Study

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This study is summarised as evidence for the following.

Action Category

Pest regulation: Use no tillage in arable fields

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Mediterranean Farmland

Crop production: Use no tillage in arable fields

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Mediterranean Farmland

Soil: Use no tillage in arable fields

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Mediterranean Farmland

Crop production: Grow cover crops in arable fields

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Mediterranean Farmland

Pest regulation: Grow cover crops in arable fields

Action Link
Mediterranean Farmland

Soil: Grow cover crops in arable fields

Action Link
Mediterranean Farmland
  1. Pest regulation: Use no tillage in arable fields

    A replicated, controlled study in 1996–1998 in an irrigated tomato field in the San Joaquin Valley, California, USA, found more weeds in plots with no tillage (and winter cover crops), compared to plots with tillage (and winter fallows), when herbicide was used on the fallows. When herbicide was not used, differences were inconsistent. Pest numbers: More weeds were found in plots with no tillage, in some comparisons (9 of 12 comparisons with herbicide use on fallows, in 1998: 4–12% vs 0–3% weed cover; two of 12 comparisons without herbicide use on fallows, in 1998: 5–6% vs 2%), but fewer weeds were found in two of 12 comparisons without herbicide use on fallows, in 1998 (4–5% vs 11%). In 1997, similar weed cover was found in plots with or without tillage (1–4%). Methods: There were 12 plots (4.5 x 27.5 m plots) for each of four treatments (two grass-legume mixtures, or two legumes without grasses, as winter cover crops, sown in October 1996–1997, killed and retained as mulch, with no tillage, in March 1997–1998) and each of two controls (bare-soil fallows in winter, with or without herbicide, and conventional tillage in spring). Tomato seedlings were transplanted in April 1997–1998. The tomatoes were irrigated (two inches/week) and fertilized (0, 100, or 200 lb N/acre). All plots were hand weeded in May, June, and July, and control plots were also cultivated in May and June. Weed cover was estimated before cultivation (July 1997 and May, June, and July 1998) or after cultivation (May and June 1997), in three quadrats/plot (1.8 m2 quadrats). It was not clear whether these results were a direct effect of cover crops or tillage.

     

  2. Crop production: Use no tillage in arable fields

    A replicated, controlled study in 1996–1998 in an irrigated tomato field in the San Joaquin Valley, California, USA, found lower tomato yields in plots with no tillage (and winter cover crops), compared to tillage (and winter fallows). Crop yield: Lower tomato yields were found in plots with no tillage, compared to tillage, in four of 16 comparisons (27–36 vs 39–42 tons/acre). Crop quality: Similar amounts of soluble solids were found in tomatoes in the treatment and control plots (data not reported). Methods: There were 12 plots (4.5 x 27.5 m plots) for each of four treatments (two grass-legume mixtures, or two legumes without grasses, as winter cover crops, sown in October 1996–1997, killed and retained as mulch, with no tillage, in March 1997–1998) and each of two controls (bare-soil fallows in winter, with or without herbicide, and conventional tillage in spring). Tomato seedlings were transplanted in April 1997–1998 and harvested in August 1997 and September 1998. The tomatoes were irrigated (two inches/week) and fertilized (0, 100, or 200 lb N/acre). It was not clear whether these results were a direct effect of cover crops or tillage.

     

  3. Soil: Use no tillage in arable fields

    A replicated, controlled study in 1996–1998 in an irrigated tomato field in the San Joaquin Valley, California, USA (same study as (1)), found less nitrate in winter and spring, but more nitrate in summer, in plots with winter cover crops (and no tillage in spring), compared to plots with winter fallows (and tillage in spring). Nutrients: Less nitrate was found in plots with cover crops, compared to fallows, when measured in winter or spring (19 of 32 comparisons: 0.9–4.1 vs 3.8–7.9 ppm, 0–30 cm depth), but more nitrate was found when measured in summer (27 of 32 comparisons: 21–41 vs 8–14 ppm, 0–30 cm depth). Methods: There were 12 plots (4.5 x 27.5 m plots) for each of four treatments (two grass-legume mixtures, or two legumes without grasses, as winter cover crops, sown in October 1996–1997, killed and retained as mulch, with no tillage, in March 1997–1998) and each of two controls (bare-soil fallows in winter, with or without herbicide, and conventional tillage in spring). Tomato seedlings were transplanted in April 1997–1998. The tomatoes were irrigated (two inches/week) and fertilized (0, 100, or 200 lb N/acre, in March 1997 and May 1998). Soil nitrate was sampled four times in 1998 (0–30 cm depth, three samples/plot). It was not clear whether these results were a direct effect of cover crops or tillage.

     

  4. Crop production: Grow cover crops in arable fields

    A replicated, controlled study in 1996–1998 in an irrigated tomato field in the San Joaquin Valley, California, USA, found lower tomato yields in plots with winter cover crops (and no tillage in spring), compared to plots with winter fallows (and tillage in spring). Crop yield: Lower tomato yields were found in plots with cover crops, compared to fallows, in four of 16 comparisons (27–36 vs 39–42 tons/acre). Crop quality: Similar amounts of soluble solids were found in tomatoes in the treatment and control plots (data not reported). Implementation options: Higher tomato yields were found in plots that were cover cropped with grass-legume mixtures, compared to legumes, in two of eight comparisons (36–38 vs 27 tons/acre). Methods: There were 12 plots (4.5 x 27.5 m plots) for each of four treatments (two grass-legume mixtures, or two legumes without grasses, as winter cover crops, sown in October 1996–1997, killed and retained as mulch, with no tillage, in March 1997–1998) and each of two controls (bare-soil fallows in winter, with or without herbicide, and conventional tillage in spring). Tomato seedlings were transplanted in April 1997–1998 and harvested in August 1997 and September 1998. The tomatoes were irrigated (two inches/week) and fertilized (0, 100, or 200 lb N/acre).

     

  5. Pest regulation: Grow cover crops in arable fields

    A replicated, controlled study in 1996–1998 in an irrigated tomato field in the San Joaquin Valley, California, USA, found more weeds in plots with winter cover crops (and no tillage in spring), compared to plots with winter fallows (and tillage in spring), when herbicide was used on the fallows. When herbicide was not used, differences were inconsistent. Pest numbers: More weeds were found in plots with cover crops, compared to fallows, in some comparisons (in 9 of 12 comparisons with herbicide-use on fallows, in 1998: 4–12% vs 0–3% weed cover; in two of 12 comparisons without herbicide-use on fallows, in 1998: 5–6% vs 2%), but fewer weeds were found in two of 12 comparisons without herbicide-use on fallows, in 1998 (4–5% vs 11%). In 1997, similar weed cover was found in plots with or without cover crops (1–4%). Implementation options: Fewer weeds were found in plots that were cover cropped with grass-legume mixtures, compared to legumes, in two of six comparisons in 1998 (in May: 4–5% vs 11–12% weed cover). Methods: There were 12 plots (4.5 x 27.5 m plots) for each of four treatments (two grass-legume mixtures, or two legumes without grasses, as winter cover crops, sown in October 1996–1997, killed and retained as mulch, with no tillage, in March 1997–1998) and each of two controls (bare-soil fallows in winter, with or without herbicide, and conventional tillage in spring). Tomato seedlings were transplanted in April 1997–1998. The tomatoes were irrigated (two inches/week) and fertilized (0, 100, or 200 lb N/acre). All plots were hand weeded in May, June, and July, and control plots were also cultivated in May and June. Weed cover was estimated before cultivation (July 1997 and May, June, and July 1998) or after cultivation (May and June 1997), in three quadrats/plot (1.8 m2 quadrats).

     

  6. Soil: Grow cover crops in arable fields

    A replicated, controlled study in 1996–1998 in an irrigated tomato field in the San Joaquin Valley, California, USA (same study as (6)), found less nitrate in winter and spring, but more nitrate in summer, in plots with winter cover crops (and no tillage in spring), compared to plots with bare fallows (and tillage in spring). Nutrients: Less nitrate was found in plots with cover crops, compared to fallows, when measured in winter or spring (19 of 32 comparisons: 0.9–4.1 vs 3.8–7.9 ppm, 0–30 cm depth), but more nitrate was found when measured in summer (27 of 32 comparisons: 21–41 vs 8–14 ppm, 0–30 cm depth). Methods: There were 12 plots (4.5 x 27.5 m plots) for each of four treatments (two grass-legume mixtures, or two legumes without grasses, as winter cover crops, sown in October 1996–1997, killed and retained as mulch, with no tillage, in March 1997–1998) and each of two controls (bare fallows in winter, with or without herbicide, and conventional tillage in spring). Tomato seedlings were transplanted in April 1997–1998. The tomatoes were irrigated (two inches/week) and fertilized (0, 100, or 200 lb N/acre, in March 1997 and May 1998). Soil nitrate was sampled four times in 1998 (0–30 cm depth, three samples/plot). It was not clear whether these results were a direct effect of cover crops or tillage.

     

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