长期施用氮磷肥对(土娄)土钾素的影响

以长期定位施肥与小麦一玉米轮作田间试验为平台,研究了施肥对(土娄)土土壤钾素的影响以及冬小麦生育期内(土娄)土土壤速效钾、缓效钾及微生物量钾的变化.结果表明:氮磷肥不同施用量对土壤全钾基本没影响,而对速效钾、缓效钾及微生物量钾的影响较大.土壤速效钾和缓效钾均随施肥量的增加而减少,而微生物量钾随施肥量的增加而增加,且0-20 cm土层土壤速效钾、缓效钾及微生物量钾含量均高于20-40 cm土层.小麦生育期内,土壤速效钾和微生物量钾含量的变化一致,均是先上升再下降,再上升,又下降的变化.土壤中微生物量钾与有机碳、全氮均呈显著正相关关系,而与土壤速效钾和缓效钾无显著相关关系.氮磷肥在一定施用量范围内,促进了土壤无机态钾素的消耗,而提高了土壤微生物量钾的含量.土壤钾素的这种变化是作物吸收、施肥等因素共同作用的结果.

Effects of Long-term Application of Nitrogen and Phosphorus Fertilizers on Potassium of Lu Soil

Based on field experiment of the long-term fertilization with wheat-corn rotation,soil total potassium,available potassium,slowly available potassium,and microbial biomass potassium were investigated for examining the effects of fertilization on soil potassium and the changes of soil inorganic potassium and microbial biomass potassium during winter-wheat growth.The results showed that different application amounts of N and P had little effect on soil total K,but had significant effect on soil available potassium,slowly available potassium and microbial biomass K.Soil available potassium and slowly available potassium decreased with the increase of fertilizer amount,while microbial biomass K increased with the increase of fertilization amount,and soil available potassium,slowly available potassium and microbial biomass K in 0-20 cm soil layer were higher than those in 20-40 cm soil layer.The contents of soil available K and microbial biomass K in the wheat growth period showed a fluctuating trend.Soil microbial biomass K is significantly positively correlated with organic C and total N,but is not significantly correlated with available potassium and slowly available potassium.The application of N and P fertilizers within a certain range promoted the inorganic K depletion and increased the content of microbial biomass K in the soil,which is the result of crop absorption,fertilization,management and other environmental factors.