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| Effects of hole application of urea mixed with biochar on nitrogen content and enzyme activity |
| Received:February 08, 2020 |
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| KeyWord:reduced nitrogen application;biochar;soil available nitrogen;soil enzymes |
| Author Name | Affiliation | E-mail | | ZHANG Li | College of Resources and Environment, Gansu Agricultural University, Lanzhou 730070, China | | | REN Jian-xin | College of Resources and Environment, Gansu Agricultural University, Lanzhou 730070, China | | | HAN Guo-jun | College of Resources and Environment, Gansu Agricultural University, Lanzhou 730070, China | hangj@gsau.edu.cn | | MA Le-yuan | College of Resources and Environment, Gansu Agricultural University, Lanzhou 730070, China | | | SUN Xiao-mei | College of Resources and Environment, Gansu Agricultural University, Lanzhou 730070, China | |
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| Abstract: |
| Biochar is widely recognized as an excellent soil ameliorant as it improves soil properties and protects the soil environment. In this study, potted experiments were conducted to investigate the effects of corn straw biochar on soil enzyme activities and soil nitrogen when urea was mixed with biochar in a hole application. In total, seven treatments were tested, including conventional urea treatment(N120, N180, and N240)and combined hole application of biochar and urea(N120B, N180B, and N240B). The amounts of applied nitrogen were 240, 180, and 120 kg·hm-2 for N240, N180, and N120, respectively, and 10 t·hm-2 each for the control treatment and urea mixed with biochar in the hole application. Soil nitrogen(nitrate, ammonium nitrogen, inorganic nitrogen, and available nitrogen)and soil enzymes(urease, sucrase, and alkaline phosphatase)were measured. The results demonstrated that the contents of ammonium nitrogen, nitrate nitrogen, inorganic nitrogen, and available nitrogen in soil after a single application of the urea treatments were 4.5~8.2, 2.0~3.0, 2.55~5.81, and 3.13~4.46 times those of the mixed urea and biochar treatment on the 5th day. The corresponding contents were 24.5~58.9, 1.21~1.37, 2.99~3.82, and 1.34~1.48 times those of the urea and mixed biochar treatments on the 10th day. No significant difference was observed between the soil nitrogen contents of the treatments on the 15th day. On the 5th and 10th days, the activity of urease in the soil subjected to the urea mixed biochar treatment was significantly higher than that in the soil subjected to the urea treatments, but no significant difference was observed between the soil enzyme contents of the treatments on the 15th day. The activities of urease, sucrase, and alkaline phosphatase in the soil subjected to the mixed urea and biochar treatment were 1.80~2.55, 1.07~1.77, and 1.18~1.22 times of those in the soil that underwent single urea treatments on the 5th day. The activity of sucrase in the soil with the mixed urea and biochar N180B treatment was the highest on the 10th day, while the activity of alkaline phosphatase was the highest for the N240B treatment, and the activity of sucrase in the soil with the mixed urea and biochar treatments was 2.35~2.37 times of that of the soil subjected to the single urea treatments. Biochar application significantly enhanced the soil urease, sucrase, and alkaline phosphatase activities. Biochar adsorbed NH4+ and NO3- from the soil and endowed it with release characteristics, while the hole application of urea mixed with biochar promoted the soil enzyme activities and reduced the risk of effective nitrogen loss from the soil. |
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