不同利用年限不同坡位的红壤水稻田化肥氮去向

采用15N微区示踪法研究了不同利用年限、不同坡位的红壤水稻田N素的运移特征与去向.试验结果表明:红壤地区新、老水稻田成熟期肥料利用率为18.71%～29.10%;残留率在5.97%～18.73%之间;老稻田耕层的土壤N素残留高于新稻田,但新稻田剖面中15～50 cm土层15N残留量占总残留量的比率明显要高于老稻田;红壤水稻田肥料损失率高达52.24%～68.91%.此外,供试田块各生育期渗漏水中NH4 -N、NO3--N浓度均为:耕层＞犁底层.

Fate of Nitrogen Fertilizer in Paddy Fields Different in Cultivation History and Slope Position in a Red Soil Region

15N tracing method was used in a field experiment to study movement and fate of nitrogen fertilizer in paddy fields different in cultivation history and slope position. Results showed that at the rice maturing stage, nitrogen fertilizer recovery rate and residue rate in paddy fields either new or old ranged between 18.71% and 29.10%, and between 5.97% and 18.73%. Old paddy fields were higher than new fields in 15N residue rate, but in the 15 ~ 50 cm layer, it was just the reverse. 15N loss rate from red soil paddy fields was as high as 52.24 % ~ 68.91%. besides, in terms of concentrations of NH4 -N and NO3--N in leachate from soil layers of the experiment plots, the layers were in the order of plough layer > plowpan.