Potential for no-tillage and clipped-weed mulching to improve soil quality and yield in organic eggplant production

Deep-inversion tillage for weed control and residue incorporation can have a detrimental effect on agroecosystems. Despite the potential for no-tillage (NT) organic farming to improve soil quality, the yield response of NT can vary. This study compared the effects of NT and conventional rotary tillage (CT), leafmould application (LM+) and no leafmould (LM–), clipped-weed mulch application (CM+) and no weed mulch (CM–) on eggplant yield and crop residue (Solanum melongena L.) and on soil chemical and physical properties under standard organic farming conditions. In both years, NT CM+ resulted in higher yield and crop residue than in NT CM–. Soil bulk density was 34 and 32% lower in 2014 and 2015, respectively, in NT compared with CT. In both years, CM+ had a significant impact on the water content in the surface-layer in both tillage systems. Soil organic carbon and active carbon concentrations, at 0–2.5 cm depth, were 85 and 20% higher in NT than in CT. In October, NO3-N, exchangeable Mg2+, Ca2+ (in 0–2.5 cm only) and available P (in 0–2.5 cm only) were higher in NT than in CT in soil layers 0–2.5 cm and 2.5–7.5 cm. CM+ resulted in increased soil inorganic nitrogen in NT plots during the growing season. The results suggested that NT with CM+ application can be a valuable conservation practice for increasing yield and soil carbon in organic farming by reducing tillage intensity.