Department of Earth Sciences, 723 West Michigan St, SL118, Indiana University Purdue University Indianapolis, Indianapolis, IN, 46202, USA.
Sci Rep. 2017 Sep 21;7(1):12117. doi: 10.1038/s41598-017-12383-7.
Although no-till (NT) has been promoted as an alternative land management practice to conventional tillage (CT), its impact on water quality, especially nitrate (NO) loss remain controversial. We conducted a meta-analysis to compare NO concentration and load in NT and CT systems via two major transport pathways: runoff and leaching. Rainfall variability, aridity, soil texture, tillage duration, crop species, and fertilizer type were used as co-varying factors. In comparison to CT, NT resulted in an overall increase of runoff NO concentration, but similar runoff NO load. In contrast, leachate NO load was greater under NT than under CT, although leachate NO concentration was similar under both tillage practices, indicating that the effect of NT on NO load was largely determined by changes in water flux. Some deviations from these overall trends, however, were recorded with different co-varying variables. In comparison to CT, NT, for example, generated lower leachate NO concentration and similar (instead of elevated) NO leachate load from soybean fields (no N fertilizer applied). These results suggest NT needs to be complemented with other practices (e.g., cover crops, reduced N rate, split N application) in order to improve soil N retention and water quality benefits.
尽管免耕（NT）作为一种替代传统耕作（CT）的土地管理实践已被推广，但它对水质，特别是硝酸盐（NO）流失的影响仍存在争议。我们进行了荟萃分析，通过两种主要的输运途径（径流和淋溶）比较了 NT 和 CT 系统中的 NO 浓度和负荷。降雨变异性、干旱、土壤质地、耕作持续时间、作物种类和肥料类型被用作协变量。与 CT 相比，NT 导致径流中 NO 浓度总体增加，但径流中 NO 负荷相似。相比之下，尽管两种耕作方式下淋溶液中 NO 浓度相似，但 NT 下的淋溶液中 NO 负荷更高，这表明 NT 对 NO 负荷的影响主要取决于水流通量的变化。然而，在不同的协变量作用下，也记录到了一些与总体趋势不符的结果。例如，与 CT 相比，NT 从大豆田中产生了较低的淋溶液 NO 浓度和相似（而不是升高）的 NO 淋溶液负荷（未施用氮肥）。这些结果表明，NT 需要与其他措施（例如覆盖作物、减少氮肥用量、氮肥分期施用）相结合，以提高土壤氮素保持和水质效益。
