Garden Organic – www.gardenorganic.org.uk – have completed another positive study on green manures – this time for the government agency responsible for agriculture – DEFRA. Green manures put nitrogen back into the soil if planted as part of normal crop rotations. The new study found that growing grazing rye over the winter reduced leaching of nitrogen by 97 per cent compared to leaving the soil bare. This is good news because it will reduce our reliance on synthetic nitrogen fertilisers, which are both bad for the environment and getting more expensive because of oil price rises. They have gone up by 15 per cent in the last three years. Although the study was on agricultural field trial level it is still relevant to gardeners, as we too want to keep as much nitrogen as possible in our soil.