Effects of road- vs. field-recommended tyre inflation pressures and small variations in soil moisture content on traffic-induced soil compaction during seedbed preparation

Abstract

Soil compaction has become one of the most common forms of soil degradation, with associated negative effects on the functioning of agricultural soils. Decades of research have led to publication of several practical measures that mitigate risk of soil compaction, yet adoption among European farmers remains limited. To improve adoption by farmers, experiments under practical conditions using common operations should be performed. A field experiment was set up to evaluate the effects of road- (200 kPa) vs. field- (140 kPa and 100 kPa) recommended tyre inflation pressure and soil moisture content (0.24 g g−1 vs. 0.22 g g−1) on traffic-induced compaction of a silt loam soil during seedbed preparation. The various tyre inflation pressures were tested using two tyre types (standard radial tyre at 200 kPa and 140 kPa; VF tyre at 100 kPa) of similar dimensions mounted onto the same tractor. Variation in experimental soil moisture content was achieved by performing the seedbed preparation on two dates in spring (early, March 30th, vs. late, April 14th). In this one-year study, reducing the standard-tyre inflation pressure from road- (200 kPa) to field-recommended (140 kPa) pressure did not prevent soil compaction. The use of VF tyres at field-recommended (100 kPa) tyre inflation pressure resulted in significant reductions in vertical contact stress and mean normal stress as compared to 200 kPa. Although non-significant, the pressure reduction from 200 kPa to 140 kPa did result in a 4 % increase in in-track dry matter sugar beet yield while a reduction from 200 kPa to 100 kPa resulted in an 11% increase. Lower tyre inflation pressure showed no significant effect on fuel consumption and penetration resistance. Seedbed preparation under slightly drier (0.22 g g−1) soil conditions negatively affected fuel consumption (+11 %) and resulted in an in-track dry matter sugar beet yield increase of 11 %. For both tested prevention strategies, the impact of soil compaction was better observable by sugar beet yield than by most of the measured soil physical parameters.