Effects of tillage on soil N availability, aggregate size, and microbial biomass in a subtropical karst region
Effects of tillage on soil N availability, aggregate size, and microbial biomass in a subtropical karst region
复制标题
耕作对亚热带喀斯特地区土壤氮素有效性、团聚体大小和微生物量的影响
DOI：
10.1016/j.still.2019.05.006
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发表时间：
2019
影响因子：
6.5
通讯作者：
Wang Ke-Lin
中科院分区：
文献类型：
--
作者：
Xiao Shuang-Shuang;Ye Ying-Ying;Xiao Dan;Chen Wu-Rong;Zhang Wei;Wang Ke-Lin
在典型的喀斯特地区，耕作会造成土壤氮素的短期流失，但集约化农业条件下影响土壤氮素含量的因素尚不清楚。在这项研究中，我们的目的是研究耕作在不同频率对土壤团聚体和微生物生物量的影响，从而对土壤氮含量。采用为期1年的原位模拟试验，研究了免耕（T0）、半年度耕作（T1）、每4个月翻耕（T2）、每2个月翻耕（T3）和每1个月翻耕（T4）5种耕作方式的土壤肥力变化。与免耕处理相比，不同频率的耕作使土壤总氮（TN）含量从0.43 g kg−1降低到0.72 g kg−1。硝态氮（NO3-）是该岩溶区溶解态氮的主要形式，可能是由于土壤pH值高，并随着耕作量的增加而急剧下降。耕作粉碎大的土壤团聚体（5-8毫米）。微生物量碳（MBC）随着耕作次数的增加而逐渐降低，而微生物量氮（MBN）则随着耕作次数的增加而急剧降低。冗余分析（RDA）结果表明，5-8 mm团聚体和MBC均显著影响氮循环（P< 0.05）。结构方程模型（SEM）分析表明，耕作通过破碎5-8 mm团聚体显著影响氮素流失量（ΔTN）。这些研究结果强调了在脆弱的生态系统中保护大团聚体以维持土壤氮库的重要性，并防止由于喀斯特地区耕作而导致的土壤氮流失，因为其高土壤NO3含量和可能的淋溶可能对地下水质量构成威胁。
Tillage results in the loss of soil nitrogen (N) over the short term in a typical karst area, but the factors affecting soil N content under intensive agriculture are poorly understood. In this study, our objective was to examine the effect of tillage at various frequencies on soil aggregates and microbial biomass, and consequently on soil N content. A one-year in situ simulation experiment was conducted using five tillage treatments: no tillage (T0), semiannual tillage (T1), and tillage every four months (T2), two months (T3), and one month (T4). Tillage at various frequencies reduced the total N (TN) content of soil from 0.43 to 0.72 g kg−1, compared with the no-till treatment. Nitrate (NO3-) was the major form of dissolved N in this karst region probably owing to high soil pH and it declined sharply with increasing tillage. Tillage disintegrated large soil aggregates (5–8 mm). Microbial biomass carbon (MBC) decreased gradually with increasing tillage frequency, while microbial biomass nitrogen (MBN) was sharply reduced by all tillage treatments including T1. In addition, redundancy analysis (RDA) indicated that both 5–8 mm-sized aggregates and MBC significantly impacted the N cycle (P< 0.05). Structural equation model (SEM) analysis showed that tillage significantly affected total N loss (ΔTN) via the fragmentation of 5–8 mm aggregates. These findings highlight the importance of preserving large aggregates for maintaining the soil N pool in fragile ecosystems, and preventing the loss of soil N due to tillage in the karst region, as its high soil NO3- content and likely leaching may be a threat to groundwater quality.