Assessing ground water quality in the irrigated plain of Triffa (north-east Morocco)

Irrigated agriculture in (semi-)arid regions may exert serious pressures on groundwater resources and jeopardise further agricultural and socio-economical developments. For assessing these pressures, we present in this paper results from a groundwater quality survey performed in 2005 within the irrigated agricultural Triffa plain in north-east Morocco. The study focuses on the physico-chemical and bacteriological quality of the groundwater body within the plain and exploits the correlation and spatial dependency of the quality parameters. It is demonstrated that the water quality in this region is critical. Nitrate levels are situated between 2 and 153 mg/l, with 73% of the observations exceeding the critical level of 50 mg/l. Nitrite, ammonia, orthophosphate and dissolved organic matter content do not exceed existing norms. Bacteriological residues (faecal, total coliforms, faecal streptococcus and clostridium sulfido-reductants), however, are retrieved in nearly all water samples. Bacteriological contamination is merely correlated with nitrite and ammonia content rather than with nitrate content, indicating a possible contribution of local pollution sources to groundwater deterioration. The variability of the nitrate and bacteriological pollution is important and spatially correlated. The spatially dependency is modelled using spherical and Gaussian semi-variograms and is used to map the nitrate and bacteriological contamination using ordinary kriging techniques. The results shown are significantly different as compared to earlier studies on groundwater quality for the studied aquifer. The differences may be explained partially by modified but inappropriate fertilizer management practices in combination with intensive irrigation. Given the agricultural developments in this area, further deterioration of the groundwater quality is expected if no mitigation strategies are developed.     

Policy incentives for reducing nitrate leaching from intensive agriculture in desert oases of Alxa, Inner Mongolia, China

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.     

Assessment of irrigation and environmental quality at the hydrological basin level: II. Salt and nitrate loads in irrigation return flows

Irrigation return flows may induce salt and nitrate pollution of receiving water bodies. The objectives of this study were to perform a salt and nitrogen mass balance at the hydrological basin level and to quantify the salt and nitrate loads exported in the drainage waters of three basins located in a 15,500 ha irrigation district of the Ebro River Basin (Spain). The main salt and nitrogen inputs and outputs were measured or estimated in these basins along the 2001 hydrological year. Groundwater inflows in the three basins and groundwater outflow in one basin were significant components of the measured mass balances. Thus, the off-site impact ascribed solely to irrigation in these basins was estimated in the soil drainage water. Salt concentrations in soil drainage were low (TDS of around 400–700 mg/l, depending on basins) due to the low TDS of irrigation water and the low presence of salts in the geologic materials, and were inversely related to the drainage fractions (DF = 37–57%). However, due to these high DF, salt loads in soil drainage were relatively high (between 3.4 and 4.7 Mg/ha), although moderate compared to other areas with more saline geological materials. Nitrate concentrations and nitrogen loads in soil drainage were highest (77 mg NO₃⁻/l and 195 kg N/ha) in basin III, heavily fertilized (357 kg N/ha), with the highest percentage of corn and with shallow, low water retention flood-irrigated soils. In contrast, the lowest nitrate concentrations and nitrogen loads (21 mg NO₃⁻/l and 23 kg N/ha) were found in basin II, fertilized with 203 kg N/ha and preponderant in deep, alluvial valley soils, crops with low N requirements (alfalfa and pasture), the highest non-cropped area (26% of total) and with fertigation practices in the sprinkler-irrigated fields (36% of the irrigated area). Thus, 56% of the N applied by fertilization was lost in soil drainage in basin III, as compared to only 16% in basin II. In summary, a low irrigation efficiency coupled to an inadequate management of nitrogen fertilization are responsible for the low-salt, high-nitrate concentrations in soil and surface drainage outflows from the studied basins. In consequence, higher irrigation efficiencies, optimized nitrogen fertilization and the reuse for irrigation of the low-salt, high-nitrate drainage waters are key management strategies for a better control of the off-site pollution from the studied irrigation district.     

基于SWAT模型的日本农业流域养分模拟（摘选）

在山田河流域利用SWAT模型对循环灌溉稻田和畜牧生产系统的流域特征进行调查。在茨城县地区土地利用呈现典型的景观镶嵌式。谷地中的稻田循环灌溉系统沿河岸在低处修建,森林、菜地和畜禽舍则建在周围地势较高处。灌期与非灌期土壤径流特征存在明显差异,通过设定参数可以利用SWAT模型对径流进行预测。灌期效率系数(ENS)、系数测定(r2)和相对误差(RE)分别为0.86、0.87和2.0%,非灌期分别为0.67、0.68和2.6%。但是对于养分浓度,模型没法给出满意的预测。对菜田及牲畜废弃物养分的模拟应对SWAT进行修正,对稻田系统的模拟应对算法进行修订。     

Lysimeter study on the use of biodrainage to control waterlogging and secondary salinization in (canal) irrigated arid/semi-arid environment

The study describes the capacity of trees to control the rise in water table and thus prevent the formation of waterlogged soils and development of secondary salinization in canal irrigated areas. It was conducted in RCC lysimeters of 1.2 m dia. and 2.5 m depth filled with sandy loam alluvial soil (Typic Ustochrept), with provisions to maintain water table depth at 1, 1.5 and 2 m from the surface and groundwater salinity at 0.4, 3, 6, 9 and 12 dS m-1. The amount of water biodrained by eucalyptus (Eucalyptus tereticornis) and bamboo (Bambusa arundinacea) at the given water table depths and groundwater salinity levels was monitored over four years by daily measuring the water needed for maintaining the water table. The trees continued to absorb and transpire water throughout the year, the capacity being more in summer and rainy than that was in the winter season. The eucalyptus plant could biodrain 2880, 5499, 5518 and 5148 mm of water in the first, second, third and fourth year of study period, from non-saline groundwater and a water table depth of 1.5 m. The amount of water biodrained was more at 1.5 m as compared to 1 and 2 m water table depths. The biodrainage capacity of trees was significantly affected by the salinity of the groundwater. However, even at salinity of 12 dS m-1, the eucalyptus plant biodrained 53% of that under non-saline conditions. It was calculated that biodrainage could control water table rises upto 1.95, 3.48, 3.76 and 3.64 m in first, second, third and fourth year, respectively. The secondary salinity developed in the root zone, upto 45 cm depth, did not exceed 4 dS m-1 even at water table depth of 1 m with salinity of 12 dS m-1. The volume of water biodrained by bamboo increased with time and could control water table rises upto 1.09, 1.86, 2.46 and 2.96 m in first, second, third and fourth year of growth, respectively.This study indicates that due to high transpiration capacity and an ability to extract water from deeper layers containing saline groundwater, the trees can control the rise in water table in irrigation command areas and prevent the formation of waterlogged and eventually the saline wastelands.     

应用改进的灰色GM(1,1)模型预测阜新地区干旱发生年

干旱是对人类及社会危害较大的一种自然灾害。近年来,干旱严重影响阜新地区的农业生产和生态平衡。利用阜新地区1961~2000年的降水资料,采用Z指标法分析阜新地区的干旱发生年,研究其干旱的发生规律,应用改进的GM(1,1)模型建立相应的干旱预测模型,并进行了干旱预测。最后提出了适当的抗旱措施。     

生态农业投入与产出的地域差异分析——基于江苏省7市31县(区)的数据

分析生态农业投入对生态农业产出的区域差异对促进生态农业优化升级的投资具有指导价值。在测算生态农业三种投入对生态农业产出的区域差异上采用三阶段DEA方法,根据研究需要选取CCR、BCC、SBM三个模型,从技术效率、规模报酬和要素利用率三个维度来探索DEA方法在生态农业投入产出分析中的应用,梳理DEA方法在生态农业投入产出测算中的不足,并运用江苏省2021年7个地级市31个县(区)收集到的数据测算不同地域的7个地级市生态农业发展的区域差距。研究发现：江苏省的生态农业PTE分布相对集中,31个县(区)的均值为0.636,高于TE、SE的均值,此外,SE方差为0.047,高于TE方差,低于PET方差,由此可知江苏省生态农业的技术效度差异显著。据此,可将生态农业发展分为两极分化、一枝独秀和发展落后三类。从规模报酬来看,研究选取的31个县(区)中有27个县(区)规模报酬递增,说明江苏省的生态农业总体态势良好。从要素利用率来看,研究选取的31个县(区)生态农业从业人员利用率(UFW)的平均值为66.03%,土地资源利用率(UAA)平均值为54.28%,现代农机的利用率(UTP)平均值为39.02%,相比欧美国家的生态农业,江苏省的要素利用率并不高,需要地方政府制定相应的鼓励政策激励要素利用率的提高。     

基于PVAR分析的农业机械化与农民收入关系研究——以山东省16地市为例

本文基于山东省各地级市2000年至2020年的数据,运用PVAR模型的基础上,运用脉冲响应函数、方差分解和Granger因果检验等方法对与农民收入的关系进行了实证研究。结果表明：农业机械化能够有效地促进农民的工资性收入和经营性收入从而有利于农民收入的增长,但其效应存在一定的时间滞后性;通过比较脉冲响应图像和方差分解的结果,表明当前山东省农业机械化的发展对农民工资性收入的促进效应大于对农民经营性收入的效应。鉴于此,本文提出因地制宜发挥农机补贴作用,加强农民技术教育培训等建议。以形成山东省农业机械化促进农民收入增长的良好互动关系。     

农村生活污染现状与防治措施——以泸县(濑溪河流域内)为例

农村环境污染问题日趋严峻,成为新时期农村发展的限制性因素。以泸县(濑溪河流域内)为例说明农村生活污染的严重性,农村生活污染物COD(化学需氧量)、NH3-N(氨氮)排放量均高于农田径流污染物COD、NH3-N排放量,相比农田径流污染物COD和NH3-N(氨氮)排放总量,农村生活污染物COD和NH3-N排放总量占有更大比重,比例基本是3∶1,可见农村生活污染尤其值得重视,并提出相应的治理建议以减小污染。     

宁夏农机购置补贴政策实施绩效研究——基于2015-2019年22县(市、区)面板数据

立足绩效评价的视角,构建由3个一级指标10个二级指标组成的宁夏农机购置补贴政策实施绩效评价指标体系,采用综合评分法和模糊聚类分析法对宁夏22个县(市、区)的实施绩效进行综合评价,并划分为五类区域.结果 表明,20152019年,五类区域绩效水平均呈上升态势且区域间绩效水平差异呈缩小态势,绩效水平与区域经济社会发展紧密相...     

Productivity impacts of the system of rice intensification (SRI): A case study in West Bengal,India

The system of rice intensification (SRI) has generated considerable debate globally, particularly with regard to its potential to raise rice yields. Proponents of SRI have reported that the average rice yield with SRI is double the current average yield and can be increased to the level of three to four times. Opponents say the reported high yields are due to measurement error and that usual information expected in support of these fantastic yields is missing. The number of SRI adopters has increased in India in recent years. We evaluate the impact of adoption of SRI practices on rice yields, the economics of paddy cultivation and labour inputs based on field research conducted in Purulia, West Bengal, India. Paddy yields with SRI were higher than those under conventional paddy cultivation by 32% and net returns were higher by 67%. Labour input was reduced by 8%. SRI adoption enabled farmers consistently to enhance paddy yields, increase returns and save labour; and enhance productivity with respect to the key inputs in terms of paddy output per unit of seed, fertilizer and labour-day. SRI promises to be a significant alternative for not only raising paddy yields, but also for managing paddy based farming in resource-starved regions.