不同施氮处理玉米根茬在土壤中矿化分解特性  

Decomposition characteristics of maize roots derived from different nitrogen fertilization fields under laboratory soil incubation conditions

作　　者：蔡苗[1] 董燕婕[1] 李佰军[1] 周建斌[1] 

机构地区：[1]西北农林科技大学资源环境学院农业部西北植物营养与农业环境重点实验室,杨凌712100

出　　处：《生态学报》2013年第14期4248-4256,共9页Acta Ecologica Sinica

基　　金：国家"十二五"科技支撑计划课题(2012BAD15B04);国家自然科学基金项目(40773057);西北农林科技大学创新团队项目

摘　　要：以黄土高原南部地区7a定位试验不同氮肥处理玉米根茬为研究对象,通过室内培养试验研究了施氮量分别为0、120和240 kg N/hm2处理玉米根茬(分别用R0、R120、R240表示)在15—20 cm和45—50 cm土层土壤中有机碳矿化及其对土壤微生物量碳、可溶性有机碳和矿质态氮含量的影响。结果表明,不同处理玉米根茬C/N为R0>R240>R120。培养条件下,R120和R240根茬的碳矿化速率高于R0根茬,R120与R240根茬之间差异不显著。不同处理根茬C/N与其培养过程中碳素累积表观矿化量呈极显著负相关关系。3种施氮量处理的玉米根茬在培养过程中有机碳矿化率、潜在碳矿化量、土壤微生物量碳、可溶性有机碳含量均为添加R120根茬的处理最高,R240次之,R0最低。添加R120和R240根茬显著提高了培养起始时土壤矿质态氮含量。R0、R120和R240根茬在15—20 cm土层土壤中的碳矿化率分别比其在45—50 cm土层土壤中高51.70%、26.41%和27.84%。在评价根茬还田对农田生态系统碳、氮等养分循环的作用时,应同时考虑施肥对根茬分解和转化的影响。In natural ecosystems, soil organic carbon is derived almost exclusively from residues of previous vegetation or from contributions of growing plants. Roots have long been suspected to be an important source of soil organic matter. After grain harvest, the decomposition of root residues which remained in the field will contribute to soil fertility and crop productivity. Different fertilizations will affect the quantity and chemical properties of crop roots to varying degrees, such as root biomass, carbon and nitrogen nutrient contents in crop root. Recently, more attention has been paid to the effects of root residue decomposition on crop yield and soil physical and chemical characteristics, for instance, crop roots remained in field play a role in sustaining soil moisture and increasing soil organic carbon in microbes. In this study, the relationship between decomposition of crop root residues and soil carbon and nitrogen transformation under different nitrogen fertilizations was discussed. We collected maize roots from a 7-year long term different cultivation and nitrogen fertilizer experimental field located at the south edge of the Loess Plateau （108°04＇07＂E, 34°17＇56＂N） in December 2010 after maize harvest. Maize roots in 0--20 em soil depth were gathered from field plots in 0, 120 and 240 kg N/hm2 treatments and marked Ro, Rl20 and R24o, respectively. At the same time, soil samples were collected in 15--20 em and 45--50 cm along the maize protection belt. Air-dried soils of 100 g in the two layers were mixed with three maize roots in proportion of 2% dry weight respectively and incubated at 25 ℃ for 105 days, soil moisture was kept at 70% of field water holding capacity. During the incubation period, soil CO2 release, microbial biomass carbon, dissolved organic carbon and mineral nitrogen contents in soils were determined regularly. Also, we applied a kinetic equation to fit the cumulative carbon mineralization amount of maize root with the incubation time. The results showed that C/N ratios

关 键 词：根茬碳矿化 土壤微生物量碳 可溶性有机碳 矿质态氮 

分 类 号：S513[农业科学—作物学]