Management of winter cover crop residues under different tillage conditions affects nitrogen utilization efficiency and yield of eggplant (Solanum melanogena L.) in Mediterranean environment

Published source details Radicetti E., Mancinelli R., Moscetti R. & Campiglia E. (2016) Management of winter cover crop residues under different tillage conditions affects nitrogen utilization efficiency and yield of eggplant (Solanum melanogena L.) in Mediterranean environment. Soil and Tillage Research, 155, 329-338.
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This study is summarised as evidence for the following.

	Action	Category
	Crop production: Use no tillage instead of reduced tillage Action Link
	Soil: Use no tillage instead of reduced tillage Action Link
	Crop production: Use no tillage in arable fields Action Link
	Crop production: Grow cover crops in arable fields Action Link
	Crop production: Use reduced tillage in arable fields Action Link
	Soil: Grow cover crops in arable fields Action Link
	Soil: Use reduced tillage in arable fields Action Link
	Soil: Use no tillage in arable fields Action Link

Crop production: Use no tillage instead of reduced tillage

A replicated, randomized, controlled study in 2009–2011 in an irrigated eggplant field in central Italy found that tillage had inconsistent effects on crop yield. Crop yield: Higher eggplant yields were found in plots with no tillage, compared to reduced tillage, in one of four comparisons (18 vs 7 Mg/ha fresh weight), but lower yields were found in two of four comparisons (11–18 vs 21–25). Methods: A mouldboard plough (30 cm depth) was used on all plots in autumn, before winter cover crops were planted. Cover crops were mown or chopped in spring, before tillage. No tillage or reduced tillage was used on 12 plots each (6 x 4 m plots). A rotary hoe (10 cm depth) was used for reduced tillage (which incorporated some of the cover crop residues into the soil). Cover crop residues were mulched and herbicide was used for no tillage. Eggplant seedlings were transplanted into the plots in May, and fruits were harvested four times/year in July–September 2010–2011. All plots were fertilized before the cover crops were grown, but not after. All plots were irrigated.
Soil: Use no tillage instead of reduced tillage

A replicated, randomized, controlled study in 2009–2011 in an irrigated eggplant field in central Italy found more nitrogen in soils with no tillage, compared to reduced tillage. Nutrients: More nitrogen was found in soils with no tillage, compared to reduced tillage, in one of four comparisons (37 vs 30 mg inorganic N/kg dry soil). Methods: A mouldboard plough (30 cm depth) was used on all plots in autumn, before winter cover crops were planted. Cover crops were mown or chopped in spring, before tillage. No tillage or reduced tillage was used on 12 plots each (6 x 4 m plots). A rotary hoe (10 cm depth) was used for reduced tillage (which incorporated some of the cover crop residues into the soil). Cover crop residues were mulched and herbicide was used for no tillage. Eggplant seedlings were transplanted into the plots in May, and fruits were harvested four times/year in July–September 2010–2011. Soil samples were collected when the seedlings were transplanted and when the last fruits were harvested each year (0–30 cm depth, six samples/plot). All plots were fertilized before the cover crops were grown, but not after. All plots were irrigated.
Crop production: Use no tillage in arable fields

A replicated, randomized, controlled study in 2009–2011 in an irrigated eggplant field in central Italy found that tillage had inconsistent effects on crop yield. Crop yield: Higher eggplant yields were found in plots with no tillage, compared to conventional tillage, in two of four comparisons (18–38 vs 14–32 Mg/ha fresh weight), but lower yields were found in one of four comparisons (11 vs 18). Methods: A mouldboard plough (30 cm depth) was used on all plots in autumn, before the winter cover crops were planted. The cover crops were mown or chopped in spring, before tillage. No tillage or conventional tillage was used on 12 plots each (6 x 4 m plots). A mouldboard plough (30 cm depth) and a disk (two passes) were used for conventional tillage (which incorporated the cover crop residues into the soil). Cover crop residues were mulched and herbicide was used for no tillage. Eggplant seedlings were transplanted into the plots in May, and fruits were harvested four times/year in July–September 2010–2011. All plots were fertilized before the cover crops were grown, but not after. All plots were irrigated.
Crop production: Grow cover crops in arable fields

A replicated, randomized, controlled study in 2009–2011 in an irrigated eggplant field in central Italy found that winter cover crops had inconsistent effects on crop yield. Crop yield: Higher eggplant yields were found in plots with winter cover crops, compared to plots with bare soil in winter, in six of nine comparisons (18–38 vs 11–21 Mg/ha fresh weight), but lower yields were found in two of nine comparisons (7–14 vs 18–21). Implementation options: Higher eggplant yields were found in plots with hairy vetch as the winter cover crop (32–38 Mg/ha fresh weight), compared to oats (7–18 Mg/ha) or oilseed rape (18–25 Mg/ha). Higher eggplant yields were found in plots with oilseed rape as the winter cover crop, compared to oats, in two of three comparisons (20–25 vs 7–14 Mg/ha fresh weight). Methods: Three species of winter cover crops (Vicia villosa hairy vetch, Brassica napus oilseed rape, or Avena sativa oats) were sown on three plots each (6 x 12 m plots) in September 2009–2010, and no cover crops were sown on three plots (weeded, bare soil). The cover crops were mown and used as mulch (50 cm wide) in eggplant rows, in May 2010–2011. Eggplant seedlings were transplanted into the plots in May, and fruits were harvested four times/year in July–September 2010–2011. All plots were fertilized before the cover crops were grown, but not after. All plots were irrigated.
Crop production: Use reduced tillage in arable fields

A replicated, randomized, controlled study in 2009–2011 in an irrigated eggplant field in central Italy found that tillage had inconsistent effects on crop yield. Crop yield: Higher eggplant yields were found in plots with reduced tillage, compared to conventional tillage, in three of four comparisons (21–36 vs 18–32 Mg/ha fresh weight), but lower yields were found in one of four comparisons (7 vs 14). Methods: A mouldboard plough (30 cm depth) was used on all plots in autumn, before winter cover crops were planted. Cover crops were mown or chopped in spring, before tillage. Reduced tillage or conventional tillage was used on 12 plots each (6 x 4 m plots). A mouldboard plough (30 cm depth) and a disc (two passes) were used for conventional tillage (which incorporated the cover crop residues into the soil). A rotary hoe (10 cm depth) was used for reduced tillage (which incorporated some of the cover crop residues into the soil). Eggplant seedlings were transplanted into the plots in May, and fruits were harvested four times/year in July–September 2010–2011. All plots were fertilized before the cover crops were grown, but not after. All plots were irrigated.
Soil: Grow cover crops in arable fields

A replicated, randomized, controlled study in 2009–2011 in an irrigated eggplant field in central Italy found more nitrogen in soils with winter cover crops, compared to bare soil. Nutrients: More nitrogen was found in soils with cover crops, compared to bare soil, for one of three cover crops (hairy vetch: 34 vs 23 mg inorganic N/kg dry soil). Implementation options: More nitrogen was found in soils with hairy vetch as the winter cover crop, compared to oats or oilseed rape (34 vs 20 mg inorganic N/kg dry soil), and no differences in nitrogen were found between soils with oats or oilseed rape as the winter cover crop. Methods: Three species of winter cover crops (Vicia villosa hairy vetch, Brassica napus oilseed rape, or Avena sativa oats) were sown on three plots each (6 x 12 m plots) in September 2009–2010, and no cover crops were sown on three plots (weeded, bare soil). The cover crops were mown and used as mulch (50 cm wide) in eggplant rows, in May 2010–2011. Eggplant seedlings were transplanted into the plots in May, and fruits were harvested four times/year in July–September 2010–2011. Soil samples were collected when the seedlings were transplanted and when the last fruits were harvested each year (0–30 cm depth, six samples/plot). All plots were fertilized before the cover crops were grown, but not after. All plots were irrigated.
Soil: Use reduced tillage in arable fields

A replicated, randomized, controlled study in 2009–2011 in an irrigated eggplant field in central Italy found more nitrogen in soils with reduced tillage, compared to conventional tillage. Nutrients: More nitrogen was found in soils with reduced tillage, compared to conventional tillage, in one of four comparisons (30 vs 24 mg inorganic N/kg dry soil). Methods: A mouldboard plough (30 cm depth) was used on all plots in autumn, before winter cover crops were planted. Cover crops were mown or chopped in spring, before tillage. Reduced tillage or conventional tillage was used on 12 plots each (6 x 4 m plots). A mouldboard plough (30 cm depth) and a disc (two passes) were used for conventional tillage (which incorporated the cover crop residues into the soil). A rotary hoe (10 cm depth) was used for reduced tillage (which incorporated some of the cover crop residues into the soil). Eggplant seedlings were transplanted into the plots in May, and fruits were harvested four times/year in July–September 2010–2011. Soil samples were collected when the seedlings were transplanted and when the last fruits were harvested each year (0–30 cm depth, six samples/plot). All plots were fertilized before the cover crops were grown, but not after. All plots were irrigated.
Soil: Use no tillage in arable fields

A replicated, randomized, controlled study in 2009–2011 in an irrigated eggplant field in central Italy found more nitrogen in soils with no tillage, compared to conventional tillage. Nutrients: More nitrogen was found in soils with no tillage, compared to conventional tillage, in one of four comparisons (37 vs 24 mg inorganic N/kg dry soil). Methods: A mouldboard plough (30 cm depth) was used on all plots in autumn, before winter cover crops were planted. Cover crops were mown or chopped in spring, before tillage. No tillage or conventional tillage was used on 12 plots each (6 x 4 m plots). A mouldboard plough (30 cm depth) and a disk (two passes) were used for conventional tillage (which incorporated the cover crop residues into the soil). Cover crop residues were mulched and herbicide was used for no tillage. Eggplant seedlings were transplanted into the plots in May, and fruits were harvested four times/year in July–September 2010–2011. Soil samples were collected when the seedlings were transplanted and when the last fruits were harvested each year (0–30 cm depth, six samples/plot). All plots were fertilized before the cover crops were grown, but not after. All plots were irrigated. It was not clear whether these results were a direct effect of cover crops or tillage.