Subsurface drainage

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  • This volume consists of a collection of current studies on free electron lasers. Free Electron Lasers covers the analysis of fundamentals and questions of design of these devices functioning from the infrared to ultraviolet or xuv wavelength regimes. In addition to the comparison with conventional lasers, analyses of some related topics concerning near-field and cavity electrodynamics, compact and table-top arrangements and strong radiation–induced exotic states of matter are presented.

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  • Drainage of water through the soil profile to groundwater and surface water appears to be the hydrologic pathway that most frequently leads to problematic nitrate contamination of surface waters in agricultural watersheds. This can occur in two ways: by natural drainage where ground water contributes to stream flow and river flow, and by artificial subsurface drainage, where perforated pipes (sometimes called tile drains) have been buried in the soil for the purpose of removing water to reduce damage caused by saturated conditions and thereby enhance crop production (Fig. 1).

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  • In most agricultural settings, commercial fertilizer provides only one source of N used for crop production. Animal manure, biological N fixation, mineralization from soil organic N, and deposition of N from the atmosphere can also contribute to soil fertility and surface water contamination. Because there are multiple sources and sinks of N in the soil, the relationship between N fertilizer application rate and nitrogen loss in drainage water is not always consistent across locations and across studies.

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  • In many settings nitrogen enrichment of surface water bodies has increased following the increased use of N fertilizers. The precise contribution of nitrogen fertilizers to surface water nitrogen has been difficult to quantify because there are multiple sources of nitrogen contributing to most water bodies, and, depending on environmental conditions, a certain portion of soil nitrogen may be converted to gaseous or immobile forms.

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  • Tham khảo sách 'materials for subsurface land drainage systems', kỹ thuật - công nghệ, tự động hoá phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả

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