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

Abstract

Increase in the size of dairy cattle farms in northwest Spain has caused an intensification of forage productionand reinforced the need for two crops per year. However, in this geographical area, the establishment of the winter crop isnot always possible because of the high rainfall and the poor workability of the land. The objective of this study is to evaluatethe no-tillage system as a possible solution for these workability problems. Although no-till planting systems have beenaccepted 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, and2002/2003). The relationship between the penetration resistance and the soil water content of a sandy loam soil was studiedduring two consecutive growing seasons (2001/2002 and 2002/2003). Conventional tillage (CT) and no-tillage (NT) werecompared in a crop of Italian ryegrass (Lolium multiflorum L.) in rotation with silage corn (Zea mays L.) during four growingseasons. Soil penetration resistance and soil water content were related to soil workability. The results showed higher coneindex values under NT than under CT and a good correlation between penetration resistance and soil water content. NTshowed 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 soilworkability. In spite of the higher CI values, dry matter yields of Italian ryegrass were not significantly different under NTthan under CT.