有机-无机肥配施对紫色土坡耕地氮素淋失的影响

通过坡地渗漏小区定位试验,研究总施氮量相同情况下,施肥方式对紫色土坡耕地氮素淋失的影响.结果表明,有机-无机肥配施会影响紫色土硝酸盐向下累积过程,显著降低紫色土坡耕地硝酸盐累积量.渗漏液中硝态氮含量在0.15～46.99mg·L-1之间,占总氮含量的66.4%～96.3%;总氮淋失量在(4.05±0.37)～(37.82±0.86)kg.hm-2之间,占当季施氮量的2.7%～25.2%.在维持总施氮量相同的条件下,与常规氮磷钾施肥相比,农家肥、秸秆与化肥配合施用的渗漏液总氮含量分别降低了71.0%、61.4%,总氮淋失量分别降低了48.1%、31.6%.这表明有机-无机肥配施能显著降低紫色土坡耕地氮素淋失量,对有效控制紫色土区浅层地下水硝酸盐污染具有重要作用.

Effects of a combination of organic and inorganic fertilization on nitrogen leaching from purple soil with sloping cropland

Lysimeter experiments in a purple soil with a hilly slope were performed to study the effects of combined application of organic and inorganic fertilizers on nitrogen leaching. The results showed that accumulated nitrate decreased significantly due to organic-inorganic fertilization, suggesting that the nitrate accumulation process of sloping cropland in purple soil was affected by fertilization styles. Measured nitrate-N contents were in the range of 0.15~46.99 mg·L-1 during the period 2004 to 2006, which accounted for 66.4%~96.3% of the total nitrogen. Total soil nitrogen contents of organic-inorganic fertilization (OMNPK, RSDNPK) declined by 71.0% and 61.4%, respectively, and total nitrogen leaching fluxes of OMNPK or RSDNPK treatments decreased by 48.1% and 31.6%, respectively, compared to conventional NPK fertilizer treatments at the same total N application rates. It could be concluded that nitrogen leaching decreases through the combination of organic and inorganic fertilization. Therefore, it is important to control nitrate pollution of shallow groundwater in the area of purple soil via changing fertilization modes.