Soil protection value of winter crops and reduced tillage on clay loams
Joniskelis Research Station of the Lithuanian Institute of Agriculture, Joniskelis, LT-5240 Pasvalys District, Lithuania;
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Experiments to reduce soil physical degradation were carried out at Joniskelis Research Station of the Lithuanian Institute of Agriculture over the period 1998–2002. The soil of the experimental site is characterised as glacial lacustrine clay loam on silty clay (Gleyic Cambisol). The following was investigated: Factor A. Crop rotations with different proportions of winter and spring crops (1. Without winter crops; 2. Winter crops 25%; 3. Winter crops 50%; 4. Winter crops 75%; 5. Winter crops 100%), growing annual and perennial grasses, spring and winter wheat, triticale, and barley. Factor B. Soil tillage systems: 1. Conventional (primary soil tillage was performed by ploughing); 2. Sustainable (after grasses the soil was ploughed, after other preceding crops the soil was loosened without inverting the topsoil). Our experimental evidence suggests that increasing winter crops in the crop rotation reduced compaction of the topsoil from high to moderate, maintained up to 37.3% of higher productive moisture reserves, improved water to air ratio, and increased the crop rotation productivity up to 44.7%. The application of reduced primary tillage in a sustainable system had persistence of high soil compaction and 8.0% lower air-filled porosity at the bottom of the topsoil, but the whole topsoil reached physical maturity more evenly in the spring. The grain yield of cereals was 6.4% lower compared with the yield after conventional soil tillage. On these clay loam soils, spring cereals were more sensitive (poorer performance) to reduced soil tillage compared with winter cereals.