Smith Chris R, Blair Peter L, Boyd Charlie, Cody Brianne, Hazel Alexander, Hedrick Ashley, Kathuria Hitesh, Khurana Parul, Kramer Brent, Muterspaw Kristin, Peck Charles, Sells Emily, Skinner Jessica, Tegeler Cara, Wolfe Zoe
Department of Biology Earlham College Richmond IN USA.
Department of Biology Earlham College Richmond IN USA; Present address: Department of Entomology University of Illinois Urbana Champaign IL USA.
Ecol Evol. 2016 Oct 14;6(22):8075-8084. doi: 10.1002/ece3.2553. eCollection 2016 Nov.
The acreage planted in corn and soybean crops is vast, and these crops contribute substantially to the world economy. The agricultural practices employed for farming these crops have major effects on ecosystem health at a worldwide scale. The microbial communities living in agricultural soils significantly contribute to nutrient uptake and cycling and can have both positive and negative impacts on the crops growing with them. In this study, we examined the impact of the crop planted and soil tillage on nutrient levels, microbial communities, and the biochemical pathways present in the soil. We found that farming practice, that is conventional tillage versus no-till, had a much greater impact on nearly everything measured compared to the crop planted. No-till fields tended to have higher nutrient levels and distinct microbial communities. Moreover, no-till fields had more DNA sequences associated with key nitrogen cycle processes, suggesting that the microbial communities were more active in cycling nitrogen. Our results indicate that tilling of agricultural soil may magnify the degree of nutrient waste and runoff by altering nutrient cycles through changes to microbial communities. Currently, a minority of acreage is maintained without tillage despite clear benefits to soil nutrient levels, and a decrease in nutrient runoff-both of which have ecosystem-level effects and both direct and indirect effects on humans and other organisms.
玉米和大豆作物的种植面积广阔，这些作物对世界经济贡献巨大。种植这些作物所采用的农业 practices 对全球范围内的生态系统健康有重大影响。生活在农业土壤中的微生物群落对养分吸收和循环有重要贡献，并且对与之共生的作物可能产生正面和负面影响。在本研究中，我们考察了所种植的作物和土壤耕作对土壤养分水平、微生物群落以及土壤中存在的生化途径的影响。我们发现，与所种植的作物相比，耕作方式（即传统耕作与免耕）对几乎所有测量指标的影响要大得多。免耕田往往具有更高的养分水平和独特的微生物群落。此外，免耕田有更多与关键氮循环过程相关的DNA序列，这表明微生物群落在氮循环中更活跃。我们的结果表明，农业土壤的耕作可能通过改变微生物群落来改变养分循环，从而加剧养分浪费和径流的程度。目前，尽管免耕对土壤养分水平有明显益处且能减少养分径流（这两者都具有生态系统层面的影响，并且对人类和其他生物有直接和间接影响），但只有少数耕地采用免耕方式。
