绵羊宿营法防除天然草地灌木杂草研究Ⅴ新鲜羊粪尿对土壤可交换性氮和植物生长的影响

Study on controlling grassland shrub and weeds by sheep night penning: Ⅴ. Effects of fresh sheep dung and urine on nitrogen in soil and plant

绵羊新鲜粪尿对土壤和植物氮转化与含量影响的结果表明 ,0～ 10 cm土壤可交换性铵态氮在绵羊宿营之后即达到最大值 ,然后逐渐下降。 10～ 2 0 cm土层最大值出现要迟半个月。绵羊宿营(UDT)处理、尿 (U)处理和粪尿 (UD)处理的土壤铵态氮浓度都较高。土壤中出现高浓度可交换性铵态氮与游离氨的相互转换 ,可能形成高浓度的游离氨 ,对植物产生一定毒害。土壤可交换性亚硝态氮在 7月 30日之前变化呈波浪型 ,说明一部分亚硝态氮迅速转化为硝态氮 ,一部分被植物吸收 ;7月 30日后 ,土壤亚硝态氮快速积累 ,形成高浓度 ,对植物产生毒害作用。土壤可交换性硝态氮与亚硝态氮的变化相关显著。植物体内粗蛋白质含量的变化表明 ,在 7月 30日前无变化或有所下降 ,而 7月 30日后迅速上升 ,但时间较短 ;至 8月 11日即不再上升而开始下降。

Soil exchageable nitrogen and plant crude protein content were affected significantly by fresh sheep dung and urine. Soil exchangeable ammonium N chagned dramatically. Exchangeable ammonium N in 0～10 cm soil reached a peak value just after 8 sheep nights, but the maximum of 10～20 cm soil delayed half a month. The high concentration of exchangeable ammonium N could be converted into free ammonia, and a high content of ammonia is toxic to plant. After July 30, soil exchangeable nitrite N accumulated quickly and reached the toxic level for plant. The crude protein content in plant decreased until July 30, then increased rapidly. From August 11 on, it started decreasing again. These demonstrated that free ammonia and nitrite N had hurted plants much.