Soil biochemical response to long-term conservation tillage under semi-arid Mediterranean conditions

Soil: Use reduced tillage in arable fields

A replicated, randomized, controlled study in 1992–2005 in a rainfed wheat-sunflower-pea field near Seville, Spain (same study as (28,33)), found more soil organisms in soils with reduced tillage, compared to conventional tillage. Soil organisms: More microbial biomass (measured as carbon) was found in soils with reduced tillage, compared to conventional tillage, in one of six comparisons (0–5 cm depth, November 2004: 316 vs 183 mg C/kg soil). Methods: Conventional tillage or reduced tillage was used on three plots each (22 x 14 m plots). A mouldboard plough (25–30 cm depth), a cultivator (12–15 cm depth, 1–3 times/year), a disc harrow (5–15 cm depth, 1–2 times/year), and herbicide were used for conventional tillage. A chisel plough (25–30 cm depth), a disc harrow (5–7 cm depth), and herbicide were used for reduced tillage. Wheat, sunflowers, and peas were grown in rotation. Wheat was fertilized, but sunflowers and peas were not. Soil samples were collected in November 2004 and December 2005 (0–25 cm depth, two samples/plot).