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Chinese Journal of Applied Ecology ›› 2023, Vol. 34 ›› Issue (4): 876-882.doi: 10.13287/j.1001-9332.202304.032

• Special Features of Black Soil Protection and Agricultural Sustainable Development • Previous Articles     Next Articles

Mechanisms of conservation tillage on nitrogen-fertilizer reduction and maize grain improvement in Mollisols of Northeast China: Insights from a 15N tracing study

MIAO He1, YUAN Lei2,3, YANG Miaoyin2,5, HU Yanyu2,3, CHEN Xin2,3, HE Hongbo2,3, ZHANG Xudong2,3, XIE Hongtu2,3, LU Caiyan2,4*   

  1. 1School of Environment, Liaoning University, Shenyang 110036, China;
    2Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China;
    3Liaoning Province Key Laboratory of Conservation Tillage and Ecological Agriculture, Shenyang 110016, China;
    4Liaoning Province Key Laboratory of Stable Isotope Techniques and Applications, Shen-yang 110016, China;
    5University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2022-12-07 Accepted:2023-03-01 Online:2023-04-15 Published:2023-10-15

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Abstract: Conservation tillage is an important management practice to guarantee soil fertility in degraded Mollisols. It is still unclear, however, whether the improvement and stability of crop yield under conservation tillage can be sustainable with increasing soil fertility and reducing fertilizer-N application. Based on a long-term tillage experiment initiated in Lishu Conservation Tillage Research and Development Station by Chinese Academy of Sciences, we conducted a 15N tracing field micro-plot experiment to investigate the effects of reducing nitrogen application on maize yield and fertilizer-N transformation under long-term conservation tillage agroecosystem. There were four treatments, including conventional ridge tillage (RT), no-tillage with 0% (NT0), 100% (NTS) maize straw mul-ching, and 20% reduced fertilizer-N plus 100% maize stover mulching (RNTS). The results showed that after a complete cultivation round, the average percentages of fertilizer N recovery in soil residues, crop usage, and gaseous loss were 34%, 50%, and 16%, respectively. Compared with conventional ridge tillage, no-tillage with maize straw mulching (NTS and RNTS) significantly increased the use efficiency of fertilizer N in current season by 10% to 14%. From the perspective of N sourcing analysis, the average percentage of fertilizer N absorbed by crop parts (including seeds, straws, roots, and cobs) to the total N uptake reached nearly 40%, indicating that soil N pool was the main source of N for crop uptakes. In comparison with conventional ridge tillage, conservation tillage significantly increased total N storage in 0-40 cm by reducing soil disturbance and increasing organic inputs, and thus ensured the expansion and efficiency increment of soil N pool in degraded Mollisols. Compared with conventional ridge tillage, NTS and RNTS treatments significantly increased the maize yield from 2016 to 2018. In all, by improving fertilizer nitrogen utilization efficiency and maintaining the continuous supply of soil nitrogen, long-term management of no-tillage with maize straw mulching could achieve a stable and increasing maize yield in three consecutive growing seasons and simultaneously reduce environmental risks derived by fertilizer-N losses, even under the condition of 20% reduction of fertilizer-N application, and thus actualize the sustainable development of agriculture in Mollisols of Northeast China.

Key words: Mollisols of Northeast China, no-tillage, straw mulching, nitrogen fertilizer reduction, 15N tracing