洱海流域北部农田养分平衡及残留特性研究

为减少农田氮磷流失,改善洱海水质、遏制富营养化发展,以洱海流域北部8个乡（镇）为研究区域,采用现场调查与分析测试相结合的方法研究了洱海流域北部10种典型轮作模式的施肥量、作物养分吸收量、农田养分盈余量以及土壤养分残留状况,对不同轮作模式农田养分平衡及残留特性进行了分析评价。结果表明,水稻-大蒜轮作模式下有机肥和氮肥的投入量显著高于其他模式,水稻-蔬菜作物轮作模式的磷肥投入量显著高于其他模式;不同轮作模式间土壤养分残留差异性以硝态氮最为突出：水稻-大蒜轮作条件下土壤硝态氮残留量达43.4mg.kg-1,明显高于其他轮作模式;10种轮作模式均处于养分盈余状态,以水稻-大蒜轮作模式养分盈余量最大,为1258.8kgN.hm-2和1472.7kgP2O5.hm-2;养分盈余量差异主要凸现在小春季作物上;土壤中易流失的硝态氮、铵态氮和速效磷与氮磷肥的投入量和养分盈余均呈显著相关。表明水稻-大蒜和水稻-蔬菜轮作是洱海流域农田环境污染风险较高的种植模式,需要重点防控。

Nutrient Balance and Soil Nutrient Status in Farmland of the Northern Watershed of Lake Erhai

Nutrients balance and soil nutrients status under different crop rotation systems in the north of Lake Erhai watershed was investigated for the risk evaluation and putting countermeasures for the nonpoint pollution from agricultural source.10 typical crop rotation systems was surveyed for the amount of organic and chemical fertilizers,nutrients uptake by crops and soil residual nutrients content in 8 townships located in the north of Lake Erhai watershed.The amount of manure and nitrogen fertilizer under rice and garlic rotation systems was significantly higher than that of other planting patterns.Phosphate inputs under the rice and vegetable crops rotation patterns were significantly higher than other systems.Soil nitrate nitrogen residue was the most susceptible nutrient under different crop rotation systems which could be as high as 43.4 mg.kg-1 for under rice and garlic rotation systems and significantly higher than the other rotation modes.Nitrogen and phosphorus budgets under all of the 10 typical crop rotation systems were positive,which means that fertilizer input are higher than the uptake by crops.Nutrients surplus was the highest under rice and garlic rotation system,which could be as high as 1 258.8 kg.hm-2 for N and 1 472.7 kg.hm-2 for P2O5,respectively.Nutrient surplus was mainly occurred in the crops which were planted in arid season from September to May.Soil nitrate,ammonium and Olsen-P content were significantly related to the fertilizer input.Rice,garlic or other vegetable crop rotation pattern is the most threatened cropping systems for the water quality of Lake Erhai and should be pay attention to.