有机肥中可溶性有机碳、氮含量及其特性

测定了7种不同种类、不同腐熟程度有机肥中可溶性有机氮（SON）和可溶性有机碳（SOC）的含量，结果表明：有机肥的水和0．01mol／LCaCl2溶液提取液中SON含量分别平均为105．2mg／L和91．6mg／L；每千克干样平均含SON分别为1188mg和1037mg；SON占可溶性总氮（TSN）和全氮（TN）的比例分别在70．5％～74．7％和4．3％～4．9％之间。水和0．01mol／LCaCl2溶液提取液中SOC含量分别平均为695mg／L和622mg／L；每千克干样平均含SOC分别为7873mg和7054mg；SOC占有机肥有机碳（TOC）比例分别平均为2．1％和1．9％；SOC／SON平均分别为6．7和6．9。SON与SOC间的相关性较高，SON与NO3^--N含量呈现负相关关系。有机肥料中的可溶性氮素绝大部分以SON形式存在，如此高的SON和SOC含量可能会成为氮、碳养分流失和环境污染的潜在来源。

Concentration and characteristics of soluble organic nitrogen (SON) and carbon (SOC) in different types of organic manures

Soluble organic nutrients in soil, including soluble organic nitrogen (SON) and carbon (SOC), play an important role in the biogeochemistry of carbon, nitrogen, and phosphorus, in pedogenesis, in the transport of pollutants, and in long-term carbon storage. Many Chinese soils have received long-term applications of organic fertilizers. Organic fertilizers, like manure, contain soluble inorganic and organic nutrients. Both types of nutrients are very active in soil. Little is known about the content and characteristics of SON and SOC in the manures used in China. A laboratory experiment was conducted to measure the concentration of SON and SOC extracted with water and 0.01 mol/L CaCl_ 2 from different types of organic manure. Additional characteristics were also evaluated. Results showed that the average concentration of water extractable SON in the seven manures was 105.2 mg/L. The average concentration of CaCl_ 2 extractable SON was 91.6 mg/L. SON in the manures accounted for 70% of the total soluble nitrogen (TSN) and 5% of the total nitrogen (TN). On a dry weight basis, the average content of water extractable SON was 1188 mg and average CaCl_ 2 extractable SON was 1037 mg/kg. The average concentration of water extractable SOC in the seven manure types was 695 mg/L. CaCl_ 2 extractable SOC averaged 622 mg/L. SOC accounted for 2% of the total organic carbon (TOC) in the manure. On a dry weight basis, the average content of water extractable SON in the manure was 7873 mg/kg. CaCl_ 2 extractable SON averaged 7054 mg/kg. The ratio of SOC/SON in the manures was about 6.8. There was a significant correlation between SON and SOC (P<0.05) in the manure. A negative correlation was observed between the concentration of SON and NO-_ 3 -N (P<0.05). The results indicate that SON and SOC are important constituents in organic manure. More attention should be paid to these constituents in order to reduce nitrogen and carbon loss from manure fertilizer to the environment.