摘要
通过在棕壤、草甸土和水稻土上进行的田间和模拟试验表明,土壤有机培肥一般使胡敏酸(HA)的数均分子量、缩合度(C/H)、羧基含量和反应热下降。除草甸土外,土壤有机培肥还能使胡敏酸的氧化度(O/C)和高温与低温放热之比降低。说明胡敏酸变得简单化和年轻化。此外,施用猪粪可以增加胡敏酸的含氮量和降低酚羟基含量,玉米秸秆则相反。
This paper deals with the effect of organic material application on the chemical and thermal properties of HAs from brown soil, meadow soil and paddy soil in the field and incubation experiments. The results obtained are summarized as follows:In the field experiment, the number-average molecular weight ((?)n) of HAs were markedly decreased by applying organic materiaIs. For example, the (?)n of HAs of CK, 18.7 (O_1) and 37.4 T/ha (O_2) of pig manure (PM) in brown soil were 1332, 835 and 578 respectively. The same changes were found in other soils. PM was more effective than corn stalk (CS) in decreasing (?)n of HAs in the incubation experiment. With the increase of the rate of organic materials applied. (?)n of HAs decreased greatly. The (?)n of HA in the incubated soil without application of organic material went up to 1768.Results of elemental analysis showed that applying PM could increase the N content of HAs but decrease the degree of oxidation (O/C) and condensation (C/H) of HAs. This effect became more obvious with the increase in the amount of PM added. For instance, the N content, O/C and C/H of HA in the incubated soil without adding organic material were 4.57%, 0.48 and 0.913 respectively, whereas the corresponding figures of incubated soil treated with 7% PM were 6.09%, 0.461 and 0.795 respectively. The same results were obtained in the incubated soils treated with CS, except for the N content of HAs.The functional group analysis aslo showed that the contents of carboxyl, penolic hydroxyl and total acidity of HAs were lower in the soils to which organic materials were applied, It suggested that the oxidation degree and aromaticity of HAs dropped after the application of organic materials.The thermal status and nature of HA in soils was studied by differential thermal analysis (DTA) method. The results showed that all the HAs had both lower and higher exothermic peaks at about 360℃ and 560℃. The reaction heat of all the HAs was 3400—23891 kJ/mol. The reaction heat and the ratio of higher to lower exothermic peak were decreased by application of organic materials. It is considered that the new-formed HA have lower energy level, which might be related to its lower aromaticity.
出处
《土壤学报》
CAS
CSCD
北大核心
1992年第2期199-207,共9页
Acta Pedologica Sinica
