No-till management is a proven practice for increasing soil organic matter in many environments. By increasing soil organic matter, no-till may increase soil N mineralization, potentially reducing crop demand for N fertilizer relative to inversion tillage. In this study, we hypothesized that, relative to inversion tillage (moldboard plowing), long-term no-till would: i) increase total N stocks, ii) increase mineralized N during the growing season, iii) increase grain yield and N uptake, and iv) reduce reliance of corn (Zea mays L.) on N fertilizer inputs. We tested these hypotheses in a long-term, continuous corn tillage and fertilizer N rate study located in Lexington, KY. We measured the total soil N and potentially mineralizable N after 48 years, the in situ mineralized N and N uptake during two corn seasons (2018–2019), and the corn grain yield for five seasons (2015–2019). We evaluated the effect of no-till on N fertilizer reliance in two ways – the first was by measuring the agronomic optimum N rate of corn in the two tillage systems, and the second was by measuring the corn yield response to late N fertilization timing in the two tillage systems. We found that the no-till system had 1000 kg N ha⁻¹ greater total soil N stocks in the top 20 cm, mineralized 65 kg ha⁻¹ more N during corn growth, and resulted in 22−71 kg N ha⁻¹ and 780−1800 kg ha⁻¹ greater N uptake and grain yield across N rates, respectively, than the plowed system. The agronomic optimum N rate (AONR) did not differ among tillage treatments, potentially because the no-till treatment yielded more and thus demanded more N. Although corn yield responded to the late N fertilization treatment, the response was similar in both the no-till and plowed treatments. We conclude that long-term no-till increases soil N mineralization and corn yield relative to inversion tillage, with minimal effect on the AONR or optimal timing of N fertilizer application.

免耕管理是在许多环境中增加土壤有机质的一种行之有效的做法。通过增加土壤有机质，免耕会增加土壤中的氮矿化程度，相对于反向耕作，可能减少作物对氮肥的需求。在这项研究中，我们假设相对于反向耕作（mol草翻耕），长期免耕将：i）增加总氮储量，ii）在生长季节增加矿化的氮，iii）增加谷物产量和氮素吸收和iv）减少玉米（Zea mays L.）对氮肥投入的依赖。我们在肯塔基州列克星敦市进行了一项长期，连续的玉米耕作和肥料氮肥施用率研究，对这些假设进行了检验。我们测量了48年后原位土壤的总氮和可能矿化的氮在两个玉米季节（2018-2019年）中矿化的氮和氮吸收量，以及五个季节（2015-2019年）的玉米籽粒产量。我们以两种方式评估了免耕对氮肥依赖的影响：一种是通过测量两种耕作系统中玉米的农艺最佳氮素利用率，第二种是通过测量玉米对后期施氮的产量响应。两个耕作系统。我们发现免耕系统在前20 cm的土壤总氮储量增加了1000 kg N ha ^-1，在玉米生长期间矿化了65 kg ha ^-1多的氮，导致22-71 kg N ha ^-1和780−1800千克公顷^-1与耕作制度相比，在不同氮素施用率下，氮素吸收和谷物产量更高。在耕作处理之间，农艺最佳氮素含量（AONR）没有差异，这可能是因为免耕处理产生的氮含量更高，因此需要更多的氮。尽管玉米产量对后期施氮处理有反应，但两种氮肥的响应相似。直到耕种。我们得出的结论是，相对于反向耕作，长期免耕可增加土壤氮矿化和玉米产量，对AONR或氮肥最佳施用时机的影响最小。