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Effect of Drainage Ditch Layout on Nitrogen Loss by Runoff from an Agricultural Watershed

Pedosphere 2013年第2期23卷 256-264页

作者： ZHANG Zhan-Yu KONG Li-Li ZHU Lei R.M.MWIYA Key Laboratory of Efficient Irrigation-Drainage and Agricultural Soil-Water Environment in Southern China Ministry of EducationHohai University College of Water Conservancy and Hydropower Engineering Hohai University

A comparison experiment was performed, by designing one field ditch （D1 treatment）, two field ditches （D2 treatment）, three field ditches （D3 treatment）, and no field ditch （CK treatment）, in an upland of a small agricultural watershed in Nanjing-Zhenjiang hilly regions to observe the farmland surface runoff and N loss characteristics under the different layouts of field ditch. As the layout density of field ditch increased, the drainage effect was improved, the timing of the runoff peak was advanced, and also the peak flow was augmented. At the same time, both the concentration and accumulated transfer flux of total nitrogen （TN） were improved, and thereinto the accumulated transfer fluxes of TN under D3, D2 and D1 treatments were increased by 1.46, 1.34 and 1.16 times, respectively, than that under CK treatment. However, the accumulated transfer fluxes of nitrate-nitrogen （NO3-N） and ammonium-nitrogen （NH4＋-N） under D3, D2 and D1 treatments were reduced by 33.9%, 21.4% and 8.6%, and 35.8%, 24.7% and 12.2%, respectively, compared with those under CK treatment. Under CK treatment, the NO3-N and NH4＋-N concentrations were more sensitive to rainfall intensity than the TN concentration. There were significant linear relationships between the transfer fluxes of TN, NO3-N and NH^-N and the runoff flux, with the correlation coefficients of 0.942, 0.899 and 0.912, respectively. In addition, this correlation was also influenced by the layout density of field ditch. Therefore, the environmental effect should be taken into account when designing and constructing field ditches. Especially in the regions of severe fertilizer loss, the approaches of properly increasing the drainage area and decreasing the layout density of field ditch could be adopted under the precondition of avoiding crops from waterlogging.

关键词： drainage velocity layout density of field ditches surface runoff transfer fluxes uplands

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Maize Cannot Be Grown in Xiengkhouang Province?

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Agricultural Sciences 2019年第10期10卷 1359-1369页

作者： Xaysatith Souliyavongsa Nivong Sipaseuth Khonpany Dounphady Tasnee Attanandana Piboon Kanghae Russell Yost Sukunya Yampracha Sunan Kunaporn Department of Agriculture Land Management Vientiane Laos Kasetsart University Bangkok Thailand Department of Plant Production Technology Faculty of Agricultural Technology King Mongkut’s Institute of Technology Ladkrabang Bangkok Thailand Department of Tropical Plant and Soil Science University of Hawai’i Honolulu Hawaii Land Development Department (Retired) Bangkok Thailand.

During a 2005 visit with National Agricultural and Forestry Institute (NAFRI) Director, Dr. Kouang Doungsila issued a challenge to these authors to determine if it was true that crops could not be grown in the extensive uplands of Xiengkhouang Province, Laos PDR. In response, a two-phase series of experiments was proposed and implemented. The Phase I experiment was to bring soil from the Xiengkhouang province uplands to a NAFRI greenhouse near Vientiane to assess possible nutrient requirements using a nutrient omission experiment. Simultaneously, soils were collected and analyzed from seven recognized agricultural regions of Laos. The initial Vientiane greenhouse experiment indicated that maize did grow, but there were multiple issues of extreme soil acidity and clear deficiencies of phosphorus and other nutrients. Phase II of the study included field studies on the site of soil selected for the greenhouse study. Field experiments were carried out for two years at the site with yields of maize exceeding 5500 kg⋅ha−1 in the first year and exceeding 6250 kg⋅ha−1 in a subsequent year. Intense symptoms of nutrient zinc (Zn) deficiency were observed, however. In 2008 another experiment was designed and carried out that included a Zn variable. The results from that experiment confirmed that maize yields nearing 6000 kg⋅ha−1 were indeed possible. Substantial amounts of lime were needed to correct the strong soil acidity, and a series of other nutrients including N, P, K, and Zn were also required. Ongoing issues are where to obtain the extensive amounts of limestone needed as well as an evaluation of the residual effect of the limestone The finely ground, very reactive burnt lime residual effect was, as expected, short-lived. The results clearly demonstrated that, indeed, it was possible for maize to be produced in the extensive uplands of Xiengkhouang province, in answer to Director Khouang’s challenging question.

关键词： Lao uplands Food Security Acid Soils of the Tropics

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