Factors affecting nitrate leaching from a calcareous loam in East Anglia

摘要: The effects of overwinter cover cropping, delayed ploughing and method straw disposal on the quantities nitrate leached (averaged over three winters during 1989-93) from a chalk loam in Eastern England were examined. recovery 'retained' nitrogen (retained through crop uptake, immobilization by straw) following spring was also assessed. In first two winters, rye decreased leaching > 90% (28 kg N/ha per year), as compared with bare fallow treatments. 1992/93 this decrease only 23% (10 kg/ha), due to early onset drainage before well established. Delayed treatments, autumn N mineralization subsequent leaching, ineffectual 1989/90 but had substantial 1990/91 ; mineralization, inferred soil mineral content, 31 35% 36 61% 1992/93, respectively. Nitrate winters) unaffected incorporation. There no evidence sown test crops (barley or sugarbeet). low input situation encountered experiment, it unnecessary sow September years average below rainfall ensure that solution concentrations remained EU drinking water limit 11 mg NO 3 -N/l. However, wetter seasons occurred taken up much N. retained against previous apparently being remobilized lost although if grown again there less than land. future, an increase extent cropping might transpiration rates therefore lead aquifer recharge.