Soil structure of a clay loam as affected by long-term tillage and residue management

Soil structure is of great importance for a number of other related properties and agricultural management affects it. Under semiarid climatic conditions, soil water for crop growth is particularly important and water retention characteristics are highly dependent on soil structure. Soil physical properties relevant to infer structure were examined along with some basic parameters in a Greek long-term experiment (Thesustill). The objectives of this study were the impacts of tillage system (conventional, reduced and no-fill) and crop residue management (removed or remaining) in a sandy clay loam on the functionality of the pore network. Soil organic carbon content and aggregate stability increased with reduction in soil disturbance and greater inputs of organic material. Dexter-n, representing the amount of organic carbon not complexed with clay, which controls soil physical behaviour, improved with addition of crop residues and even more so with reduction in tillage intensity. No-fill had a negative impact on soil bulk density and penetration resistance, water retention was increased between pF 1.5 to 4.2. A major result was that reduced tillage was most beneficial in terms of plant available water, also the pore network and its connectivity improved as indicated by gas diffusion results. No-fill had far lower air-filled porosities at comparable matric potentials than filled soils, but diffusivities were high, suggesting well-connected pipe-like pores. Results were unaffected by textural variability. Reduced tillage overall is the most promising option, the impact of residue management likely needs more time to induce the expectable improvements.