内蒙古典型草原马粪分解过程中氮素组分的变化

Changes of nitrogen fractions in horse dung during its decomposition on the typical steppe of Inner Mongolia,North China

2008年6月至2009年9月,在野外条件下,采用堆置于地表和埋入地下2种处理方式,研究了内蒙古典型草原马粪分解过程中氮素组分的变化特征.结果表明:2种处理残留马粪中,氨态氮、氨基酸态氮和氨基糖态氮在分解前期(0～90d)维持较高浓度,后期(330～450d)浓度显著降低;酸解未知氮和非酸解未知氮浓度随分解呈升高趋势,分解后期升高幅度更为明显.鲜马粪中,铵态氮是无机氮的主要存在形态,随分解呈逐渐降低趋势;鲜马粪中的硝态氮浓度较低,其在残留马粪中的淋溶损失较低,随分解逐渐累积.马粪埋入地下,对铵态氮以气态氨的挥发过程有显著影响,对其他氮素组分的影响不明显.马粪分解前期,氮素矿化的主要有机氮源为氨态氮、氨基酸态氮和氨基糖态氮,后期主要为酸解未知氮和非酸解未知氮.铵态氮的生物有效性主要体现在马粪分解前期,硝态氮则体现在分解后期.

From June 2008 to September 2009, a field experiment was conducted to study the change characteristics of the nitrogen fractions in horse dung during its decomposition on the typical steppe of Inner Mongolia. Two treatments were installed, i. e. , deposited the horse dung on the ground and buried the horse dung in soil. In the two treatments, the concentrations of ammonia nitrogen （NH3-N）, amino acid nitrogen （AAN）, and aminosugar nitrogen （ASN） in residual horse dung were maintained at a higher level in the earlier period of horse dung decomposition （0-90 d）, but declined obviously in the later period （330-450 d）. The concentrations of acid-hydrolysable unknown nitrogen （AHUN） and non-acid-hydrolysable unknown nitrogen （UUN） presented an increasing trend with the decomposition of horse dung, and increased to a higher level in the later period. In fresh horse dung, NH4^-N was the main fraction of inorganic nitrogen, and its concentration in residual horse dung decreased with the decomposition of horse dung. The concentration of NO3--N in fresh horse dung was lower, its leaching loss from the residual horse dung was weak, and it was accumulated in the residual horse dung with the decomposition of horse dung. The horse dung buried in soil had significant effects on the gaseous ammonia volatilization of NH4^＋-N, but minor effects on the other nitrogen fractions. The main nitrogen sources of nitrogen mineralization in the earlier period of horse dung decomposition were NH3-N, AAN and ASN, and those in the later period were AHUN and UUN. The bio-availability of NH4^＋-N was mainly revealed in the earlier period of horse dung decomposition, while that of NO3^--N was in the later period.