PENETRATION RESISTANCE, SOIL WATER CONTENT, AND WORKABILITY OF GRASSLANDS SOILS UNDER TWO TILLAGE SYSTEMS

摘要

Increase in the size of dairy cattle farms in northwest Spain has caused an intensification of forage production and reinforced the need for two crops per year. However, in this geographical area, the establishment of the winter crop is not always possible because of the high rainfall and the poor workability of the land. The objective of this study is to evaluate the no-tillage system as a possible solution for these workability problems. Although no-till planting systems have been accepted for many years in some regions, it is relatively new to the area where this study was conducted. Cone index (CI) values under two tillage systems were studied during three consecutive growing seasons (2000/2001, 2001/2002, and 2002/2003). The relationship between the penetration resistance and the soil water content of a sandy loam soil was studied during two consecutive growing seasons (2001/2002 and 2002/2003). Conventional tillage (CT) and no-tillage (NT) were compared in a crop of Italian ryegrass ( Lolium multiflorum L.) in rotation with silage corn ( Zea mays L.) during four growing seasons. Soil penetration resistance and soil water content were related to soil workability. The results showed higher cone index values under NT than under CT and a good correlation between penetration resistance and soil water content. NT showed a greater ability to bear traffic load and, therefore, an improvement in soil workability throughout the growing season. This improvement was more valuable in autumn at the time of ryegrass drilling, the critical time from the point of view of soil workability. In spite of the higher CI values, dry matter yields of Italian ryegrass were not significantly different under NT than under CT