Comment on soil-2021-113

Abstract

Conservation agriculture (CA) relies on two key practices to improve agricultural sustainability—reduced tillage and cover crop usage. Despite known soil physics benefits (reduced soil compaction and strength, enhanced soil porosity and permeability), inconsistent reports on short-term CA results have limited its adoption in European agroecosystems. To elucidate the short-term effects, a three-year experiment in the low-lying Venetian plain (Northern Italy) was undertaken. Bulk density, penetration resistance, and soil hydraulic measures were used to evaluate results obtained by combining three tillage intensities (conventional tillage (CT), minimum tillage (MT), no tillage (NT)) with three winter soil coverages (bare soil (BS), tillage radish cover crop (TR), winter wheat cover crop (WW)). Among the tillage methods and soil layers, CT, on average, reduced BD (1.42 g cm−3) and PR (1.64 MPa) better in the 0–30 cm tilled layer. Other treatments yielded higher values (+4 % BD and +3.1 % PR) in the same layer. Across the soil profile, reduced tillage coupled with WW improved soil physics even below the tilled layer, as evidenced by root growth-limiting threshold declines (−11 % in BD values > 1.55 g cm−3 and −7 % in PR values > 2.5 MPa). Soil hydraulic measures confirmed this positive behaviour; NT combined with either BS or WW produced a soil saturated conductivity of 2.12 × 10−4 m s−1 (four-fold that of all other treatments). Likewise, sorptivity increased in NT combined with BS versus other treatments (3.64 × 10−4 m s−1 vs an all-treatment average of 7.98 × 10−5 m s−1). Our results suggest that despite some measure declines due to reduced tillage, the strategy enhances soil physics. In the short term, cover crop WW moderately increased physical soil parameters, whereas TR had negligible effects. This study demonstrates that CA effects require monitoring several soil physical parameters.