A comparison analysis of edge-of-field run-off from two sugarcane fields

Agricultural run-off is an important source of nonpoint source pollution. Surface run-off driven by rainfall events was analyzed at two sugarcane fields (SC1 and SC2) in Louisiana, USA. The study site was within a watershed confined by the Mississippi River levee and a drainage canal (St. James Canal). In total, 14 representative rainfall run-off events were analyzed. For comparison with onsite monitoring, a modeling technique was used to estimate run-off. The results show that run-off/rainfall ratios at SC1 were significantly higher (p < 0.0001, n = 14) than at SC2, probably mainly due to a higher sand content of the soil and a higher infiltration rate at SC2 than at SC1. Model-calculated run-off showed substantial overestimation compared with the monitoring results, especially at SC2. Comparison analysis suggests that significant infiltration following precipitation is expected in sandy fields, and water discharge into the groundwater aquifer cannot be ignored. Without considering groundwater discharge in model algorism, the model calculation may significantly overestimate actual surface run-off.     

水文过程中降雨径流对非点源污染的影响(英文)

[目的]研究降雨径流对非点源污染的影响,拟通过控制降雨径流产生的污染来减少非点源污染。[方法]通过分析降雨径流的水文过程、其与非点源污染物的作用机理及其对非点源污染的影响,以及水文模型在该研究中的应用,探讨如何有效的减少非点源污染。[结果]降雨径流是非点源污染的主要原因,通过源头控制,加强地表非点源污染物清除和控制,在坡地上种植植被,可有效减少降雨径流对土地的冲刷和侵蚀,减少水土流失。水文模型的应用使该研究简单化。[结论]研究表明对降雨径流过程进行控制将有效减少非点源污染。     

水文过程中降雨径流对非点源污染的影响

[目的]研究降雨径流对非点源污染的影响,拟通过控制降雨径流产生的污染来减少非点源污染。[方法]通过分析降雨径流的水文过程、其与非点源污染物的作用机理及其对非点源污染的影响,以及水文模型在该研究中的应用,探讨如何有效的减少非点源污染。[结果]降雨径流是非点源污染的主要原因,通过源头控制,加强地表非点源污染物清除和控制,在坡地上种植植被,可有效减少降雨径流对土地的冲刷和侵蚀,减少水土流失。水文模型的应用使该研究简单化。[结论]研究表明对降雨径流过程进行控制将有效减少非点源污染。     

Afforestation with ‘multipurpose trees’ in ‘media lunas’, a case study from the Tarija basin,Bolivia

Human-induced soil erosion has already affected all of the potential farming land in the Tarija basin/South Bolivia. It is described as an afforestation method involving media lunas and multipurpose trees, whose implementation is associated with a high degree of mobilization of the target group.On sites where a sufficient number of media lunas have been established, surface runoff is drastically reduced. They diminish the risk of failure of newly planted trees during frequently occurring dry phases, and promote their growth by preventing excessively large fluctuations in the soil-water balance and increasing soil moisture in general. Mostly indigenous multipurpose trees (Acacia and Prosopis) serve to stabilize erosion-prone sites on a long-term basis, and become invaluable because they provide a source of firewood, improve the soil, and yield protein-rich livestock forage during dry season. Media lunas provide more favorable conditions for natural vegetation.     

森林水文研究概述

森林是一个复杂的生态系统, 森林水文是近年来研究的热点。如何正确看待森林对流域径流的调节作用, 评价森林水文效应, 是值得长期探讨的话题。文中主要探讨了森林对流域径流的调节作用, 以及如何利用流域水文模型模拟森林流域水文动态过程, 正确评价森林水文效应。     

Herbicide movement in soils: principles, pathways and processes

European legislation concerning ground- and surface-water quality and the protection of non-target organisms in surface-water from pesticide contamination has initiated more stringent data requirements from regulatory authorities concerning the movement of all pesticides in soils. Other interested parties, such as water companies, environment agencies and consumer-driven organizations, have sought to influence the use of herbicides and their impact on the environment. The resulting studies and associated research have led to a better understanding of the fate and behaviour of herbicides in the soil environment. The amount of herbicide that moves away from the area of application will depend on the physico-chemical properties of the chemical and the agroclimatic characteristics of the target site. Under average conditions, the amount of herbicide lost by movement from a soil profile is typically <0.1% to 1% of the applied mass but, under certain localized circumstances, can reach up to 5% or greater. Leaching, drain-flow and surface run-off are the main pathways responsible for herbicide movement within soils. The soil/herbicide processes determining the losses are also variable in both time and space. It is therefore necessary to understand the spatial characteristics of soils, their hydrology and the associated herbicide use patterns.     

A Summary of Literature References of Factors Affecting Moisture Content Determination with D.C. Resistance Measurements

The protective effect of ectomycorrhizae of Pinus patula Schlecht. et Cham against the root pathogen Phytophthora cinnamomi was investigated. Three methods were employed to evaluate this effect. Firstly, extracts were prepared from the root systems of mycorrhizal plants and tested for antibiotic activity against P. cinnamomi. Secondly, fungal antagonism between two mycobionts Amanita muscaria and Boletus edulis, and the pathogen was tested for in vitro; and thirdly, in situ studies were conducted to determine the protective effect afforded under natural conditions. No fungal antagonism was observed in vitro, but significant protection was obtained in situ and when the pathogen was exposed to the extracts. The mechanism involved could thus probably be attributed to the production of antibiotic substances by the macrobiont and mycobiont, and the formation of a physical barrier, the Hartig-net and the fungal mantle.     

红松人工林水文效应的初步研究

为了探讨人工林生态系统的生态功能与效应，根据生态学理论，采用长期定位观测的方法，系统地研究了东北林业大学老山人工林实验站地产流的特点。结果表明：⑴红松人工林对降雨的分配具有特殊的规律性，平均林冠截雨率为１３．４％，树干径流率为５．３％；⑵林内各降雨分量与林外降雨量呈显著的线性关系；⑶与落叶松人工林相反，红松人工林平均截雪率为３３．３％，明显强于截水能力；⑷红松人工林内地表径流很少发生，其他表径流率     

不同耕作方式对豫西旱区坡耕地水肥利用与流失的影响

为筛选适宜豫西早坡地应用的耕作技术，对深松覆盖、免耕覆盖、一次深翻和传统耕作等4种耕作方式的土壤水分、养分及其利用与流失情况进行了研究，结果表明：深松覆盖、免耕覆盖能提高土壤蓄水量，土壤有机质和氮、磷、钾含量明显高于传统耕作，特别是对上层土壤全氮及碱解氮和深层土壤的有效磷及速效钾的影响更为明显，并能有效地减少地表产流次数和径流量，减少土壤养分的流失，提高水分利用效率和养分的生产效率，显著提高小麦产量。与传统耕作相比，深松覆盖和免耕覆盖水分利用效率提高16．37％和10．62％，氮素生产效率提高17．40％和10．27％，磷素生产效率提高19．80％和12．54％，钾素生产效率提高19．44％和12．19％，小麦产量提高23．22％和15．38％，经济效益提高29．36％和21．13％。     

Slurry acceptance mapping of Northern Ireland for run-off risk assessment

Using geographic information system techniques, hydrology of soil types (HOST) classes were combined with slope, rockiness, flood hazard and soil moisture deficit classes within a risk matrix to produce a slurry acceptance map for Northern Ireland (NI) on a 50 m grid. Moreover, due to the whole territory of NI being designated as a nitrate vulnerable zone, a nitrates action programme is to be implemented across the region in the near future and this is likely to restrict slurry applications to the growing season. To assess the risk classes associated with slurry applications during the growing season, an additional slurry acceptance map for NI was created in which the HOST factor was excluded from the analysis. The maps created showed that, for the period January–December, the majority (80%) of agricultural soils in NI were in the severe risk category following application of 50 m³ ha^?1 of slurry. However, this proportion was reduced to only 29% when the same volume of slurry was applied during the growing season, when the soils were not saturated and significant rainfall was not received in the period immediately after slurry application.