Providing evidence to improve practice

Action: Water: Use reduced tillage in arable fields Mediterranean Farmland

Key messages

Water use (3 studies): Two replicated, randomized, controlled studies from Spain and Turkey found that crops used water more efficiently in plots with reduced tillage, compared to conventional tillage, in some comparisons. One replicated, randomized, controlled study from Egypt found that crops used water more efficiently in plots with less-frequent tillage (one pass with a plough, compared to two), but crops used water less efficiently in plots with shallow tillage, compared to deep tillage.

Water availability (14 studies)

  • Water content (12 studies): Six controlled studies (five replicated and randomized) from Egypt and Spain found more water in soils with reduced tillage, compared to conventional tillage, in some or all comparisons. Two of these studies also found less water in soils with reduced tillage, compared to conventional tillage, in some comparisons. Two replicated, randomized, controlled studies from Lebanon and the USA found less water in soils with reduced tillage, compared to conventional tillage, in some comparisons. Four controlled studies from Egypt, Italy, and Spain (three of which were replicated and randomized), found similar amounts of water in soils with reduced tillage or conventional tillage, in all comparisons.
  • Water loss (2 studies): One replicated, controlled study from France found that less water was lost through drainage from soils with reduced tillage, compared to conventional tillage, during the growing season, but more water was lost during the fallow season, in some comparisons. One replicated, randomized, controlled study from Egypt found that less water was lost through runoff from soils with less-frequent tillage (one pass with a plough, compared to two), but more water was lost through runoff from soils with shallow tillage, compared deep tillage.
  • Water infiltration (3 studies): One replicated, randomized, controlled study from Egypt found that water infiltration rates were faster in soils with reduced tillage, compared to conventional tillage, in some comparisons. Two replicated, controlled studies from Spain and the USA found that water infiltration rates were similar in soils with reduced tillage or conventional tillage.

Pathogens and pesticides (1 study): One replicated, randomized, controlled study from France found that less herbicide was leached from soils with reduced tillage, compared to conventional tillage.

Nutrients (0 studies)

Sediments (0 studies)

Implementation options (2 studies): One replicated, randomized, controlled study from Egypt found more water and faster water infiltration rates in soils that were tilled at slower tractor speeds, but found that water losses and water-use efficiencies were similar in plots that were tilled at different tractor speeds. One replicated, randomized, controlled study from Turkey found that water-use efficiencies were similar in plots with different types of reduced tillage (rototilling and disking, compared to double disking).

Supporting evidence from individual studies

1 

A replicated, randomized, controlled study in 1998–2000 in an irrigated vegetable field in the Salinas Valley, California, USA, found less water in soils with reduced tillage, compared to conventional tillage. Water availability: Less water was found in soils with reduced tillage, compared to conventional tillage, in 12 of 16 comparisons (0.07–0.26 vs 0.08–0.27 g water/g soil; 0–15 cm depth). Methods: There were four plots (0.52 ha), for each of four treatments (reduced tillage or conventional tillage, with or without added organic matter). In plots with added organic matter, compost was added two times/year, and a cover crop (Merced rye) was grown every autumn or winter. Lettuce or broccoli crops were grown in raised beds. Sprinklers and drip irrigation were used in all plots. Soils were disturbed to different depths (conventional tillage: disking to 50 cm depth, cultivating, sub-soiling, bed re-making, and bed-shaping; reduced tillage: cultivating to 20 cm depth, rolling, and bed-shaping). Soils were collected, along the planting line, with 6 cm soil cores.

 

2 

A controlled study in 1994–1999 in a rainfed legume-cereal field near Barcelona, Spain, found more water in soils with reduced tillage, compared to conventional tillage. Water availability: More water was found in soils with reduced tillage, compared to conventional tillage (29 vs 26 mm mean topsoil water content in February–May). Methods: Reduced tillage or conventional tillage was used on one plot each (90 x 30 m plots). A mouldboard plough was used for conventional tillage, and a chisel plough was used for reduced tillage, in September (depths not reported). Herbicide was used in both plots in September and January, and fertilizer was added in October. Seeds were sown with a seed drill in December and crops were harvested in July. Crop residues were removed from all plots before tillage. Water was measured weekly (February–May, two time-domain reflectometer probes/plot, 20 cm depth).

 

3 

A replicated, randomized, controlled study in 2001–2004 in a rainfed wheat-vetch field in the Marmara region, Turkey, found higher water-use efficiencies in plots with reduced tillage, compared to conventional tillage. Water use: Higher crop yields (relative to rainfall) were found in plots with reduced tillage, compared to conventional tillage, in one of two comparisons (7.6 vs 7.2 precipitation use efficiency). Implementation options: Similar crop yields (relative to rainfall) were found in plots that were rototilled and disked or double disked (7.6 vs 7.4 precipitation use efficiency). Methods: Conventional tillage with a mouldboard plough (20–22 cm depth) and a double disc (two passes, 8–10 cm depth), reduced tillage with a rototiller (20–22 cm depth) and a double disc (one pass, 8–10 cm), or reduced tillage with a double disc (two passes, 8–10 cm) was used on three plots each (15 x 75 m plots). Fertilizer and herbicide were used on all plots. Wheat was sown in December 2001, October 2002, and November 2003. Vetch was sown in December 2001, November 2002, and December 2003. Wheat and vetch were harvested in June 2002–2004 (3 m2 samples, three/plot).

 

4 

A replicated, randomized, controlled study in 2003–2005 on rainfed farms in the Ebro river valley, Spain, found that tillage had inconsistent effects on water in soils. Water availability: More water was found in soils with reduced tillage, compared to conventional tillage, in 4 of 18 comparisons, in the two days after tillage (0.10–0.23 vs 0.09–0.20 g water/g soil), but less water was found in 6 of 18 comparisons (0.05–0.11 vs 0.08–0.14). Methods: Reduced tillage or conventional tillage was used on seven plots each (33–50 x 7–10 m plots), on a total of two farms, with multiple crops. A mouldboard or subsoil plough was used on plots with conventional tillage (25–40 cm depth). A cultivator (15 cm depth) or chisel plough (25–30 cm depth) was used on plots with reduced tillage. Water was measured in soil samples (5 cm depth), at three times (0, 24, and 48 hours after tillage).

 

5 

A replicated, randomized, controlled study in 1996–2008 in a rainfed barley field in northeast Spain (same study as (8,9)) found more water in soils with reduced tillage, compared to conventional tillage, in some comparisons. Water availability: More water was found in soils with reduced tillage, compared to conventional tillage, in 10 of 16 comparisons (0.07–0.21 vs 0.05–0.18 g water/g dry soil). Methods: Reduced tillage or conventional tillage was used on nine plots each (50 x 6 m). A mouldboard plough or a disc plough was used for conventional tillage (25–30 cm depth, 100% incorporation of crop residues). A cultivator was used for reduced tillage (10–15 cm depth, 50% incorporation of crop residues). Two-thirds of the plots were fertilized (60 or 120 kg N/ha). Water content was measured in soil samples (0–5 cm depth).

 

6 

A replicated, randomized, controlled study in 2005–2007 in a rainfed field in the central Bekaa Valley, Lebanon, found less water in soils with reduced tillage, compared to conventional tillage, in one of 10 comparisons. Water availability: Less water was found in soils with reduced tillage, compared to conventional tillage, in one of 10 comparisons (water content not reported). Methods: Reduced tillage or conventional tillage was used in four plots each (14 x 6 m), in October. Conventional plots were ploughed (25–30 cm depth) and then shallowly disc cultivated. Reduced plots were shallowly disc cultivated (10 cm depth). Barley, chickpeas, and safflower were planted in November. Barley and safflower were fertilized (60–100 kg N/ha). Soil water was measured at two depths (25 and 50 cm), on five dates from 30 March 2005–16 August 2006, with a time domain reflectometer.

 

7 

A replicated, controlled study in 2004–2008 in an irrigated maize field in the Garonne River corridor, southern France (same study as (10)), found that tillage had inconsistent effects on water loss. Water availability: Less water was lost through drainage from soils with reduced tillage, compared to conventional tillage, during three of four growing seasons, but more water was lost during two of four fallow seasons (drainage volumes not reported for significant comparisons). Methods: Conventional tillage or reduced tillage was used on six plots each (20 x 50 m plots). Three of these plots had winter cover crops (white mustard or oats) and three had bare soil. A mouldboard plough (28–30 cm depth) and a cultivator (8 cm depth, 1–2 passes) were used for conventional tillage, in April–May. A cultivator (7–9 cm depth) and a disc harrow (8–12 cm depth) were used for reduced tillage, in March–April. Maize was sown in April–May 2005–2008 and harvested in October 2005–2008. Drainage from soils was measured with fiberglass-wick lysimeters (40 cm depth, two lysimeters/plot), on 67 sampling dates. A centre-pivot sprinkler was used for irrigation (857–943 mm water/year, irrigation plus rainfall).

 

8 

A replicated, randomized, controlled study in 1996–2009 in a rainfed barley field in the Ebro river valley, Spain (same study as (5,9)), found that tillage had inconsistent effects on water in soils. Water availability: More water was found in soils with reduced tillage, compared to conventional tillage, in five of 16 comparisons (160–235 vs 135–215 g water/g soil), but less water was found in one of 16 comparisons (100 vs 115). Methods: Reduced tillage or conventional tillage was used on nine plots each (50 x 6 m plots), in October or November. A mouldboard plough was used for conventional tillage (25–30 cm depth, 100% incorporation of crop residues). A cultivator was used for reduced tillage (10–15 cm depth, 50% incorporation of crop residues). Two-thirds of the plots were fertilized (60 or 120 kg N/ha). Soil samples were collected four times/year in 2005–2009 (0–100 cm depth).

 

9 

A replicated, randomized, controlled study in 1996–2009 in a rainfed barley field in the Ebro river valley, Spain (same study as (5,8)), found higher water-use efficiency in plots with reduced tillage, compared to conventional tillage, in two of three comparisons. Water use: Higher water-use efficiency was found in plots with reduced tillage, compared to conventional tillage, in two of three comparisons (4.3–5.2 vs 1.8–2.1 kg barley grain/mm rainfall). Methods: Reduced tillage or conventional tillage was used on nine plots each (50 x 6 m plots), in October or November. A mouldboard plough was used for conventional tillage (25–30 cm depth, 100% incorporation of crop residues). A cultivator was used for reduced tillage (10–15 cm depth, 50% incorporation of crop residues). Two-thirds of the plots were fertilized (60 or 120 kg N/ha). Soil samples were collected five times/year (two samples/plot, 4 cm diameter soil auger, 0–100 cm depth) in 2005–2009. Mature barley was harvested in June 2006–2009.

 

10 

A replicated, controlled study in 2004–2008 in an irrigated maize field in the Garonne River corridor, in southern France (same study as (7)) found that less herbicide was leached from soils with reduced tillage, compared to conventional tillage. Pathogens and pesticides: Less herbicide was leached from soils with reduced tillage, compared to conventional tillage (10 vs 15% of applied herbicide). Methods: Conventional tillage or reduced tillage was used on two plots each (20 x 50 m plots). A mouldboard plough (28–30 cm depth) and a cultivator (8 cm depth, 1–2 passes) were used for conventional tillage, in April–May. A cultivator (7–9 cm depth) and a disc harrow (8–12 cm depth) were used for reduced tillage, in March–April. The herbicide (75 g/L Isoxaflutole) was sprayed 1–3 days after the maize was sown, in April–May 2005–2008. Herbicide leaching was measured in drainage water, with fiberglass-wick lysimeters (40 cm depth, two lysimeters/plot, 11–21 samples/year, 6–272 days after treatment with herbicide). A centre-pivot sprinkler was used for irrigation (650–736 mm water/year, irrigation plus rainfall).

 

11 

A controlled study in 1990–2007 in a rainfed wheat field in southern Italy found similar amounts of water in soils with reduced tillage or conventional tillage. Water availability: Similar amounts of water were found in soils with reduced tillage or conventional tillage (0.19–0.38 vs 0.20–0.36 cm3 water/cm3 soil). Methods: A mouldboard plough (40–45 cm depth) was used on one plot (conventional tillage), and a disc harrow (20–25 cm depth) was used on another plot (reduced tillage), from 1990–2007. Each plot was 23 x 10 m. Water content was measured in soil samples (5 cm height, 5 cm diameter, six samples/plot), during the growing season (March 2005, June 2006, May 2007).

 

12 

A replicated, randomized, controlled study in 1991–2008 in a rainfed wheat-sunflower-pea field near Seville, Spain, found similar amounts of water infiltration in soils with reduced tillage or conventional tillage. Water availability: Similar amounts of water infiltration were found in soils with reduced tillage or conventional tillage (0.28 vs 0.38 mm conductive macro-pore diameter). Methods: Reduced tillage or conventional tillage was used on three plots each (22 x 14 m plots). A mouldboard plough and a chisel plough were used for conventional tillage (25–30 cm depth), and crop residues were burned (1992–2003, but not 2004–2008). A chisel plough and herbicide were used for reduced tillage (25–30 cm depth), and crop residues were retained. Wheat, sunflowers, and peas were grown in rotation. Wheat was fertilized, but sunflowers and peas were not. Water infiltration was measured with an infiltrometer (between –60 and –20 mm tension) in 2008.

 

13 

A replicated, controlled study in 2007–2008 in an irrigated tomato field in Davis, California, USA, found similar rates of water infiltration in soils with reduced tillage or conventional tillage. Water availability: Similar rates of water infiltration were found in soils with reduced tillage or conventional tillage (6.5 vs 7.4 litres/foot/90 minutes). Methods: Conventional tillage or reduced tillage was used on four plots each (90 x 220 feet). Broadcast disking, subsoiling, land planing, and rebedding were used for conventional tillage. A Wilcox Performer was used for reduced tillage (two passes; beds were conserved). Sprinklers, furrow irrigation, and drip-tape (in furrows) were used to irrigate the tomatoes. All plots were fertilized. Water infiltration was measured in 2008 (using the blocked furrow method). Winter cover crops (triticale) were grown on half of each plot, and the other half was fallow in winter.

 

14 

A replicated, randomized, controlled study in 2008–2013 in a rainfed wheat-sunflower-pea field near Seville, Spain, found similar amounts of water in soils with reduced tillage or conventional tillage. Water availability: Similar amounts of water were found in soils with reduced tillage or conventional tillage (7.23–13.4 vs 7.11–14.0% soil moisture). Methods: Reduced tillage or conventional tillage was used on three plots each (6 x 33.5 m plots). A mouldboard plough (25–30 cm depth), a chisel plough (25 cm depth, twice/year), and a disc harrow (12 cm depth) were used for conventional tillage. A chisel plough (25 cm depth, once/year), a disc harrow (5 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 moisture was measured in May 2013 (0–5 cm depth, time-domain-reflectrometry probes) and early June (0–10 cm depth, gravimetric).

 

15 

A replicated, randomized, controlled study in 1987–2010 in rainfed cereal fields in the Ebro river valley, Spain, found more water in soils with reduced tillage, compared to conventional tillage. Water availability: More water was found in soils with reduced tillage, compared to conventional tillage, in one of 15 comparisons (in Selvanera: 150 vs 110 mm volumetric water content). Methods: Reduced tillage or conventional tillage was used on ten plot each (Peñalba: three plots each, 34 x 175 m plots, established in 2005; Agramunt: four plots each, 9 x 50 m plots, established in 1990; Selvanera: three plots each, 7 x 50 m plots, established in 1987). In Peñalba, a disk plough (20 cm depth) and a cultivator (10 cm depth) were used for conventional tillage. In Agramunt, a mouldboard plough (25 cm depth) and a cultivator (15 cm depth) were used for conventional tillage. In Selvanera, a subsoil plough (40 cm depth) and a chisel plough (15 cm depth) were used for conventional tillage. A cultivator (Peñalba: 10 cm depth; Agramunt: 15 cm) or a chisel plough (Selvanera: 15 cm) was used for reduced tillage. Barley (Peñalba) or wheat (Agramunt and Selvanera) was planted in November 2009 with a seed drill (2–4 cm depth) and harvested in June–July 2010. Soil samples were collected two times (at tillering and flowering, four samples/plot, 0–90 cm depth).

 

16 

A replicated, randomized, controlled study in 1994–2013 in a rainfed field near Madrid, Spain, found similar amounts of water in soils with reduced tillage or conventional tillage. Water availability: Similar amounts of water were found in soils with reduced tillage or conventional tillage (50–151 g water/kg soil). Methods: Conventional tillage or reduced tillage was used on eight plots each (10 x 25 m plots). A mouldboard plough was used for both conventional tillage (25 cm depth) and reduced tillage (20 cm depth). Crop residues were shredded and retained. Soil samples were collected six times, in October 2010–April 2013 (soil cores, 0–15 cm depth, 5 cm diameter).

 

17 

A replicated, randomized, controlled study in 2012–2013 in a rainfed wheat field in Wadi Madwar, northwestern Egypt, found more water, more efficient water use, faster infiltration, and less runoff in plots that were tilled less frequently, but found less efficient water use and more runoff in plots with shallower tillage, compared to deeper. More water and faster infiltration were found in soils that were tilled at slower speeds. Water use: Crops used water more efficiently in plots with reduced tillage, compared to conventional tillage (7.78 vs 7.14 kg grain/ha/mm rainfall). Crops used water less efficiently in plots that were tilled to 15 cm depth, compared to 20–25 cm depth (8.35 vs 9.22–9.23 kg grain/ha/mm rainfall). Water availability: More water was found in soils with reduced tillage, compared to conventional tillage (67 vs 43 mm). Similar amounts of water were found in soils that were tilled to different depths (15–25 cm depth: 66–68 mm water). Less runoff was found in plots with reduced tillage, compared to conventional tillage (10 vs 11 mm runoff). More runoff was found in plots that were tilled to 15 cm depth, compared to 20–25 cm depth (9.4 vs 8.5–8.6 mm runoff). Faster infiltration rates were found in soils with reduced tillage, compared to conventional tillage (7 vs 6 cm/hour). Faster infiltration rates were found in soils that were tilled to 20 cm depth, compared to 25 cm depth (8.2 vs 7.7 cm/hour), but similar infiltration rates were found in soils that were tilled to 15 cm or 25 cm depth (7.9 vs 7.7 cm/hour). Implementation options: No differences in water use or runoff water were found in plots that were tilled at different tractor speeds (8.39–9.26 kg grain/ha/mm rainfall, 8.6–9.2 mm runoff). More water was found in soils that were tilled at slower tractor speeds (0.69–1.25 m/s: 67–69 mm water), compared to the fastest speed (1.53 m/s: 65 mm water). Faster infiltration rates were found in soils that were tilled at slower tractor speeds (0.69–1 m/s: 8.5 cm water/hour), compared to faster tractor speeds (1.25 m/s: 7.8 cm; 1.53 m/s: 7 cm). Methods: Reduced tillage or conventional tillage was used on three plots each (0.45 ha plots). A chisel plough was used for both reduced tillage (one pass) and conventional tillage (two passes). Each plot had three subplots (0.15 ha subplots, tilled to 15, 20, or 25 cm depth). Each subplot had four sub-subplots (size not reported; tilled at 0.69, 1, 1.25, or 1.53 m/s). Runoff water was collected in buried containers, downhill from each sub-subplot, after each storm. Soil water content was measured in soil cores (5.5 cm diameter, 0–60 cm length, three samples/sub-subplot, once before tillage and thrice in the dry season). Infiltration was measured with a double-ring infiltrometer (three measurements/sub-subplot, before tillage and three weeks after emergence). Wheat was planted in December 2012, fertilized, and harvested in May 2013.

 

Referenced papers

Please cite as:

Shackelford, G. E., Kelsey, R., Robertson, R. J., Williams, D. R. & Dicks, L. V. (2017) Sustainable Agriculture in California and Mediterranean Climates: Evidence for the effects of selected interventions. Synopses of Conservation Evidence Series. University of Cambridge, Cambridge, UK.