Soil erosion and surface runoff under strip tillage for sugar beet (Beta vulgaris L.) in Central Europe

Soil erosion due to cultivation of row crops on soils with a high silt content can result in hazardous on-site and off-site damages. An effective and sustainable soil protection measure is to reduce the intensity of tillage. On-farm trials were conducted to compare the effect of strip tillage (ST), full-width reduced tillage (RT) and intensive tillage (IT) systems on surface runoff and soil loss in sugar beet crops grown on four typical loess sites in hilly regions of southern Germany in 2014 and 2015. Heavy rainfall (24 mm 20 min(-1)) was simulated in the 4-6 leaf stage of sugar beet with a small portable nozzle rainfall simulator. Observed data were used to establish soil loss ratios for ST as part of the cropping and management factor of RUSLE. Compared to IT, surface runoff was 55% and 92% lower for RT and ST, respectively, caused by increased water infiltration presumably due to (i) higher earthworm activity and (ii) the absence of negative effects of reduced tillage intensity on penetration resistance. Moreover, reducing tillage intensity increased surface residue cover, initial water content and organic carbon content in the topsoil layer. Soil loss was 85% and 98% lower for RT and ST compared to IT, respectively, as a result of (i) decreased runoff rates, (ii) higher stability of aggregates against the impact of raindrops and (iii) reduced velocity of the runoff flow and thereby lower sediment concentrations. Based on residue cover, the soil loss ratio calculated for ST agreed well with values established for other tillage systems. Overall, reducing, tillage intensity by strip tillage was proven to offer environmental benefits due to reduced surface runoff and soil loss. In addition, plant-available water likely increases through enhanced infiltration. (C) 2016 Elsevier B.V. All rights reserved.