不同肥料配比对南方烟田土壤养分淋溶的影响

为探明大田烤烟基肥施用方式对土壤养分淋溶的影响，通过田间小区试验，对5种不同肥料配比下土壤养分淋溶规律进行了研究。结果表明，烤烟生长期的烟田土壤氮素淋失以硝态氮为主，呈现出先低后高，然后降低的趋势，单施无机肥处理的淋溶量最大，对地下水污染存在潜在危险；铵态氮淋溶量很少，下层土壤淋溶水铵态氮的质量浓度呈现低－高－低的趋势，不同处理间差异明显，施用高比例有机肥有利于减少铵态氮淋溶；土壤淋溶水速效钾动态变化呈现低－高－低的规律，有机、无机肥配施可不同程度减少速效钾的淋失率，单施无机肥对地下水的污染威胁高于其它处理。为减少土壤养分淋溶，在我国南方烤烟基肥施用方式上，提倡20%以上的有机肥与无机肥配施。

Effects of Different Fertilizer Ratio on Nutrient Leaching in Tobacco Fields of South China

A field experiment with five fertilizer treatments was carried out to study the effects of various fertilizer rates on nutrient leaching in soil in Liuyang, Hunan Province. Results indicated that NO3--N was the main part of nitrogen leaching in growth stage of flue-cured tobacco, and the content of NO3--N decreased firstly, then increased and decreased subsequently. The maximum level of NO3-N leaching was observed in the treatment of zero organic fertilizer, with potential pollution to underground water. The loss of NH4+-N by leaching was quite low, and the content of NH4+-N decreased firstly, followed by increase and decrease in lower soil layer. Significant difference occurred between different treatments, and higher ratio of organic fertilizer could reduce the leaching level of NH4+-N. Dynamic changes of potassium content appeared low to high to low subsequently, and the leaching level of soluble potassium decreased with the increasing ratio of organic fertilizer, with higher pollution rate to underground water in zero organic treatment. The organic fertilizer exceeding 20% of basal fertilizer might be favorable for less leaching of soil nutrients in South China.