黄土高原典型土壤有机氮矿化过程

以黄土高原从北向南不同地区典型土壤类为对象,采用Bremner淹水培养法,研究黄土高原典型土壤有机氮的矿化过程。结果表明,淹水培养期间矿化出的部分NH4+-N会被粘土矿物固定,固定量因土壤不同而异,因此在测定有机氮矿化量时,只有考虑这一部分氮素,才可获得可靠结果。不同土壤有机氮量矿化明显不同,表现为土垫旱耕人为土>黄土正常新成土>简育干润均腐土>干润砂质新成土,从南到北氮素矿化量呈减小趋势。添加C/N低(C/N比为21.7)的紫花苜蓿(Medicago stativa)茎叶有利于促进土壤有机氮矿化,而添加C/N高(C/N比为43.3)的长芒草(Stipa bungeana)会促进矿质氮的生物固定;不同类型植被土壤间在培养20、40d和60d时的矿化量差异显著(p值分别为0.0177、0.0109和0.0073),均表现为均为林地土壤>裸地土壤>草地土壤>农田土壤;从平均看,加(NH4)2SO4后有机氮矿化量有一定减少。在不同培养阶段,不同土类间氮素矿化率不同,在20d和40d时存在显著差异(p分别为0.0092和0.0381),60d时差异不显著,不同土类氮素矿化率的大小顺序为干润砂质新成土>黄土正常新成土>...

The objective of this experiment was to improve our understanding of soil organic N mineralization in the Loess Plateau. Typical soils were sampled from north to south in the Loess Plateau and soil organic N mineralization was measured in the soils using the Bremner incubation method. The soils were incubated for 60 d. The results showed that part of NH+4-N released during mineralization was fixed by clay minerals in these soils, so in order to get reliable results, we must consider this when determining to...