共查询到20条相似文献,搜索用时 31 毫秒
1.
Policy incentives for reducing nitrate leaching from intensive agriculture in desert oases of Alxa, Inner Mongolia, China 总被引:2,自引:0,他引:2
Yongping Wei Deli Chen Kelin Hu Ian R. Willett John Langford 《Agricultural Water Management》2009,96(7):1114-1119
Excessive irrigation and nitrogen applications result in substantial nitrate leaching into groundwater in intensively cropped oases in desert areas of Alxa, Inner Mongolia. An integrated modelling approach was developed and applied to compare policy incentives to reduce nitrate leaching. The integrated model consists of a process-based biophysical model, a meta-model, a farm economic model and an assessment of policy incentives. The modelling results show that there are “win-win” opportunities for improving farm profitability and reducing nitrate leaching. We found that 4471 Yuan ha−1 of farm gross margin could be obtained with a reduction in nitrate leaching of 373 kg ha−1. Farmers’ lack of knowledge about water and nitrogen in soil, and on crop requirements for water and nitrogen could explain the differences, so that agricultural extension is an appropriate policy incentive for this area. When the economic optimum is obtained reductions in nitrate leaching are not achievable without profit penalties and there is a “trade-off” relationship between farm profitability and groundwater quality protection. The combination of low elasticity of nitrate leaching and large elasticity of farm gross margin against water price increases results in very high costs for reducing nitrate leaching (105.6 Yuan kg−1). It is suggested that if the water price increases were coupled with subsidies for adopting nitrate leaching mitigation practices, environmental gains could come at a lower cost. 相似文献
2.
《Agricultural Water Management》2005,74(3):219-242
The regular application of nitrogen fertilizers by irrigation is likely responsible for the increase in nitrate concentrations of groundwater in areas dominated by irrigated agriculture. Consequently, sustainable agricultural systems must include environmentally sound irrigation practices. To reduce the harmful effects of irrigated agriculture on the environment, the evaluation of alternative irrigation water management practices is essential. Micro-irrigation offers a large degree of control, enabling accurate application according to crop water requirements, thereby minimize leaching. Furthermore, fertigation allows the controlled placement of nutrients near the plant roots, reducing fertilizer losses through leaching into the groundwater. The presented two-dimensional modeling approach provides information to improve fertigation practices. The specific objective of this project was to assess the effect of fertigation strategy and soil type on nitrate leaching potential for four different micro-irrigation systems. We found that seasonal leaching was the highest for coarse-textured soils, and conclude that fertigation at the beginning of the irrigation cycle tends to increase seasonal nitrate leaching. In contrast, fertigation events at the end of the irrigation cycle reduced the potential for nitrate leaching. For all surface-applied irrigation systems on finer-textured soils, lateral spreading of water and nitrates was enhanced by surface water ponding, causing the water to spread across the surface with subsequent infiltration downwards and horizontal spreading of soil nitrate near the soil surface. Leaching potential increased as the difference between the extent of the wetted soil volume and rooting zone increased. 相似文献
3.
Drip system uniformity is one of the important factors affecting the deep percolation and nitrate leaching under drip-irrigated crops. Field experiments were conducted during two growing seasons of spring maize (Zea may L.) in 2011 and 2012 in North China Plain to evaluate the influence of drip irrigation system uniformity on deep percolation and nitrate leaching under semi-humid conditions. In the experiments, three Christiansen uniformity coefficients of 59, 80, and 97 % (the equivalent distribution uniformity DU values were 57, 71, and 95 %, respectively) and three levels of nitrogen applied at 0, 120, and 210 kg ha?1 were tested. The results of the study demonstrated that nitrate leaching was most importantly affected by the nitrogen applied, followed by the initial nitrogen content in the soil and the drip irrigation system uniformity. An increasing amount of nitrogen applied and initial nitrogen content increased the seasonal nitrate leaching significantly, while an improving system uniformity decreased the nitrate leaching. The conventional nitrogen application rate of 210 kg ha?1 could be reduced, and an extremely low drip uniformity of less than 60 % is not recommended to reduce the risk of deep percolation and nitrate leaching in the semi-humid region of North China Plain. 相似文献
4.
《Agricultural Water Management》2001,48(1):37-50
High value crops such as carrot planted in coarse soils of the Southern San Joaquin Valley in California are prime candidates for nitrate leaching through irrigation nonuniformity. A 2-year study was carried out to explore the impact of irrigation uniformity on nitrate leaching. Irrigation uniformity was measured using catchcans. Soil nitrate (NO3-N) and ammonium (NH4-N) contents were measured from soil sampled at different depths and times during two growing seasons. Nitrate leaching was determined using ion-exchange resin bags at 1-m depth sampled three times during each season. Although, soil NO3-N as well as seasonal irrigation was significantly higher along the lateral irrigation pipe than between the sprinklers, nitrate leaching was not significantly higher. As expected, soil nitrate content decreased as percolation increased for both years. Nitrate leaching, as estimated by anion-exchange resin bags, was positively correlated to soil NO3-N content but was not correlated to irrigation depth, irrigation uniformity, or deep percolation. Field variation in saturated hydraulic conductivity (Ks), soil organic matter (OM), and soil water retention at field capacity had limited effect on NO3-N and NH4-N distributions in the profile and on nitrate leaching. The results of this experiment suggest that irrigation nonuniformity has less impact on nitrate movement than suggested by earlier studies. 相似文献
5.
《Agricultural Water Management》2002,52(3):177-196
Due to the competitive use of available water resources, it has become important to define appropriate strategies for planning and management of irrigated farmland. To achieve effective planning, accurate information is needed for crop water use requirements, irrigation withdrawals, runoff and nitrate leaching as a function of crop, soil type and weather conditions at a regional level. Interfacing crop models with a geographic information system (GIS) extends the capabilities of the crop models to a regional level. The objective of this study was to determine the irrigation requirements, annual runoff and annual nitrate leaching for the most important crops of the Tibagi river basin in the State of Parana, Brazil. The computer tool selected for this study was the Decision Support System for Agrotechnology Transfer (DSSAT) version 3.5 (98.0) and its associated crop modeling and spatial application system AEGIS/WIN. It was assumed that farms within the same county use similar management practices. To achieve representative estimates of irrigation requirements, the weather data from stations located within each county or the nearest weather station were used. A weighting factor based on the proportion of soil type and crop acreage was applied to determine total annual irrigation withdrawals, annual runoff and nitrate leaching for each county in the river basin. The model predicted outputs, including yield, irrigation requirements, runoff and nitrate leached for different soil types in each county, were analyzed, using spatial analysis methods. This allowed for the display of thematic maps for irrigation requirements, annual runoff and nitrate leaching, and to relate this information with irrigation management and planning. The maximum annual irrigation withdrawal, runoff and nitrate leaching were 22,969 m3 per year, 31,152 m3 per year and 1488 t N per year in the Tibagi river basin. This study showed that crop simulation models linked to GIS can be an effective planning tool to help determine irrigation requirements for river basins and large watersheds. 相似文献
6.
Simulation of bromide and nitrate leaching under heavy rainfall and high-intensity irrigation rates in North China Plain 总被引:5,自引:0,他引:5
Heavy rainfall and irrigations during the summer months in the North China Plain may cause losses of nitrogen because of nitrate leaching. The objectives of this study were to characterize the leaching of accumulated N in soil profiles, and to determine the usefulness of Br− as a tracer of surface-applied N fertilizer under heavy rainfall and high irrigation rates. A field experiment with bare plots was conducted near Beijing from 5 July to 6 September 2006. The experiment included three treatments: no irrigation (rainfall only, I0), farmers’ practice irrigation (rainfall plus 100 mm irrigation, I100) and high-intensity irrigation (rainfall plus 500 mm irrigation, I500), with three replicates. Transport of surface-applied Br− and NO3− (assuming no initial NO3− in the soil profile) and accumulated NO3− in soil profiles were all simulated with the HYDRUS-1D model. The model simulation results showed that Br− leached through the soil profile faster than NO3−. When Br− was used as a tracer for surface-applied N fertilizer to estimate nitrate leaching losses, the amount of N leaching may be overestimated by about 10%. Water drainage and nitrate leaching were dramatically increased as the irrigation rate was increased. The amounts of N leaching out of the 2.1-m soil profile under I0, I100 and I500 treatments were 195 ± 84, 392 ± 136 and 612 ± 211 kg N ha−1, equivalent to about 20 ± 5%, 40 ± 6% and 62 ± 7% of the accumulative N in the soil profile, respectively. N was leached more deeply as the irrigation rate increased. The larger amount of initial accumulated N was in soil profile, the higher percentage of N leaching was. N leaching was also simulated in summer under different weather conditions from 1986 to 2006. The results indicated that nitrate leaching in rainy years were significantly higher than those in dry and normal years. Increasing the irrigation times and decreasing the single irrigation rate after fertilizer application should be recommended. 相似文献
7.
Simulation of nitrate leaching under potato crops in a Mediterranean area. Influence of frost prevention irrigation on nitrogen transport 总被引:1,自引:0,他引:1
The Sa Pobla area (Majorca Island, Spain) heavily depends on the use of groundwater resources for irrigation and urban water supply and is characterised by the presence of intensive potato farming activities. The Plioquaternary aquifer is unconfined and contains high levels of nitrate concentrations. To analyse the risk of contamination to the aquifer arising from agricultural practices, the amount of water and nitrogen leached below the root zone was simulated by the GLEAMS code. Data for model calibration and validation were obtained from field experiments on six potato crops for the years 2004-2007.When air temperatures drop below 1 °C irrigation water is applied to prevent crops from frost damage. During times of anomalously low air temperatures, the risk of nitrate leaching is increased by as much as 318% from frost prevention irrigation under normal local conditions.The GLEAMS simulation model was successfully calibrated for Sa Pobla conditions under potato cropping as shown by RMSE values for the water transport module of 0.19, 0.14 and 0.13 for the calibration period and 0.20, 0.25 and 0.15 for the validation period at depths of 0.3, 0.6, and 0.9 m respectively; and for the chemical transport module the R2 value was 0.82 for the calibration period and 0.60 for the validation period. Consequently, for Sa Pobla conditions, GLEAMS can be used to assess the effectiveness of different agricultural management practices to reduce nitrate leaching. It was concluded that additional irrigation water applied for frost prevention plays a very important role in nitrate leaching below the root zone, which enhances the nitrogen loading to the aquifer. 相似文献
8.
9.
《Agricultural Water Management》2001,49(2):97-114
Six supplementary irrigation management options for grazed grassland were defined and their effects on both agricultural production and nitrate leaching to the groundwater were studied. Data were available from the De Marke experimental farm for sustainable dairy farming. The calibrated and validated simulation models SWACROP and ANIMO were used to calculate the effects of the different irrigation management options on crop transpiration, and on water fluxes and nitrate concentrations for three fields of the farm. Comparisons with the common practice at the farm were made. A change in application volume from 25 to 15 mm per irrigation resulted in higher irrigation efficiencies and lower annual water use for supplementary irrigation with only small changes in the ratio of actual and potential transpiration (Ta/Tp). The advisory system ‘irrigation planner’ generally also resulted in high irrigation efficiencies combined with a reduction of water use and a small effect on the transpiration ratio. The different irrigation strategies had no significant effect on nitrate concentrations in the leachate from two dry fields studied. For the relatively wet field in this study an increase of irrigation water use would improve agricultural production conditions and reduce nitrate concentrations at 1 m depth. For the evaluation of environmental effects of irrigation management options it is advised to assess the actual nitrate concentrations and not only the water fluxes, which potentially cause solute leaching. 相似文献
10.
11.
G.J. Hoffman J.D. Oster E.V. Maas J.D. Rhoades J. Van Schilfgaarde 《Agricultural Water Management》1984,9(1):61-78
A field experiment was conducted for 5 years in the Wellton-Mohawk Irrigation and Drainage District of southwest Arizona to investigate the potential for reducing the salt load in irrigation return flow by decreased leaching in citrus. Leaching treatments of 5, 10, and 20%, replicated nine times, were established on mature Valencia orange trees (Citrus sinensis L.) and compared with conventional flood irrigation management.The annual evapotranspiration was found to be about 1470 mm. The leaching fractions, determined indirectly by several techniques, were close to those intended. The leaching fraction for the flood check was 0.47. During the first 4 years, the leaching treatments had no observable influence on fruit yield or quality or on tree growth. During the last year of the study, however, the yield of the 5% leaching treatment was significantly lower than the other treatments. Thus, with some uncertainty, the leaching requirement for Valencia orange irrigated with Colorado River water exceeds 5% but is less than 20%.Results verify that water applications could be reduced substantially below typical commercial practice without loss of crop yield. At the conclusion of the experiment reducing the leaching fraction to 0.20 for the 3000 ha of citrus in the District would reduce the salt load in the irrigation return flow by 127000 Mg annually. After steady state conditions are reached at 20% leaching the annual reduction would be 42500 Mg. 相似文献
12.
Field experiments were carried out over a 2-year period on a loamy soil plot under corn in Montpellier (south-east France). The effectiveness of improved irrigation practices in reducing the adverse impact of irrigation on the environment was assessed. Different irrigation and fertiliser treatments were applied to identify the best irrigation and fertilisation strategy for each technique (furrow and sprinkler) to ensure both good yields and lower NO3- leaching. No significant differences in corn yield and NO3- leaching were found for the climatic scenario of 1999 between sprinkler and furrow irrigation during the irrigation season. Following the rainy events occurring after plant maturity (and the irrigation season), differences in N leaching were observed between the treatments. The study shows that both the fertiliser method, consisting of applying a fertiliser just before ridging the furrows, and the two-dimensional (2D) infiltration process, greatly influence the N distribution in the soil. N distribution seems to have a beneficial impact on both yield and N leaching under heavy irrigation rates during the cropping season. But, under rainy events (particularly those occurring after harvesting), the N, stored in the upper part of the ridge and not previously taken up by plants, can be released into the deeper soil layers in a furrow-irrigated plot. In contrast, the 1D infiltration process occurring during sprinkler irrigation events affects the entire soil surface in the same way. As a result the same irrigation rate would probably increase N leaching under sprinkler irrigation to a greater extent than under furrow-irrigation during an irrigation period. In order to assess the robustness of these interpretations derived from soil N-profile analysis, a modelling approach was used to test the irrigation and fertilisation strategies under heavy irrigation rates such as those occurring at the downstream part of closed-end furrows. The RAIEOPT and STICS models were used to simulate water application depths, crop yield and NO3- leaching on three measurement sites located along the central furrow of each treatment. The use of a 2D water- and solute-transport model such as HYDRUS-2D enabled us to strengthen the conclusions derived from the observations made on the N distribution under a cross-section of furrow. This model helped to illustrate the risk of over-estimation of N leaching when using a simplified 1D solute-transport model such as STICS. 相似文献
13.
Zornitsa Popova 《Irrigation and Drainage Systems》2006,20(1):1-21
Water distribution can be nonuniform along the furrow length under surface irrigation. This “down field” nonuniformity is
combined with “inter-row” non-uniformity which is a consequence of differences in infiltration characteristics across the
plot. Global nonuniformity of application depth causes variation of yield, drainage and nitrogen leaching. In addition to
that, due to year-to-year variability of climate, irrigation depths range significantly (from 0 to 360 mm/season). The objective
of this paper is to study the impact of the nonuniformity of irrigation-water distribution within a furrow plot on yield,
water and nitrogen losses when climate variation is taken into account. Six maize vegetation seasons on a Chromic Luvisol
soil in the Sofia region with varying irrigation requirements are considered. Irrigation water is distributed in relative
terms over the plot at different levels of nonuniformity (coefficient of variation Cv ranging from 13 to 66%) by the FURMOD model. Water and nitrogen cycle and crop growth are simulated then compared at 30 representative
points in the set with various “climate-irrigation nonuniformity” combinations by the CERES-maize model. It was established
that non-uniformity of irrigation is not important in wet vegetation periods. The drier the irrigation season, the higher
the yield loss and risk to environment due to nonuniformity of irrigation water distribution. In moderate and dry irrigation
seasons it causes yield losses of 2–14%, significant variation (30% < Cv < 200%) of drainage, nitrogen leaching and residual soil nitrate over the furrow set. Surface irrigation performances can
be improved by reducing lateral nonuniformity of stream advance. 相似文献
14.
利用地中渗透仪测坑开展了田间灌溉试验,研究了猪场废水和等氮投入清水处理土壤铵态氮、硝态氮含量在时间、剖面上的变化规律,根据氮平衡原理对不同处理氮输入和氮输出项进行对比分析,估算了不同处理的氮矿化量。结果表明:各处理土壤铵态氮和硝态氮含量在时间上的变化规律基本一致,表现为追肥期出现峰值,随后下降的趋势;土壤铵态氮含量随土层深度的增加而迅速下降,土壤硝态氮含量随土层深度的增加变化规律不明显,且易淋移至下层土壤并累积。PWH(猪场废水高氮)处理土壤铵态氮、硝态氮含量在追肥期出现峰值后下降的幅度较慢,而CKH(清水高氮)处理下降的幅度较快。猪场废水高氮处理PWH作物吸氮量及氮矿化量比等氮清水处理CKH分别高6.91%和21.29%,表明该处理有利于土壤有机氮的矿化,但同时硝态氮深层淋溶量也较大,比CKH高出11.82%。 相似文献
15.
塔里木灌区棉田的水盐动态和水盐平衡问题探讨 总被引:9,自引:0,他引:9
利用2004年在极端干旱的塔里木盆地绿洲棉田灌溉试验数据,对常规地面沟灌和膜下滴灌棉田在不同灌溉定额下水盐动态进行了研究,对节水灌溉与农田水盐平衡问题进行了深入探讨。主要结论包括:①在2700m3/hm2灌溉定额时,常规地面沟灌和膜下滴灌棉田在生育期0~60 cm土层积盐,膜下滴灌的积盐率(12.4%)要高于常规地面沟灌的积盐率(3.4%);②在小于6000 m3/hm2的4种不同灌溉定额条件下,生育期棉田1 m土体上总体表现为积盐;③对于土壤初始含盐量高的新垦荒地,灌溉淋洗的作用要好于土壤盐分本底值低的土壤;④为了保持农田的水盐平衡,在极端干旱区需要进行非生育期以淋洗盐分为目的的灌溉。 相似文献
16.
[目的]揭示负压水肥一体化灌溉对红壤水分及氮素运移特征的影响。[方法]配置6种不同质量浓度硝酸铵溶液(0、10、15、20、25、30mg/L),设置无压(负水头高度为0)和负压(1/2极限负水头高度)2个水平进行红壤入渗试验,分析了其入渗特性及氮素分布规律。[结果]硝酸铵溶液促进水分入渗,无压和负压状态下,入渗溶液质量浓度为25mg/L和15mg/L时水平与垂直方向湿润锋运移均达到最大,与相应CK相比累积入渗量最大分别增长2.69倍和3.00倍,平均入渗率分别增长2.38倍和2.18倍;土壤硝态氮和铵态氮量显著增加(p<0.05),与相应CK相比无压和负压状态下硝态氮量最大分别增长8.05倍和7.75倍,铵态氮量最大分别增长13.37倍和10.42倍。停渗时刻,同一质量浓度入渗溶液无压状态下水平与垂直方向湿润锋运移距离、累积入渗量均显著高于负压状态,各处理最大分别高出2.01、2.148和4.69倍;距出水点相同的距离,无压状态下土壤含水率、硝态氮和铵态氮量均高于负压状态。[结论]负压灌溉显著缩短水平与垂直方向湿润锋运移距离,降低土壤累积入渗量、含水率、硝态氮和铵态氮量。2种入渗条件下,土壤硝态氮量随入渗距离增加而增加,而土壤铵态氮量随入渗距离增加则呈下降趋势。 相似文献
17.
Joséphine Semaan Guillermo Flichman Alessandra Scardigno Pasquale Steduto 《Agricultural Systems》2007
Nitrate leaching is one of the many forms of environmental pollution resulting from irrigation and intensive agriculture. In this work, a method of combining an agronomic simulation model (EPIC) and a mathematical multi-objective programming model is used to analyse the effects of three agricultural policies on farmer’s revenue and nitrate leaching. An evaluation of the net social costs associated with the different policy measures is also given. The farmer’s behaviour in different policy scenarios was studied in terms of selected crops, irrigation technique and method, and adopted management practices with focus on farm management practices and water application efficiency. Irrigation water pricing, subsidies to adopt improved management levels, and taxation on the use of nitrogen fertilizer were examined. A trade-off emerges between the levels of nitrate leaching and net farmer’s revenue more pronounced for nitrogen tax policies than for water pricing. The results obtained indicate that nitrate leaching can be reduced by about 40% with an associated net social cost of 269 €/ha for the water pricing policy, 183 €/ha for the tax on fertilizer and 95 €/ha for subsidies to high efficiency management. 相似文献
18.
水氮供应对温室黄瓜氮素吸收及土壤硝态氮分布的影响 总被引:3,自引:1,他引:2
采用温室小区试验,研究了不同水氮供应条件对温室黄瓜氮素吸收及土壤硝态氮分布的影响。结果表明,氮素在植株体各器官中的累积量随生育期的推进不断增大,在盛果期累积量达到最大,且总体增长趋势呈"S"型;在不同生育期,黄瓜各器官中氮累积量均表现为叶茎根,而在盛果期,果实中的氮累积量达到最大,且随灌水量和施肥量的增加而增加;灌水量、施氮量及水氮交互作用对黄瓜氮累积量、UPE及PFP均有显著性影响,在同一灌水条件下,NUE、UPE及PFP均随着施氮量的增加而减少,而对于同一施氮水平,UPE、PFP均随着灌水量的增加显著提高,NUE在不同灌水量条件下变化趋势则有所不同。灌水量及施氮量对土壤硝态氮分布有重要影响,且施氮量是影响土壤硝态氮累积的关键因素,随灌水量的增加表层土壤中硝态氮累积量呈逐渐降低的趋势,而随施氮量的增加则逐渐增大,且施氮量越高,淋洗现象越明显。 相似文献
19.
Tomato nitrogen accumulation and fertilizer use efficiency on a sandy soil, as affected by nitrogen rate and irrigation scheduling 总被引:4,自引:0,他引:4
Tomato production systems in Florida are typically intensively managed with high inputs of fertilizer and irrigation and on sandy soils with low inherent water and nutrient retention capacities; potential nutrient leaching losses undermine the sustainability of such systems. The objectives of this 3-year field study were to evaluate the interaction between N-fertilizer rates and irrigation scheduling on crop N and P accumulation, N-fertilizer use efficiency (NUE) and NO3-N leaching of tomato cultivated in a plastic mulched/drip irrigated production system in sandy soils. Experimental treatments were a factorial combination of three irrigation scheduling regimes and three N-rates (176, 220, and 330 kg ha−1). Irrigation treatments included were: (1) surface drip irrigation (SUR) both the irrigation and fertigation line placed underneath the plastic mulch; (2) subsurface drip irrigation (SDI) where the irrigation drip was placed 0.15 m below the fertigation line which was located on top of the bed; and (3) TIME (conventional control) with the irrigation and fertigation lines placed as in SUR and irrigation applied once a day. Except for the TIME treatment all irrigation treatments were soil moisture sensor (SMS)-based with irrigation occurring at 10% volumetric water content. Five irrigation windows were scheduled daily and events were bypassed if the soil water content exceeded the established threshold. The use of SMS-based irrigation systems significantly reduced irrigation water use, volume percolated, and nitrate leaching. Based on soil electrical conductivity (EC) readings, there was no interaction between irrigation and N-rate treatments on the movement of fertilizer solutes. Total plant N accumulation for SUR and SDI was 12-37% higher than TIME. Plant P accumulation was not affected by either irrigation or N-rate treatments. The nitrogen use efficiency for SUR and SDI was on the order of 37-45%, 56-61%, and 61-68% for 2005, 2006 and 2007, respectively and significantly higher than for the conventional control system (TIME). Moreover, at the intermediate N-rate SUR and SDI systems reduced NO3-N leaching to 5 and 35 kg ha−1, while at the highest N-rate corresponding values were 7 and 56 kg N ha−1. Use of N application rates above 220 kg ha−1 did not result in fruit and/or shoot biomass nor N accumulation benefits, but substantially increased NO3-N leaching for the control treatment, as detected by EC monitoring and by the lysimeters. It is concluded that appropriate use of SDI and/or sensor-based irrigation systems can sustain high yields while reducing irrigation application as well as reducing NO3-N leaching in low water holding capacity soils. 相似文献