Development and evaluation of an integrated simulation model for assessing smallholder crop-livestock production in Yucatán, Mexico

Mixed farming systems constitute a large proportion of agricultural production in the tropics, and provide multiple benefits for the world’s poor. However, our understanding of the functioning of these systems is limited. Modeling offers the best approach to quantify outcomes from many interacting causal variables in these systems. The objective of this study was to develop an integrated crop-livestock model to assess biophysical and economic consequences of farming practices exhibited in sheep systems of Yucatán state, Mexico. A Vensim™ dynamic stock-flow feedback model was developed to integrate scientific and practical knowledge of management, flock dynamics, sheep production, partitioning of nutrients, labor, and economic components. The model accesses sheep production and manure quantity and quality data generated using the Small Ruminant Nutrition System (SRNS), and interfaces on a daily basis with an Agricultural Production Systems Simulator (APSIM) model that simulates weather, crop, and soil dynamics. Model evaluation indicated that the integrated model adequately represents the complex interactions that occur between farmers, crops, and livestock.     

Regional analysis of irrigation water requirements using kriging: Application to potato crop (Solanum tuberosum L.) at Trás-os-Montes

Aiming at the analysis of the regional variation of potato crop irrigation water requirements over the Trás-os-Montes region, data from 106 rainfall stations and eight weather stations were utilized in an irrigation scheduling simulation model to estimate net irrigation water requirements of the potato crop. The simulation model was first validated using a field experiment which allows to derive the required crop data to be used in the simulations. The reference evapotranspiration (ET₀) was estimated using the FAO Penman–Monteith method. The model was applied to all 106 locations, each with a data set spanning a 19-year period. As a result of this application, series of the net irrigation water requirements for a 19-year period were obtained for each location. The resulting 106 point values of the net water requirements of the potato crop have been treated as a regionalized variable. The respective semivariograms have been computed and the kriging method then applied to estimate the spatial distribution of the water requirements in the region. Contour lines of this regionalized variable have been drawn using a GIS system. Results show an estimation error averaging 5% for the entire region.     

Application of a simulation model for assessing integration of smallholder shifting cultivation and sheep production in Yucatán, Mexico

Simulation models are effective tools to examine interactions between livestock, cropping systems, households, and natural resources. Our study objective was to use an integrated livestock and crop model to assess the outcomes from selected suites of management decisions observed in smallholder sheep-cropping systems of Yucatán, Mexico. The scenarios contrasted specialized systems versus mixed farming, and evaluated the outcomes of increased crop-livestock integration. Mixed enterprise scenarios involving sheep provided more income than specialized enterprises, and capitalized on a lower price of on-farm maize grain, efficient utilization of surplus labor, and availability of common land. Labor and management income was greatest for the unintegrated and partially integrated crop and livestock scenarios. It was more profitable for producers to sell excess grain and maize stover, and use common land to feed the livestock, suggesting that increased integration does not always result in improved outcomes. The results are consistent with a system not yet pushed to the point where integration is inevitable. For all sets of scenarios, the model structure was able to accommodate subtle management differences to produce appropriate biophysical, labor, and economic outcomes. We conclude there is potential to use similar model development methods to describe other crop-livestock systems, thus providing tools for learning, scenario analysis, and impact assessment.     

Assessment of a groundwater quality monitoring network using vulnerability mapping and geostatistics: A case study from Heretaunga Plains, New Zealand

A groundwater monitoring network can provide quantity and quality data necessary to make informed decisions regarding the state of the environment. A properly designed monitoring system provides a representative understanding of the state of the monitored area. The selection of the optimum number of monitoring sites and their spatial distribution is a major challenge for the hydrogeologist.On the one hand, improper distribution of monitoring sites or insufficient number of sites will not provide a representative view of the state of the environment. On the other hand, if the sampled sites are too many, the information obtained is redundant and the monitoring network is costly and inefficient.A new methodology combining vulnerability mapping and geostatistics is proposed to help define the most efficient groundwater quality monitoring network on a regional scale.Vulnerability mapping identifies areas with high pollution potential, and in turn, prioritises for monitoring. A geostatistics methodology is then used to interpret the obtained data and to examine the spatial distribution of monitored parameters at different sites. The accuracy of spatial mapping reflects the effectiveness of the distribution of the monitoring sites.The methodology was applied to assess the nitrate monitoring network in the Heretaunga basin, Hawke's Bay, New Zealand. The DRASTIC approach was used to prepare a vulnerability map for the area of study, and kriging variance was used to check the spatial distribution of the sites. Based on this study, it was found that some areas with high vulnerability are not covered within the existing network indicating the number of monitoring sites and their distribution is not efficient. Some sites should be dropped and some others need to be added to the existing network.     

The financial viability of irrigation management companies: A case study of Cu Chi irrigation system,Vietnam

A crucial, yet little understood, element in the economic studies of irrigation is the role played by companies who manage the supply of water. Many of these companies are publicly managed as they have the potential to act as monopolists. Possibly as a consequence of their ownership structure, analysts have questioned the economic viability and management of these firms. The case is made that many of these companies do not run profitably, that they rely on government subsidies to survive, that they do not spend enough on maintenance and that they run down their capital base. The purpose in this paper is to specify the measures that allow analysts to examine the financial viability of a publicly owned irrigation management companies and to apply these to a scheme in Vietnam. Of concern and contention in any irrigation scheme is the price that a company should charge for water in order to recover costs in the short-run. It was found that the company under investigation could not operate without subsidies and did run down their assets. It was found that a great disparity exists between what the consumers were charged for water and what the company received for supplying it. To ensure the sustainability of the Irrigation Management Companies in long term, they may have to increase the water fee by 3.75 times the current rate set by the provincial government (US$ 20 per ha).     

Farmer participation in irrigation management: The case of Doroodzan Dam Irrigation Network, Iran

The importance of farmer participation in system design and management has been emphasized in previous studies. The purpose of this study was to identify the factors affecting farmer participation in irrigation management using survey research. The study was conducted in Doroodzan Dam Irrigation Network in Fars province, Iran. Multistage stratified random sampling was used to collect data from 270 farmers as the research sample. Results reveal that farmers’ attitudes toward participation in irrigation management, attitudes toward personnel of the State Water Authority and the Agricultural Extension Service Centers (AESCs), family size, the problem perception, dependence on the dam for water, and educational background have influenced their participation in irrigation management. By contrast, contact with information sources, animal units, sociability, age and agricultural experience did not affect farmers’ participation. Moreover, based on farmers’ perspectives, unequal water distribution among farms, dissatisfaction with Water Authority operators and high water fees and charges were the main problems and obstacles toward farmer participation in irrigation management.     

The impact of small-scale irrigation on household food security: The case of Filtino and Godino irrigation schemes in Ethiopia

Ethiopia’s irrigation potential is estimated at 3.7 million hectare, of which only about 190,000 ha (4.3% of the potential) is actually irrigated. There is little information on the extent to which the so far developed irrigation schemes have been effective in meeting their stated objectives of attaining food self-sufficiency and eradicating poverty. Therefore, the aim of this paper is to identify the impact of small-scale irrigation on household food security based on data obtained from 200 farmers in Ada Liben district of Ethiopia in 2006. The resulting data was analyzed using Heckman’s Two-step Estimation procedure. Studies elsewhere revealed that access to reliable irrigation water can enable farmers to adopt new technologies and intensify cultivation, leading to increased productivity, overall higher production, and greater returns from farming. Our study findings confirm some of these claims. In the study area about 70% of the irrigation users are food secure while only 20% of the non-users are found to be food secure. Access to small scale irrigation enabled the sample households to grow crops more than once a year; to insure increased and stable production, income and consumption; and improve their food security status. The study concludes that small-scale irrigation significantly contributed to household food security.

The adoption of improved irrigation technology and management practices—A study of two irrigation districts in Alberta, Canada

Irrigation is by far the largest consumer of water in Alberta. The government is therefore dependent on this sector to achieve water savings for reallocating water to other sectors. Hence, a major objective of a recent government strategy is to see an increase in water efficiency and productivity of 30%. A survey of two irrigation districts was undertaken to determine the measures irrigators have taken and plan to take in the future to improve irrigation technologies and management practices to enhance water use efficiency and which factors facilitate or impede the adoption of such measures. As anticipated, the adoption rate varied between the two districts as a result of differences in production characteristics. The major drivers of adoption were to ensure security of water supply during drought, to increase quantity and quality of crops, and to save cost, while the major impediments were financial constraints and physical farm conditions. It seems that most feasible technological improvements have been implemented and considerable financial improvements or subsidies will be necessary to encourage a significant increase in adoption. There seems to be considerable scope for improvement through the adoption of better management practices. Considering that farmers in the two irrigation districts also have modest plans to adopt improved management practices, promotion and education campaigns that encourage new practices that involve minimal cash outlays might yield the greatest water savings in the future.     

Response of <Emphasis Type="Italic">Sorghum bicolor</Emphasis> varieties to soil salinity for feed and food production in Karakalpakstan,Uzbekistan

Water and land salinization, caused by ill-practiced irrigation and drainage is acute and widespread in Karakalpakstan, Uzbekistan. A crop frequently grown in these marginal areas is sorghum because of its capability to adapt to saline conditions. However, the salt uptake potential of local varieties for salt-ameliorative purposes, as well as possible income-generation benefits, have not yet been studied. Therefore, field experiments on low, medium and highly saline soils were conducted using four sorghum cultivars (S. vulgare, S. cernuum, S. durra, and S. technicum). The effect of soil salinity on biomass, stover and grain yield, the baking and feed quality, and total water soluble salt (TDS) accumulation, was assessed according to varieties, plant fractions and growth phases. Results showed that S. cernuum had the highest grain yield on the low (5.13 t ha⁻¹), medium (6.05 t ha⁻¹) and highly (3.3 t ha⁻¹) saline soil. S. technicum showed the lowest growth potential under all salinity levels. TDS accumulation varied between 406 and 185 kg ha⁻¹ depending on variety, site, plant fractions and growth stage. Irrespective of the soil salinity levels and varieties, TDS was highest in stover and leaves, while highest TDS uptake, mainly chlorides and bicarbonates, occurred between booting and flowering. Baking quality of all varieties was extremely low, whereas the in-vitro feed was assessed as of medium quality. The findings indicate the scope of local sorghum varieties for phytomelioration of marginal lands in Karakalpakstan, while concurrently satisfying a wider range of rural livelihood needs.     

Volumetric water control in a large-scale open canal irrigation system with many smallholders: The case of Chancay-Lambayeque in Peru

Volumetric water control (VWC) is widely seen as a means to increase productivity through flexible scheduling and user incentives to apply just enough water. However, the technical and social requirements for VWC are poorly understood. Also, many experts assert that VWC in large-scale open canals with many smallholders is not feasible. This article debates the practice of VWC, drawing on field studies in the arid North Coast of Peru. Here the large-scale Chancay-Lambayeque irrigation system achieved high allocation, distribution and financial performance with on demand delivery to some 22,000 smallholdings, under a VWC approach, with full cost recovery for operation and maintenance. This study shows there are options to promote VWC if its different elements - volumetric allocation, distribution, metering and pricing - are planned together.     

Analysing agricultural users’ patterns of behaviour: The case of OPTIRas™, a decision support system for starch crop selection

Redesigning IT systems for specific user groups encompasses a lot of effort with respect to analysing and understanding user behaviour. The goal of this paper is to provide insights into patterns of behaviour of agricultural users, during the usage of a decision support system called OPTIRas™. This system aids agricultural users in their cultivar selection activities. We analyse logs resulting from OPTIRas™, and we get insights into user’s navigational patterns. We claim that the results of our analysis can be used to support the redesign of decision support systems in order to address specific agricultural users’ characteristics.     

A measure for the efficiency of water use and its determinants,a case study of small-scale irrigation schemes in North-West Province,South Africa

This paper analyses the efficiency with which water is used in small-scale irrigation schemes in North-West Province in South Africa and studies its determinants. In the study area, small-scale irrigation schemes play an important role in rural development, but the increasing pressure on water resources and the approaching introduction of water charges raise the concern for more efficient water use. With the data envelopment analysis (DEA) techniques used to compute farm-level technical efficiency measures and sub-vector efficiencies for water use, it was shown that under constant returns to scale (CRS) and variable returns to scale (VRS) specification, substantial technical inefficiencies, of 49% and 16%, respectively, exist among farmers. The sub-vector efficiencies for water proved to be even lower, indicating that if farmers became more efficient using the technology currently available, it would be possible to reallocate a fraction of the irrigation water to other water demands without threatening the role of small-scale irrigation. In a second step, Tobit regression techniques were used to examine the relationship between sub-vector efficiency for water and various farm or farmer characteristics. Farm size, landownership, fragmentation, the type of irrigation scheme, crop choice and the irrigation methods applied showed a significant impact on the sub-vector efficiency for water. Such information is valuable for extension services and policy makers since it can help to guide policies towards increased efficiency.     

The other side of the coin: A case study on the impact of financial autonomy on irrigation management performance in the Philippines

The paper assesses the impact of the removal of operating subsidies to the Philippine National Irrigation Administration on the management performance of a small canal irrigation system in Southern Luzon. It shows that in this case the creation of financial autonomy of the agency did not fully engender the often assumed positive effects regarding both accountability relationships and irrigation management performance. The conclusions specify a number of issues related to the theory of financial autonomy which require further study.     

丘陵区村镇水厂取水水源地水环境特征与综合治理-以四川省乐至县为例

对乐至县石河堰型水源地和水库型水源地进行调研,在对其自然环境和水环境对比分析的基础上,对石河堰型水源地和水库型水源地的水环境治理模式进行探讨,提出了源头控制结合生态修复的综合治理模式。     

Irrigation modernization and water conservation in Spain: The case of Riegos del Alto Aragón

This study analyzes the effects of irrigation modernization on water conservation, using the Riegos del Alto Aragón (RAA) irrigation project (NE Spain, 123354 ha) as a case study. A conceptual approach, based on water accounting and water productivity, has been used. Traditional surface irrigation systems and modern sprinkler systems currently occupy 73% and 27% of the irrigated area, respectively. Virtually all the irrigated area is devoted to field crops. Nowadays, farmers are investing on irrigation modernization by switching from surface to sprinkler irrigation because of the lack of labour and the reduction of net incomes as a consequence of reduction in European subsidies, among other factors. At the RAA project, modern sprinkler systems present higher crop yields and more intense cropping patterns than traditional surface irrigation systems. Crop evapotranspiration and non-beneficial evapotranspiration (mainly wind drift and evaporation loses, WDEL) per unit area are higher in sprinkler irrigated than in surface irrigated areas. Our results indicate that irrigation modernization will increase water depletion and water use. Farmers will achieve higher productivity and better working conditions. Likewise, the expected decreases in RAA irrigation return flows will lead to improvements in the quality of the receiving water bodies. However, water productivity computed over water depletion will not vary with irrigation modernization due to the typical linear relationship between yield and evapotranspiration and to the effect of WDEL on the regional water balance. Future variations in crop and energy prices might change the conclusions on economic productivity.     

不同水肥条件下土壤N、P、K分布规律研究

通过田间试验对不同水肥条件下土壤NO3--N、速效磷、速效钾、盐分分布进行研究,结果表明：在滴灌施肥条件下,土壤剖面NO3--N分布主要集中在湿润体边缘,速效磷主要分布在0～30cm范围,速效钾主要分布在0～40cm范围;合理水肥比例可提高红枣对养分的吸收和减少养分在土壤中的积累且影响土壤盐分分布。试验结果为盐渍化土壤水肥一体化管理提供参考。     

InfoCrop: A dynamic simulation model for the assessment of crop yields,losses due to pests,and environmental impact of agro-ecosystems in tropical environments. I. Model description

The problems of agriculture in many tropical countries are gradually becoming more intense due to increasing food demand led by population growth, stagnation in farm productivity, mounting yield losses due to multiple pests, increasing vulnerability to global environmental changes and the need to reduce emission of greenhouse gases. Tools and techniques are needed to assist in developing strategies that can lead to higher food production, prevent crop production losses, and ensure minimal greenhouse gas emissions while maintaining soil fertility. Several dynamic models have been developed in recent past but most of these are generally strong either in soils and crops, or in greenhouse gases (GHG) emissions. Pest induced yield losses, a critical issue in the tropics, is not addressed in most models. InfoCrop, a generic dynamic crop model, has been developed to meet these specific requirements. It provides integrated assessment of the effect of weather, variety, pests, soil and management practices on crop growth and yield, as well as on soil nitrogen and organic carbon dynamics in aerobic as well as anaerobic conditions, and greenhouse gas emissions. The model considers the key processes related to crop growth, effects of water deficit, flooding, nitrogen management, temperature and frost stresses, crop–pest interactions, soil water and nitrogen balance and (soil) organic carbon dynamics. Its general structure relating to basic crop growth and yield is largely based on several earlier models, especially SUCROS series, and is written in Fortran Simulation Environment (FSE) programming language. The model has been validated for dry matter and grain yields of several annual crops, losses due to multiple diseases and pests, and emissions of carbon dioxide, methane and nitrous oxide in a variety of agro-environments. To increase the applications of model in research and development, an extremely simple menu driven version of InfoCrop has also been developed. The users of this version do not need any background in programming.     

Hydrological impacts of rainwater harvesting (RWH) in a case study catchment: The Arvari River, Rajasthan, India. Part 1: Field-scale impacts

Rainwater harvesting (RWH), the small-scale collection and storage of runoff to augment groundwater stores, has been seen as a solution to the deepening groundwater crisis in India. However, hydrological impacts of RWH in India are not well understood, particularly at the larger catchment-scale. A key element to grasping RWH impact involves understanding the generated recharge variability in time and space, which is the result of variability in rainfall-runoff and efficiency of RWH structures. Yet there are very few reported empirical studies of the impact of RWH. Catchment-scale impacts are best studied using a water balance model, which would require a basic level of field data and understanding of the variability. This study reports the results of a 2-year field study in the 476 km² semi-arid Arvari River catchment, where over 366 RWH structures have been built since 1985. Difficulties associated with working in semi-arid regions include data scarcity. Potential recharge estimates from seven RWH storages, across three different types and in six landscape positions, were calculated using the water balance method. These estimates were compared with recharge estimates from monitored water levels in 29 dug wells using the water table fluctuation method. The average daily potential recharge from RWH structures varied between 12 and 52 mm/day, while estimated actual recharge reaching the groundwater ranged from 3 to 7 mm/day. The large difference between recharge estimates could be explained through soil storage, local groundwater mounding beneath structures and a large lateral transmissivity in the aquifer. Overall, approximately 7% of rainfall is recharged by RWH in the catchment, which was similar in the comparatively wet and dry years of the field analysis. There were key differences between RWH structures, due to engineering design and location. These results indicate that recharge from RWH affects the local groundwater table, but also has potential to move laterally and impact surrounding areas. However, the greatest weakness in such analysis is the lack of information available on aquifer characteristics, in addition to geology and soil type.     

InfoCrop: A dynamic simulation model for the assessment of crop yields,losses due to pests,and environmental impact of agro-ecosystems in tropical environments. II. Performance of the model

InfoCrop, a generic crop model, simulates the effects of weather, soils, agronomic management (planting, nitrogen, residues and irrigation) and major pests on crop growth, yield, soil carbon, nitrogen and water, and greenhouse gas emissions. This paper presents results of its evaluation in terms of its validation for rice and wheat crops in contrasting agro-environments of tropics, sensitivity to the key inputs, and also illustrates two typical applications of the model. Eleven diverse field experiments, having treatments of location, seasons, varieties, nitrogen management, organic matter, irrigation, and multiple pest incidences were used for validation. Grain yields in these experiments varied from 2.8 to 7.2 ton ha⁻¹ in rice and from 3.6 to 5.5 ton ha⁻¹ in wheat. The results indicated that the model was generally able to explain the differences in biomass, grain yield, emissions of carbon dioxide, methane and nitrous oxides, and long-term trends in soil organic carbon, in diverse agro-environments. The losses in dry matter and grain yield due to different pests and their populations were also explained satisfactorily. There were some discrepancies in the simulated emission of these gases during first few days after sowing/transplanting possibly because of the absence of tillage effects in the model. The sensitivity of the model to change in ambient temperature, crop duration and pest incidence was similar to the available field knowledge. The application of the model to quantify multiple pests damage through iso-loss curves is demonstrated. Another application illustrated is the use of InfoCrop for analyzing the trade-offs between increasing crop production, agronomic management strategies, and their global warming potential.