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| DOI：10.13522/j.cnki.ggps.2025326 |
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| Synergistic effects of biogas slurry and biogas residue applications on soil water movement, thermal regime and organic matter content |
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Zheng Jian, Fan Panpan, Ma Biao, Liu Haitao, Wang Junjie, Guo Yajun
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1. School of Civil and Hydraulic Engineering, Lanzhou University of Technology, Lanzhou 730050, China;
2. Key Laboratory of Multi-supply System with Solar Energy and Biomass, Gansu Province, Lanzhou 730050, China;
3. Key laboratory of Degraded and Unused Land Consolidation Engineering, the Ministry of Natural Resources,
Xi’an 710000, China; 4. Shaanxi Agricultural Development Group Co., Ltd., Xi’an 710000, China;
5. Shule River Basin Water Resources Utilization Center of Gansu Province, Yumen 735211, China
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| Abstract: |
| 【Objective】Biogas slurry and residue are rich in nutrients, and their combined application can improve soil quality. This study experimentally investigates the synergistic effect of biogas slurry and biogas residue on soil water movement and soil organic matter.【Method】The laboratory infiltration experiment included four biogas residue application rates (mass of biogas residue/mass of soil): 0% (S0), 1% (S1), 2% (S2) and 4% (S4), and three biogas slurry concentration treatments (volumetric ratio of biogas slurry to water): 0 (W0), 1∶8 (W1:8) and 1∶4 (W1:4). For each treatment, we measured soil water-holding capacity, wetting front advancement, cumulative infiltration, cumulative evaporation, diurnal soil temperature variation, and soil organic matter content. Temporal variations in wetting front migration distance, cumulative infiltration, and cumulative evaporation were fitted to the power function, Kostiakov model and Rose model, respectively.【Result】①Soil water-holding capacity increased with increasing biogas residue application rate and biogas slurry concentration. The volumetric soil water content under S4W1:4 was 15.84% higher than that under S0W0. The water retention curves of all treatments were well fitted by the van-Genuchten model, with a coefficient of determination (R2) ≥ 0.998 5. ②Increasing biogas residue application and biogas slurry concentration remarkably reduced water infiltration. When irrigation was 120 mm, the S4W1:4 treatment prolonged the infiltration duration by 106.49% compared with S0W0. The relationship between wetting front distance and infiltration time can be described by a power-law function (R2 ≥ 0.993 2, RRMSE ≤ 0.055 0, NS ≥ 0.993 4). The Kostiakov model well described the temporal change in cumulative infiltration (R2 ≥ 0.994 7, RRMSE ≤ 0.059 5, NS ≥ 0.992 5). ③With the increase in biogas residue application rate, soil evaporation first increased and then decreased; increasing biogas slurry concentrations reduced soil evaporation. The cumulative evaporation in the S4W1:4 was 32.34 mm, the lowest among all treatments. The Rose model accurately described the temporal change in cumulative evaporation (R2≥ 0.953 5, RRMSE ≤ 0.048 8, NS ≥ 0.958 7). With increasing biogas residue application, the diurnal temperature amplitude of each soil layer initially increased and then decreased. Biogas slurry irrigation effectively reduced diurnal soil temperature variation. Soil organic matter content was positively correlated with both biogas residue application rate and biogas slurry concentration.【Conclusion】The combined application of 4% biogas residue and 1∶4 biogas slurry dilution can effectively balance soil water infiltration and evaporation in silty loam soil. |
| Key words: biogas slurry; digestate; soil moisture characteristic curve; cumulative evaporation; cumulative infiltration volume; soil temperature; organic matter |
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