有机物料对紫色土微生物量碳、氮及氮素供应的影响

以猪粪沼渣(PM)、牛粪沼渣(CM)、污泥堆肥(SC)、农村生活垃圾堆肥(RWC1)、农村生活垃圾与污泥的堆肥产物(污泥比例20%,RWC2)为材料,采用培养试验和盆栽试验研究了有机物料对酸性紫色土和石灰性紫色土中微生物量碳(MBC)、氮(MBN)含量及玉米幼苗氮吸收的影响.结果表明,有机物料使酸性和石灰性紫色土MBC含量分别提高了53. 63%～102. 91%和12. 14%～137. 00%,有机物料分解愈慢、碳氮比(C/N)愈高,土壤MBC愈大;而MBN含量分别提高了23. 37%～150. 08%和35. 02%～160. 02%,受物料的有机氮形态影响.两种土壤MBC/MBN随物料C/N的升高总体降低,高C/N物料有利于MBN的长期维持.除牛粪沼渣外,有机物料均可提高两种紫色土中玉米幼苗的生物量及氮吸收量,提高幅度为SC PM RWC2 RWC1,但其对氮素吸收的促进效果不及化肥.牛粪沼渣对玉米幼苗氮吸收的抑制作用与其较高的C/N有关,而其余物料的促进作用随MBC/MBN降低而增高.因此,有机物料对氮素吸收利用的影响不仅与其性质有关,也与其对土壤MBC/MBN的作用有关.

Effects of Organic Amendments on Microbial Biomass Carbon and Nitrogen Uptake by Corn Seedlings Grown in Two Purple Soils

An incubation experiment and a pot experiment were carried out to investigate the effects of organic materials on microbial biomass carbon (MBC) and nitrogen (MBN) content, dry weight, and nitrogen uptake of maize seedlings grown in an acidic purple soil and a calcareous purple soil. The organic materials used included pig manure biogas residue (PM), cattle manure biogas residue (CM), sludge compost (SC), compost from rural domestic waste both with and without 20% sludge (RWC1 and RWC2, respectively). The results showed that MBC content in the acidic and calcareous purple soils increased by 53.63%-102.91% and 12.14%-137.00%, respectively. The slower the decomposition of organic materials and the higher the C/N ratio, the bigger the MBC content of the soils. Furthermore, MBN contents, which were affected by the different forms of organic, increased by 23.37%-150.08% and 35.02%-160.02%, respectively. The MBC/MBN contents of both soils decreased with the increase in the C/N ratio of the organic materials, but a higher C/N ratio was beneficial for maintaining a higher MBN content over an extended period of time. With the exception of CM, the addition of organic materials improved the biomass of maize seedlings, and their nitrogen uptake and utilization rate in both soils were also significantly enhanced, although these effects were less than that achieved through conventional fertilization. The uptake and utilization of nitrogen followed the order of SC > PM > RWC2 > RWC1. The inhibiting effect of CM was related to its higher C/N ratio, while the promoting effect of the other materials on nitrogen uptake by the corn seedlings increased as soil MBC/MBN content decreased. Therefore, the influence of organic materials on the change and supply of soil nitrogen was not only related to their properties but also to their effects on soil MBC/MBN content.