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Acta Prataculturae Sinica ›› 2015, Vol. 24 ›› Issue (4): 57-65.DOI: 10.11686/cyxb20150407

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Simulation study of nutrient leaching from soils irrigated with biogas slurry under different environmental temperatures

ZHANG Zhen1, TANG Hua2, GUO Yan-Jun1*   

  1. 1.College of Agronomy and Biotechnology, Southwest University, Chongqing 400716, China;
    2.College of Animal Science and Technology, Southwest University, Chongqing 400716, China
  • Received:2014-08-21 Revised:2014-10-08 Online:2015-04-20 Published:2015-04-20

Abstract: Biogas slurry is widely used in agriculture due to its high nutrient utilization rate in soil. However, temperature might influence nutrient leaching from the slurry by affecting the physical and chemical characteristics of soils. In this study, nutrient leaching under different environmental temperatures was analyzed using the soil column simulation method, with the aim of providing advice for slurry use in different seasons. Three simulations were investigated: 300 mL water as control, 40 mL slurry plus 260 mL water, and 80 mL slurry plus 220 mL water, with application rates equaling to 0, 130 and 260 kg N/ha respectively. 300 mL of each solution were applied per soil column (7.5 cm, height 20 cm) with irrigation periods of 30 min. Leached solutions were collected until no further leaching was observed. The soil columns were cultured under 20 and 30℃ conditions and leached every 6 days for 5 times in total. The leached solution was analyzed to determine levels of total nitrogen, NO3-N, NH4-N, total potassium, total phosphorus, available phosphorus and electric conductance. Results showed that NO3-N, NH4-N, total phosphorus, total potassium and electric conductance decreased with increased leaching times only for the water control. Compared to the control, slurry applications increased the amounts of leached nitrogen, phosphorus and potassium. With the 40 mL solution, total nitrogen, total potassium and total phosphorus increased on average by 73%, 880% and 388% respectively. The amount of leached nutrient increased with increased slurry application rates and with higher environmental temperatures. Compared with 20℃, the 30℃ leached solutions showed increased total nitrogen, total phosphorus and total potassium by 14.7%, 33.6%, and 24.1% respectively. Higher environmental temperatures thus increase the amount of nutrient leaching from soils irrigated with biogas slurry. It is thus suggested that application times should be reduced in summer and increased in spring and autumn. However, the total amount of biogas slurry should be less than 130 kg N/ha to avoid excessive leaching and pollution of surrounding environment.