Irrigated Agriculture

Water for irrigation is a major limitation to agricultural production in many parts of the world. Use of waters with elevated levels of salinity is one likely option to meet the supply of increased demands. The sources of these waters include drainage water generated by irrigated agriculture, municipal wastewater, and poor quality groundwater. Soil salinity leaching requirements that were established

Human-made ecologic transformations have occurred at an unprecedented rate over the past 50 years. Prominent among them are water resource development projects. An estimated 40,000 large dams and 800,000 small dams have been built, and 272 million hectares of land are currently under irrigation worldwide. The establishment and operation of water projects has had a history of facilitating a change in the frequency and transmission dynamics of malaria, but analyses of these environmental risk factors are sparse. Here, we present a comprehensive review of studies that assessed the impact of irrigation and dam building on malaria prevalence or incidence, stratified by the World Health Organization's (WHO) sub-regions of the world, and link these studies with the latest statistics on disability adjusted life years, irrigated agriculture, and large dams. We also present estimates of the population at risk due to proximity to irrigation schemes and large dam reservoirs. In WHO sub-regi...

The Middle Ebro Valley (MEV) is a semiarid area in northeast Iberia where the original riparian ecosystems are almost extinct and were replaced by intensive irrigated agricultural lands. To minimize crop damages and to understand the impact of wild boar on relict riparian ecosystems, a culling program was undertaken from 1994 until 2004. To assess the impact of wild boars, we analyzed stomach contents and surveyed crop damage. In the MEV, wild boars feed mainly on crops, particularly, maize. Other elements of the diet that are of agricultural origin include wheat, barley, and alfalfa, which are the alternatives to maize in the period between harvest and seeding, which is the basis of seasonal changes in diet. Results indicate that wild boar actively selected maize crops and consumed wheat in proportion to its abundance; barley and alfalfa fields were damaged less than expected based on their abundance. In the MEV, the wild boar population is limited by the availability of shelter areas found in the scarce riparian ecosystems, which do not provide important food items for this population. We conclude that in the region of this study, wild boars are not a significant threat to the flora and fauna of riparian ecosystems, although as these habitats are restored and areas are protected, the carrying capacity for wild boars might increase.

Increasing economic pressures on water resources are causing countries to (re)consider various mechanisms to improve water use efficiency. This is especially true for irrigation agriculture, a major consumer of water. “Getting prices right” is seen as one way to allocate water, but how to accomplish this remains a debatable issue. Methods of allocating water are sensitive to physical, social, institutional

Desertification is the process that turns productive deserts into non-productive deserts as a result of poor land-management. Desertification reduces the ability of land to support life, affecting wild species, domestic animals, agricultural crops and humans. The reduction in plant cover that accompanies desertification leads to accelerated soil erosion by wind and water. South Africa is losing approximately 300–400 million tons of topsoil every year. As vegetation cover and soil layer are reduced, rain fall impact and run-off increases. This paper discusses the extent of desertification, its potential threat to sustained irrigated agriculture and possible measures adopted to control ongoing desertification processes to minimize the loss of agricultural productivity in an arid country such as the Kingdom of Saudi Arabia.

ABSTRACT ABSTRACT The Lower Jordan River Valley is a place of extreme water scarcity and constitutes an overexploited closed river basin. No surface runoff currently leaves the area and the water level of the Dead Sea, as the final sink, has already dropped by more than 20 m over the past fifty years as a result. This demonstrates, that even apart from water quality considerations, total inflows into the system do not match outflows, resulting in a continuous depletion of the available storage, i.e. all available water is already utilised. The only means of providing additional volumes of water to the area are water imports or reduction of evaporation from open water bodies or reduction of evapotranspiration from irrigated agriculture. Wastewater reuse and desalinisation would increase the amount of water fit for human demand but not affect the water balance in total. Increasing the amount of managed aquifer recharge (MAR) would be beneficial to the water availability of the region ...

This research study identifies the types and estimates the quantity of pesticides used in selected Palestinian districts. A survey of farmers (n = 126) was conducted in five districts of the West Bank and Gaza Strip, where pesticides are mostly used on irrigated land cultivated with vegetables. Data analysis of received questionnaires (87%) revealed a total number of 217 pesticides including 13 soil sterilizers, while 134 kinds with different active ingredients (insecticides 62; fungicides 45; herbicides 20) were applied in all districts. Based on the total irrigated land cultivated, the rate of pesticides per dunum reached 0.77 L in Gaza strip and 0.18 L in the West Bank districts. Contrary to earlier published data, our results support a trend of general decrease in the use of agricultural pesticides in the districts under study further to recent efforts encouraging pest management practice.

Based on predicted changes in the magnitude and distribution of global precipitation, temperature and river flow under the IPCC SRES A1B and A2 scenarios, this study assesses the potential impacts of climate change and CO2 fertilization on global agriculture. The analysis uses the new version of the GTAP-W model, which distinguishes between rainfed and irrigated agriculture and implements water as

Dilfuza Egamberdievaa, Giancarlo Renellab, Stephan Wirthc, and Rafiq Islamd*

aNational University of Uzbekistan, Faculty of Biology and Soil Sciences, Tashkent 700175, Uzbekistan, bDept. Plant Nutrition and Soil Science, University of Florence, Italy, cLeibniz-Centre for Agricultural Landscape Research, Institute of Landscape Matter Dynamics, Germany, dSoil and Water Resources, Ohio State University South Centers, Piketon, OH, USA.

Secondary soil salinilization is a big problem in irrigated agriculture. We have studied the effects of irrigation-induced salinity on microbial biomass of soil under traditional cotton (Gossypium hirsutum L.) monoculture in Sayhunobod district of the Syr-Darya province of north-west Uzbekistan. Composite samples were randomly collected at 0 - 30 cm depth from weakly saline (2.3+0.3 dS m-1), moderately saline (5.6+0.6 dS m-1), and strongly saline (7.1+0.6 dS m-1) replicated fields, 2-mm sieved, and analyzed for pH, electrical conductivity (EC), total C, organic C (COrg), and extractable C (Cext), total N and P, and exchangeable ions (Ca2+, Mg2+, K+, Na+, Cl-, and CO32-), microbial biomass (Cmic). The Na+ and Cl- concentrations were 36 to 80% higher in strongly saline compared to weakly saline soil. The COrg concentration was decreased by 10%, and CExt by 40% by increasing soil salinity, whereas decrease in Cmic ranged from 18 to 42% and the percentage of COrg present as Cmic from 8 to 26%. We conclude that irrigation-induced secondary salinity significantly affects soil chemical properties, and the size of soil microflora.

The socio-economic pressure for improvements in irrigation efficiencies is increasing due to intense competition for water between agricultural, domestic and industrial users as well as demands for compliance with environmental regulations. Precision irrigation technology involving less irrigation water and uniform application across the field is therefore important. In the context of declining water allocation for irrigation and the variations in weather and drought patterns attributed to global climate change, efficient and precise applications are necessity. Traditional irrigation methods such as furrow, flood and sprinkler are neither efficient nor environmentally benign. Precision irrigation methods such as drip and subsurface drip irrigation are advocated because they are more water use efficient and because they offer a possible approach to meet projected food demand, a doubling by the 2050. In spite of greater water use efficiency afforded by minimal soil surface evaporation and deep drainage, and ease of automation, wide scale adoption of surface and subsurface drip irrigation technology is limited. This is due to their high investment cost for installation. They often lack a significant yield benefit when compared to conventional irrigation practice. Reasons are probably linked to a sustained wetting front around emitters. These emitters impose a condition of low oxygen content in the root-dense rhizosphere surrounding emitters that impede root respiration, and negatively impact on plant uptake of water and nutrients, leading to constrained yield performance. Here we review aspects of soil oxygen dynamics during irrigation and present evidence for sustained hypoxia in the wetting fronts associated with drip and subsurface drip irrigation. This condition of low oxygen content in the ­rhizosphere conditioned by the drip irrigation we term as the irrigation paradox. At dissolved oxygen concentrations one half of that at saturation root respiration and function start to decline. The pros and cons of different approaches to maintain aeration of the crop root zone are reviewed and we suggest that the best approach to overcome hypoxia is through aeration of the irrigation water stream, a practice known as oxygation. This conclusion is based on the evidence derived from a number of controlled environment experiments and field trials on crops where consistent increases of 10–30% in yield and water use efficiency were reported with aerated irrigation water. Aerated drip delivery of irrigation also allows for the simultaneous application of agro-chemicals directly into the crop root zone. We define this approach of delivering multiple agro-chemicals with aerated drip irrigation as multigation. Delivering nutrients and other chemicals with irrigation water according to the crop requirements reduces the cost of application and improves input use efficiencies and becomes increasingly ­practical with adoption of automation using dosing equipment. The dynamics and fate of agrochemicals in the soil with aerated water irrigation differs from those of non-aerated water irrigation, e.g. oxygen provided greater salt exclusion by roots compared to non-aerated treatments. Opportunities also exists for improving the use of treated effluent water for irrigation with multigation as treated effluent water has high biological oxygen demand and often record poor dissolved ­oxygen concentration causing hypoxia upon crop irrigation. Review of previous research and modelling suggests that the behaviour of multiphase components in aerated irrigation water streams, and subsequently in the soil, and their interaction with plant roots influences the dynamics of salt, nutrients and pesticides and therefore provides opportunity for the sustainable management of these inputs for irrigated agriculture.

The purpose of this study was two fold: (i) to investigate the casual relationship between energy consumption and agricultural technology factors, and (ii) electricity consumption and technological factors in the agricultural sector of Pakistan. The study further evaluates four alternative but equally plausible hypotheses, each with different policy implications. These are: (i) Agricultural technology factors cause energy demand (the conventional view), (ii) energy demand causes technological factors, (iii) There is a bi-directional causality between the two variables and (iv) Both variables are causality independent. By applying techniques of Cointegration and Granger causality tests on energy demand (i.e., total primary energy consumption and electricity consumption) and agricultural technology factors (such as, tractors, fertilizers, cereals production, agriculture irrigated land, high technology exports, livestock; agriculture value added; industry value added and subsides) over a period of 1975–2010. The results infer that tractor and energy demand has bi-directional relationship; while irrigated agricultural land; share of agriculture and industry value added and subsides have supported the conventional view i.e., agricultural technology cause energy consumption in Pakistan. On the other hand, neither fertilizer consumption and high technology exports nor energy demand affect each others. Government should form a policy of incentive-based supports which might be a good policy for increasing the use of energy level in agriculture.► Find the direction between green technology factors and energy demand in Pakistan. ► The results indicate that there is a strong relationship between them. ► Agriculture machinery and energy demand has bi-directional relationship. ► Green technology causes energy consumption i.e., unidirectional relationship. ► Agriculture expansion is positive related to total primary energy consumption.

This study uses a hydro-economic model to examine the role of water trading, and the economic impacts of climate change and reduced surface water availability in the Murray–Darling Basin. The results show that losses to irrigated agriculture under a median climate change scenario are modest, but under a 'mod-ified 2030 dry extreme scenario' there would be substantial reductions in water use, irrigated land use and profits. Nevertheless, the Basin-wide proportional economic impacts would be less than the percentage decline in water use. A comparison of model results with and without interregional water trade shows that interregional water trade in periods of much reduced water availability mitigates the on-farm impacts of climate change. Given that agricultural production in the Basin is likely to be affected by climate change, the development of drought-tolerant crops and cultivars along with learning and extension of best farming practices to reduced water use could also assist irrigated agriculture adapt to climate change within the Basin.

This paper presents archaeobotanical and invertebrate evidence from the flotation and analyses of 46 archaeological contexts from six middens from the Samaca and Ullujaya basins, lower Ica Valley, south coast of Peru. This is part of one of the world’s driest deserts and organic remains can enjoy extraordinary preservation in its hyperarid climate. Each of these contexts represents snapshots with which to piece together a picture of changing human ecology in the lower Ica Valley over nearly two millennia, from Ocucaje Phases 3/4 of the Early Horizon (c. 750 b.c.); through to Early Nasca Phases 2/3 (c. a.d. 100–450); Late Nasca Phases 6/7 (c. a.d. 450–600) and Middle Horizon Epoch 2 (c. a.d. 900). They also offer proxy evidence of wider ecological changes in these basins. Read together with geoarchaeological and pollen data, the archaeobotanical data we present show a gradual intensification of agriculture from small-scale Early Ocucaje societies subsisting mainly on gathered marine and terrestrial resources, through to sophisticated irrigation agriculture by Nasca times, but culminating in a collapse of agricultural production and a return to the gathering of wild marine and plant resources much later, during the Middle Horizon. This trajectory of human ecology is consistent with the model presented elsewhere of a gradual removal of Prosopis dominated riparian woodland for the purpose of increasing agricultural production, which in time exposed the landscape of the lower Ica Valley to high-energy, episodic flood events and of one of the world’s strongest and most persistent wind regimes.

For semi-arid regions, methods of assessing aquifer recharge usually consider the potential evapotranspiration. Actual evapotranspiration rates can be below potential rates for long periods of time, even in irrigated systems. Accurate estimations of aquifer recharge in semi-arid areas under irrigated agriculture are essential for sustainable water-resources management. A method to estimate aquifer recharge from irrigated farmland has been tested. The water-balance-modelling approach was based on VisualBALAN v. 2.0, a computer code that simulates water balance in the soil, vadose zone and aquifer. The study was carried out in the Campo de Cartagena (SE Spain) in the period 1999–2008 for three different groups of crops: annual row crops (lettuce and melon), perennial vegetables (artichoke) and fruit trees (citrus). Computed mean-annual-recharge values (from irrigation+precipitation) during the study period were 397 mm for annual row crops, 201 mm for perennial vegetables and 194 mm for fruit trees: 31.4, 20.7 and 20.5% of the total applied water, respectively. The effects of rainfall events on the final recharge were clearly observed, due to the continuously high water content in soil which facilitated the infiltration process. A sensitivity analysis to assess the reliability and uncertainty of recharge estimations was carried out. En régions semi-arides, les méthodes d’estimation de la recharge des aquifères prennent généralement en compte l’évapotranspiration potentielle. Les taux d’évapotranspiration actuels peuvent être inférieurs aux taux potentiels sur une longue période de temps même sous systèmes irrigués. Une estimation précise de la recharge des aquifère en zone semi-aride avec une agriculture irriguée est essentielle à la gestion adéquate de la ressource en eau. Une méthode pour estimer la recharge d’un aquifère sous terrains agricoles irrigués a été testée. La modélisation du bilan hydrique se base sur l’utilisation de VisualBALAN v. 2.0, un code informatique qui simule le bilan hydrique du sol, de la zone vadose et de l’aquifère. L’étude a été menée sur le Campo de Cartagena (SE de l’Espagne) durant la période 1999–2008 et sur trois types différents de cultures : culture annuelle en rang (salade et melon), végétaux vivaces (artichaut) et arbres fruitiers (agrumes). Les recharges moyennes annuelles calculées (irrigation+précipitation) durant la période d’étude sont de 397 mm pour les cultures en rang, 201 mm pour les végétaux vivaces et 194 mm pour les arbres fruitiers: respectivement 31.4, 20.7 et 20.5% de l’apport en eau total. Les effets des évènements pluvieux sur la recharge finale sont clairement observés, du fait d’une teneur en eau des sols continuellement élevée qui facilite les processus d’infiltration. Une analyse de sensibilité a été effectuée afin d’estimer la fiabilité et l’incertitude des estimations de recharge. Los métodos para evaluar la recarga de acuíferos en las regiones semiáridas habitualmente consideran la evapotranspiración potencial. Los ritmos de evapotranspiración real pueden estar por debajo de la evapotranspiración potencial para largos períodos de tiempo, aún en sistemas irrigados. Las estimaciones precisas de la recarga de un acuífero en áreas semiáridas bajo agricultura irrigada son esenciales para el manejo sustentable de los recursos de agua. Se ha probado un método para estimar la recarga del acuífero a partir de tierras de granjas irrigadas. La aproximación del modelado del balance de agua se basó en VisualBALAN v. 2.0, un programa de computación que simula un balance de agua en el suelo, la zona vadosa y el acuífero. El estudio fue llevado a cabo en el Campo de Cartagena (SE de España) en el período 1999–2008 para tres grupos diferentes de cultivos: cultivos anuales en filas (lechuga y melón), hortalizas perennes (alcachofa) y árboles frutales (citrus). Los valores computados de recarga anual media (a partir de irrigación + precipitación) durante el período de estudio fueron 397 mm para cultivos anuales en filas, 201 mm para hortalizas perennes y 194 mm para árboles frutales: 31.4, 20.7 y 20.5% del agua total utilizada, respectivamente. Se observaron claramente los efectos de los eventos de la precipitación en la recarga final, debido a un permanente alto contenido de agua en el suelo lo que facilitó los procesos de infiltración. Se llevó a cabo un análisis de sensibilidad para evaluar la confiabilidad e incerteza de las estimaciones de la recarga. 对半干旱区含水层补给量评估的方法往往考虑潜在蒸散发. 即使在灌溉区, 实际蒸散发率也可能低于长期的潜在蒸发.在半干旱的灌溉农业区, 含水层补给量的精确估计对可持续水资源的管理是必不可少的.一种评估灌溉农业区含水层补给量的方法通过测试.这种水均衡模拟方法以模拟土壤, 包气带, 含水层中的水量均衡的电脑程序VisualBALAN v. 2.0为基础. 从1999到2008年, 在Campo de Cartagena (西班牙东南部) 选取三种不同类型的作物: 一年生行间作物 (生菜和甜瓜), 多年生蔬菜 (朝鲜蓟) 和果树 (柑橘) 进行研究. 计算整个模拟期的年平均补给量 (来自灌溉和降水), 一年生中耕作物为397 mm,多年生蔬菜为201 mm,果树为194 mm, 分别占总可利用水量的31.4, 20.7 ,20.5%.因为土壤中连续不断的高含水量促进了渗透过程,降雨量对最终补给量的影响清晰可见. 对补给量可靠性及不确定性进行了灵敏度分析. Em regiões semi-áridas, os métodos de análise da recarga de aquíferos geralmente consideram a evapotranspiração potencial. O valor de evapotranspiração real pode ser inferior ao potencial por longos períodos de tempo, mesmo em sistemas irrigados. Estimativas precisas da recarga de aquíferos em zonas semi-áridas irrigadas para fins agrícolas são essenciais para uma gestão sustentável dos recursos hídricos. Testou-se um método para estimar a recarga de aquíferos em parcelas agrícolas irrigadas. O modelo de balanço hídrico utilizado foi baseado no VisualBALAN v. 2.0, um código numérico que simula o balanço hídrico no solo, zona vadosa e aquífero. O estudo foi desenvolvido em Campo de Cartagena (SE de Espanha) no período entre 1999–2008, para três tipos de culturas diferentes: culturas anuais (alface e melão), culturas de hortícolas perenes (alcachofra) e árvores de fruto. Os valores médios anuais de recarga anual estimados (da irrigação+precipitação) para o período de estudo foram 397 mm para as culturas anuais, 201 mm para as hortícolas perenes e 194 mm para as árvores de fruto; correspondem a 31.4, 20.7 e 20.5% do volume total de água aplicado, respectivamente. Os efeitos dos eventos de precipitação na recarga final foram claramente observados, devido ao valor continuamente elevado de água no solo que facilitou o processo de infiltração. Desenvolveu-se uma análise de sensibilidade para caracterizar a fiabilidade e a incerteza dos valores de recarga estimados.