Pedosphere 34(1): 146--158, 2024
ISSN 1002-0160/CN 32-1315/P
©2024 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Laboratory and numerical modelling of irrigation infiltration and nitrogen leaching in homogeneous soils |
Lei WU1,2,3,4 , Ruizhi LI1,4, Yan WANG1,4, Zongjun GUO1,4, Jiaheng LI1,4, Hang YANG1,4, Xiaoyi MA1,4 |
1 Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas, Ministry of Education, Northwest A & F University, Yangling 712100 (China);
2 Blackland Research and Extension Center, Texas A&M AgriLife Research, Texas A&M University, Temple TX 76502 (USA);
3 State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A & F University, Yangling 712100 (China);
4 College of Water Resources and Architectural Engineering, Northwest A & F University, Yangling 712100 (China) |
| Corresponding Author:Lei WU |
| ABSTRACT |
| Nitrogen (N) plays a key role in crop growth and production; however, data are lacking especially regarding the interaction of biochar, grass cover, and irrigation on N leaching in saturated soil profiles. Eighteen soil columns with 20-cm diameter and 60-cm height were designed to characterize the effects of different grass cover and biochar combinations, i.e., bare soil + 0% biochar (control, CK), perennial ryegrass + 0% biochar (C1), Festuca arundinacea + 0% biochar (C2), perennial ryegrass + 1% biochar (C3), perennial ryegrass + 2% biochar (C4), perennial ryegrass + 3% biochar (C5), F. arundinacea + 1% biochar (C6), F. arundinacea + 2% biochar (C7), and F. arundinacea + 3% biochar (C8), on periodic irrigation infiltration and N leaching in homogeneous loess soils from July to December 2020. Leachates in CK were 10.2%–35.3% higher than those in C1 and C2. Both perennial ryegrass and F. arundinacea decreased the volumes of leachates and delayed the leaching process in the 1%, 2%, and 3% biochar treatments, and the vertical leaching rate decreased with biochar addition. The N leaching losses were concentrated in the first few leaching tests, and both total N (TN) and nitrate (NO3-)-N concentrations in CK and C1–C8 decreased with increasing leaching test times. Biochar addition (1%, 2%, and 3%) could further reduce the leaching risk of NO3--N and the NO3--N loss decreased with biochar addition. However, compared to 1% biochar, 2% biochar promoted the leaching of TN under both grass cover types. The N leaching losses in CK, C1, C2, C3, C4, C6, and C7 were primarily in the form of NO3--N. Among these treatments, CK, C1, and C2 had the highest cumulative leaching fractions NO3--N (> 90%), followed by those in C3, C4, C6, and C7 (> 80%). The cumulative leaching fraction of NO3--N decreased with increasing leaching test times and biochar addition, and 3% biochar addition (i.e., C5 and C8) reduced it to approximately 50%. The one-dimensional advective-dispersive-reactive transport equation can be used as an effective numerical approach to simulate and predict NO3--N leaching in saturated homogeneous soils. Understanding the effects of different biochar and grass combinations on N leaching can help us design environmentally friendly interventions to manage irrigated farming ecosystems and reduce N leaching into groundwater. |
| Key Words: leaching loss,nitrate nitrogen,biochar,grass cover,analytical modelling |
| Citation: Wu L, Li R Z, Wang Y, Guo Z J, Li J H, Yang H, Ma X Y. 2024. Laboratory and numerical modelling of irrigation infiltration and nitrogen leaching in homogeneous soils. Pedosphere. 34(1): 146–158. |
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