Maize seedling response to the soil environment at varying distances from a mulched soil-bare soil boundary

Abstract Planting machinery generally sweeps surface mulch away from the row zone. Insight into the influence of a mulched inter-row zone on the conditions in a bare row zone was sought by examining the seedling response of maize to soil physical conditions across a sharp boundary between bare soil and mulched soil. The data were collected in the semi-arid tropics at Katherine, N.T., using coconut fibre matting as a mulch on a loamy sand and a clay loam soil. Mulching increased shoot growth rate before and after emergence. Surface mulch also increased the length of the first internode, thereby positioning the apical meristem of the plant at a shallower depth in mulched soil. The differences in the response of the plant are consistent with the higher maximum and longer exposure to high temperature in the bare soil. When maximum soil temperature at 25 mm was > 37°C, pre-emergent shoot growth declined rapidly and the first internode was shortened. The effect of mulch on soil temperature and plant response decline rapidly, and was negligible 100 mm from the boundary. While it is beneficial to have mulched soil over the seed, the effort and cost required to achieve this demands consideration of optimal strategies of mulch placement.