Irrigation for crops in a sub-humid environment VII. Evaluation of irrigation strategies for cotton

Summary Empirical functions to predict the nitrogen uptake, increase in LAI and minimum leaf water potential (LWP) of cotton were incorporated into a water balance model for the Namoi Valley, N.S.W. A function was then developed to describe the lint yield of irrigated cotton as a function of water stress days at 4 stages of development, total nitrogen uptake and days of waterlogging. A water stress day was defined as predicted minimum leaf water potential less than -1.8 MPa up to 90 days after sowing and -2.4 MPa there-after; stress reduced yield by up to 40 kg lint ha^–1 d^–1 with greatest sensitivity at 81–140 days after sowing and when N uptake was highest. Nitrogen uptake was reduced by 0.98 kg per ha and yield reduced by 33.2 kg lint ha^–1 for each day of waterlogging. The model was used to evaluate various irrigation strategies by simulating production of cotton from historical rainfall data. With a water supply from off farm storage, net returns ($ M1^–1) were maximized by allocating 7 Ml ha^–1 of crop. The optimum practice was not to irrigate until 60 days from sowing and until the deficit in the root zone reached 50%. When the supply of water was less than 7 Ml ha^–1 there was no advantage in either delaying the start of irrigation or irrigating at a greater deficit; it was economically more rational to reduce the area shown or, if already sown, to irrigate part with 6 Ml ha^–1 and leave the rest as a raingrown crop. Irrigation decisions are compromises between reducing the risk of water stress and increasing the risk of waterlogging. The simulation showed that there is no single set of practices that is always best in every season; in a number of seasons practices other than those which on average are best, give better results.     

Systematic design and evaluation of crop rotations enhancing soil conservation, soil fertility and farm income: a case study for vegetable farms in South Uruguay

Rapid changes in the social and economic environment in which agriculture is developing, together with the deterioration of the natural resource base threatens sustainability of farm systems in many areas of the world. For vegetable farms in South Uruguay, survival in the long term depends upon the development of production systems able to reduce soil erosion, maintain or improve physical and biological soil fertility, and increase farmer’s income to socially acceptable levels. We propose a model-based explorative land use study to support the re-orientation of vegetable production systems in South Uruguay. In this paper we present a new method to quantitatively integrate agricultural, environmental and socio-economic aspects of agricultural land use based on explicit design objectives. We describe the method followed to design and evaluate a wide variety of land use activities for Canelón Grande (South Uruguay) and we illustrate the usefulness of this approach in an ex-ante evaluation of new farming systems using data from 25 farms in this region. Land use activities resulted from systematic combination of crops and inter-crop activities into crop rotations, different crop management techniques (i.e., mechanisation, irrigation and crop protection) and animal production. We identified and quantified all possible rotations and estimated inputs and outputs at crop rotation scale, explicitly considering interactions among crops. Relevant inputs and outputs (i.e., soil erosion, balance of soil organic matter and nutrients, environmental impact of pesticides, labour and machinery requirements, and economic performance) of each land use activity were quantified using different quantitative methods and following the target-oriented approach. By applying the methodology presented in this paper we were able to design and evaluate 336,128 land use activities suitable for the different soil types in Canelón Grande and for farms with different availability of resources, i.e., land, labour, soil quality, capital and water for irrigation. After theoretical evaluation, a large subset of these land use activities showed promise for reducing soil erosion, maintaining soil organic matter content of the soil and increasing farmer’s income, allowing improvement of current farming systems in the region and providing a widely diverse set of strategic options for farmers in the region to choose from. This method can be used as a stand-alone tool to explore options at the field and farm scale or to generate input for optimisation models to explore options at the farm or regional scale.     

Modelling weekly rainfall data for crop planning in a sub-humid climate of India

In this study, two and three-parameter probability distributions have been compared to identify the most appropriate distribution to describe the weekly rainfall data in a sub-humid climate of India. The “best” distribution among different data sets has been identified using probability plot and Anderson–Darling (AD) test for goodness-of-fit, along with the appropriateness of estimated percentiles. One single probability distribution has not been found appropriate to represent all the data sets though Weibull distribution has been found promising for most of the data sets. Gamma probability distribution, which is generally employed for describing weekly rainfall data, was found to grossly approximate the underlying process. Likelihood ratio (LR) test revealed that three-parameter distributions did not significantly improve the fit over two-parameter distributions within the same family. The developed models for different data sets have been employed for computing minimum assured amount of rainfall at different probability levels. Minimum assured rainfall at 40% probability level was found to be in close agreement with the long-term average weekly rainfall data as depicted by L2 and Chebycheff norms. The effect of departure from minimum assured rainfall at 70% probability level on yield of rainfed maize in the region has also been studied using the available experimental data collected from three different field experiments. The effect of intervening drought was found to be most serious in reducing the crop yield by 37–58% as compared to other scenarios representing rainfall amount and its distribution under a sub-humid climate.     

Participatory decision support for agricultural management. A case study from Sri Lanka

Agricultural policy makers were helped to construct and use a decision support system (DSS) to identify problems and assess potential solutions for a river basin in Sri Lanka. Through building the DSS themselves, policy makers should reach better decisions. The main aim of the study was to test whether this could be done using a tool called a Bayesian network (BN) which is accessible to non-specialists and able to provide a generic, flexible framework for the construction of DSS. Results from a workshop indicated that the approach showed promise, providing a common framework for discussion and allowing policy makers to structure complex systems from a multi-disciplinary perspective. The need for a multi-disciplinary perspective was clearly demonstrated. The study also suggested improvements to the ways in which BNs can be used in practice. Further workshops with farmers highlighted the importance of involving them in the planning process and suggested more effective ways of doing this while using BNs.     

Assessing the profitability of different crop protection strategies in cotton: Case study results from Shandong Province,China

The paper compares the economic performance of different crop protection strategies in cotton including the use of transgenic varieties in Shandong Province, China. By means of a Monte Carlo simulation model a comparison was made between conventional insecticide strategies, planting of bollworm-resistant Bt varieties and a strategy of combining both technologies. To account for the observed variation in the toxin content of the Bt varieties in China, two different quality levels of Bt seed are included in the model.The data for the model are season-long records of input use and yield of 150 small-scale cotton producers in five villages in Shandong Province, which are complemented with a survey of Chinese cotton experts. Results show that the high cost pest control strategy based on expensive, good quality Bt seeds is economically inferior to low cost strategies. Scenarios for different pest population levels were included and while the use of low quality Bt seed with need-based applications of insecticides is the dominant control strategy for the normal and high pest pressure scenarios, the use of non-Bt varieties performs well under low pest pressure conditions. These results imply the need to include agro-ecosystem aspects such as pest pressure conditions and the impact of control interventions on both pests and natural enemies in the assessment of pest control strategies.     

Spreadsheets for water management — a case study from the Brantas Delta,East Java

The use of commercially available spreadsheet programs for scheduling of water supplies for large scale irrigation networks is a relatively new phenomenom. The paper describes the development and application of such a program for a 30 000 ha irrigation scheme in the Brantas Delta, East Java. The program has been in use for day-to-day scheduling of main system supplies since April 1986, during which time refinements and adjustments have been necessary to formulate a working package. The paper draws conclusions regarding the value of the program for improving water management.     

A method for exploring sustainable development options at farm scale: a case study for vegetable farms in South Uruguay

The methodology presented in this paper aims at analysing whether there is room for improvement of vegetable farmers’ income in Canelón Grande (Uruguay), while reducing soil erosion and improving physical and biological soil fertility, and to gain insight in the influence of farmers’ resource availability on the opportunities for sustainable development. The (generic) approach we developed to support re-design of farming systems in this region is unique in dealing with complex temporal interactions in crop rotations and spatial heterogeneity on farms in one integrated method, while revealing trade-off between economic and environmental objectives. Rather than an arbitrary sub-set, all feasible crop rotations were generated, using a tool named ROTAT. The crop rotations were combined with a range of production techniques according to pre-defined design criteria to create a wide variety of alternative production activities at the field scale. We used process-based simulation models supplemented with empirical data and expert knowledge to quantify inputs and outputs of production activities. We developed a mixed integer linear programming model (MILP), named Farm Images, to allocate production activities to a farm with land units differing in soil quality, while maximising or minimising socio-economic and environmental objectives, subject to constraints at the farm level. Production activities comprised current practices as well as activities new to the area. We used Farm Images to design farm systems for seven existing farms in Canelón Grande with different resource availability. The farm systems designed by the model had higher family income than current systems for six of the seven farms studied. The estimated average soil erosion per ha decreased by a factor of 2–4 in the farm systems proposed compared to the current systems, while the rate of change of soil organic matter increased from negative in the current systems to +130 to +280 kg ha⁻¹ yr⁻¹ in the proposed farm systems. The degree to which the objectives could be achieved was strongly affected by farm resource endowment, i.e., particularly by the fraction of the area irrigated, soil quality and labour availability per ha. The study suggests that decreasing the area of vegetable crops by introducing long crop rotations with pastures and green manure during the inter-crop periods and integrating beef cattle production into the farm systems would often be a better strategy than the actual farmers’ practice.     

Water and nutrient use efficiency of a low-cost hydroponic greenhouse for a cucumber crop: An Australian case study

The Australian greenhouse industry is primarily dominated by low-cost hydroponic greenhouses for delivery of water and nutrients to plants to grow a variety of vegetable crops including cucumber and tomato. The nutrient rich drainage water from these greenhouses is generally released into the local environment causing pollution concerns. This study was initiated to investigate the opportunities in recycling drainage water to increase water and nutrient-use efficiency of hydroponic greenhouses and reduce the environmental impact of the drainage water discharge. Results indicated that a total of 4.15 ML/ha of irrigation water was applied during the 13 weeks crop growing period of which 2.56 ML/ha was drained off and 1.59 ML/ha was used to meet the crop evapotranspiration demand. The study showed that the recycling of the drainage water resulted in a 33% reduction in potable water used for irrigation in cucumber production. The drainage water contained 59% applied N, 25% applied P and 55% applied K and illustrated the potential for nutrient recovery and production cost savings through the reuse of drainage water. This case study demonstrates that some relatively simple changes in irrigation practices within greenhouse systems to recycle drainage water can considerably improve sustainability of low-cost hydroponic greenhouses and help minimise the environmental footprint of the greenhouse industry.     

Impact of crop rotation and minimum tillage on water use efficiency of irrigated cotton in a Vertisol

Crop water use efficiency of irrigated cotton was hypothesized to be improved by a combination of minimum tillage and sowing a wheat (Triticum aestivum L.) rotation crop. This hypothesis was evaluated in a Vertisol near Narrabri, Australia from 1997 to 2003. The experimental treatments were: continuous cotton sown after conventional or minimum tillage and minimum-tilled cotton–wheat. Soil water content was measured with a neutron moisture meter, and runoff with trapezoidal flumes. Application efficiency of irrigation water was estimated as the amount of infiltrated water/total amount applied. Plant available water was estimated using the maximum and minimum soil water storage during the growing season. Evapotranspiration was estimated with the water balance method using measured and simulated soil water data. Seasonal evapotranspiration was partitioned into that coming from rainfall, irrigation and stored soil water. Crop water use efficiency was calculated as cotton lint yield per hectare/seasonal evapotranspiration. Rotation of cotton with wheat and minimum tillage improved water use efficiency in some years and application efficiency in all years. Average seasonal evapotranspiration was higher with minimum tillage than with conventional tillage. In years when cotton was sown in all plots, average cotton crop water use efficiencies were 0.23, 0.23 and 0.22 kg (lint)/m³ for minimum-tilled cotton–wheat and continuous cotton, and conventionally tilled continuous cotton, respectively. In-season rainfall efficiency, transpiration and soil evaporation were unaffected by cropping system.     

Modelling the effects of climate variability and water management on crop water productivity and water balance in the North China Plain

In the North China Plain (NCP), while irrigation using groundwater has maintained a high-level crop productivity of the wheat-maize double cropping systems, it has resulted in rapid depletion of groundwater table. For more efficient and sustainable utilization of the limited water resources, improved understanding of how crop productivity and water balance components respond to climate variations and irrigation is essential. This paper investigates such responses using a modelling approach. The farming systems model APSIM (Agricultural Production Systems Simulator) was first calibrated and validated using 3 years of experimental data. The validated model was then applied to simulate crop yield and field water balance of the wheat-maize rotation in the NCP. Simulated dryland crop yield ranged from 0 to 4.5 t ha⁻¹ for wheat and 0 to 5.0 t ha⁻¹ for maize. Increasing irrigation amount led to increased crop yield, but irrigation required to obtain maximum water productivity (WP) was much less than that required to obtain maximum crop yield. To meet crop water demand, a wide range of irrigation water supply would be needed due to the inter-annual climate variations. The range was simulated to be 140-420 mm for wheat, and 0-170 mm for maize. Such levels of irrigation applications could potentially lead to about 1.5 m year⁻¹ decline in groundwater table when other sources of groundwater recharge were not considered. To achieve maximum WP, one, two and three irrigations (i.e., 70, 150 and 200 mm season⁻¹) were recommended for wheat in wet, medium and dry seasons, respectively. For maize, one irrigation and two irrigations (i.e., 60 and 110 mm season⁻¹) were recommended in medium and dry seasons, while no irrigation was needed in wet season.     

A new approach to water management of tropical peatlands: a case study from Malaysia

The use of peatlands in the humid tropics requires drainage to remove excess rainfall. The design principles for the drainage systems currently being implemented on peatlands are the same as for mineral soils. The objective of such systems is the timely removal of excess rainfall by surface runoff. For peatlands, with their different soil-hydraulic characteristics, these systems have resulted in poor watertable control and high rates of irreversible subsidence. Concerns about this rate of subsidence and the level of sustainability of the present land use have prompted a study to develop a new water management system. This new system includes a shift from a drainage system that focuses on discharge of excess water towards a system that combines drainage and water conservation. In the new two-step design, the drain spacing and corresponding drain discharges are obtained with a steady-state approach. These outputs are used to calculate the capacity of the drains, including control structures, using an unsteady-state approach. The new system results in a shallower but more narrowly spaced drainage system and maintains a more constant but relatively high watertable and reduces subsidence. It should be remembered however, that even with the improved water management, subsidence cannot be arrested; it is the price one has to pay for the use of tropical peatlands.     

Pasture and forage crop systems for non-irrigated dairy farms in southern Australia: 3. Estimated economic value of additional home-grown feed

Dairy systems in southern Australia rely on grazed feed from pasture to supply between 50% and 70% of total herd feed requirements on an annual basis. However, the dominant pasture type in the region, which is based on perennial ryegrass (Lolium perenne), commonly results in feed deficits in summer which must be filled with supplements purchased off-farm, and feed surpluses in spring which must be conserved. Both of these strictures impose costs on farm businesses. It is likely, therefore, that additional grazeable feed available to dairy herds in southern Australia may have different economic value when interactions between season, stocking rate, calving date, and locality are taken into account. The analysis reported in this paper aimed to estimate, using the farm systems simulation model UDDER, the effect of these interactions on the efficiency with which extra feed can be converted to extra milk production, and therefore the possible gross economic value of the additional feed.‘Base’ farm simulations for ‘average’ and ‘top 10%’ farms (ranked according to farm profitability) in two localities (Terang: average annual rainfall 796 mm, 8 month growing season; and Ellinbank: average annual rainfall 1085 mm, 9-10 month growing season) were created to mimic the physical production and profitability of these farms as seen in regional farm benchmark datasets. These simulations were then altered to add the equivalent of 10% of the total annual herbage accumulation used in the Base simulation either on a pro-rata basis all year round, or in autumn only, in winter only, in spring only, or in summer only. The additional feed amounted to 620 and 780 kg DM/ha for Terang average and top 10% farms respectively, and 735 and 905 kg DM/ha for Ellinbank average and top 10% farms respectively. The management policies used in the Base simulations were then adjusted to harvest as much of the extra feed as possible, either by direct grazing or through silage conservation, while keeping the key system state indicators of cow condition score and average farm pasture cover within the limits known to result in long-term sustainable production.The efficiency with which extra feed was utilised was greatest in summer in all scenarios (80-100% of the extra feed supplied was harvested, all by direct grazing). This translated into consistently high gross economic returns of between $0.26 and $0.34 per kg DM of extra feed added to the model. Utilisation efficiency was lower in all other seasons and/or required marked increases in silage conservation, both of which resulted in lower gross economic returns per kg DM of additional feed. The impact of interactions between locality, season, stocking rate (higher in top 10% farm simulations than average farm simulations) and calving date (earlier at Terang than at Ellinbank) were clearly captured in the model. These interactions have very large effects on the profitability of growing extra feed at different times of the year. Agronomic research for the southern Australia dairy industry should focus on low-cost ways for supplying additional grazeable feed in summer, since current forage species options for this time of year are limited.     

Water management in raised bed systems: a case study from the Chao Phraya delta,Thailand

Agricultural diversification is a major trend in Asian rice-based systems. In lowlands, however, soil and water conditions are mostly suitable for rice cultivation and the development of raised beds is often required to accommodate vegetables or fruit trees. Raised bed systems go together with specific techniques of water management, both at the polder level (between the plots and the canals) and at the plot level (bed irrigation). Details of this management in the Chao Phraya Delta are given for three different crops: mango, grapes and asparagus and differences are explained. The water balance over 1 year is specified, showing the impact of seepage and estimating water requirements. Water quality is shown to be a major issue.     

VegSyst, a simulation model of daily crop growth, nitrogen uptake and evapotranspiration for pepper crops for use in an on-farm decision support system

The VegSyst simulation model was developed to assist with N and irrigation management of sweet pepper grown in plastic greenhouses in the Mediterranean Basin. The model was developed for use in an on-farm decision support system with the requirement for readily available input data. Dry matter production (DMP), crop N uptake and crop evapotranspiration (ET_c) are simulated on a daily basis. DMP is calculated from daily fraction of intercepted photosynthetically active radiation (PAR), PAR radiation, and radiation-use efficiency. Fraction of intercepted PAR is calculated from relative thermal time. Crop N uptake is calculated as the product of DMP and N content which is described by a power function of DMP. ET_c is the product of daily reference evapotranspiration (ET_o) using an adapted Penman–Monteith equation, and a daily simulated crop coefficient value. The VegSyst model for soil-grown, greenhouse pepper was calibrated in one crop and validated in three different crops. In the validation, the model accurately simulated crop growth, N uptake and ET_c. Relative to measured values, simulated DMP at final harvest was 0.89–1.06, and crop N uptake was 0.97–1.13. Simulated cumulative ET_c for complete crops was 0.95–1.05 of measured values.     

Leaching of nutrients from a sugarcane crop growing on an Ultisol in Brazil

Leaching is disadvantageous, both for economical and environmental reasons since it may decrease the ecosystem productivity and may also contribute to the contamination of surface and ground water. The objective of this paper was to quantify the loss of nitrogen and sulfur by leaching, at the depth of 0.9 m, in an Ultisol in São Paulo State (Brazil) with high permeability, cultivated with sugarcane during the agricultural cycle of crop plant. The following ions were evaluated: nitrite, nitrate, ammonium, and sulfate. Calcium, magnesium, potassium, and phosphate were also evaluated at the same depth. The sugarcane was planted and fertilized in the furrows with 120 kg ha⁻¹ of N-urea. In order to find out the fate of N-fertilizer, four microplots with ¹⁵N-enriched fertilizer were installed. Input and output of the considered ions at the depth of 0.9 m were quantified from the flux density of water and the concentration of the elements in the soil solution at this soil depth: tensiometers, soil water retention curve and soil solution extractors were used for this quantification. The internal drainage was 205 mm of water, with a total loss of 18 kg ha⁻¹ of N and 10 kg ha⁻¹ of S. The percentage of N in the soil solution derived from the fertilizer (%NSSDF) was 1.34, resulting in only 25 g ha⁻¹ of N fertilizer loss by leaching during all agricultural cycle. Under the experimental conditions of this crop plant, that is, high demand of nutrients and high incorporation of crop residues, the leached N represented 15% of applied N and S leaching were not considerable; the higher amount of leached N was native nitrogen and a minor quantity from N fertilizer; and the leached amount of Ca, Mg, K and P did not exceed the applications performed in the crop by lime and fertilization.     

The use of measured water flows in furrow irrigation management — a case study in Swaziland

The use of measured water in controlling flows for the irrigation of sugarcane was found to be vital for the rehabilitation and management of surface irrigation on a 5000 ha sugarcane project. Methods of water delivery, measurement and control at Inyoni Yami Swaziland Irrigation Scheme (IYSIS) are described. Improvements to the irrigation, using existing methods of water measurement, were carried out over a period of four years. The lessons gained in this programme of improvements confirmed the benefits of using modulus gates which allow a constant, measured, discharge of water.     

Identification and selection of technology for a specific agricultural region: A case study of sheep husbandry and dryland farming in the northern Negev of Israel

The chances that innovative technology will succeed in a given agricultural region are difficult to determine in advance. Information that would point to the likely or optimum course of development would be very useful for development planning and applied agricultural research administration. An approach is presented whereby the diffusion of new technology can be analysed in the context of a developing region. The development of sheep husbandry and wheat cultivation systems in a semi-arid agropastoral region in the northern Negev of Israel is used as a case study. The approach employed involves defining the input/output relations of a set of technologies based on wheat cultivation and on an increasingly intensive range of sheep production systems. The region is defined by its borders, land classes, physical and financial capital, available labour, plant and animal genetic stock and climatic conditions. An optimum mix of technologies over a development period is determined by using a multiperiod linear programming routine. The technology assessment is then conducted by varying the future socio-economic scenarios of the region and analysing the response of the model.The results indicated that the most fertile sheep breed, the Finn cross, would be selected only if labour were plentiful and cheap. It would also be selected whenever the demand for sheep created high shadow prices—especially at the beginning of a development period. The local, relatively extensive, breed of sheep (Awassi) is maintained over a long period even when meat: grain price ratios are high. Eventually, it tends to phase out in favour of a more intensive breed, the German Mutton Merino. The high price ratio did not result in massive transfer to confined, intensive husbandry but increased the use of improved pasture on cultivable land.     

Evaluation of the water cost effect on water resource management:: Application to typical crops in a semiarid region

The greatest water consumption takes place during irrigation of arid and semiarid areas, therefore, water resource management is fundamental for sustainability. For correct management, several tools and decision-making systems are necessary while paying close attention to aspects such as profitability, water cost, etc. Water resources are scarce and some of them are of low quality. This extremely delicate situation occurs in some regions of the world and it explains increasing water cost. In Europe, the policies relating to water use (2000/60/EC) pay particular attention to the need of its protection and conservation. To ensure this, a large number of measures, including the establishment of prices which really correspond to their usage costs, have been set forth. Water subsidies are relatively important in all European countries. In this study, a specific methodology is applied to a Spanish semi-arid region. It is useful and easy to apply, not only by farmers, but also by water managers and politicians in charge of policy. The methodology also helps in the decision-making process about water cost in agriculture. In this area (Hydrogeological System 08.29, Spain), the resources are mainly underground water with a high variable cost and without any direct subsidies. This model allows us to analyse the effect of different water costs and to find the optimum strategy giving the maximum gross margin in line with water cost and its main determining factors (irrigation system, climatic variability, etc.).The methodology is based on the effect of irrigation on crop yield with its production function, integrating the effect of application efficiency. In this way, a relationship between gross margin and gross irrigation depth is obtained. Working with permanent irrigation systems and four crops (barley, garlic, maize and onion), the main conclusion is that the optimum gross irrigation depths are always fewer than those necessary for maximum crop yield and when irrigation depths are fewer water cost increases. Irrigation depths, which maximise the economic efficiency in the use of water (€ m⁻³), are fewer than those which maximise the gross margin; therefore, this aspect must be considered in irrigation scheduling. The results also show important differences among crops, depending on their water requirements and their economic profitability.     

A simplified input-output model for farming systems with varying input mixes. The case of peasant and state farms in Poland in the 1970s

A simplified input-output model of the two principal sectors of Polish farming, the peasant and the state farms, has been used to illustrate the direct and indirect impacts of production in these two groups of farms. The capital-intensive state farms may be depended upon to rapidly increase the market supply of food, provided the industrial inputs, such as fertilizers, machines and concentrate feedstuffs, are available. The peasant farms, on the other hand, require relatively less industrial inputs but market a lower share of their total output. They provide jobs for approximately a quarter of the national labor force, however, and most of the food consumed by the nearly ten million persons living in the 2.6 million peasant households is produced there and does not enter the market. A comparison of direct and indirect input-output coefficients has shown peasant farms to be highly productive, the principal factor being the abundant resource of cheap labor.     

Simulated effect of drainage water management operational strategy on hydrology and crop yield for Drummer soil in the Midwestern United States

The hypothetical effects of drainage water management operational strategy on hydrology and crop yield at the Purdue University Water Quality Field Station (WQFS) were simulated using DRAINMOD, a field-scale hydrologic model. The WQFS has forty-eight cropping system treatment plots with 10 m drain spacing. Drain flow observations from a subset of the treatment plots with continuous corn (Zea mays L.) were used to calibrate the model, which was then used to develop an operational strategy for drainage water management. The chosen dates of raising and lowering the outlet during the crop period were 10 and 85 days after planting, respectively, with a control height of 50 cm above the drain (40 cm from the surface). The potential effects of this operational strategy on hydrology and corn yield were simulated over a period of 15 years from 1991 to 2005. On average, the predicted annual drain flows were reduced by 60% (statistically significant at 95% level). This is the most significant benefit of drainage water management since it may reduce the nitrate load to the receiving streams. About 68% of the reduced drain flow contributed to an increase in seepage. Drainage water management increased the average surface runoff by about 85% and slightly decreased the relative yield of corn crop by 0.5% (both are not statistically significant at 95% level). On average, the relative yield due to wet stress (RYw) decreased by 1.3% while relative yield due to dry stress (RYd) increased by 1%. Overall, the relative crop yield increased in 5 years (within a range of 0.8-6.9%), decreased in 8 years (within a range of 0.2-5.5%), and was not affected in the remaining 2 years. With simulated drainage water management, the water table rose above the conventional drainage level during both the winter and the crop periods in all years (except 2002 crop season). The annual maximum winter period rise ranged between 47 cm (1995) and 87 cm (1992), and the annual maximum crop period rise ranged between no effect (2002) and 47 cm (1993).