Nitrate accumulation in the soil profile: Long-term effects of tillage, rotation and N rate in a Mediterranean Vertisol
This study is summarised as evidence for the following.
Soil: Use crop rotationsAction Link
Soil: Use no tillage in arable fieldsAction Link
Soil: Use crop rotations
A replicated, randomized, controlled study in 1992–2010 in a rainfed wheat field in southern Spain found inconsistent differences in nitrate between soils with or without crop rotations. Nutrients: Less nitrate was found in soils with crop rotations, compared to continuous wheat, in three of four rotations (55–117 vs 124 kg nitrate/ha), but more was found in one of four rotations (wheat-faba bean: 139 kg/ha). Methods: Wheat was grown continuously (one plot/year) or in two-year rotations with chickpeas, faba beans, sunflower, or fallows (each with two plots/year: one wheat, one alternate), in each of two tillage treatments (conventional tillage or no tillage), in each of three blocks. Each plot had four subplots (10 x 5 m), each with a different amount of fertilizer (0–150 kg N/ha). Soil samples were collected every three years (0–90 cm).
Soil: Use no tillage in arable fields
A replicated, randomized, controlled study in 1986–2010 in a rainfed wheat field in southern Spain (same study as (21)) found less nitrate in soils with no tillage, compared to conventional tillage. Nutrients: Less nitrate was found in plots with no tillage, compared to conventional tillage (104 vs 112 kg NO3-N/ha). Methods: No tillage or conventional tillage was used on three plots each (10 x 5 m plots). A mouldboard plough, a disk harrow, and/or a vibrating tine cultivator were used for conventional tillage (depth not reported). A seed drill and pre-emergence herbicide was used for no tillage. Post-emergence herbicide was used on some subplots (which had different wheat rotations), and some subplots were fertilized (0–150 kg N/ha/year). Soil samples were collected before sowing (Eijkelkamp auger, three samples/plot, 0–90 cm depth), in 1993–2010.