Zero tillage has important consequences for soil pore architecture and hydraulic transport: A review

Abstract

• Soil macroporosity decreases in ZT soils at the surface. • Soil structure changes are dependent on texture, depth, and time since conversion. • Changes in soil structure are not always reflected by hydraulic functionality. • ZT pore networks may increase losses of soluble material by preferential transport. Following the adoption of zero-tillage (ZT) from conventional tillage (CT), the soil pore network undergoes immediate and significant changes. As soil remains undisturbed for an extended period, a soil structure emerges that is primarily generated and stabilised by both biotic and abiotic processes. There is limited understanding concerning how the adoption of ZT influences the soil porous architecture and associated soil hydraulic properties, and specifically over what timeframe these changes occur. Since a previous synthesis of such information over 20-years ago, there has been a substantial number of new investigations aimed at addressing this knowledge gap. Here we review 34 papers that illustrate ZT can influence porosity depending on soil texture, pore size class, depth and time, and also influence important transport mechanisms likely to impact the fate of agrochemicals in soils. We found decreased macroporosity in surface layers of soil under ZT when compared with CT. In addition, soil pore connectivity tended to increase in soil under ZT though the associated effects on hydraulic transport were less clear. Our investigation reveals the value of a prospective examination of an evolving ZT pore network both visually and functionally across temporal and spatial scales. We also highlight the necessity for standardised methodology to aid in future data compatibility and quantitative analysis.