多年生黑麦草草地矿质氮淋溶与径流流失的关系

以人工放水模拟冲刷试验 ,研究多年生黑麦草草地土壤矿质氮素淋溶和径流流失的关系。当硝态和铵态氮肥用量分别达到 50 0 0 kg N/ km2 ,冲刷强度为 1 mm/ min,冲刷时间为50 min时 ,观测氮素径流流失 ,于 48h后检测土壤矿质氮动态。结果表明 ,坡度为 2 5°、2 0°、1 5°、1 0°和 5°土壤 ,铵态氮径流流失量分别为 97.3、87.9、79.0、57.1和 50 .4kg/ km2 ,分别占施氮量的1 .9%、1 .8%、1 .6%、1 .1 %和 1 .0 %。铵态氮淋溶深度仅达到 60 cm,其淋溶量占施氮量的 55.3%～ 86.1 %,且随着坡度的增大淋溶量逐渐减少。硝态氮随着径流的流失量分别为 575.4、330 .3、2 82 .6、1 40 .1和 91 .0 kg/ km2 ,分别占施氮量的 1 1 .5%、6.6%、5.7%、2 .8%和 1 .8%。硝态氮淋溶与土壤水分入渗同步 ,随着坡度的降低淋溶深度则逐渐增加 ,硝态氮主要在 0～ 60 cm土层累积 ,其累积量介于 2 0 96～ 3433kg/ km2 之间 ,占施肥量的 41 .9%～ 68.7%,而在 60～ 1 0 5cm土层累积量则介于 72 3～ 2 52 1 kg/ km2 之间 ,占施氮量的 1 4.5%～ 50 .3%。

The Relationship of Mineral Nitrogen Leaching in Perennial Ryegrass Land with Its Runoff Loss

The soils fertilized by 5000kgN/km2 ammonium and nitrate fertilizers,are scoured by water with lmm/min flux,after water-scoured 48 hours,the available N in soil profile are surveyed.The water-scoured result shows as fellows.The ammonium fertilizer losses in runoff,loss amounts in 25°，20°，15°，10°and 5° slope land,are 97.3,87.9,79.0,57.1 and 50.4 kg/km2 respectively, which account as 1.9%,1.8%,1.6%,1.1% and 1.0% of ammonium fertilizer.The ammonium fertilizer infiltrating amounts in 60cm depth of soil profile account as 55.3%～86.1%.The nitrate losses in runoff,the loss amounts in different slope gradients are 575.4,330.3,282.6,140.1 and 91.0 kg/km2 respectively,which account as 11.6%,6.6%,5.7%,2.8% and 1.8% of nitrate fertilizer.The nitrate infiltrating depth is same as water within 48 hours.The accumulation amounts of nitrate fertilizer in 0～60cm and 60～105cm soil profiles are 2096～3433,723～2521 kg/km2 respectively,accounting for 41.9%～68.7% and 14.5%～50.3% of nitrate fertilizer.