Center Pivot Research Articles

PSIV-21 Comparing the Nutritional Value and the Trade-Off Between Sugars and Starch of Male-Sterile with Non-Sterile Sorghum Hybrids

Abstract The objective of this study was to assess the effect male-sterile versus non-sterile sorghum hybrids on nutritional value with emphasis on carbohydrates. The experiment was conducted on a dairy farm in West Texas under center pivot irrigation. Two male-sterile (Non-BMR, F465; and BMR12, F430) and three non-sterile sorghum hybrids (non-BMR F10; BMR12, F382, and F431; Richardson Seeds) were used in a split-plot design to reduce cross-pollination. Because of westerly prevailing winds, male-sterile hybrids were allocated to the west and non-sterile hybrids to the east, plots were blocked by irrigation section, and replicated 3 times. Plots were harvested 148 days after seeding with non-sterile hybrids after the hard dough stage and male-sterile hybrids 7 weeks after boot stage and harvested with a self-propelled forage harvester with a theoretical length of cut of 12 mm and roll gap setting at 2 mm. Duplicate samples of freshly chopped forage were obtained from each plot and immediately placed into a cooler with ice until harvest was completed. Samples were then frozen until shipped to Rock River laboratory where near-infrared spectroscopy analysis was performed. In addition, water soluble carbohydrates (WSC) and NDFD at 30h were analyzed with wet chemistry methods. The statistical analysis was performed using mixed linear regression models (GLIMMIX procedure of SAS). Type (Sterile and non-Sterile), trait (BMR12 and non-BMR) and its interaction were included as predictor variables in all models. Normal distribution of residuals was assessed using Shapiro-Wilk test (P > 0.05) and visual diagnostic of residual plots. A summary of the results is presented in Table 1. WSC was 2.5-fold greater for the sterile hybrids when compared with non-sterile, whereas starch was 2.2-fold greater for non-sterile when compared with sterile hybrids (P < 0.0001). Non-fiber carbohydrates were greater for non-sterile over sterile sorghum hybrids (P < 0.0001); however, non-sterile hybrids were past the optimal stage of harvest (soft dough), which would result in poor digestibility of grain starch and protein. In addition, crude protein (CP) was less for sterile than non-sterile (8.29% and 10.2% respectively; P < 0.0001). Compared with non-sterile hybrids, male sterile hybrids DM was decreased (28.4% and 40.8%, respectively; P < 0.0001) due to its proportionally greater vegetative plant parts compared with reproductive plant parts. The trade-off between WSC and starch in male-sterile sorghum hybrids is because sugars are not translocated to the grain where starch is developed as in non-sterile hybrids. This research indicates that concerns about low sorghum starch digestibility can be overcome by using male-sterile sorghum hybrids that will, at least partially, compensate for the reduced starch yield by increasing water-soluble carbohydrates storage.

Static Mechanics and Dynamic Analysis and Control of Bridge Structures Under Multi-Load Coupling Effects

With the rapid development and wide application of large-span bridges, the problem of dynamics and safety control of bridge structures under multiple loads is becoming more and more prominent. To realize the dynamic analysis and mechanical control of the girder structure, this paper designs a new type of magnetorheological (MR) mechanical damper based on the mechanistic analytical method and establishes a coupled dynamics model of the vehicle-rail-MR mechanical damper. The simulation and validation results show that the error between the semi-analytical method and the finite element theory calculation results is only 1.0%, while the kinetic simulation is consistent with the measured frequency domain trend. The analytical results show that: After applying MR mechanical damper for mechanical control, the moment live load and shear values of side spans were reduced by 27.68% and 10.79%, respectively; and the maximum moment and shear values generated at the center pivot were reduced by 28.19% and 10.81%, respectively. After applying the mechanical damper, the stress distribution of the cable-stayed bridge is more balanced, and the maximum diagonal stress of the overall structure is reduced from 3.8 MPa to 2.9 MPa. After safety control, the root-mean-square (RMS) value of the mid-span displacement amplitude was reduced by 59.32% and the maximum value was reduced by 11.46%, which improved the stability of the girder dynamics. After mechanical control, the dynamic acceleration response of the beam within the span decreased between 2 and 8 seconds and increased between 8 and 10 seconds. The overall response fluctuated around −5 m/s2 with a relatively smooth trend.

Reconstruction of the Posterior Cruciate Ligament and Medial Collateral Ligament With a Single Combined Femoral Tunnel

Background: Lesions of the medial collateral ligament (MCL) are the most common knee ligament injuries and, when they occur in isolation, they often progress with satisfactory outcomes using conservative treatment. However, MCL lesions associated with anterior cruciate ligament or posterior cruciate ligament (PCL) injuries in knee dislocations should be reconstructed to prevent failure of the central pivot. In knees with combined injuries involving the PCL and the MCL, the confluence of tunnels in the medial femoral condyle can be a potential problem during reconstruction surgery. Indications: The indication of this technique is the combined injury of the PCL and the MCL. Technique Description: The technique consists in the reconstruction of the PCL and the MCL with an Achilles tendon allograft. The bone plug of the graft is fixed on the tibial bed with the inlay technique. The graft passes through a single femoral tunnel drilled in the medial femoral condyle, with entrance point on the footprint of the PCL on the inner wall of the condyle and exit on the origin of the native MCL, near to the medial epicondyle. The graft is fixed in the femoral tunnel with an interference screw and continues to the isometric point of the anatomic insertion of the MCL in the tibia, where an interference screw is used to fix it. Results: Results from our group using this technique have shown good clinical outcomes, with complications and failure rates similar to other series in the literature. Discussion/Conclusion: This technique is an excellent option for surgeons, when an Achilles tendon allograft is available, to avoid confluence of tunnels in the medial femoral condyle. It presents good results and acceptable complication rates, compatible with the severity of this lesion. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.

Use of Geoprocessing in Identification of Areas Suitable for the Implementation of Center Pivot Irrigation in the District of Mossurrize, in Republic of Mozambique

With population growth, there is an increase in the demand for food, making irrigation an important technology for this purpose. Therefore, planning, and technical knowledge of environmental variables are essential for the implementation of irrigation, facilitated by geoprocessing techniques, which can help in decision-making, mainly due to the ability and ease of working large areas. The objective of this study is to analyze areas with potential for the implementation of a center pivot irrigation system in the district of Mossurrize. The analysis was carried out using geoprocessing tools through QGIS 2.3.20.0 and ArcGIS software. The methodology considers the combined analysis of different information plans to generate a synthesis map. The information plan variables were reclassified with weights from 1 to 9, demonstrating the influence of each element on the considered phenomenon. Then the variable maps were submitted to weighted analysis. The tools for spatial analysis through geoprocessing proved to be efficient in the manipulation and integration of the data used to identify and quantify the areas suitable for the implantation of a center pivot irrigation system and may be a viable alternative for decision making.

Semiautomatic Mapping of Center Pivot Irrigated Areas Using Sentinel-2 Images and GEOBIA Approach

Image analysis and feature extraction of remoted sensing data are significant for mapping irrigated agriculture areas as a source of information to improve water management and agricultural planning. This paper presents an image segmented base approach GEOBIA (Geographic Object-Based Image Analysis) to extract irrigated areas by Center Pivot Irrigation System (CPIS). This study suggests a semi-automated recognition of circular patterns for the mapping of irrigated regions by center pivots, using Sentinel -2 MSI images, 10 meters spatial resolution. A set of images from different seasons, humid and dry are used to maximize de CPIS’s occurrence. A multiresolution segmentation method was applied, and a large number of segment-based shape features was extracted and used as input to a feature selection procedure (shape descriptors: Area; Compactness; Circularity Factor; Length/Width; Radius of smallest enclosing ellipse; and Roundness). In addition, another shape descriptor “Circularity Factor” was developed in this research and played an important role during preliminaries classification processes. The accuracy assessment of preliminaries classifications has validated used the Circularity Factor together with the other chosen shape descriptors to reach better results to CPIS’s detection. Furthermore, 86.23% of the CPIS mapped in the classification process is in accordance with the ground truth map. This methodology can be used to map large areas in a relatively short time and provides a tool for monitoring irrigated areas.

TRANSFORMAÇÕES DAS PAISAGENS E DO TERRITÓRIO DA CHAPADA DIAMANTINA PELA INSERÇÃO DO PIVÔ CENTRAL COMO IRRIGAÇÃO

Objective: This research analyzes the changes in landscapes and territory in Chapada Diamantina, with emphasis on the municipalities of Ibicoara-BA and Mucugê-BA, caused by the implementation of central pivot irrigation systems and the appropriation of these spaces by agribusiness. Theoretical framework: This study was conducted based on theoretical reflections on environmental issues, the relationship between society and nature and theories on space and territory. Water use issues, granting policies and the procedures that bodies in the environmental sector used to monitor access to water and its multiple uses. Method: It is based on the use of data collection with thematic mapping, use of satellite images and theoretical discussion. The data were obtained from the Brazilian Institute of Geography and Statistics (IBGE), the National Water Agency (ANA), the Brazilian Agricultural Company - Embrapa and the Institute of the Environment and Water Resources (INEMA). Results and conclusion: The results demonstrate strong growth in agribusiness in Chapada Diamantina and a high impact on environmental resources, especially due to the removal of vegetation cover from the surfaces of Gerais and an increase in demand for water. Implications of the research: The environmental and territorial approach of the research questions the development model implemented in the region, pointing out intra-regional inequalities, and the environmental problems arising from the massive land and water in the area with high environmental fragility. Originality/value: This research has social, economic, scientific and environmental value with the data analyzed and the originality of the discussions presented.

Determination of effective irrigation intervals in the center pivot sprinkler system for maize (Zea mays L.) varieties

The increasing importance of the corn plant in animal nutrition as silage and grain feed has led to expand of corn cultivation in large areas. One of the best ways to meet the demand for irrigation of corn in large areas in Iraq is to establish a center pivot sprinkler system. This experimental study was carried out to determine the effective irrigation intervals in the center pivot sprinkler system in the cultivation of some corn varieties registered in Iraq in Kirkuk Governorate / Iraq in 2021. Another aim of this study is to identify the variety or varieties that have higher yields under different irrigation interval conditions. Another aim of this study was to determine the variety or varieties with higher yield under different irrigation interval conditions. The experiment was conducted in a randomized block design with three replications. Five registered maize varieties (AlFajer, AlMaha, AlSafa, Buhooth-106 and Sara) were used as experiment materials and three irrigation intervals (2, 4 and 6 day periods) were applied using the pivot sprinkler method. According to the result of this experiment, Buhooth-106 variety had the highest yield (7.23 kg ha⁻ˡ). Although the 6-day irrigation interval resulted in the lowest grain yield for all varieties, the difference in terms of corn grain yield between 4-day and 2-day irrigation interval was not found significant, statistically. In conclusion, the 4-day irrigation interval application using the center pivot irrigation system and Buhooth-106 variety can be recommended growing corn in conditions of Kirkuk Governorate of Iraq.

Closure to “An Explicit Equation for the Maximum Water Application Depth in Center Pivot Irrigation”

Closure to “An Explicit Equation for the Maximum Water Application Depth in Center Pivot Irrigation”

Discussion of “An Explicit Equation for the Maximum Water Application Depth in Center Pivot Irrigation”

Discussion of “An Explicit Equation for the Maximum Water Application Depth in Center Pivot Irrigation”

Water-energy-food linkages in community smallholder irrigation schemes: Center pivot irrigation in Rwanda

Water, energy, and food are linked in intricate ways in irrigated agriculture and understanding the interplay of these components is crucial for sustainable and profitable crop production, particularly in smallholder setting such as in sub-Saharan Africa. This study evaluates water-energy-food linkages, engineering and economic performance, irrigation decision making, and challenges faced around water management in a community-based mechanized irrigation scheme in Rwanda. The research is the first to analyze such as scheme, which uses technology typically used by large farmers in a smallholder setting. The study investigates the variation in water requirements and the relationship and impacts of this variability on crop yield for the crops grown in the scheme: maize, French beans, and dry beans. Observed irrigation decision-making analyses demonstrate a lack of irrigation planning during growth stages and significant field-to-field variation in irrigation; this is linked to yield reduction in major crops. Results suggest that farmers irrigated only 31% of modeled irrigation water in dry beans and 27% of modeled irrigation water in maize. An econometric model assessment is used to understand the relationship between yield and energy inputs. A related policy analysis considers the impacts of changes in crop and water management on field-level profits and system-level financial sustainability. This study has implications for understanding irrigation policies in the context of the water-energy-food nexus and decision-making in Sub-Saharan Africa.

Field evaluation of a commercial variable-rate irrigation decision support system – a study for maize and sweet corn

ABSTRACT The agricultural sector is facing a pressing need to adopt variable-rate irrigation decision support systems (VRI–DSS) to address global challenges such as water quality, water scarcity, food security, and climate change. This study evaluated a model-based VRI–DSS for maize and sweetcorn crops in a commercial field with two soil zones and a VRI center pivot. The evaluation involved assessing the farmer’s use of the system and comparing the VRI–DSS outputs using default parameters (e.g. virtual climate data) with outputs using local data. The results showed good agreement between the virtual and local climate data (R2 = 0.94, RMSE = 0.51 °C for air temperature; R2 = 0.79, RMSE = 0.53 mm/day for evapotranspiration), except for rainfall, which was overestimated by 12% by the VRI–DSS. The soil water deficit estimates from the local data also matched well with the neutron probe measurements. The farmer applied less irrigation due to water restrictions, but water use efficiency varied between soil zones for sweetcorn. The evaluation showed that VRI–DSS, with accurate climate data, is a useful tool for estimating variable-irrigation requirements for maize and sweetcorn under one system. However, more field data and local rainfall data are required to validate the decision software system.

Maize nitrogen uptake, grain nitrogen concentration and root-zone residual nitrate nitrogen response under center pivot, subsurface drip and surface (furrow) irrigation

Maize nitrogen uptake, grain nitrogen concentration and root-zone residual nitrate nitrogen response under center pivot, subsurface drip and surface (furrow) irrigation

Maize nitrogen uptake and use efficiency, partial factor productivity of nitrogen, and yield response to different nitrogen and water applications under three irrigation methods

AbstractThe effects of irrigation and nitrogen (N) on grain yield, actual crop evapotranspiration (ETa), N uptake efficiency (NUE), partial factor productivity of N (PFPN), and N utilization efficiency (NUtE) of maize (Zea mays L.) under centre pivot (CP), subsurface drip (SDI) and gravity (furrow) irrigation (FI) were quantified. Field experiments were conducted in two growing seasons under the full irrigation treatment (FIT), limited irrigation treatments of 80% FIT and 60% FIT and rainfed treatment (RFT). The highest NUE was observed under limited irrigation in the order of 80% FIT > FIT ≥ 60% FIT in non‐traditional treatment‐1 (NT‐1) in both the CP and SDI methods. NUtE increased with irrigation amount. There were strong correlations between NUtE and grain yield regardless of irrigation method. ETa increased with N amount, and the slopes of these relationships varied substantially between irrigation and N levels and irrigation methods. PFPN increased with irrigation amount across the irrigation methods and N treatments. A higher PFPN was observed in the lowest total applied N plots and in‐season split N application treatments. The pooled data for the CP and SDI methods showed significantly higher PFPN (20.3%) than the FI method, whereas the PFPN values in the CP and SDI methods were equal.

Mapping center pivot irrigation systems in global arid regions using instance segmentation and analyzing their spatial relationship with freshwater resources

Ensuring freshwater availability and supply sufficient for socio-economic development is important for human health and productivity. Globally, increasing industrial agriculture is driving crop productivity, with increasing surface water and groundwater being withdrawn for irrigation. This study mapped center pivot irrigation systems (CPIS), which are indicators of intensified industrial agriculture and large-scale investment in agriculture, with satellite data using a convolutional neural network in global arid areas. A cascade instance segmentation network was adopted, and both the convolutional block attention module technique and PointRend technique were used to increase the performance of off-the-shelf algorithms. Geospatial analysis methods were used to derive the relationships between CPIS and freshwater resources. Overall there were about 10.26 million hectares (Mha) of irrigated areas equipped with CPIS in global arid areas in 2021, and there were 4.41 Mha of CPIS-equipped irrigated fields added in the past twenty years at a relative increase of 75% compared with those at the beginning of this century. Although the largest extent of increased CPIS-equipped irrigated fields was in North America, the other five continents had higher relative increases, with Africa having the highest relative growth of 253%. The analysis of spatial relationships between CPIS and freshwater resources indicates that the stress on freshwater resources from industrial agriculture is intensifying in arid areas globally. Overall, the world's arid regions with the highest water stress from CPIS are mostly located in western North America, northern Africa, and the Arabian Peninsula. The results facilitate a better understanding of the current status of freshwater stress and ecosystem sustainability in relation to the development of agricultural intensification in global arid areas. The outcomes support governments to judge better the environmental consequences of agricultural modernization and further help them make balanced agriculture and water management policies.

Response of Conilon coffee cultivars in the central cerrado in irrigated management pivot sprinkler

Coffee cultivation has been growing significantly, since the world demand has increased considerably in recent decades. Among the coffees, conilon coffee has been a good option for cultivation in the Cerrado, as it presents good production in areas of high altitudes, however the study of canefora coffee in irrigated system in the Cerrado is something recent. The work aimed to analyze the productive potential of superior clones of caneflower coffee cultivars through agronomic performance under irrigated conditions in the Central Cerrado and to select the outstanding clones for future use in genetic improvement programs. The experiment was conducted in the experimental area of Embrapa Cerrados in Planaltina - DF, in a randomized block design with three replications. The cultivars evaluated were Diamante ES 8112, ES 8122 - Jequitibá and Centenária ES 8132, each composed of 9 clones totaling 27 conilon coffee genotypes, with different maturation times. The clones were planted with 3.5 x 0.5 m spacing in a center pivot irrigation system. The characteristics evaluated from two harvests (2018 and 2020) were: average grain yield (PMG); percentage of grains retained in sieve 16 (sieve > 16); percentage of mocha grains (GMO); average plant height (AP), crown projection (PC) and number of productive nodes (NNP). Data were submitted to analysis of variance and means were grouped by the Scott-Knott test at 5% significance level. Based on the result of the analysis of variance, there was a significant difference in all maturation cycles for the traits PMG, sieve > 16, GMO, AP, PC and NNP. The averages of grain size percentage in sieve size 16 or larger were distinct in the 3 groups analyzed. It was found that the averages of production of processed grains (PMG) were different in the two years evaluated, due to the environmental conditions imposed from one year to another. Within the clones, clone 207 presented the highest grain yield value in 2020 with 12493 kg ha-1. There was genotypic variability in the behavior of clonal varieties and their respective clones, being able to select clones and use them within breeding programs, for targeted crosses and subsequent development of new cultivars.

Opinions on Irrigation Water Management Tools and Alternative Irrigation Sources by Farmers from the Delta Region of Mississippi

AbstractWater withdrawals for irrigation at an unsustainable rate resulted in a decline in the groundwater levels in the Mississippi River Valley Alluvial Aquifer (MRVAA) in the central southern USA. This drawdown of groundwater threatens agricultural production in the Mississippi Delta, an important agricultural region in the state of Mississippi, USA. Effective and efficient use of available resources is important to sustain and enhance agricultural productivity in this area. This study assessed the opinions of farmers on water conservation management practices and technologies that improve irrigation management and save water in the Mississippi Delta region based on data collected in an irrigation survey conducted in 2012. Most landowners believed that water conservation practices were effective in reducing irrigation water use without reducing maximum crop yields and have a positive return on investment. Land forming, tailwater recovery system, on‐farm storage, instream weirs to pond surface water, computerized hole selection for furrow irrigation, short irrigation runs, and irrigation scheduling were considered efficient water conservation technologies by landowners. Perceptions about use of different practices also depend upon the crops produced by the respondents. About 20 to 24% and 14.9 to 86% of survey respondents thought that on‐farm storage and center pivot, respectively, were inefficient water conservation practices for irrigating crops in the Mississippi Delta. The adoption of these practices may be increased if the landowners know the economic returns of implementing them.

The Effect of Operating Pressures and Speed Ratios on The Evaluation Criteria of The Center Pivot Irrigation System (Valley) in Al Baghdadi Region

A study conducted during the 2021winter season in Al Baghdadi region (150) km west of Ramadi City (Iraq) to show the effect of operating pressure and equipment speed on evaluation criteria of the center Pivot Irrigation Systems. Three operating pressures were used in the experiment, which are 25, 30 and 35 pounds inch−2, with three speeds of 25%, 50% and 75% for each pressure. Study result showed that The pressure 30 pounds inch−2 achieved the highest values for the average of the studied traits, as it was 97.22% while the lowest value was recorded at a pressure 25 pounds inch−2 which amounted to 88.70% with a decrease Ratio 9.6%. The pressure 35 pounds inch−2achieved the lowest average water depth 24.13 mm, while the highest average depth of water was at pressure 30 pounds inch−2 35.89 mm with a height Ratio 32.7%. The lowest average value of the water depth variance (qvar.) was 8.34% at pressure 30 pounds inch−2 while the average of this value increased to 28.63% at pressure 35 pounds inch−2 with increase 70.8%. The ratio of the rotational speed of the arm of the system significantly affected the values of each of the studied traits, the velocity 25% achieved the highest average values 30.93 mm and 93.10%, while the speed 75% achieved the lowest rate 26.58 mm and 89.63% With a decrease 16.4% and 3.8% for each of the applied water depth and Uniformity coefficient, respectively. This speed 25% also achieved the lowest average water depth variance, which amounted to 16.02%, while speed75%achieved the highest value of water depth variance, which amounted to 26.59%, with an increase rate 39.7%.

Calculation of Evaporation Losses for Center Pivot Sprinkler Irrigation Systems Type (Lindsay) by Effect of Timer Percentage of Speed and the Increase of Sprayer Nozzles from Soil Surface

The experiment was conducted during summer season (July, August, September) 2019 in some field in Anbar governorate, Saqlawiya city, Gisaba area to calculate water losses by evaporation through water depths by calculating the discharges that come from nozzles and water depths to collect in side cans while calculating uniformity coefficient above soil surface. The results showed that the increase of spray nozzles in soil surface at 1.0m gave the lowest depths from evaporated water by changing the timer speed percent; where it was 0.18mm 100% speed, while increased to 3.39mm at 20% speed compared 0.66mm at 100% speed till 5.91mm at 20% speed when expanding the sprayer nozzles to 1.50m from soil surface. The 100% speed gave low percentage of losses (1.79%) and the high percentage was obtained at 20% speed (33.70%) at 1.0m height, which is better that height of 1.50m in rationalizing water in order to irrigate new areas that water was not enough for. this is due to variation in the height of spray nozzles above the ground, as well as variations in temperature and wind speed steadfastly speed up the system.

Toward automated irrigation management with integrated crop water stress index and spatial soil water balance

AbstractDecision support systems intended for precision irrigation aim at reducing irrigation applications while optimizing crop yield to achieve maximum crop water productivity (CWP). These systems incorporate on-site sensor data, remote sensing inputs, and advanced algorithms with spatial and temporal characteristics to compute precise crop water needs. The availability of variable rate irrigation (VRI) systems enables irrigation applications at a sub-field scale. The combination of an appropriate VRI system along with a precise decision support system would be ideal for improved CWP. The objective of this study was to compare and evaluate two decision support systems in terms of seasonal applied irrigation, crop yield, and CWP. This study implemented the Spatial EvapoTranspiration Modeling Interface (SETMI) model and the Irrigation Scheduling Supervisory Control and Data Acquisition (ISSCADA) system for management of a center pivot irrigation system in a 58-ha maize-soybean field during the 2020 and 2021 growing seasons. The irrigation scheduling methods included: ISSCADA plant feedback, ISSCADA hybrid, common practice, and SETMI. These methods were applied at irrigation levels of 0, 50, 100, and 150% of the full irrigation prescribed by the respective irrigation scheduling method. Data from infrared thermometers (IRTs), soil water sensors, weather stations, and satellites were used in the irrigation methods. Mean seasonal irrigation prescribed was different among the irrigation levels and methods for the 2 years. The ISSCADA plant feedback prescribed the least irrigation among the methods for majority of the cases. The common practice prescribed the largest seasonal irrigation depth among the methods for three crop-year cases. The maize yield in rainfed was found to be significantly lower than the irrigated levels in 2020 since 2020 was a dry year. No significant differences were observed in crop yield among the different irrigation methods for both years. The CWP among the different irrigation methods ranged between 2.72 and 3.15 kg m−3 for 2020 maize, 1.03 and 1.13 kg m−3 for 2020 soybean, 3.57 and 4.24 kg m−3 for 2021 maize, and 1.19 and 1.48 kg m−3 for 2021 soybean. Deficit level (50%) had the largest irrigation water productivity in all crop-year cases in this study. The ISSCADA and SETMI systems were found to reduce irrigation applications as compared to the common practice while maintaining crop yield. This study was the first to implement the newly developed integrated crop water stress index (iCWSI) thresholds and the ISSCADA system for site-specific irrigation of maize and soybean in Nebraska.

Measuring Evapotranspiration Suppression from the Wind Drift and Spray Water Losses for LESA and MESA Sprinklers in a Center Pivot Irrigation System

Wind drift and evaporation loss (WDEL) of mid-elevation spray application (MESA) and low-elevation spray application (LESA) sprinklers on a center pivot and linear-move irrigation machines are measured and reported to be about 20% and 3%, respectively. It is important to estimate the fraction of WDEL that cools and humidifies the microclimate causing evapotranspiration (ET) suppression, mitigating the measured irrigation system losses. An experiment was conducted in 2018 and 2019 in a commercial spearmint field near Toppenish, Washington. The field was irrigated with an 8-span center pivot equipped with MESA but had three spans that were converted to LESA. All-in-one weather sensors (ATMOS-41) were installed just above the crop canopy in the middle of each MESA and LESA span and nearby but outside of the pivot field (control) to record meteorological parameters on 1 min intervals. The ASCE Penman–Monteith (ASCE-PM) standardized reference equations were used to calculate grass reference evapotranspiration (ETo) from this data on a one-minute basis. A comparison was made for the three phases of before, during, and after the irrigation system passed the in-field ATMOS-41 sensors. In addition, a small unmanned aerial system (UAS) was used to capture 5-band multispectral (ground sampling distance [GSD]: 7 cm/pixel) and thermal infrared images (GSD: 13 cm/pixel) while the center pivot irrigation system was irrigating the field. This imagery data was used to estimate crop evapotranspiration (ETc) using a UAS-METRIC energy balance model. The UAS-METRIC model showed that the estimated ETc under MESA was suppressed by 0.16 mm/day compared to the LESA. Calculating the ETo by the ASCE-PM method showed that the instantaneous ETo rate under the MESA was suppressed between 8% and 18% compared to the LESA. However, as the time of the ET suppression was short, the total amount of the estimated suppressed ET of the MESA was less than 0.5% of the total applied water. Overall, the total reduction in the ET due to the microclimate modifications from wind drift and evaporation losses were small compared to the reported 17% average differences in the irrigation application efficiency between the MESA and the LESA. Therefore, the irrigation application efficiency differences between these two technologies were very large even if the ET suppression by wind drift and evaporation losses was accounted for.