过碳酰胺对红壤pH、活性铝含量及玉米幼苗生长的影响

过碳酰胺是一种新型精细化工品，也是一种新型氮肥，在国外已得到广泛的应用和开发，而中国对其开发和应用刚刚起步。研究了南方3种酸性土壤中施入过碳酰胺后，对土壤pH值变化、铝元素活性及玉米幼苗生长的影响。静态试验结果表明：对3种酸性红壤施用不同浓度过碳酰胺，其pH值在短期内都随着施入过碳酰胺浓度的增大而急剧上升，交换性铝含量随着施用过碳酰胺浓度的增大而急剧下降。动态试验表明，施用过碳酰胺后，土壤pH值上升的现象是短期的，pH值达到最大值后缓慢下降，而土壤中铝元素的有效性与土壤pH的变化趋势呈显著负相关。植物实验表明，短期内，经过碳酰胺处理的玉米幼苗主根明显缩短，侧根生长受到抑制，并且其玉米铝毒明显重于不经过碳酰胺处理的玉米，被玉米吸收的铝主要分布在玉米的地下部分（即根内），只有较少的铝被转移到地上部分。

Transformation Character of Percarbamide in Acidity and Alkalinity Soil

Percarbamide is an important chemical product and a new fertilizer. It is widely used in foreign, but just beginning in china. Effects of changes of pH, active Al and growth of maize in 3 acidic soils induced by Percarbamide were studied. The results indicated that：At 25℃, the changes of pH in acidic soils increased quickly, but soil exchangeable Al decreased, with the increasing concentrations of applied Percarbamide. The time-course experiment revealed that the increase of soil pH was short-term, with a subsequently slow drop after reached their maximum, and there was a obviously negative relationship between soil exchangeable Al and soil pH. Plant experiment showed that mayor roots of maize were shorten obviously, and the growth of side roots were inhibited. moreover, the Al toxicity of maize with Percarbamide were more serious than that without Percarbamide, and majority of Al absorbed by maize were largely in roots, minority were in stems and in leaves．