Winter cover crops effects on soil organic carbon and soil physical quality in a Typical Argiudoll under continuous soybean cropping

SALAZAR, M.P.; SORACCO C.G.; VILLARREAL, RAFAEL; POLICH, NICOLAS; BELLORA, G.L.; TURINETTO, M.J.; LOZANO L.A.

REVISTA BRASILEIRA DE CIêNCIA DO SOLO

SOC BRASILEIRA DE CIENCIA DO SOLO

Lugar: Vicosa; Año: 2020

0100-0683

The massive adoption of no-tillage (NT), along with the simplification of the cropping sequences has led to physical and chemical degradation of soils. In order to recover degraded soils, cover crops have been proposed as an alternative to increase soil organic carbon (SOC) and to improve soil physical quality (SPQ). The aims of this study were (i) To determine the content of SOC and its physical and chemical fractions at different depths and positions, in a soil with a soybean crop under NT with and without winter cover crops, and (ii) To determine SPQ indicators in a soybean crop under NT with and without winter cover crops. Measures and samples were made on a field experiment in a typical Argiudoll of the Argentinean Pampas. SOC, coarse and fine particulate organic carbon (POCc and POCf), mineral associated organic carbon (MOC), fulvic acids (FA), humic acids (HA) and humins (H) were determined. SPQ indicators determined were: soil bulk density and total porosity from field samples, and saturated hydraulic conductivity, water-conducting macro and mesoporosity and total porosity connectivity from field water infiltration data. After 8 years, cover crops did not cause any observable change in whole SOC content, but significant differences were observed for some SOC fractions. HA and POCc had 40 and 25% increases, respectively, in the cover crop treatment. MOC and H, decreased by 9 and 7 % in cover crop treatment. SPQ did not improve after 8 years of cover crops. This can be related to degradation processes after 20 years of soybean monoculture under NT, and to the low ability of Argiudolls to recover from physical degradation.