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Soil physical state as influenced by long-term reduced tillage, no-tillage and straw management

Since 1999, a long-term field experiment has been done at the Experimental Station of the Lithuanian University of Agriculture (currently – Vytautas Magnus University). The current research was conducted in 2013–2015. The aim of the study was to evaluate the effects of long-term tillage systems and straw management on soil penetration resistance, shear strength and soil aggregate stability. The soil of the experimental site was Epieutric Endocalcaric Endogleyic Planosol. A short crop rotation was introduced: winter wheat → spring barley → spring oilseed rape. According to two factor field experiment, the straw was removed from one part of the experimental field, and on the other part of the field the straw was chopped and spread at harvesting (factor A). Six tillage systems: conventional (deep) and shallow ploughing, shallow loosening, shallow rotovating, catch cropping and rotovating, and no-tillage, were used as a subplot (factor B). During a 16-year (1999–2015) period, long-term application of reduced tillage resulted in a significant increase in soil penetration resistance and shear strength. The results of current study show that the lesser the tillage depth, the higher the soil penetration resistance and shear strength. The effect of straw residue spreading was lower comparing with treatment without straw. Soil aggregate stability was highly dependent on tillage. Shallow rotovating before sowing increased soil aggregate stability by up to 1.8 times, incorporation of plant residues of white mustard into the soil by a rotovator before sowing increased it by up to 2.0 times and no-tillage by up to 1.9 times, compared with conventional ploughing.