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Individual study: Cover crops under different managements vs. frequent tillage in almond orchards in semiarid conditions: Effects on soil quality

Published source details

Ramos M.E., Benitez E., García P.A. & Robles A.B. (2010) Cover crops under different managements vs. frequent tillage in almond orchards in semiarid conditions: Effects on soil quality. Applied Soil Ecology, 44, 6-14


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Water: Use organic fertilizer instead of inorganic Mediterranean Farmland

A replicated, randomized, controlled study in 2006 in a rainfed almond orchard near Granada, Spain, found less water in organically-fertilized soils, compared to inorganically-fertilized soils. Water availability: Less water was found in organically-fertilized soils, compared to inorganically-fertilized soils, in one of two comparisons (June: 4.6 vs 5.6 g water/100 g soil). Methods: Organic fertilizer (1,500 kg compost/ha, made from sheep manure and turf) or mineral fertilizer (250 kg/ha, 4.6% N, 1.2% P, 1.5% K) was used on 18 plots each (588 m2). Some organic fertilizer was used on all plots (30 t manure/ha), and one-third of the plots were grazed by sheep (7 kg organic C/ha from excrement). All plots had cover crops. Soil samples were collected on 7 June and 18 July 2006 (0–20 cm depth). It was not clear whether these results were a direct effect of the type or amount of fertilizer.

 

Soil: Use organic fertilizer instead of inorganic Mediterranean Farmland

A replicated, randomized, controlled study in 2006 in a rainfed almond orchard near Granada, Spain, found no differences in organic matter, nutrients, or soil stability between plots with organic or inorganic fertilizer. Organic matter: Similar amounts of organic carbon were found in soils with organic or inorganic fertilizer (8.8 vs 8.6 g C/kg soil). Nutrients: Similar amounts of nitrogen (1.1 g N/kg soil), phosphorus (1.7 vs 2 mg P/kg soil), and potassium (156 vs 153 mg K/kg soil), and similar pH levels (pH 8.3), were found in soils with organic or inorganic fertilizer. Soil erosion and aggregation: Similar soil stability was found in plots with organic or inorganic fertilizer (62% of soil aggregates were water-stable; 16% vs 15% change in the mean weight diameter of soil aggregates after sieving). Methods: Organic fertilizer (1,500 kg compost/ha, made from sheep manure and turf) or mineral fertilizer (250 kg/ha, 4.6% N, 1.2% P, 1.5% K) was used on 18 plots each (588 m2). Some organic fertilizer was used on all plots (30 t manure/ha), and one-third of the plots were grazed by sheep (7 kg organic C/ha from excrement). All plots had cover crops. Soil samples were collected on 18 July 2006 (0–20 cm depth). It was not clear whether these results were a direct effect of the type or amount of fertilizer.

 

Soil: Plant or maintain ground cover in orchards or vineyards Mediterranean Farmland

A site comparison in 2006 in two rainfed almond orchards near Granada, Spain, found more organic matter and nitrogen, less phosphorus, and lower pH in soils with cover crops (without tillage), compared to soils with conventional tillage (without cover crops). Organic matter: More organic carbon was found in soils with cover crops (without tillage), compared to soils with conventional tillage (without cover crops) (8.4–9 vs 5.4 g total organic C/kg soil). Nutrients: More nitrogen was found in soils with cover crops (without tillage), compared to soils with conventional tillage (without cover crops) (1.1 vs 0.83 g total N/kg soil), but less phosphorus was found in one of two comparisons (oat-vetch cover crop: 1.6 vs 2.1 mg available P/kg soil), and lower pH was found (8.3 vs 8.5), but similar amounts of potassium were found (148–162 vs 186 mg available K/kg soil). Soil erosion and aggregation: Higher soil stability was found in plots with cover crops (without tillage), compared to plots with conventional tillage (without cover crops), in one of two comparisons (61–62% vs 44% of aggregates were water-stable), but lower soil stability was found in two of four comparisons (15% vs 13% change in the mean weight diameter of soil aggregates after sieving). Implementation options: More phosphorus was found in soils that were cover cropped with oats, compared to oats and vetch (2.1 vs 1.6 mg available P/kg soil). Methods: Conventional tillage (chisel plough, 20–25 cm depth, 3–4 times/year in 2001–2005, October 2005, and April and June 2006) was used in one orchard, and no tillage was used in another orchard with two cover crops (oats and vetch or oats only, sown in January 2006 on one 1 ha plot each). Both orchards were fertilized (30 t compost/ha), but the orchard with cover crops got more fertilizer (1,500 kg organic fertilizer/ha on one-third of each plot, 250 kg mineral fertilizer/ha on one-third). The orchard with cover crops had cereal-fallow rotations before the cover crops, and it was tilled in November. Soil samples were collected on 18 July 2006 (0–20 cm depth). It was not clear whether these results were a direct effect of cover crops, tillage, fertilizer, or site.

 

Water: Plant or maintain ground cover in orchards or vineyards Mediterranean Farmland

A site comparison in 2006 in two rainfed almond orchards near Granada, Spain, found less water in soils with cover crops, compared to conventional tillage. Water availability: Less water was found in soils with cover crops (2–5 vs 5–9 g water/100 g soil). Methods: Conventional tillage (chisel plough, 20–25 cm depth, 3–4 times/year in 2001–2005, October 2005, and April and June 2006) was used in one orchard, and no tillage was used in another orchard with two cover crops (oats and vetch or oats only, sown in January 2006 on one 1 ha plot each). Both orchards were fertilized (30 t compost/ha), but the orchard with cover crops got more fertilizer (1,500 kg organic fertilizer/ha on one-third of each plot, 250 kg mineral fertilizer/ha on one-third). The orchard with cover crops had cereal-fallow rotations before the cover crops, and it was tilled in November. Soil samples were collected on 7 June and 18 July 2006 (0–20 cm depth). It was not clear whether these results were a direct effect of cover crops (and tillage), fertilizer, or site.