Sustainable Tillage Options under Flood-Based Farming Systems

Floodplains are usually endowed with abundant water resources and fertile soils making them the world’s most productive ecosystems. However, these floodplains are prone to soil erosion, eutrophication and increased emission of greenhouse gases (GHG). Therefore, sustainable tillage is critical for sustainable agriculture in these ecosystems. This chapter discusses sustainable tillage methods for flood-based farming systems (FBFS) with focus on flood-recessing cropping. Two categories of tillage methods were identified: flat land and raised land. In flat land tillage, there is minimum soil disturbance and crops are grown on the flat, for example, hand-dug planting holes and furrows made using the mouldboard plough. Raised land tillage includes 10–40 cm high ridges, cropping dykes and up to 150 cm high-raised fields. Mulching using crop residues and green manuring were implemented under raised land tillage but not flat land methods. There is limited research on soil fertility and yield benefits of FBFS tillage methods. We recommend complementing flat land tillage with mulching to conserve soil water and alley cropping to reduce soil erosion. Bio-tillage and precision tillage are emerging tillage methods for FBFS, but the later will not be relevant for the foreseeable future in low-technology systems. Bio-tillage reduces soil compaction, and improves soil aeration and hydraulic properties, and increases crop yields. Research is required to (i) evaluate the effect of plant residue retention on soil fertility, carbon sequestration, crop yield and GHG emission under the FBFS tillage methods; and (ii) to optimise bio-tillage through selection and management of effective plants.