Reduced tillage for sustainable dryland farming

Abstract

The use of reduced tillage and residue placement hold much promise for the development of sustainable dryland agriculture. Dryland soils are nutrient poor and are characterised by low soil moisture and high soil erosion. Due to the lack of irrigation in dryland farming soil moisture can only be conserved through reduced tillage. The limitation imposed by nutrients and carbon can be removed by the exogenous supply of plant residue in combination with inorganic fertilizer. Reduced tillage system reduces fuel energy inputs, enhances water retention and infiltration, enhances nutrient retention in the effective rooting zone and improves crop growth. Reduced tillage leads to greater accumulation of better quality organic matter and increased microbial biomass which acts as a large dynamic source and sink of nutrients. Microbial communities can be managed through residue placement for long-term conservation of soil organic matter in the fragile dryland soils. Evidence is presented to show that nutrient availability can be modified through microbial management by varying the resource quality.