Previous Season Cover Crop Effects on Soil Moisture Distribution and Yield in the Subsequent Season

摘要

A primary factor in determining the yield potential of an agricultural crop is the availability of soil moisture during the growing season. The previous season cover crop can influence the soil moisture availability of the subsequent growing season, thereby, affecting the crop yield. The influence of berseem clover (Trifolium alexandrium) cover crop in oats (Avena sativa) grown in 2005 on subsequent spring soil thawing, soil moisture availability and yield of canola (Brassica napus) grown in the 2006season was investigated. Time domain reflectometry and neutron scattering methods were used to measure the unfrozen and total water contents, respectively. Thermocouples were used to measure soil temperatures. There was no significant difference in the2005 yield of oats with or without a cover crop (1.52 vs 1.691 ha~(-1), respectively). Compared to the previous non-cover crop treatment, the previous season cover crop treatment thawed earlier in spring 2006 and had significantly lower soil moisture during the following growing season (0.16 vs. 0.22 m~3 m~(-3) during flowering stage) leading to poor crop performance. The canola yield in 2006 was significantly affected by the presence of a cover crop in 2005 (1.99 t ha~(-1) with a previous cover crop vs2.721 ha~(-1) with no previous cover crop). The presence of the cover crop in the previous season can negatively affect the crop performance and yield of the subsequent season. Depletion of soil moisture by cover crop should be taken into account when selecting a crop sensitive to soil moisture stress in the subsequent season.