Abstract: Intercropping is an effective way of utilize natural resources. The objective of this study was to test if growing oat (Avena sativa L.) at the end of growing season of alfalfa (Medicago sativa) as an intercropping model could increase forage yield and affected soil nutrients. The row spacing of alfalfa was 30 cm and 40 cm. Two oat varieties ‘Leader’ (early mature type) and ‘Baylor’ (late type) were planted at 7 and 11 days after the second harvest of alfalfa. Analysis of plant growth characteristics and yield was conducted,and soil samples were collected from the 0~10 cm,10~20 cm,20~30 cm depths immediately after the final harvest. We found that seeding oat 7 days after the second harvest of alfalfa with row spacing of 40 cm reduced soil pH in 0~10 cm and 10~20 cm. In addition,soil organic C,total N and P,as well as available P and K increased because of the intercropping. The results of this study suggested that an ideal intercropping model,including the timing and density,could improve soil nutrients,and organic carbon could be used as an indicator to evaluate the soil fertility of the intercropping system.

Key words: Alfalfa, Oat, Interplanting, Yield, Soil nutrients

摘要： 以末茬紫花苜蓿（Medicago sativa L.）套种饲用燕麦（Avena sativa L.）的牧草种植模式为对象，试验采用裂区设计，测定紫花苜蓿行距为30 cm和40 cm、燕麦播种日期为苜蓿第二茬刈割后7天和11天、燕麦播种品种为早熟品种（领袖）和晚熟品种（贝勒）的生长特性和产量，分析0~10 cm，10~20 cm，20~30 cm土壤的常规理化性质和有机碳含量，研究紫花苜蓿套种饲用燕麦的种植模式对植物生长、生产、土壤养分的影响，为选择合理的套作模式提供理论依据。结果表明：以苜蓿行距40 cm、苜蓿二茬刈割后第7天播种早熟品种燕麦的种植模式，与其他模式相比，能够极显著地降低0~10 cm，10~20 cm土层的pH值（P<0.01），极显著地增加各土层土壤全氮、全磷、速效磷、速效钾、有机碳的含量（P<0.01），而株高、生长速率、存活率、返青率与单作相比差异不显著（P>0.05）；合理的间套作模式（包括时间和密度），将有利于土壤养分和饲草产量的增加，且有机碳可以作为评价套作系统土壤肥力的指标。

关键词: 紫花苜蓿, 饲用燕麦, 套作, 饲草产量, 土壤养分