Tillage-planting systems and cover cropping for sweet corn production in the western Fraser Valley

摘要

A combination of conservation tillage and winter cover crops might reduce soil degradation problems in the western Fraser Valley. This study was conducted to determine the effects of conventional spring tillage (ST) and conservation no-spring tillage (NST) following winter wheat (Triticum aestivum L.) and spring barley (Hordeum vulgare L.) cover crops on soil physical characteristics, slug and earthworm populations, soil available N, and sweet corn (Zea mays L. saccharata Sturt.) performance. The study was carried out in 1993, 1994, and 1995 on a silty clay loam Humic Gleysol in Delta, BC.;In the three years, bulk density, aeration porosity and aggregate stability were not affected by type of tillage, nor by type of cover crop. Before spring tillage there was no difference in soil penetration resistance between the two tillage systems. After spring tillage soil penetration resistance was higher in NST than in ST in the upper 15 to 20 cm of the soil profile and it ranged from 1500 to 2250 kPa. Spring barley cover crop resulted in higher soil penetration resistance than winter wheat in two out of three years. Lower soil water contents were observed at 20 cm depth with NST than with ST, while at other depths of measurement soil water contents were similar with both tillage treatments. Type of cover crop did not affect soil water content. Soil temperatures were lower by 0.4 to 1.0$spcirc$C at 3 cm depth in NST than in ST during three weeks following corn planting, but NST soil temperatures were above the minimum temperature required for corn emergence and early corn growth.;In the fall of 1995, earthworm population was higher in NST than in ST. At the same time, spring barley cover crop resulted in higher earthworm numbers than winter wheat. Mild winter conditions in 1993/94 and 1994/95 led to high slug populations in NST during the following spring. Slug infestation in NST plots caused serious damage to young corn plants and was one of the main reasons for the crop failure in the 1994 and 1995 seasons. Sweet corn yields were greater with ST than with NST in two out of three years, while type of cover crop did not affect sweet corn yield. Greater sweet corn response to N application was observed under winter wheat than under spring barley cover crop in 1993, and the opposite was true in 1994 and 1995. Soil NO$sb3$ concentrations were higher in NST than in ST during latter parts of 1993 and 1995 growing seasons, while in 1994 ST had higher soil NO$sb3$ than NST at corn planting. Throughout the whole 1993 growing season higher concentration of soil NO$sb3$ was observed with spring barley than with winter wheat cover crop, while in 1994 and 1995 this was true only at corn planting.;Elimination of spring tillage is not the best management option for sweet corn production in this region, since it resulted in a crop failure in two out of three years of this study that was carried out on the same site. Modifications of NST practice may hold promise for successful establishment of annual crops in the western Fraser Valley.