Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN, 55108, USA.
BioTechnology Institute, University of Minnesota, 140 Gortner Lab, 1479 Gortner Ave, St. Paul, MN, 55108, USA.
Appl Microbiol Biotechnol. 2016 Nov;100(21):9331-9341. doi: 10.1007/s00253-016-7736-9. Epub 2016 Jul 27.
Incorporation of organic material into soils is an important element of organic farming practices that can affect the composition of the soil bacterial communities that carry out nutrient cycling and other functions crucial to crop health and growth. We conducted a field experiment to determine the effects of cover crops and fertilizers on bacterial community structure in agricultural soils under long-term organic management. Illumina sequencing of 16S rDNA revealed diverse communities comprising 45 bacterial phyla in corn rhizosphere and bulk field soil. Community structure was most affected by location and by the rhizosphere effect, followed by sampling time and amendment treatment. These effects were associated with soil physicochemical properties, including pH, moisture, organic matter, and nutrient levels. Treatment differences were apparent in bulk and rhizosphere soils at the time of peak corn growth in the season following cover crop and fertilizer application. Cover crop and fertilizer treatments tended to lower alpha diversity in early season samples. However, winter rye, oilseed radish, and buckwheat cover crop treatments increased alpha diversity in some later season samples compared to a no-amendment control. Fertilizer treatments and some cover crops decreased relative abundance of members of the ammonia-oxidizing family Nitrosomonadaceae. Pelleted poultry manure and Sustane® (a commercial fertilizer) decreased the relative abundance of Rhizobiales. Our data point to a need for future research exploring how (1) cover crops influence bacterial community structure and functions, (2) these effects differ with biomass composition and quantity, and (3) existing soil conditions and microbial community composition influence how soil microbial populations respond to agricultural management practices.
将有机物质纳入土壤是有机农业实践的重要组成部分，它会影响执行养分循环和其他对作物健康和生长至关重要功能的土壤细菌群落的组成。我们进行了一项田间试验，以确定覆盖作物和肥料对长期有机管理下农业土壤中细菌群落结构的影响。Illumina 16S rDNA 测序揭示了玉米根际和大田土壤中包含 45 个细菌门的多样群落。群落结构受位置和根际效应的影响最大，其次是采样时间和施肥处理。这些效应与土壤物理化学性质有关，包括 pH 值、水分、有机质和养分水平。在覆盖作物和肥料施用后，季节中玉米生长高峰期，处理之间的差异在根际和非根际土壤中都很明显。覆盖作物和肥料处理在季节早期样本中往往会降低 alpha 多样性。然而，与不施肥对照相比，冬黑麦、油菜和荞麦覆盖作物处理在某些后期样本中增加了 alpha 多样性。肥料处理和一些覆盖作物降低了氨氧化家族硝化单胞菌科成员的相对丰度。颗粒状家禽粪肥和 Sustane®（一种商业肥料）降低了根瘤菌目的相对丰度。我们的数据表明，需要进一步研究探索（1）覆盖作物如何影响细菌群落结构和功能，（2）这些影响如何随生物质组成和数量而变化，以及（3）现有土壤条件和微生物群落组成如何影响土壤微生物种群对农业管理实践的响应。
