title: [Changes of nitrogen fractions in horse dung during its decomposition on the typical steppe of Inner Mongolia, North China].
abstract: 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.
authors.affiliation: College of Chemistry and Environmental Science, Inner Mongolia Normal University, Huhhot 010022, China. chenhaiyan@yeah.net
authors.forename: Hai-Yan
authors.initials: HY
authors.lastname: Chen
authors.lastname: Arengaowa
authors.forename: Xin-Min
authors.initials: XM
authors.lastname: Liu
mesh_terms: D000818:Animals; D002681:China; D017753:Ecosystem; D005243:Feces / Q000737:chemistry*; D005308:Fertilizers; D006736:Horses; D009584:Nitrogen / Q000737:chemistry / Q000378:metabolism*; D006109:Poaceae / Q000254:growth & development / Q000378:metabolism*; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
chemical_list: D005308:Fertilizers; D012987:Soil; D009584:Nitrogen