有机物料对不同作物根系土壤腐殖质组成和结构的影响

为探讨施用有机物料后不同作物根系土壤腐殖质各组分含量和胡敏酸元素组成的变化情况,以吉林农业大学试验田培肥2a的黑土为研究对象,试验选取3种作物(玉米、大豆、白菜),每种作物设4种施肥处理,包括化肥(CK)、玉米秸秆配施化肥、树叶配施化肥和鸡粪配施化肥。采用腐殖质修改法提取水溶性物质(WSS)、胡敏酸(HA)、富里酸(FA)、胡敏素(HM),利用重铬酸钾外加热法测定腐殖质各组分有机碳含量,采用分光光度计法测定HA和FA的光学性质,通过光密度E_4/E_6值和元素组成分析HA的结构变化。结果表明:土壤总有机碳(TOC)和腐殖质各组分有机碳含量均表现为白菜玉米大豆。相比CK,配施有机物料后作物根系土壤TOC、WSS、HA含量分别显著增加5%~8%,34%~55%,8%~20%,FA含量变化不明显。相比树叶和鸡粪,秸秆可显著提高TOC含量;WSS在各物料之间差异不明显;HM含量表现为秸秆树叶鸡粪CK。有机物料对PQ值的影响因作物而异,秸秆和鸡粪对玉米、大豆根系土壤PQ值(HA占腐殖酸的比率)的影响相似,而鸡粪对白菜根系土壤PQ值的影响显著高于玉米秸秆。施用有机物料后HA的E_4/E_6未发生明显改变,FA的E_4/E_6显著提高。有机物料使根系土壤HA缩合度升高,分子结构更加复杂,且有利于HA含氮基团的形成,以秸秆处理作用最好。由此可见,有机物料具有良好的培肥效果,其中鸡粪对白菜根系土壤培肥效果最显著,秸秆与鸡粪对玉米、大豆根系土壤培肥效果相似,均显著高于化肥。

Effects of Organic Materials on the Composition and Structure of Humic Substance in the Rhizosphere Soil of Different Crops

In order to study the changes in the composition of humic substance and elemental composition of humic acid in the rhizosphere soil of different crops,a two-year field experiment in Jilin Agriculture University experimental field was carried out.Three crops (corn,soybean and cabbage) were selected in the experiment and each crop was subjected to four fertilizer treatments,including chemical fertilizer (CK),straw combined with chemical fertilizer,leaves combined with chemical fertilizer,and poultry manure combined with chemical fertilizer.The water-soluble substance (WSS),humic acid (HA),fulvic acid (FA),and humic material (HM) were extracted by the modified method of humic substance composition.The organic carbon contents of soil humic components were measured by the method of K2 Cr2 O7 thermal oxidation,the optical properties of HA and FA were measured by a spectrophotometer,and the structural changes of humic acid were indicated from the ratio of E4/E6 and elemental composition.The results showed that the contents of total organic carbon and humic components followed the order of cabbage＞corn＞soybean.Compared with the CK,the application of organic materials significantly increased the organic carbon contents of TOC,WSS,HA in the rhizosphere soil of different crops by 5％ to 8％,34％ to 55％ and 8％ to 20％,respectively.Organic materials had no significant effect on carbon contents of FA.Compared with leaves and poultry manure,the application of maize straw significantly increased total organic carbon,application of different types of organic materials did not show a remarkable difference in organic carbon contents of WSS,the order of carbon contents of humic material were:maize straw＞leaves＞poultry manure＞CK.The effect of organic materials on the PQ values (the radio of HA/(HA+FA)) varied with different crops.The maize straw and poultry manure treatments had similar effects on PQ values in the rhizosphere soil of corn and soybean,and the poultry manure significantly increased PQ values in the rhizosphere soil of cabbage.The application of organic materials resulted in a significant increase of the E4/E6 value in fulvic acid,while a little bit decreased E4/E6of humic acid.Organic materials enhanced condensation degree,complicated the structure of HA,and increased the contents of nitrogen-containing groups of HA,with the effect of maize straw being the most significant.In general,organic materials showed better fertilization effect on soil than chemical fertilizer.The effect of poultry manure on the rhizosphere soil of cabbage was the most significant,maize straw and poultry manure treatments had similar effects on the rhizosphere soil of corn and soybean.