Agricultural land management strategies to reduce phosphorus loads in the Gippsland Lakes, Australia

A target to reduce phosphorus flows into the Gippsland Lakes in south-eastern Australia by 40% in order to improve water quality has previously been established by stakeholders. This target, like many others worldwide, has been set mostly on the basis of environmental concerns, with limited consideration of issues such as technical feasibility, socio-economic constraints, political factors and associated costs and benefits. An integrated analysis at the catchment scale is undertaken to assess the agricultural land management changes required to achieve this target, and to evaluate the cost-effectiveness of these changes. Based on assumptions used, it appears technically feasible to achieve a 40% reduction in P load entering the Lakes. However, the least-costly way of doing so would require around A$1 billion over 25 years, a dramatic increase in the current levels of funding provided for management. Results of a sensitivity analysis indicate that there is little or no chance of investment in a 40% reduction being cost-effective. On the other hand, a 20% P reduction could be achieved at much lower cost: around $80 million over 25 years and requiring more modest land-management changes. Reliance on voluntary adoption of ‘Current Recommended Practices’ is unlikely to deliver changes in management practices at the scale required to have sufficient environmental impacts. Enforcement of existing regulations for the dairy industry would be amongst the most cost-effective management strategies. The major implications of this work for agriculturally induced diffuse-source pollution include the need for feedback between goal setting and program costs, and consideration of factors such as the levels of landholder adoption of new practices that are required and the feasibility of achieving those adoption levels. Costs, landholder adoption of new practices and socio-political risks appear neglected in the formulation of many water quality programs. The study provides a demonstration of an approach to integrated multidisciplinary research addressing complex environmental problems with multiple decision makers, multiple stakeholders, and high uncertainty. On the evidence of experience in this study, the approach deserves consideration in other contexts.     

A multi-objective programming approach to feed ration balancing and nutrient management

This paper examines the potential to use multiple objective programming to reduce nutrient excretion from dairy cows through incorporation of nutrient excretion functions into a ration formulation framework. In a typical ration formulation model, a ration is formulated to minimize cost while providing sufficient nutrients to meet the needs of the animal type being fed. To reduce the nutrient loading, rations can be formulated to minimize cost, and nitrogen and phosphorus excretion using multiple objective programming. Rations were initially formulated to minimize cost, nitrogen excretion and phosphorus excretion. Compromise programming was then utilized to examine the impacts on ration formulation of combining the three individual objectives. The multiple objective ration formulation reduced phosphorus excretion by 5% and marginally reduced nitrogen excretion with a small increase in ration cost compared to the single objective minimum cost ration. Multiple objective programming does have the potential to reduce nutrient excretion.     

On farm testing of integrated nutrient management strategies in eastern Uganda

This paper reports on a Participatory Learning and Action Research (PLAR) process that was initiated in three villages in eastern Uganda in September 1999 to enable small-scale farmers to reverse nutrient depletion of their soils profitably by increasing their capacity to develop, adapt and use integrated natural resource management strategies. The PLAR process was also used to improve the participatory skills and tools of research and extension personnel to support this process. The farming systems of the area were characterised for socio-economic and biophysical conditions that included social organisations, wealth categories, gender, crop, soil, agro forestry and livestock production. Farmers identified soil fertility constraints, their indicators, and causes of soil fertility decline, and suggested strategies to address the problem of soil fertility decline. Soil fertility management diversity among households indicated that most farmers were not carrying out any improved soil fertility management practices, despite previous research and dissemination in the area. Following the diagnosis stage and exposure visits to other farmer groups working on integrated soil fertility projects, the farmers designed 11 experiments for on-farm testing. One hundred and twenty farmers then chose, for participatory technology development, sub-sets of these 11 experiments, based on the major agricultural constraints and the potential solutions identified and prioritised by the farmers. Quantitative and qualitative results from the testing, farmer evaluation and adaptation, training, dissemination strategies and socio-economic implications of these technologies are discussed.     

Simulating the influence of management decisions on the nutrient balance of dairy farms

In order to evaluate the influence of management decisions on the nutrient balance of dairy farms a simulation model was developed. Three farm systems have been simulated: zero grazing, winter milk and summer milk. From the simulated farm systems the zero grazing farm has in all scenarios the lowest N-surplus. The winter milk farm system has a higher N-surplus than zero grazing but lower than the summer milk farm system. The results further indicate the positive effects of maize feeding in addition to grazing. More maize in the ration is especially good to lower the N-surplus during the grazing period in the summer. The benefits of more maize in the ration decrease when the fertilizer application rates decrease.     

Adaptive management of stocking rates to reduce effects of drought on cow-calf production systems in semi-arid rangelands

We used simple ecological sustainability simulator (SESS) [Díaz-Solís, H., Kothmann, M.M., Hamilton, W.T., Grant, W.E., 2003. A simple ecological sustainability simulator (SESS) for stocking rate management on semi-arid grazinglands. Agric. Syst. 76, 655–680. <http://dx.doi.org/10.1016/j.agsy.2005.07.008>], modified to represent each of five management strategies (sets of decision rules) for adjusting stocking rates, to identify strategies that could reduce effects of drought on cow-calf production systems in semi-arid rangelands. We parameterized the model to represent a region of extensive cow-calf production in the northeastern portion of the Mexican state of Coahuila, and evaluated animal performance (animal body condition, cow mortality, and calf production) and range condition resulting from each strategy under random precipitation conditions typical of the region. To evaluate the validity of the randomly generated precipitation, we conducted the simulations under an historical (1950–1994) precipitation regime.The five management strategies included one with no adjustments to stocking rate (CONTROL, most common current practice), one with stocking rate adjustment rules based on changes in animal body condition (BCS), and three with different stocking rate adjustment rules based on various comparisons of recent-year precipitation with long-term mean precipitation during the growing season (March–November) (REPLA, PPT 1Y, PPT 2Y). Each strategy was evaluated at each of three initial base-level stock cow stocking rates (125, 250 and 500 AUY · 5000 ha⁻¹). Stocking rate adjustments consisted of partial or total de-stocking, with the re-establishment, or not, of the initial number of stock cows before the beginning of the subsequent breeding season.Results of 45-year simulations under both random and historical precipitation suggest CONTROL and PPT 2Y (based on comparison of current year and previous year precipitation with the long-term mean) strategies, combined with the high base-level stocking rate, are the worst and best, respectively. Under the historical precipitation regime, in the last period of time simulated (1980–1994) these two strategies resulted, respectively, in poor (0.5) versus good range condition (1.0), animal body condition scores of 2.6 versus 5.2, annual cow mortalities of 76 versus 5%, and calf production rates of 0.9 versus 10.6 kg ha⁻¹ year⁻¹ at weaning. The PPT 1Y strategy (based on comparison of current year precipitation with the long-term mean) produced results fairly similar to PPT 2Y, with BCS and REPLA strategies producing results intermediate between CONTROL and PPT 2Y. Our results suggest it is advantageous to adjust stocking rates based on precipitation during the current growing season since it improves cattle production without damaging range condition. Considering the practical feasibility of the strategies, we recommend the PPT 1Y strategy because it maintains range condition at moderate stocking rates, results in good animal performance and does not require total de-stocking of the ranch.The simple method we developed to stochastically generate monthly precipitation produces a time series of precipitation values that were representative of general historical precipitation patterns and provided realistic levels of uncertainty in simulated forage production to evaluate alternative management strategies.     

Dairy farm nutrient management model: 2. Evaluation of different strategies to mitigate phosphorus surplus

To reduce (P) surpluses on dairy farms and thereby the risk of P losses to natural waters we studied different management alternatives by a nutrient balance model described in the companion paper. The strategies evaluated mitigating the P surpluses were: mineral P fertilisation, dietary mineral P supplementation, replacement rate, animal density, production level, feeding intensity, dietary P concentration and nutrient efficiency in crop production. Responses to several interventions (e.g. mineral P fertilisation, purchased feed P, replacement rate) were similar to those observed in Finnish field studies. Reducing or completely giving up the use of purchased mineral P fertilisers was the most efficient measure to reduce P surplus. The slope between the amount of mineral fertilisers and P surplus was 0.98-0.99 (in the field data 1.0). Increased animal density resulted in a greater P surplus, but the slope between P input from purchased feed and surplus was considerably smaller (0.65) than that of P fertilisation. Increasing milk yield with improved genetic potential of the cows would have minimal effects on P surplus per unit of product, but it would increase P surplus per hectare. When the intensity of energy and protein feeding was increased, P surplus rose markedly both per unit of product and hectare. This is (1) due to increased dietary P concentration and (2) due to smaller marginal production responses than those calculated from feeding standards. Reducing dietary P concentration by constraining P excess per kg milk in least-cost ration formulation improved P efficiency in milk production and dairy farming system. However, feed cost increased as low P energy (sugar-beet pulp) and protein (soybean meal) supplements are more expensive than cereal grains or rapeseed feeds. Improving the nutrient use efficiency in crop production had a strong influence in the whole-farm efficiency and P surplus. The modelling results showed that Finnish dairy farms have a great potential to improve P efficiency and reduce P losses to the environment, even by increasing production intensity (milk/ha). It is concluded that the most cost-effective scenario to mitigate P surpluses at a dairy farm would be to reduce or give up the use of mineral P as fertilisers and supplements, and to improve the use of present soil P reserves.     

Adoption of sustainable irrigation management practices by stone and pome fruit growers in the Goulburn/Murray Valleys, Australia

The management of water resources by orchards in the south-eastern region of Australia is an increasingly important policy issue, especially given the low water allocations and concerns about salinity in recent years. Optimal management for economic and environmental sustainability can be described as best management practice (BMP). A project was developed to run an extension program, which aimed to achieve behavioural change among orchardists through the adoption of irrigation BMPs and benchmarks. The effectiveness of the extension program was evaluated and the drivers for adoption assessed. In the first stage of the project both BMPs and benchmarks were determined for irrigation management. A survey of 200 growers showed no relationship between yield and irrigation system or irrigation volume suggesting that increased yields were not a key driver for adoption of sustainable irrigation practices. Stage two of the project involved undertaking an extension program aimed to facilitate the adoption of BMPs and benchmarks and incorporated a suite of activities to meet the learning needs of a diversity of participants (40 growers). The program was effective in establishing behavioural change for many of the growers involved; however, it was resource intensive requiring significant one-on-one input. Stage three aimed to analyse the key drivers for adoption of sustainable irrigation practices for the whole of the stone and pome fruit industry in south-eastern Australia using market research. The study determined that water use efficiency was not a key driver for adoption of sustainable irrigation practices (micro irrigation and soil moisture monitoring) and adoption was generally not limited by lack of knowledge. Groups of growers were identified where extension programs could be effective by focussing on specific information e.g. redevelopment of orchard. Other groups had no need and/or ability to change unless the external operating environment was to change e.g. regulation, access to pressurised water. The voluntary adoption of more sustainable irrigation practices will probably require extensive resources using one-on-one methodology. The extension program should not focus on the broader social objective of improved water use efficiency but promote other potential benefits (e.g. labour saving, redevelopment of production systems, management flexibility) with targeted messages for specific groups.     

Water savings, nutrient leaching, and fruit yield in a young avocado orchard as affected by irrigation and nutrient management

This project was designed to determine the effect of fertilizer rate and irrigation scheduling on water use, nutrient leaching, and fruit yield of young avocado trees (Persea americana Mill. cv. Simmonds). Seven nutrient and irrigation management practices were evaluated: (1) irrigation based on crop evapotranspiration (ET) with 50% fertilizer at a standard rate (FSR); (2) ET irrigation with FSR (typical for avocado production in the area); (3) ET irrigation with 200% FSR; (4) irrigation based on exceedance of 15-kPa (SW) soil water suction with 50% FSR; (5) SW with FSR; (6) SW with 200% FSR; and (7) irrigation at a set schedule (based on timing and frequency typically used in local avocado production) with FSR. The SW with FSR treatment saved 87% of the water volume applied and reduced total phosphorus leached by 74% compared to the set schedule irrigation with FSR. The SW with FSR treatment had higher avocado fruit production, tree water-use efficiency, and fertilizer-use efficiency than the other six treatments. Thus, the use of soil water monitoring for irrigation management can substantially increase sustainability of young avocado orchards in southern Florida.     

美国的保护性耕作策略

任何一项农业技术的推广使用都属于综合性的运作。它的抉择要受农场和农民的影响,受技术的限制,受经济的和政策的制约。对于保护性耕作来说就更容易受到一些因素的影响。例如,土地所有权的问题就会影响到保护性耕作的实施。农场主比给别人经营农场的农民在是否采用保护性耕作上     

Comparison of adaptive techniques to predict crop yield response under varying soil and land management conditions

Decision-making processes in agriculture often require reliable crop response models to assess the impact of specific land management. While process-based models are often preferred over empirical ones in current modelling communities, empirical crop growth models can play an important role in identifying the hidden structure of crop growth processes relating to a wide range of land management options. This study investigates the potential of predicting crop yield responses under varying soil and land management conditions by applying three different adaptive techniques: general linear models (GLMs), artificial neural networks (ANNs), and regression trees (RTs). The crop yield data used in this research consist of 720 maize yield indices from 11 different land management trials in southern Uganda. GLM showed the poorest results in terms of modelling accuracy, prediction accuracy, and model uncertainty, which might suggest its inability to model the non-linear causal relationships present in complex soil–land and crop-management interactions. The other two non-parametric adaptive models show significantly higher prediction accuracy than GLM. RT is the most robust technique for predicting crop yield at the study site. ANN is also a promising tool for predicting crop yield and offers insight into the causal relationships through the use of sensitivity analyses, but the complex parameterization and optimum model structure require further attention. The three adaptive techniques compared in this research showed different advantages and disadvantages. When these methods are used together, valuable information can be provided on crop responses, and more reliable crop growth models may result.     

Environmental impact and economic benefits of site-specific nutrient management (SSNM) in irrigated rice systems

Site-specific nutrient management (SSNM) provides a field-specific approach for dynamically applying nutrients to rice as and when needed. This approach advocates optimal use of indigenous nutrients originating from soil, plant residues, manures, and irrigation water. Fertilizers are then applied in a timely fashion to overcome the deficit in nutrients between the total demand by rice to achieve a yield target and the supply from indigenous sources. We estimated environmental impact of SSNM and evaluated economic benefits in farmers’ fields in southern India, the Philippines, and southern Vietnam for two cropping seasons in 2002–2003. On-farm research comparing SSNM and the farmers’ fertilizer practice showed increased yield with SSNM for the three locations, even with reduced fertilizer N rates in some cases. SSNM increased partial factor productivity (kg grain kg⁻¹ fertilizer N) when fertilizer N use efficiency with the farmers’ fertilizer practice was relatively low such as at locations in Vietnam and the Philippines. Use of on-farm data with the DNDC model revealed lower percentage of total N losses from applied fertilizers with SSNM during an annual cycle of cropping and fallows. At the location in India, SSNM showed the potential of obtaining higher yields with increased fertilizer N use while maintaining low N₂O emissions. SSNM in the Philippines and Vietnam showed greater yields with less fertilizer N through improved fertilizer use efficiency, which could reduce N₂O emissions and global warming. Use of SSNM never resulted in increased emissions of N₂O per unit of grain yield, and in environments where higher yield could be obtained with less fertilizer N, the use of SSNM could result in reduced N₂O emissions per unit of grain yield. For the economic analysis, data were generated through focus group discussions (FGD) with farmers practicing SSNM and with other farmers not practicing SSNM. Based on FGD, the seasonal increase in yield of farmers solely due to use of SSNM averaged 0.2 Mg ha⁻¹ in southern Vietnam, 0.3 Mg ha⁻¹ in the Philippines, and 0.8 Mg ha⁻¹ in southern India. Farmers practicing SSNM at the study site in India used less pesticide. The added net annual benefit due to use of SSNM was 34 US$ ha⁻¹ year⁻¹ in Vietnam, 106 US$ ha⁻¹ year⁻¹ in the Philippines, and 168 US$ ha⁻¹ year⁻¹ in India. The increased benefit with SSNM was attributed to increased yield rather than reduced costs of inputs.     

Steps toward sustainable ranching: An emergy evaluation of conventional and holistic management in Chiapas, Mexico

Conventional ranching in Chiapas, Mexico typically includes annual pasture burns and agrochemical use that decrease the biodiversity and forest cover of ranch lands. Members of a holistic ranching “club” in the Frailesca region of Chiapas, Mexico have moved away from this conventional management by eliminating burns and agrochemicals from their systems after decades of use because they believed that the land and their production process were growing unhealthy; they were further motivated by extension courses on holistic ranching. They have also implemented sophisticated systems of rotational grazing and diversified the use of trees. For this study all seven holistic ranchers and 18 neighboring conventional ranchers were interviewed about their cattle ranches and production strategies. An emergy analysis was conducted to compare the resource use, productivity and sustainability of the conventional and holistic ranches. Holistic ranches were found to have double the emergy sustainability index (ESI) values of conventional ranches, and the emergy yield ratio was 25% higher in holistic systems. Government assistance programs were found to have a negative impact on the ESI and were variably administered among holistic ranchers during the year of emergy evaluation. Overall improved emergy sustainability did not decrease milk nor cattle productivity. Transformities and specific emergies, the emergy of one type required to make a unit of energy (transformity) or mass (specific emergy) of another type, did not differ between conventional and holistic systems. Transformities for milk production ranged between 3.4E5 and 1.2E7 solar emjoules/joule (sej/J). Specific emergy for cattle production ranged from 3.5E10 to 1.5E11 sej/g. To improve the ESI assistance programs could be re-targeted toward incentive programs for increased forest cover in ranching systems and startup costs for holistic ranching. The results from this study show that productivity can be maintained as the sustainability of rural dairy ranches is increased. These results also show that local knowledge and understanding of the surrounding ecosystem can drive positive environmental change in production systems.     

我国微灌技术发展的回顾与预测

1　我国微灌技术发展现状与初步评价11　我国微灌技术的发展历程自1974年由墨西哥政府赠送我国三套滴灌设备开始引进滴灌技术以来,已有20多年的发展历程,大体经历了以下三个阶段:第一阶段(1974～1980年):引进滴灌设备、消化吸收、设备研制和应用试验与试点阶段。在党和国家领导人的关心下经水电部正式立项,由中国水科院和辽宁省水科院会同沈阳市塑料7厂联合攻关,于1980年研制生产了我国第一代成套滴灌设备,通过了水电部技术鉴定,填补了我国没有滴灌设备产品的空白。从此我国有了自行设计生产的滴灌设备产品。第二阶段(1981～1986年):设备产…     

Application of a simple ecological sustainability simulator (SESS) as a management tool in the semi-arid rangelands of northeastern Mexico

We use a simple ecological sustainability simulator (SESS) [Diaz-Solis, H., Kothmann, M.M., Hamilton, W.T., Grant, W.E., 2003. A simple ecological sustainability simulator (SESS) for stocking rate management on semi-arid grazinglands, 76, 655] for rangelands with mean annual precipitation of 500 mm to evaluate tendencies in range productivity and cattle production under four management options: (1) supplemental feeding, (2) short-term reduction of stocking rate, (3) early weaning, and (4) adjustment of breeding seasons. We have made five modifications to SESS for the present paper. (1) Cattle mortality now occurs each month as a function of body condition. (2) Cows that are not pregnant 2 months after the end of the breeding season are sold. (3) Forage intake is calculated separately for each cohort of cows. (4) Cows that have been sold or have died are replaced just before the beginning of each breeding season (except for the short-term reduction of stocking rate strategy). (5) The calculation of stocking rate now includes cows, bulls, nursing calves, weaned heifers less than 20 months of age, and pre-reproductive heifers aged 20 months or older.Simulation results suggest the four management options might be ranked from best to worst, in terms of increasing cattle production while maintaining range productivity, as: (1) short-term reduction of stocking rate, (2) adjustment of breeding seasons, (3) early weaning, and (4) supplementation. Short-term reduction of high stocking rates reduces the deterioration of range productivity because of the reduction in the number of stock. Adjustment of breeding seasons such that periods of highest energy requirements of cows and calves coincide with periods of highest forage production increases percentage pregnancy. Early weaning of calves improves the body condition of cows and increases annual production of weaned calves, but does not reduce the stocking rate and thus does not improve range productivity. Supplemental feeding, and other management practices that artificially sustain herbivores, break the negative feedback that promotes good range productivity and maintains long-term system stability. In general, strategies to increase cattle production in semi-arid rangelands should be based on the improvement of natural forage production.     

The Use of Ozone to reduce the Concentration of Malodorous Metabolites in Swine Manure Slurry

A pilot-scale ozonation system was constructed and operated to reduce the malodours emanating from fresh and stored swine manure slurry. The concentrations of the malodorous bacterial metabolites (phenol,p-cresol,p-ethylphenol and skatole) found in the liquid fraction of the manure slurry were found to increase during three weeks of storage. The fresh and stored manure slurry was ozonated at dosages of 0·25, 0·5, 0·75 and 1·0 g/l. Ozonation eliminated these metabolites from the manure slurry. On the contrary, no useful decrease in the concentration of all the above metabolites was observed after treatment with either nitrogen or oxygen. The odour intensity of the manure slurry was also significantly reduced (P<0·05) after ozonation at a dosage of 0·5 g/l. In contrast, neither stripping with nitrogen nor oxidation using oxygen had a significant effect on the odour acceptability of the mature. The use of hydrogen peroxide and ozone did not offer additional benefit over that obtained with ozone alone. Within the range of 14–25°C, temperature had no effect on the efficiency of ozonation. The ozonated manure did not regain its original malodour after one month of storage subsequent to ozonation.     

变压器差动保护减小励磁涌流影响的措施

变压器差动保护减小励磁涌流影响的措施,差动保护对于容量较大的变压器来说都是必不可少的,它用作变压器内部、套管及引出线上的各类短路故障保护,并且与瓦斯保护互相配合作为变压器的主保护。     

10kV及以下配电网降低损耗措施

农网的损耗主要是指在给定的时间内有变电站出现例计量点至客户计量点之间的电气设备和元件损耗的电能.文章针对10kV及以下农村电网的现状所引起的损耗大的问题,从技术上提出了具体的解决措施,指出损耗是有技术损耗和管理损耗组成,是供电企业的一项主要经济技术指标,也是衡量电力企业综合管理的重要标志.     

Adoption of agroforestry in the hills of Nepal: a logistic regression analysis

Widespread deforestation and increasingly intensive use of land to sustain a growing population has increased soil erosion, lowered soil fertility, and reduced agricultural productivity in the hills of Nepal. This has raised concern over sustainability of the hill farming system. There is growing evidence that agroforestry can be a potential solution to above problems. However, the development of agroforestry as a viable alternative for farmers in diverse ecological and socioeconomic conditions has become a very challenging issue. The objective of this paper was to identify factors influencing the adoption of agroforestry by subsistence farmers in the hills, with reference to an agroforestry project initiated by Nepal Agroforestry Foundation (NAF). Necessary information for this study came from a survey of 223 households (82 project and 141 non-project) from Kumpur, Nalang, and Salang villages in Dhading district in 1998. The results showed that male membership in local NGOs, female education level, livestock population, and farmer's positive perception towards agroforestry have significantly positive effects, while the number of children below 5 years of age, number of males aged 10–59 years, male education, female's Non-Governmental Organization (NGO) membership, and respondents' age had significantly negative effects on adoption of agroforestry among project households. Among non-project households, those with more livestock and male membership to local NGOs were found more likely to adopt, while the households headed by males were less likely to adopt agroforestry.     

Linking hydro-meteorological factors to the assessment of nutrient loadings to streams from large-plotted paddy rice fields

Excessive nutrient loadings from rice paddy fields has been a great concern in Korea as rice paddy area spans over 1,153,000 ha, which covers approximately 60% of the total agricultural land area in Korea. The principal tasks of this study included undertaking work to better identifying the scope of the nutrient loadings from paddy fields to assess their adverse effects. Hydro-meteorological factors, rainfall and surface discharge, were considered as the major driving forces of nutrients into the water. A Generalized Regression Neural Network (GRNN) model was applied and its capability evaluated to predict the nutrient loading into the neighboring water. The 15 ha paddy fields surrounded by drainage and irrigation channels were chosen as a study area. Field data, such as rainfall, quantities of irrigation and discharge water, and nutrient contents (total nitrogen (T-N) and total phosphorus (T-P)) from two different water sources, were obtained throughout the study period. Simulation results showed that surface discharge had a positive correlation with rainfall (R = 0.84). In addition, the resulting predictions for nutrient concentrations corresponding to surface discharge were varied (R = 0.72 and 0.40 in total nitrogen and total phosphorus, respectively). This study found that both natural and artificial variations of nutrient contents in irrigation streams were significantly influenced the model results of nutrient predictions. Therefore, the nutrient loadings into the neighboring water can be accurately described with a more comprehensive and sufficient representation of both environmental inputs and hydrological processes.     

Using economic incentives and regulations to reduce seawater intrusion in the Batinah coastal area of Oman

Excessive groundwater abstraction is a major problem in Oman, primarily in the Batinah coastal area where it results in seawater intrusion. The Government began to address the problem in the 1990s by encouraging the use of more efficient irrigation systems, replacing date palms with winter vegetable crops and using treated wastewater for municipal irrigation. However, 15 years later, seawater intrusion in the Batinah aquifers is still advancing at an alarming pace. This paper analyses the relative merits of strategies to control groundwater pumping based on water quotas, electricity quotas and electricity pricing. A cost benefit approach is used to evaluate the feasibility of three strategies over a period of 25 years and to compare them to the “business as usual” option. Results show that the net present loss to the community when no active policy is implemented amounts to (−$288) million. Imposing water quotas on tubewells would give a net present benefit of $153 million. However, such quotas would give the lowest present benefit and create inequity among farmers. Other possible approaches would be to control the pumping of groundwater from all wells - tubewells and dug wells - by enforcing energy quotas and by increasing the price of electricity used to pump water. The net present benefits would be greater and the costs to farmers would be more fairly spread. The results of cost-benefit analysis show that enforcing an electricity quota, coupled with removal of the subsidy on the electricity price, is the easiest and most equitable solution to implement.