The role of forage legumes in reducing on-farm non-renewable energy use
Inputs such as machinery, fuel, pesticides, and fertilizers contribute to energy expended in cropping systems. Reducing non-renewable energy use and increasing energy use efficiency can make cropping systems more sustainable. Nitrogen benefits of legumes are well documented. This study examined the effect of forage and green manure legumes on energy efficiency of crop production for three western Canadian crop rotation studies (Glenlea, MB; Indian Head, SK; Swift Current, SK). Relative to continuous grain rotations, rotations containing 50% perennial forage legumes decreased energy use by 85% and increased energy use efficiency by 409%. Relative to cereal, pulse, and oilseed rotations, they reduced energy use by 28% and increased energy use efficiency by 294%. Green manure rotations, while decreasing energy use by 26%, did not affect energy use efficiency. The primary contribution of forage legumes to lower energy use was nitrogen addition to the soil.
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