Nitrogen Fertilization Elevated Spatial Heterogeneity of Soil Microbial Biomass Carbon and Nitrogen in Switchgrass and Gamagrass Croplands.
Nitrogen Fertilization Elevated Spatial Heterogeneity of Soil Microbial Biomass Carbon and Nitrogen in Switchgrass and Gamagrass Croplands.
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DOI：
10.1038/s41598-017-18486-5
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发表时间：
2018-01-29
影响因子：
4.6
通讯作者：
Hui D
中科院分区：
文献类型：
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作者：
Li J;Guo C;Jian S;Deng Q;Yu CL;Dzantor KE;Hui D
高强度施氮对生物质能农田土壤微生物空间分布的影响尚不清楚。为了量化氮肥对土壤微生物量碳（MBC）和氮（MBN）空间异质性的影响，在美国田纳西州中部的两个生物能源农田进行了为期三年的施肥试验，采用空间显式设计，在两个15 m2的地块内对3个施肥处理下的表层矿质土层（0-15 cm）进行取样。3个施肥处理分别为无氮输入（NN）、低氮输入（LN：84 kg N ha−1尿素）和高氮输入（HN：168 kg N ha−1尿素）。这两种作物是柳枝稷（SG：Panicum virgatum L.）（GG：Tripsacum dacquitides L.）。结果表明，施氮对微生物指标的中心趋势影响不大，但相对于LN，HN显著增加MBC和MBC：MBN（仅GG）。除MBN（仅GG）外，HN具有最大的区内方差。HN和LN图下的空间格局一般很明显，NN图下的空间格局要小得多。农田之间（GG > SG）和变量之间（MBN，MBC：MBN > MBC）也存在显著的空间差异。本研究表明，生物能源作物施肥不均匀可能导致施肥土壤微生物生物量的空间异质性增加。
The effects of intensive nitrogen (N) fertilizations on spatial distributions of soil microbes in bioenergy croplands remain unknown. To quantify N fertilization effect on spatial heterogeneity of soil microbial biomass carbon (MBC) and N (MBN), we sampled top mineral horizon soils (0-15 cm) using a spatially explicit design within two 15-m2 plots under three fertilization treatments in two bioenergy croplands in a three-year long fertilization experiment in Middle Tennessee, USA. The three fertilization treatments were no N input (NN), low N input (LN: 84 kg N ha−1 in urea) and high N input (HN: 168 kg N ha−1 in urea). The two crops were switchgrass (SG: Panicum virgatum L.) and gamagrass (GG: Tripsacum dactyloides L.). Results showed that N fertilizations little altered central tendencies of microbial variables but relative to LN, HN significantly increased MBC and MBC:MBN (GG only). HN possessed the greatest within-plot variances except for MBN (GG only). Spatial patterns were generally evident under HN and LN plots and much less so under NN plots. Substantially contrasting spatial variations were also identified between croplands (GG > SG) and among variables (MBN, MBC:MBN > MBC). This study demonstrated that spatial heterogeneity is elevated in microbial biomass of fertilized soils likely by uneven fertilizer application in bioenergy crops.