total amount (p < 0.01) 0.01). overall results indicated appropriate (DR2) conducive promoting absorption crop.