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| DOI：10.13522/j.cnki.ggps.2021342 |
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| Optimal Timing of Fertilization in Drip Fertigation for Bioavailable Water and Nitrogen in Soils of Different Textures |
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SUN Weihao, SHEN Xiaojun, Mounkaila Hamani Abdoul Kader, et al.
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1. Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences/Key Laboratory of Crop Water Requirement and Regulation, Ministry of Agriculture and Rural Affairs, Xinxiang 453002, China; 2. Graduate School of Chinese Academy of Agricultural Sciences, Beijing 100081, China; 3. College of Water Conservancy Engineering, Tianjin Agricultural University, Tianjin 300392, China
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| Abstract: |
| 【Objective】Designing irrigation and fertilization scheduling needs to understand how water and fertilizer move in soil. The aim of this papers is to experimentally study the movement of water and nitrogen (N) in soils of different texture as impacted by timing of fertilization in drip fertigation.【Method】The experiment was conducted indoor using tanks repacked with sandy (S1), loam (2) and clay (3) soil. For each soil, there were four fertilizations with the fertilization lasting half of the irrigation duration but starting at different times: in the first half (T1), in the central half (T2), and commencing 3/8 way after the onset of irrigation (T3). Irrigation without fertilization was taken as the control (CK). In each treatment, we measured the movement of the wetting front and distributions of water and nitrate in the soil.【Result】When the irrigation amount and dripping rate were the same, there were significant differences in water movement between the three soil types. The maximum water infiltration depth in the sandy soil was 29.5 cm, compared to 21 cm in the loam soil and 15 cm in the clay soil. Nitrate accumulated at the edge of the wetting fronts, and delaying fertilization timing slowed down nitrate migration towards the wetting front. There were differences in nitrate distribution between the three soil types, and the difference varied with the timing of the fertilization. In the sandy soil, nitrate in the subsoil soil under T4 was least. In the loam soil, the nitrate distribution was more uniform than that in T3. In the clay soil, T2 reduced nitrate accumulation in the surface soil.【Conclusion】Soil texture and timing of fertigation had significant impacts on nitrogen distribution. For the sandy, loam and clay soil we studied, the best timing for fertilization under drip fertigation was 3/8 way after the irrigation commenced, in the central half and in the first half, respectively. These reduced the risk of nitrogen leaching while in the meantime improving nitrogen use efficiency by crops. |
| Key words: drip fertigation; soil texture; timing of fertilization; wetting front; nitrate distribution |
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