苜蓿不同种植模式下土壤结构及养分的响应

The Responses of Soil Structures and Nutrients under Different Alfalfa-planting Patterns

为了探究出适合山东地区苜蓿的最优生态种植模式,合理利用土地,在苜蓿轮作小麦地、苜蓿复种冬牧70黑麦地与苜蓿连作地3种种植模式下,采用定期采集土壤样品,测定土壤的水分、容重、总孔隙度、pH值、有机质含量、碱解氮及全氮含量的方法,研究了3种模式下土壤表层结构的变化及养分的消耗和利用情况。研究结果表明,苜蓿轮作模式与苜蓿连作和复种相比：可以明显降低土壤容重,0-30 cm土壤平均总孔隙度增加7.716%;可以降低土壤酸碱度,除5月份20-30 cm土层高于AA处理0.805,6月份10-20,20-30,0-30 cm土层高于AR处理1.413,0.673,0.569外,其余时间整体略低于其他处理;可以提高有机质和碱解氮的含量、有效性及活化率。复种与苜蓿连作相比,整个生长期中容重、总孔隙度、pH值差异不显著,但是其土壤水分、全氮含量显著高于其他2种种植模式,有机质的积累也高于苜蓿连作。综合比较,在改善土壤结构、改良土壤酸碱度方面,轮作〉复种≈连作;在养分方面,恢复土壤含水量、提高固氮能力上,复种〉轮作〉连作;在提高氮活化率方面,轮作〉复种〉连作;在提高有机质含量方面轮作、复种改良效果无显著差异,表现为轮作≈复种〉连作。因此,建议对多年连作的苜蓿田进行适时的轮作或复种,以改善土壤质量、提高作物的产量与品质。

In order to study the optimal ecological alfalfa-planting pattern in Shandong,use the land rationally.Under three alfalfa-planting patterns（ alfalfa rotation with wheat,multiple cropping rye Dongmu 70 in alfalfa field and alfalfa sequential cropping）,the soil water content,bulk density,soil porosity,pH value,organic matter,available N and total N content were measured in the soil samples collected regularly. By comparing above indexes,the changes of soil＇ s surface structure and nutrient＇ s consumption and utilization were studied. The research results showed that,compared with the sequential cropping alfalfa and multiple cropping rye Dongmu 70 in alfalfa field,alfalfa crop rotation could reduce significantly soil bulk density,increased soil porosity by an average of 7. 716% at0-30 cm depth; also reduced soil pH value,and the pH value was the lowest in three crop growing modes except in May 0. 805 higher at 20-30 cm depth than alfalfa sequential cropping in June 1. 413,0. 673,0. 569 higher at 10-20,20-30,0-30 cm depth than the multiple cropping. the content of organic matter and available N were higher than alfalfa sequential cropping,its effectiveness and activation rate also were increased. In the whole growth period,multiple cropping rye Dongmu 70 in alfalfa field compared with alfalfa sequential cropping,the bulk density,soil porosity,pH value had no change,but the soil water content,total N increased significantly than the other two kinds of planting patterns,and the accumulation of organic matter was also higher than sequential cropping. Sum up,the advantages in the aspects of improving soil structure and improving soil pH 〉value,alfalfa rotaition multiple cropping≈sequential cropping; and in the aspects of nutrient,recovering soil water content and increasing nitrogen-fixing capacity,multiple cropping 〉alfalfa rotation 〉sequential cropping; and in the aspects of improving soil pH value,increasing nitrogen activating rate,alfalfa rotation 〉multiple cropping〉 sequential cropping; and in the aspects of increasing soil organic matter which had no significant difference between crop rotation and multiple cropping,alfalfa rotation≈multiple cropping 〉sequential cropping. Therefore,alfalfa rotation or multiple cropping should be recommended to take the place of sequential cropping after many years planting,so that the soil and crops quality and the yield of crops will be improved.