Short-Term Impact of Conservation Agriculture on Soil Strength and Saturated Hydraulic Conductivity in the South African Semiarid Areas

The severe limitation of agricultural land productivity induced by physical soil degradation has become a major concern in semiarid climates, especially in the Eastern Cape Province, South Africa. A randomized complete block design in a split-split-plot arrangement was used to evaluate the short-term (2012–2015) effects of tillage (no-till (NT) and conventional tillage (CT)), rotation (maize-fallow-maize (MFM); maize-fallow-soybean (MFS); maize-wheat-maize (MWM) and maize-wheat-soybean (MWS)) and residue management (residue removal (R−) and residue retention (R+)) on bulk density (BD), penetration resistance (PR), soil hydraulic conductivity (Ks) and macroporosity hydraulic conductivity. The interaction of tillage × crop rotation × residue management was not significant (p > 0.05) with respect to BD, PR, Ks and macroporosity. The MFM rotation had the highest BD (1.40 g cm−3), followed by MWM rotation (1.36 g cm−3), and the least BD was observed in the MFS rotation (1.29 g cm−3). Penetration resistance was significantly higher in CT (2.43 MPa) compared to NT (1.46 MPa). The study concludes that inclusion of MFS and MWS rotations can potentially reduce BD in the short term. Similarly, conversion from CT to NT reduces soil resistance.