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Chinese Journal of Applied Ecology ›› 2025, Vol. 36 ›› Issue (9): 2639-2648.doi: 10.13287/j.1001-9332.202509.019

• Special Features of Productivity Improvement in Grain Field with Multiple factor Obstacles (Special Feature Organizer: SUN Zhimei, HUANG Shaohui, ZHANG Junhua) • Previous Articles     Next Articles

Effect of combined application of nitrogen fertilizer and humic acid on soil quality and crop yield in sandy low-to-medium productivity farmland

HU Jiayu1, GAO Bingyang1, GAO Yifan1, YANG Xue1, HUANG Yufang1, GUO Jingli2, YE Youliang1, ZHAO Yanan1*   

  1. 1College of Resources and Environment, Henan Agricultural University, Zhengzhou 450046, China;
    2Henan Xinlianxin Chemical Industry Group Co. Ltd., Xinxiang 453700, Henan, China
  • Received:2025-03-03 Accepted:2025-07-21 Online:2025-09-18 Published:2026-04-18

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Abstract: Understanding the effects of combined nitrogen (N) and humic acid (HA) application on soil quality and crop yield in low-to-medium productivity farmland can provide a scientific basis for enhancing soil productivity and optimizing nutrient management. We conducted a field experiment from 2021 to 2023 in a wheat-maize rotation system in Xinxiang County, Henan Province. There were three N application rates: 0 (N0), 180 (N180), and 270 (N270) kg·hm-2; and four HA levels: 0 (HA0), 1500 (HA1500), 3000 (HA3000), and 6000 (HA6000) kg·hm-2, following a two-factor split-plot design. We examined the effects of combined application of N fertilizer and HA on crop yield, nutrient uptake, soil aggregates and soil nutrients in sandy fluvo-aquic soils, identified key drivers and pathways affecting soil quality and crop yield by random forest (RF) and partial least squared path modeling (PLS-PM). The results showed that under the N0 level, the application of HA increased the two-year average wheat and maize yields by 7.1% and 10.6%, respectively, compared with HA0. Under the N180 level, both wheat and maize yields peaked at HA3000 application, with an annual yield increase of 9.1% over HA0. However, under the N270 level, the application of HA did not affect crop yields. The application of HA at various N levels increased wheat N absorption to varying degrees and improved soil aggregate stability and soil nutrient content. The soil quality index (SQI) was optimal when HA was applied at the N180 level, with total soil N, pH, and organic carbon being key factors affecting SQI. The PLS-PM showed that N fertilizer and HA mainly had positive impact on wheat and maize yields by affecting soil aggregate distribution and soil nutrients. In conclusion, the combined application of 180 kg·hm-2 N fertilizer with 3000 kg·hm-2 HA showed a good effect on enhancing the productivity of low-to-medium productivity farmland in local sandy fluvo-aquic soils.

Key words: soil productivity improvement, humic acid, sandy fluvo-aquic soil, soil fertility, soil aggregate