玉米间作夏季绿肥对当季植物养分吸收和土壤养分有效性的影响

本试验在重庆冬油菜种植区,于油菜收获后,选择竹豆,田菁和柽麻3种夏季绿肥作物,通过与夏玉米间作,分析了间作模式下土壤当季速效养分,植物养分吸收性能及地上部生物产量变化情况.结果表明,间作柽麻后玉米地上部产量显著提高35%,间作田菁后玉米产量显著下降21%,而间作竹豆无显著影响.单作绿肥除田菁地上部全氮含量显著低于间作田菁外,其余两个品种的全氮,全磷含量与间作绿肥无显著差异;而单作绿肥全钾含量均显著高于间作绿肥.与单作玉米比较,间作竹豆和田菁时玉米全氮含量,全磷含量显著增加,而间作柽麻时无显著变化;玉米全钾含量整体呈增加趋势.绿肥周围土壤的硝态氮含量显著高于间作玉米周围土壤.间作玉米周围土壤硝态氮含量,速效磷含量和速效钾含量呈现出整体高于单作玉米土壤的趋势,且相关分析结果表明土壤硝态氮含量与植物全氮含量呈显著正相关关系.综合分析认为,柽麻植株有较高的全氮含量和生物产量,且与柽麻间作的玉米地上部产量也最高,适宜作为玉米夏季间作的豆科绿肥.

The effects of corn and green manure intercropping on soil nutrient availability and plant nutrient uptake

Intensive cropping and a high multiple cropping index have been shown to be important for food secu-rity in China.However,inappropriate cropping systems decreases soil quality and causes environmental prob-lems.In this study,three legume green manures,Crotalaria junceal ,Phaseolus calcaltus and Sesbania canna-bina were intercropped with summer corn in a winter canola production area in Chongqing,southwestern Chi-na.Soil nutrient availability,plant nutrient content,and aboveground biomass yields were assessed.Corn yield increased 35% when intercropped with C.junceal,reduced by 21% when intercropped with S .cannabina,and was not affected by P .calcaltus .No differences in plant nitrogen and phosphorus were detected apart from S .cannabina which had higher nitrogen when intercropped.Potassium contents were higher under monocul-ture compared with intercropping for all three intercrop species.Compared with monoculture corn,nitrogen, phosphorus and potassium increased in corn intercropped with green manures.Soil NO3 nitrogen,available phosphorus and available potassium under intercropped corn were all higher than under monoculture corn.Cor-relation analysis indicated that nitrogen content was positively correlated with soil NO3 levels.Among the three legume green crops,S .cannabina had the lowest plant nitrogen content and aboveground yield which negative-ly influenced corn yield;P .calcaltus had higher aboveground yield and had no effect on corn yield,however its long vines hindered the corn harvest.However,C.junceal had high nitrogen content and high yield,and in-creased corn yield suggesting that C.junceal might be a suitable legume green manure crop with summer corn.