Irrigation Application Efficiency Research Articles

Improvement of Soil and Water Productivity for Sugar Beet under Salt Affected Soils at North Nile Delta, Egypt

A field trial was conducted during the two consecutive growing seasons of 2016/17 and 2017/18 at Sakha Agricultural Research Station Farm, Kafr El-Sheikh Governorate. The aim of this current study was to evaluate the effect of four irrigations treatments; cut-off at 100 (I1, traditional practice), 90%(I2), 80% (I3) and 70% (I4) from furrow length and five fertilization treatments; F1 (90 Kg N Fed.-1), F2 (67.5 kg N+3 ton compost fed.-1), F3 (45 kg N+5 ton compost fed.-1), F4 (22.5 Kg N+7 ton compost fed-1) and F5 (10 ton compost fed.-1) (ha =2.4 fed) on some water parameters, some soil properties and yield of sugar beet. The experiments were designed as spilt plot with three replications. The main plots were occupied by cut-off irrigation, while subplots were devoted to fertilization rates. The main results can be summarized as follows: The highest values of applied water (3678 and 3562 m3 fed-1); water consumptive use (2381 and 2210 m3 fed-1) and water stored (2525 and 2456 m3 fed-1) were recorded under I1 (local farmers practice) in the 1st and 2nd seasons, respectively. On the other hand, the lowest values of applied water (3168 and 3094 m3 fed.-1); water consumptive use (2218 and 2062 m3 fed-1) and water stored (2325 and 2335 m3 fed-1) were recorded with I4 in the 1st and 2nd seasons, respectively. The highest values of water saving was recorded under I4 as average of the two growing seasons (12.14 cm and 11.14 cm, respectively) which saved about 100*106 m3 water in sugar beet fields at the national level (200*103 fed) comparing with check treatment (I1). The highest values of irrigation application and consumptive use efficiencies in both seasons were achieved under irrigation treatment I4 but the lowest values were recorded under irrigation treatment I1 in the two studied seasons. Concerning to water productivity ( ) and productivity of irrigation water (PIW), the highest values of (14.09 and 16.74 Kg m-3) and PIW (9.70 and 11.61 kgm-3) were recorded under I3 in the first and second seasons, respectively. On the other hand, the lowest values of (12.16 and 14.99 kgm-3) and IPW (7.88 and 9.30 Kgm-3) were recorded with I1 in both seasons, respectively. Concerning to the role of fertilization in and PIW, F2 treatment achieved the highest values of (14.38 and 17.38 kg m-3) and PIW (9.99 and 11.23 kg m-3), while F4 treatment gave the lowest values of both parameters in both seasons, respectively The soil ECe, SAR and ESP as mean values of both seasons were affected by irrigation cut-off and fertilization treatments. The highest reduction of ECe, SAR and ESP was induced by F5 under I1, while the lowest reduction was recorded with F1 and I4. The highest root yields (18.78 and 20.61 ton fed-1) were achieved with I3, while F5 was the best fertilization treatment (15.76 and 18.13 ton root fed.-1) in both seasons, respectively. So, the highest significant effects of cut- off and fertilization treatments on sugar beet root, shoot and sugar yields in both growing seasons were achieved with I3 and F5. Also, there were high significant effects on such parameters due to the interactions between different treatments.

Evaluation of Object Surface Edge Profiles Detected with a 2-D Laser Scanning Sensor.

Canopy edge profile detection is a critical component of plant recognition in variable-rate spray control systems. The accuracy of a high-speed 270° radial laser sensor was evaluated in detecting the surface edge profiles of six complex-shaped objects. These objects were toy balls with a pink smooth surface, light brown rectangular cardboard boxes, black and red texture surfaced basketballs, white smooth cylinders, and two different sized artificial plants. Evaluations included reconstructed three-dimensional (3-D) images for the object surfaces with the data acquired from the laser sensor at four different detection heights (0.25, 0.50, 0.75, and 1.00 m) above each object, five sensor travel speeds (1.6, 2.4, 3.2, 4.0, and 4.8 km h−1), and 8 to 15 horizontal distances to the sensor ranging from 0 to 3.5 m. Edge profiles of the six objects detected with the laser sensor were compared with images taken with a digital camera. The edge similarity score (ESS) was significantly affected by the horizontal distances of the objects, and the influence became weaker when the objects were placed closer to each other. The detection heights and travel speeds also influenced the ESS slightly. The overall average ESS ranged from 0.38 to 0.95 for all the objects under all the test conditions, thereby providing baseline information for the integration of the laser sensor into future development of greenhouse variable-rate spray systems to improve pesticide, irrigation, and nutrition application efficiencies through watering booms.

Performance of irrigation regimes and water salinity on winter wheat as influenced by planting methods

Shortage and salinity of irrigation water are two major constraints that influence wheat production in arid and semi-arid regions of Iran. In this study, effects of deficit furrow irrigation with different salinity levels and planting methods (in-furrow and on-ridge) as strategies for coping with water and salinity stress on yield and yield quality of winter wheat was investigated in a two-year experiment. Irrigation treatments were full irrigation (FI), 0.65FI, and 0.35FI, and salinity levels of irrigation water were 0.6 (well water), 5.0, 7.5, and 10.0 dS m−1. In the first year, grain yield was reduced by 20% and 26% in irrigation regimes of 0.65FI (381 mm) and 0.35FI (217 mm), respectively. These reductions were 17% and 30% in the second year, respectively. The corresponding irrigation water reductions were 33% and 62% in both years for 0.65FI (381, and 355 mm compared to 573 mm) and 0.35FI (217, and 203 mm compared to 533 mm), respectively. Therefore, it is indicated that the proportion of irrigation water reduction to the grain yield reduction is 2:1 in benefit of the deficit irrigation mostly due to the seasonal rainfall of 363 and 439 mm in the first and second years, respectively. Although the majority of rainfall occurred in winter, the winter wheat growth is at rest. Results also indicated that in FI with irrigation application efficiency of 80% (leaching fraction of 20%), the salinity level of 3.36 dS m−1 produced no grain yield reduction. Furthermore, salinity level of 7.5 dS m−1 for irrigation regimes of 0.65FI and 0.35FI, respectively did not show significant difference in grain yield compared with that obtained in 0.6 dS m−1 salinity level. Therefore, by deficit irrigation, higher salinity level is applicable due to lower salt accumulation in soil. In-furrow planting resulted in 4% (statistically significant) higher grain yield compared with that obtained in on-ridge planting with 5% higher irrigation water productivity (IWP). By considering acceptable grain yield production in 0.65FI, its IWP (1.03 kg m−3 and 1.1 kg m−3 in the first and second year, respectively) was significantly higher than those obtained in FI (0.85 kg m−3 and 0.87 kg m−3 in the first and second year, respectively). In in-furrow planting, grain yield in salinity level of 7.5 dS m−1 was suitable with irrigation regime of 0.65FI; whereas, for on-ridge planting appropriate salinity is 5.0 dS m−1. Therefore, in non-limited irrigation water condition, FI with salinity level of 5.0 dS m−1 and in-furrow planting is the appropriate irrigation management for winter wheat. However, with limited water supply, 0.65FI with salinity of 7.5 dS m−1 and in-furrow planting would be appropriate in winter wheat irrigation management in the study region. The root water uptake was predicted by Homaee-Feddes method with higher accuracy and its value was used in grain yield prediction with Doorenbos-Kassam yield-ET function with higher accuracy.

Performance of small-scale irrigation schemes in Lake Tana Basin of Ethiopia: technical and socio-political attributes

ABSTRACTThis study was conducted to investigate technical and socio-political attributes that lead to the underperformance of two selected irrigation schemes (Shina and Bebeks) in the Lake Tana floodplains, Ethiopia. Irrigation application efficiency (AE) at nine experimental fields showed a wide range, from 20 to 80%, but was mostly between 40 and 60%. Irrigation water-use efficiency (IWUE) varied from 1.9 to 7.2 kg m−3 for onion and 0.9 to 1.2 kg m−3 for maize. The lined and earthen canal conveyance losses in Bebeks were 0.037 and 0.047 l s−1 m−1, whereas in Shina they were 0.033 and 0.044 l s−1 m−1, respectively. The overall consumed ratio (OCR) of water was 0.58 for Bebeks and varied from 0.73 to 1.2 in Shina. Both schemes are performing below the standard based on technical performance indicators. Irrigation water user associations (WUAs) were not implemented, but irrigation committees (ICs), composed of local political leaders, are managing both schemes. Canal and reservoir sedimentation from erosion of upstream catchment areas during the rainy season was the major problem.

EFFECTS OF SCHEDULING TECHNIQUES OF WATER APPLICATION FOR DRIP IRRIGATION SYSTEM ON TOMATO YIELD IN ARID REGIO

Irrigation is necessary in order to produce tomato in arid regions such as Saudi Arabia, with limited water supplies. Drip irrigation (DI) is being adopted in these areas to conserve water under economical crop production. Field experiment was carried out to study effects of different irrigation scheduling management strategies on fruit yield, quality of drip-irrigated fresh market tomatoes, water use efficiency and irrigation application efficiency. The experiment included three scheduling methods, which were used to irrigate tomato field: Evapotranspiration (ET) controller, soil moisture sensor (watermark sensor) and control treatment based on weather data. All irrigation-scheduling methods were effective, prescribing different amount of water for a given season. Irrigation amount increased from 841.5 mm (ET controller) to 882.60 mm (watermark sensor) and 1034.33 mm (control treatment), during two seasons. Both WUE and IWUE increased with decrease in irrigation water depth. The maximum average WUE (7.26 kg-m–3) and IWUE (4.66 kg-m– 3) values were for ET controller as average, during the two seasons. In addition, ET controller method conserved up to 7 % and 18% water compared to the watermark sensor and control treatments, respectively. Based on the above results, it is recommended that if the tomatoes are well irrigated based on ET controller, the farmer can get higher tomato yield in areas experiencing severe drought, such as Saudi Arabia.

Alternate wetting and drying for different subsurface drainage systems to improve paddy yield and water productivity in Iran

Alternate wetting and drying (AWD) irrigation for different subsurface drainage systems was tested in an experimental paddy field in Sari, Mazandaran Province, Iran. During two growing seasons in 2014 and 2015, two local rice cultivars (Daylamani and Hashemi) were tested for four combinations of subsurface drainage systems with 15 and 30m drain spacing, and 0.65 and 0.90m drain depths and compared to a control plot with only surface drains with a depth of 1.2m. Subsurface drainage improved water use efficiency of the Hashemi (17.9–1.8%) and Daylamani (1.4–15.4%) cultivars compared with the surface drainage in the control plot. Under subsurface drainage conditions, Hashemi, with an overall crop yield of 5392kgha−1, performed better than Daylamani, with an overall crop yield of 5010kgha−1. These yields were considerably higher than the corresponding yields in the control plot, 4405kgha−1 for Hashemi and 4972kgha−1 for Daylamani. Of the subsurface drainage systems, the drain depth/spacing combination D0.90/L30m performed better than the others. No significant difference in the irrigation application efficiency was found between subsurface and surface drained plots. The results showed that subsurface drainage practices in combination with AWD can be an effective strategy to improve land and water productivity in paddy fields if an appropriate drying period is selected by considering drought tolerance of different cultivars.

Provide management package in irrigation networks to achieve optimal performance measures

Saving water and improving water productivity influence the socioeconomic measures like equity that should be considered in water distribution management especially in drought conditions. In this research for different scenarios of irrigation water management, the performance measures of water equity and productivity in Ordibehesht channel (Doroodzan irrigation network) was optimised simultaneously by using genetic algorithm (GA). The results showed that rising water reduction fraction (WRF) (0.0 to 0.8) has the incremental effect on water equity and productivity (on average 39.2% and 43.3%, respectively). With increasing irrigation application efficiency (Ea) (40% to 90%), the values of water equity and productivity increased by on average 59.9% and 113.5%, respectively. Increment of conveyance efficiency of channels (Ec) (70% to 90%) resulted in minimum incremental effect on water equity and productivity (on average 19.8% and 14.1%, respectively). Furthermore, the values of performance measure decreased from wet water year to drought water year.

Irrigation application efficiency and uniformity of water distribution using multi-outlet pipe and resource conservation technologies

Irrigation experiments were conducted during November to April under wheat crop in the winter season of 2012-13 and 2013-14 in the farmer’s field at Galibkhedi village located in Karnal District, Haryana State, India. In the study, collapsible multi-outlet pipe (MOP) along with single outlets pipe (SOP) was tested in farmer’s field under wheat cultivation. Irrigation was carried out in five treatments including tillage (T) with SOP and MOP; zero-tillage (ZT) with SOP and MOP, and furrow irrigation with raised bed (FIRB). Iso-time profile of waterfront spreading and advance indicated that irrigation water distribution was uniform under the plot irrigated using MOP as compared to plot irrigated using SOP. In addition, water distribution was uniform under zero tilled plots as compared to tilled plot. Results implied that MOP has several advantages over SOP in terms of application efficiency (AE) and uniformity of water distribution. Average application efficiency for the first study year was found to be in the order of ZT-MOP (82.41%) > FIRB (76.79%) > ZT-SOP (75.25%) > T-MOP (74.85%) > T-SOP (69.79%). Average application efficiency for the second study year was found to be in the same order as first year with some deviation in values. In the second year values of mean application efficiencies were ZT-MOP (82.58%) > FIRB (77.13%) > ZT-SOP (73.04%) > T-MOP (69.65%) > T-SOP (66.13%). Overall, this study concludes that irrigation under wheat crop using collapsible multi-outlet pipe (MOP) with zero tillage practices is a suitable option for surface irrigation that accomplishes uniform distribution of water with higher application efficiency.

Irrigation scheduling and water use efficiency of cucumber grown as a spring-summer cycle crop in solar greenhouse

This 3-year study aimed to determine the most appropriate irrigation application and water use efficiency programs based on Class A Pan evaporation for mini (Lebanese) type cucumber plants grown as a first crop under protected conditions in a solar greenhouse. Research was carried out in an unheated solar greenhouse constructed on the lands of Ataturk Soil Water and Agricultural Meteorology Research Institute in Kirklareli, Northwestern Turkey. In order to prevent excessive increase in temperature within the protective structure, the semicircular shaped unheated greenhouse with sidewall ventilation was screened with 75% green-coloured shading net. The experimental layout of the study was a split-plot design with 3 replications. Two irrigation intervals (D1–2days and D2–4days) and four different plant–pan coefficients (0.75, 1.00, 1.25 and 1.50) were applied to main and subplots in the experiment. It was determined that cucumber yields increased with the increase in the irrigation water amount and reached averages of 128.2 and 126.5tonha−1 with use of highest plant pan coefficients of 1.50 and 1.25 vs. 90.7 and 90.9tonha−1 under the lowest Ecp coefficient of 0.75. The highest irrigation water use efficiency (IWUE) and water use efficiency (WUE) values of about 56kgha−1m−3 and 42kgha−1m−3 were obtained from the conditions with least applied irrigation water amounts. The average seasonal value of the yield response factor (ky) estimated on the basis of data from the 3-year study was determined as 0.75.

Evaluation of Stemflow Effects on the Spatial Distribution of Soil Moisture Using TDR Monitoring and an Infiltration Model

AbstractThe partitioning of crop canopy water may affect soil water distribution and this may in turn affect sprinkler irrigation application efficiency. The aim of this work was to develop a methodology to evaluate spatial and temporal soil water content distribution in the case of sprinkler irrigation application efficiency considering stemflow. Time domain reflectometry (TDR) soil moisture monitoring was carried out on eight soil water sensor locations for both center pivot and traveling big gun irrigation in different phenological and tillage cases. The two case studies were chosen because they show the two opposite limits of the methodology’s application. Two water distribution estimation methods were employed: raw measured soil moisture and model simulation of the infiltration process. The infiltration process was modeled by means of the two-dimensional (2D) Richard’s equation. The simulations were calibrated on the data measured at eight soil water sensor locations. The stemflow and surface runoff ...

Effect of Various On-Farm Water Management Scenarios on Equity and Productivity in Irrigation Networks

This research investigated the optimum on-farm water management methods for a summer crop (Maize). Water equity and productivity were optimized simultaneously by using genetic algorithms in Doroodzan Irrigation Network. Increase in water reduction fraction (WRF) (0.0 to 0.8) has the incremental effect on water equity (on average 19.4 %), however by increasing WRF, water productivity initially increased (on average 25.3 % at WRF = 0.4) and then decreased. With increasing irrigation application efficiency (Ea) (40 to 90 %), the values of water equity and productivity increased by on average 52.8 and 91.5 %, respectively. Increment of conveyance efficiency of channels (Ec) (70 to 90 %) resulted in minimum incremental effect on water equity and productivity (on average 18.5 and 11.9 %, respectively). Furthermore, the values of performance measure decreased from wet water year to drought water year. Tape irrigation system was considered as the best choice at low quantities of WRF ( = 0.6), sprinkler irrigation system was considered as the best choice for achieving higher values of water equity and productivity. Meanwhile, when equity and productivity were considered together for a specific method of deficit irrigation scheduling, under specified quantity of irrigation water, with increasing equity the water productivity reduction was negligible.

Irrigation application efficiency calculation of sprinkler irrigated container plants grown under sensor based irrigation scheduling

Irrigation application efficiency calculation of sprinkler irrigated container plants grown under sensor based irrigation scheduling

Species-specific irrigation scheduling with a spatially explicit biophysical model: A comparison to substrate moisture sensing with insight into simplified physiological parameterization

Predictive modeling and sensing based approaches to scheduling irrigation are increasingly being adopted by commercial nurseries due to their potential to automate irrigation and improve crop production. This study had two overarching objectives: first, to compare the irrigation scheduling performance of a substrate moisture sensing approach to that of a three-dimensional predictive transpiration modeling approach in five tree species grown in a containerized pot-in-pot production system. For comparison we measured tree growth (crown leaf area and stem caliper), volume of water applied and irrigation application efficiency (Ae) for each method. The predictive method (i.e., a linked photosynthesis-stomatal conductance (An-gs) scheme) applied 18–56% more water than the sensing-based method in four species and 6% less in the fifth. Mean Ae was 80.1 and 89.5% for predictive and sensing-based treatments, respectively. Across species, predictive scheduling yielded 19–53% greater leaf area and 3.4–11% more caliper growth than sensing-based scheduling. Our second objective was to determine if the accuracy of the An-gs scheme could be retained while using generalized multi-species means for key physiological input parameters instead of species-specific values. We found the accuracy of transpiration estimates to largely depend upon two parameters—g0: the minimum gs, and g1: the marginal water cost per unit of carbon gain. When just these two parameters were characterized on a species-specific basis, transpiration estimates were within 10% error >65% of the time and within 20% error >95% of the time. We conclude that the predictive transpiration modeling approach to scheduling irrigation was a superior method for producing greater tree growth but at the cost of greater water use and slightly lower Ae. Furthermore, species-specific parameterization of g0 and g1 in the An-gs scheme are critical to accurate species-specific transpiration estimates, whereas most other physiology parameters may be generalized—circumventing the need for comprehensive An-gs parameterization.

Irrigation scheduling and winter wheat grain yield estimation under precipitation uncertainty – A case study in Badjgah area (Fars Province, Iran)

Addressing deficit irrigation scheduling (DIS) for strategic crop production (especially wheat) under precipitation uncertainty is a priority for irrigation scheduling in drought conditions. This research investigated the precipitation uncertainty by enacting optimistic and pessimistic scenarios for the next 20 years by considering the statistical record of climate in Badjgah area. DIS was conducted in spring in two ways: (1) reducing the quantity of irrigation water at each irrigation event; (2) reducing the number of full irrigation events. Results indicated that, owing to the effect of precipitation increase on yield enhancement, grain yield in the optimistic scenario was on average 7% higher than those obtained in the pessimistic scenario. Furthermore, grain yields obtained via the second method of DIS was on average 8% higher than those obtained by the first method of DIS and further by increasing the water reduction fraction (WRF) to 0.6, this difference reached about 20% due to the effect of early spring irrigation events on yield enhancement. At low irrigation application efficiency (Ea), the difference between DIS methods was greater at higher WRF. Net income obtained through the second method of DIS was on average 70% higher than those obtained via the first method of irrigation for all conditions due to decreasing the number of irrigation events and thus decreasing the production costs. Eventually, results indicated that in both scenarios of the precipitation uncertainty in drought conditions, the second method of DIS, i. e., application of available water based on growth stage, was more fruitful.

The Effect of Heterogeneity Due to Inappropriate Tillage on Water Advance and Recession in Furrow Irrigation

In surface irrigation, uniformity of longitudinal slope and depth of tillage are very important factors in advance duration time. Inappropriate tillage and land preparation can cause uneven surfaces and non-uniform slopes in fields which is especially important in furrow irrigation due to their influence on advance times. The purpose of this study is to evaluate the effect of non-uniform longitudinal slope due to inappropriate tillage on advance and recession phases in furrow irrigation system, which plays an important role in irrigation uniformity and application efficiency. For this purpose 12 furrows, each 42 m long were made with different longitudinal slopes and a width of 0.6 meter. The number of irrigation was 5 with irrigation interval of 4 days and input discharge of 0.8 lps. Results showed that advance times are very different in furrows especially in the first irrigation and varied from 19min up to 50min. The values for recession time were 9 to 29 min. The results of these five irrigation events indicate that non-uniform slope has significant effect on advance and recession time. Therefore with attention to the water crisis and the need to increase efficiency and uniformity of water distribution in surface irrigation, using modern machinery and paying more attention to accurate preparation of land are necessary in order to obtain uniform furrows in fields.

Consideration of Water Productivity for Farm Water Management in Different Conditions of Water Availability for Dominant Summer Crops

ABSTRACT- Efficient use of irrigation water for summer crops should be considered seriously due to rare occurrence of precipitation in summer. This research was focused on the assessment of water use efficiency for dominant crops of summer cropping pattern in the study area (i.e., maize and rice) via considering water productivity (WP) with different water management scenarios at farm level at different climatic conditions. Results indicated that in most cases the maximum WP was not occurred at full irrigation scenario. With increasing irrigation application efficiency (Ea), WP increased and the maximum WP shifted toward higher water reduction fraction (WRF). For maize, in deficit irrigation scheduling (DIS) methods with full irrigation at flowering stage, more deficit irrigation application was economically acceptable. For rice, with increasing Ea and WRF, WP increased and deficit irrigation at different growth stages was economically acceptable. Considering the real cost of water, economic water productivity ratio (EWPR) decreased greatly and in surface irrigation system, Ea should be increased and high WRF should be avoided (WRF should be lower than 0.4). In solid-set sprinkler system, EWPR increased with increasing Ea and application of WRF higher than 0.2 (0.2-0.6 for maize) was acceptable. Tape irrigation of maize was acceptable only for WRF less than 0.2; also, 0.2-0.4 was acceptable for WRF by decreasing the Ea.

Developing and normalizing average corn crop water production functions across years and locations using a system model

Crop water production functions (CWPFs) are often expressed as crop yield vs. consumptive water use or irrigation water applied. CWPFs are helpful for optimizing management of limited water resources, but are site-specific and vary from year to year, especially when yield is expressed as a function of irrigation water applied. Designing limited irrigation practices requires deriving CWPFs from long-term field data to account for variation in precipitation and other climatic variables at a location. However, long-term field experimental data are seldom available. We developed location-specific (soil and climate) long-term averaged CWPFs for corn (Zea mays L.) using the Root Zone Water Quality Model (RZWQM2) and 20 years (1992–2011) of historical weather data from three counties of Colorado. Mean CWPFs as functions of crop evapotranspiration (ET), ET due to irrigation (ETa–d), irrigation (I), and plant water supply (PWS=effective rainfall+plant available water in the soil profile at planting+applied irrigation) were developed for three soil types at each location. Normalization of the developed CWPF across soils and climates was also developed. A Cobb–Douglas type response function was used to explain the mean yield responses to applied irrigations and extend the CWPFs for drip, sprinkler and surface irrigation methods, respectively, assuming irrigation application efficiencies of 95, 85 and 55%, respectively. The CWPFs developed for corn, and other crops, are being used in an optimizer program for decision support in limited irrigation water management in Colorado.

Linking groundwater use and stress to specific crops using the groundwater footprint in the Central Valley and High Plains aquifer systems, U.S.

AbstractA number of aquifers worldwide are being depleted, mainly by agricultural activities, yet groundwater stress has not been explicitly linked to specific agricultural crops. Using the newly developed concept of the groundwater footprint (the area required to sustain groundwater use and groundwater‐dependent ecosystem services), we develop a methodology to derive crop‐specific groundwater footprints. We illustrate this method by calculating high‐resolution groundwater footprint estimates of crops in two heavily used aquifer systems: the Central Valley and High Plains, U.S. In both aquifer systems, hay and haylage, corn, and cotton have the largest groundwater footprints, which highlights that most of the groundwater stress is induced by crops meant for cattle feed. Our results are coherent with other studies in the High Plains but suggest lower groundwater stress in the Central Valley, likely due to artificial recharge from surface water diversions which were not taken into account in previous estimates. Uncertainties of recharge and irrigation application efficiency contribute the most to the total relative uncertainty of the groundwater footprint to aquifer area ratios. Our results and methodology will be useful for hydrologists, water resource managers, and policy makers concerned with which crops are causing the well‐documented groundwater stress in semiarid to arid agricultural regions around the world.

Effects of bentonite on water infiltration in a loamy sand soil

Water loss as deep percolation is considerable in furrow irrigation in light soils due to the high infiltration rate. Application of soil conditioners such as bentonite reduces the infiltration rate and improves irrigation application efficiency (Ea) in these soils. The effects of bentonite application rates (BAR) of 0, 2, 4 and 6 g L−1 on infiltration of a loamy sand soil were determined in a soil column in the laboratory. The exponent of the Kostiakov infiltration equation was not influenced by BAR. Maximum reduction in infiltration equation coefficient and final infiltration rate (i f) occurred with 2 g bentonite L−1 and this reduction was lower on increasing BAR from 2 to 4 and 4 to 6 g L−1 compared with control. The effect of 2 g L−1 BAR on infiltration and its effect on the design of furrow irrigation in a field with a loamy sand soil indicated that in the first irrigation after field ploughing and seed planting, longer furrow length, lower deep percolation and higher Ea are obtained.

Farm economic impacts of water supply deficits for two irrigation expansion scenarios in Alberta

A study was conducted to assess the farm financial impact and risk of two irrigation expansion scenarios based on the potential for water supply deficits in the irrigation districts of southern Alberta. The Irrigation Demand Model (IDM) was used to determine irrigation water demand based on annual crop water requirements, crop mix, irrigation system types and application efficiencies, irrigation district infrastructure, and the level of irrigation management within each irrigation block defined in the Water Resources Management Model (WRMM). Irrigation water supply values each year were then established for each irrigation block using the WRMM. The Farm Financial Impact and Risk Model (FFIRM), a farm financial simulation model that tracks farm finances (assets and liabilities) with time, subject to variability in crop water demand and crop prices, was used to determine the optimum allocation of water among fields within each farm operation during years of water supply deficits. Three scenarios were examined with the FFIRM – a baseline scenario and two irrigation expansion scenarios. Irrigation expansion was found to have negligible or very small adverse impacts on the financial well-being of typical farms in all six irrigation regions. Representative farms experienced essentially no change in net farm income (NFI) in the recent expansion (EXP1) scenario, and very small reductions in NFI in the future expansion (EXP2) scenario. Water conserved through irrigation efficiency gains in the next decade will likely offset the increased risk of negative impacts on NFI with irrigation expansion to the current limit.