Pivot Irrigation Research Articles

Water distribution characteristics of deflector plates used in center pivot irrigation systems

Water distribution characteristics of deflector plates used in center pivot irrigation systems

Animal performance over 16 years after implementing a lucerne grazing system on Bog Roy Station - a case study

In 2023, the animal performance data for Bog Roy station show 151 t weaned lamb is being produced from 4272 ewes plus 9.0 t from hogget lambs. The ability to mate merino hoggets has resulted from increased feed supply that means mixed age ewes are now consistently averaging 65.6±1.17 kg/hd at mating (2019-2023). This has enabled an emphasis on two-tooth weight at mating, which has also increased 0.74±0.14 kg/hd/yr (R2 = 0.64) from 52 kg/hd in 2012 to 61 kg/hd in 2023. Consequently, scanning is consistently ~167±1.59% for the mixed age ewes (2012-2023) and increased from 113% (2008) to 154% (2023) in the two-tooths. Lamb wastage for the mixed age ewes has decreased 0.70±0.08%/yr (R2 = 0.88) to 15% in 2023 and, although more variable (R2 = 0.13), the wastage in two-tooths has also reduced from 32% (2014) to 21% (2023). Lamb wastage is negatively related to two-tooth weight at set-stocking, so feeding young stock is a priority. Since 2016, pre-weaning merino lamb growth rates have averaged 286±4.39 g/hd/d with weaning now at 79.3±2.56 days. This consistency coincided with the addition of 210 ha of feed under pivot irrigation that was initially sown in red and white clover and is now in lucerne/grass mixes. The additional feed has meant wool production has remained constant throughout the 15 years of pasture development. Cow numbers have been used to buffer the changes in pasture supply as the dryland and pivot development occurred. These have now increased to their highest level since the development began. The major change in farm income has resulted from the earlier sale of more lambs at a higher average price because they are heavier due to the extra feed. This unique long-term dataset of on-farm performance provides a commercial example of transformational change that has resulted from changes in the farm system, driven by direct feeding of dryland lucerne and irrigation development focused on growing young stock in this 420 mm rainfall environment.

Effect of center-pivot and subsurface drip irrigation systems on growth and evapotranspiration of volunteer corn in corn, soybean, and sorghum

Abstract Volunteer corn (Zea mays L.) is a competitive weed in corn-based cropping systems. Scientific literature does not exist about the water use of volunteer corn grown in different crops and irrigation systems. The objectives of this study were to characterize the growth and evapotranspiration (ETa) of volunteer corn in corn, soybean [Glycine max (L). Merr.], and sorghum [Sorghum bicolor (L.) Moench] under center-pivot irrigation (CPI) and subsurface drip irrigation (SDI) systems. Field experiments were conducted in south-central Nebraska in 2021 and 2022. Soil moisture sensors were installed at depths of 0 to 0.30, 0.30 to 0.60, and 0.60 to 0.90 m to track soil water balance and quantify seasonal total ETa. Corn was the most competitive, as volunteer corn had the lowest biomass, leaf area, and plant height compared with the fallow. Soybean was the least competitive with volunteer corn, as the plant height, biomass, and leaf area of volunteer corn in soybean were similar to fallow at 15, 30, 45, and 60 d after transplanting (DATr). Averaged across crop treatments, irrigation type did not affect volunteer corn growth at 15 to 45 DATr. Soil water depletion and ETa were similar across crop treatments with and without volunteer corn, as water was not a limiting factor in this study. The ETa of volunteer corn was the highest in soybean (623 mm), followed by sorghum (622 mm), and corn (617 mm) under CPI. The SDI had higher irrigation efficiency, because without affecting crop yield, it had 3%, 6%, and 8% lower ETa in soybean (605 mm), sorghum (585 mm), and corn (571 mm), respectively. Although soil water use did not differ with volunteer corn infestation, a soybean yield loss of 27% was observed, which suggests that volunteer corn may not compete for moisture under fully irrigated conditions; however, it can impact the crop yield potential due to competition for factors other than soil moisture.

Remote detection of water stress in cotton using a center pivot irrigation system-mounted sensor package.

Much research has been invested in infrared temperature (IRT)-based methods for cotton (Gossypium hirsutism L.) water stress detection using in-field sensors, but adoption of these is low, perhaps due to logistical challenges. Alternatively, the Water Deficit Index (WDI) was developed for crop water stress assessment using remote sensors not embedded in the canopy. The objective of this research was to evaluate the performance of a sensor package-including modern IRT and normalized difference vegetation index (NDVI) sensors facing downward at 45˚, and a mini weather station-attached unintrusively to a center pivot irrigation system for detecting cotton water stress using WDI. Sensor packages were evaluated in a two-year field study that included four irrigation treatments (0, 30, 60, and 90% ET replacement) and in two production cotton fields. Overall, the tested system was effective at distinguishing crop water stress among irrigation rates. Comparison of the results to a ground-based station and simulations indicated that WDI overestimated water stress at the highest irrigation rate, but performed well otherwise. Accuracy of the system could be improved by measuring canopy coverage (Fc) from the same vantage point as the IRT and NDVI sensors (from the pivot, downward at a 45˚ angle).

Detecting Defect in Central Pivot Irrigation System using YOLOv7 Algorithms

Central Pivot Irrigation System (CPIS) is a significant method for intelligent irrigation used in global agriculture. It is used to cultivate important crops like wheat, which contribute to global food security. However, the CPIS encounters technical issues that result in malfunctions in its automatic control system, leading to damage to the primary pipes and towers. This can result in significant material losses for farmers and their crops. Repairing the system is also a time-consuming process. To address this issue, a study was conducted using YOLO algorithm which contains several models, and this study used the Yolov7 models to detect defects in the CPIS machine accurately. The study used a dataset gathered from agricultural areas in Salah al-Din Governorate. The models were used to determine whether the CPIS was in a safe or dangerous state. The RGB color system with Yolov7x achieved a 95% detection rate with an accuracy, F1-score, and precision values of 0.798 and 0.954. Similarly, Yolov7x achieved a 93% detection rate with accuracy, F1-score, and precision values of 0.77 and 0.932 in the Grayscale color system. Based on the outcome, this study can conclude that the yolov7x model with RGB Color System accurately detects the CPIS in both its safe and dangerous states. This makes them useful in real-time systems for CPIS defect monitoring and control.

Spatio-Temporal Dynamics of Center Pivot Irrigation Systems in the Brazilian Tropical Savanna (1985–2020)

The 204-million-hectare Brazilian tropical savanna (Cerrado biome), located in the central part of Brazil, constitutes the main region of food and natural fiber production in the country. An important part of this production is based on center pivot irrigation. Existing studies evaluating the spatio-temporal dynamics of center pivots in Brazil do not consider their retraction. This study aimed to evaluate the expansion and retraction of center pivots in the Cerrado biome in the period 1985–2020. We relied on the data produced by the MapBiomas Irriga project. In this period, the area occupied by center pivots increased from 47 thousand hectares in 1985 to 1.2 million hectares in 2020, mostly concentrated in the states of Minas Gerais, Goiás, São Paulo, and Bahia, confirming previous reports available in the literature. Among the 13 irrigation poles recognized by the National Water Agency (ANA), the Oeste Baiano (Bahia State) and the São Marcos (Goiás State) presented the largest areas of center pivots (173,048 ha and 101,725 ha, respectively). We also found that 76% of the center pivots are concentrated in the regions with low water availability (0.01–0.45 mm day−1). Within this 16-year period (2005–2020), more than 10% of center pivots found in 2005 were either abandoned or converted into rain-fed crop production. The results of this study can provide an important foundation for public policies directed toward the sustainable use of water resources by different consumers.

Wheat Crop Management and growth stage monitoring in some gypsiferous soil units using remote sensing

The study used remote sensing to manage and monitor wheat crop health in some gypsiferous soil units. Five sites cultivated with wheat and irrigated by a central pivot irrigation system were selected within gypsiferous soil units in some agricultural lands. Soil and plant samples were collected at the best spectral and vegetative growth stage (grain filling stage) from each site. Three samples of the plant and soil were collected with three replicates, resulting in a total of (5 × 3 × 3 = 45 samples for both soil and plant). Samples were prepared for conducting laboratory analyses Satellite imagery of the OLI type from the Landsat 8 satellite, acquired on 24/2/2020, was used to calculate the following spectral indices: NDVI, SAVI, OSAVI, GOSAVI, GDVI, NDMI, CMFI, LAI. The results showed a variation in the concentration of fertile elements in the soil and plants between the study sites, with the third site relatively outperforming the other sites. On the other hand, we observed a variation in the values of spectral indices between the study sites for all the spectral indices and an increase in values with the progress and increase in the size of the canopy cover to reach the best spectral growth stage at the stage of ear fullness, which is the stage of spectral stability and appropriate for monitoring crop productivity and assessing plant health. The results also concluded that NDVI and LAI are among the most important pieces of evidence that have a strong relationship with plant density and estimation of its general condition, as the relationship was strong logarithmic and linear with nitrogen, as the values of R2 reached 0.91 and 0.88, respectively, and the value of the coefficient of determination R2 reached with The phosphorus concentration was 0.67 and 0.67, respectively. Also, the use of spectral indices depends on the spectral bands that fall at the wavelength of 0.6-0.7 micrometers, which is the region where a high absorption process occurs if the vegetation cover is intact and healthy, especially the NDVI index.

Review of Integrated Management of Cereal Cyst Nematode Heterodera avenae on Wheat Crop under Centre Pivot Irrigation System

Review of Integrated Management of Cereal Cyst Nematode Heterodera avenae on Wheat Crop under Centre Pivot Irrigation System

Water-energy-food-greenhouse gas nexus: An approach to solutions for water scarcity in agriculture of a semi-arid region

CONTEXTAgricultural systems involve intricate interdependencies among water, energy, and food. Increasing understanding of these linkages, along with implications for greenhouse gas (GHG) emissions and developing new assessment approaches are critical for achieving key sustainability goals. OBJECTIVES1) Evaluation of the impacts of tillage, irrigation and residue management practices on water and energy consumption, and GHG emission in the cultivation of irrigated wheat and rapeseed, 2) Developing a novel Water-Energy-Food-Greenhouse gas (WEFG) nexus index to provide a holistic assessment of the linkages among water, energy, food, and GHG emissions in agriculture, and 3) Assessing the sustainability of irrigated wheat and rapeseed cultivation under different methods of tillage, irrigation and residue management applying the WEFG nexus index. METHODSThis study formulated a new WEFG nexus index applying eight indicators of water and energy consumption, CO2-eq (CO2 equivalent) emission, water and energy mass productivity, water, energy and CO2-eq economic productivity to evaluate the sustainability of wheat and rapeseed cultivation under two field management practices: 1) furrow irrigation with conventional tillage (FICT), and 2) center pivot irrigation with no-tillage (CPNT), within a semi-arid region in northeastern Iran. Irrigation in both systems was done by applying a deficit irrigation approach. RESULTS AND CONCLUSIONSCPNT resulted on average in 46% and 53% energy consumption reductions from water and diesel usage, respectively, compared to FICT. The mean CO2-eq emission under CPNT was 26% lower than that recorded under FICT. Furthermore, the WEFG nexus index score for wheat and rapeseed under CPNT was 0.91 and 0.73, respectively, out of 1, compared to 0.18 and 0.12 for FICT. These scores suggest that the CPNT approach is a more appropriate strategy than FICT, as it effectively reduced water and energy consumption while aligning better with long-term environmental and economic aims. SIGNIFICANCEThe study applies more accurate GHG emission-based indicators to introduce a new WEFG nexus index, and it uses these for evaluation of different field management at the farm level to reduce the uncertainties in the large-scale studies. The proposed methodology for assessing multiple aspects of the WEFG nexus can change previous perceptions about agricultural management in other regions confronting multiple resources and environmental crises.

No increase of soil wind erosion with the establishment of center pivot irrigation system in Mu-Us sandy land

Center Pivot Irrigation system (CPIs) is widely used in newly exploited arable land in sandy lands. These sandy lands are currently stable because of climate change and ecological restoration efforts since the beginning of the 21st century in northern China. The exploitation of these fixed sandy lands to arable land with CPIs may affect the soil wind erosion, yet it remains unknown. The temporal changes of CPIs and its effect on wind erosion module were analyzed and modeled from 2000 to 2020 in Mu-Us sandy land using satellite images and Revised Wind Erosion Equation (RWEQ). The establishment of CPIs started from 2010, boomed in 2015 and peaked in 2020. They were mainly transformed from woodland, grassland, and barren land near rivers in east and southeast, and from cropland in inter-dunes in west and southwest of Mu-Us sandy land. The temporal and spatial pattern of CPIs well aligns with the land consolidation and requisition-compensation balance policies. In most of the Mu-Us sandy land, the annual erosion module is <25 t ha−1 a−1. Despite great variation, the annual, Winter and Spring erosion module of the Mu-Us sandy land or in Otog Qian and Yuyang, the CPIs concentrated counties, all decreased during 2000–2019. Although, wind erosion module in CPIs was lower than the surrounding area, it increased in 2019 given the same climate conditions as in 2010. Our results suggest 1) the establishment of CPIs in Mu-Us sandy land greatly depends on the local policy and natural endowment, and 2) although the set-up of CPIs showed no impact on the wind erosion with CPIs accounting for <1 % of Mu-Us sandy land, post-harvest of CPIs should be carefully concerned to prevent soil wind erosion.

An Assessment of Some Mechanical Properties of Harvested Potato Tubers cv. Spunta

Mechanical properties of vegetables or crop materials play a noteworthy part in designing new related implements. These properties can be extracted from force–deformation curves. Several factors, such as soil preparation, irrigation, and pre- and post-harvest treatments influence them. The core objective of this investigation work was to analyze force–deformation curves obtained from compression, penetration, and shear tests of potatoes (Spunta cv.) produced with three tillage implements. The potatoes cv. Spunta were cultivated in loamy sand soil under the center-pivot irrigation system. The tillage implements used were a disc harrow plow, chisel plow, and moldboard plow. The trials were performed at a constant planting depth (15 cm) below the soil and a single plowing speed of 5.4 km/h. All data were expressed as an average of five replicates ± standard deviation. The force–deformation curves analysis showed that the modulus of elasticity for potatoes cv. Spunta ranged from 4.32 to 5.8 N/mm, the bioyield force ranged from 84.25 to 114.12 N, and rupture forces ranged from 100.90 to 139.78 N. Furthermore, the results showed that the average values of the elastic and plastic ranges were 3.0 and 2.1 mm, respectively. The mean value of hardness was 1671.53 N·mm. No significant differences were observed with respect to the two planting seasons, but tillage implements had a significant impact on the characteristics extracted from the compression tests. The mean of the maximum forces required to penetrate the potato during the penetration stage were 41.24 N, 44.86 N, and 47.16 N for potatoes produced with the disc harrow plow, chisel plow, and moldboard plow, respectively. Similarly, the means of the maximum forces required to cut the potato in the shear stage were 724.38 N, 761 N, and 773.43 N for the disc harrow plow, chisel plow, and moldboard plow, respectively. The force–deformation curves showed that additional information might be required to obtain a complete description of the potato quality necessary to harvest potatoes cv. Spunta using harvesting and handling equipment with reduced economic loss. An extensive study of the soil characteristics and the above-mentioned properties is also recommended. The results obtained about the mechanical characteristics of potatoes cv. Spunta can be useful in providing information that aids in designing potato harvesting machines and in potato products factories.

Integrating hydrologic modeling and satellite remote sensing to assess the performance of sprinkler irrigation

ABSTRACT Improving irrigation water management is a key concern for the agricultural sector, and it requires extensive and comprehensive tools that provide a complete knowledge of crop water use and requirements. This study presents a novel methodology to explicitly estimate daily gross and net crop water requirements, actual crop water use, and irrigation efficiency of center pivot irrigation systems, by mainly utilizing the Sentinel-2 MultiSpectral Instrument (MSI) imagery at the farm scale. ETMonitor model is adapted to estimate actual water use (as the sum of canopy transpiration and evaporation of water intercepted by canopy and evaporation from soil) at daily/10-m resolution, benefiting from the high-resolution Sentinel-2 data and thus to assess the irrigation efficiency at the farm scale. The gross irrigation water requirement is estimated from the net crop water requirement and the water loss, including the water droplet evaporation directly into the air during application before droplets fall on the canopy and canopy interception loss. The method was applied to a pilot farmland with two major crops (wheat and potato) in the Inner Mongolia Autonomous Region of China, where modern equipment and appropriate irrigation methods are deployed for efficient water use. The estimated actual crop water use showed good agreement with the ground observations, e.g. the determination coefficients range from 0.67 to 0.81 and root mean square errors range from 0.56 mm/day to 1.24 mm/day for wheat and potato when comparing the estimated evapotranspiration with the measurement by the eddy covariance system. It also showed that the losses of total irrigated volume were 25.4% for wheat and 23.7% for potato, respectively, and found that the water allocation was insufficient to meet the water requirement in this irrigated area. This suggests that the amount of water applied was insufficient to meet the crop water requirement and the inherent water losses in the center pivot irrigation system, which imply the necessity to improve the irrigation practice to use the water more efficiently.

Assessment of climate change impacts on rainfall and streamflow in the Alto Paranapanema Basin, Brazil

ABSTRACT Climate change has the potential to fundamentally transform landscapes on global scale. Leveraging advanced predictive modeling to enhance water resource management within the Alto Paranapanema Basin (Brazil), holds the potential to proactively anticipate challenges and alleviate the impacts and conflicts arising from this phenomenon. This is particularly important in a region boasting over 1,600 centerpivot irrigation systems. This study employs the Soil Moisture Accounting Procedure, a physical model, to simulate long-term climate datasets and flows. Future climate scenarios, rooted in the Representative Concentration Pathways, are developed through the downscaling of Global Climate Models. The findings reveal a temporal shift in rainfall patterns, characterized by a reduction during the wet season of up to 40% compared to the average historical rainfall, and an increase throughout the dry season up to 40% compared to the same historical, estimated by the Eta -BESM model. These changes present challenges regarding to water availability, hydroelectric generation, and agricultural. By fostering collaboration among different governmental entities responsible for the managements of basins and harnessing the potential of predictive models, this research advocates for the adoption of proactive strategies in management of water resources. These strategies are imperative to effectively counteract the far-reaching effects of climate change.

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

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

Spatiotemporal Changes of Center Pivot Irrigation Farmland in the Mu Us Region and Its Impact on the Surrounding Vegetation Growth

Accurately understanding the distribution and changing trends of Center Pivot Irrigation (CPI) farmland in the Mu Us region and exploring the impact of CPI farmland construction on sandy land vegetation growth hold significant importance for local sustainable development. By using Landsat images to extract CPI farmland information and applying buffer zone analysis to explore the impact of CPI farmland construction on the surrounding vegetation growth, the results revealed the following key findings: (1) The number and area of CPI farmland units showed a continuous growth trend from 2008 to 2022. Spatially, Etoke Front Banner was the focal point of the CPI farmland unit construction, gradually expanding outward. In terms of scale, small-scale CPI farmland units (0–0.2 km2) dominated, while large-scale CPI farmland units (&gt;0.4 km2) were primarily distributed in Yulin City (Mu Us). (2) The growth rate of CPI farmland units in Yulin City gradually slowed down, while that in Ordos City (Mu Us) continued to exhibit a high growth trend. Affected by water-resource pressure and policies, CPI farmland units in Ordos City may continue to increase in the future, while they may stop growing or even show a downward trend in Yulin City. (3) CPI farmland mainly came from the conversion of cultivated land, but over time, more and more grassland was reclaimed as CPI farmland. The absence of cover planting after crop harvesting and the lack of shelterbelt construction may exacerbate land desertification in the region. (4) Within the typical region, CPI farmland unit construction promoted vegetation growth within the CPI units and the 500 m buffer zone but had an inhibitory effect on vegetation growth within the 500–3000 m buffer zone and no significant effect on vegetation growth within the 3000–5000 m buffer zone. (5) The decrease in groundwater reserves caused by CPI farmland unit construction was the primary reason for inhibiting the vegetation growth within the 500–3000 m buffer zone of CPI farmland units in the Mu Us region. This study can provide a scientific basis for the sustainable development of CPI farmland in semi-arid areas.

Mapping and Characterization of Center Pivot and Lateral Move Irrigation Systems in South Carolina Using Quantum Geographic Information System

In recent decades, the adoption of overhead irrigation systems, especially center pivots, to irrigate row crops has been steadily increasing in South Carolina. The adoption of irrigation in the state has been enhanced by the predominance of coarse-textured soils with low water-holding capacities, which increases the likelihood of obtaining a significant and profitable crop yield response to irrigation. As the number of overhead irrigation systems in the state increases, it is vital to understand their number, location, and characteristics for better planning and managing available water resources. The objective of this project was to map and characterize the overhead irrigation systems (center pivots and lateral moves) available in each county in South Carolina. The Quantum Geographic Information System (QGIS) was used to manually locate and measure each overhead irrigation system in the state using a 2022 Google satellite image. Basic measurements included the length, number of spans, and wetted radius. In addition, the rotation angle of center pivots and the field length of lateral move systems were measured. This study found that with a few exceptions, the overwhelming majority of the overhead irrigation systems in the state were located in the central part of the Coastal Plain region, between the Fall Line and the coast, where groundwater resources are more abundant. Also, this study found a total of 2,980 center pivots and 15 lateral move irrigation systems in South Carolina. A total of 64,694 hectares were irrigated by center pivots, while lateral moves irrigated only 80 hecatares. Out of the 46 counties in the state, those with the highest number of center pivots were Orangeburg (633 pivots), Calhoun (361), Lee (296), Clarendon (249), Sumter (248), Lexington (197), Bamberg (130), Darlington (121), Hampton (117), and Barnwell (114). All the lateral move systems were located in the counties of Barnwell (11) and Darlington (4). Water stakeholders and agencies in South Carolina could use this information for long-term water resources planning at various levels. This research is also useful nationally to inform the understanding of irrigation practices in the southeastern United States.

Agricultural practices for maize crop water production under pivot irrigation in Toshka, Egypt

Agricultural practices for maize crop water production under pivot irrigation in Toshka, Egypt

Sustainable Water Management for Small Farmers with Center-Pivot Irrigation: A Hydraulic and Structural Design Perspective

In Pakistan, surface water supply for irrigation is decreasing, while water demand is increasing for agriculture production. Also, due to the fast rate of population growth, land holding capacity is decreasing. So, there is a need to develop appropriate technologies and design approaches for small-scale farmers to improve modern irrigation practices. In this study, a hydraulic and structural layout of CPIS was designed for small-scale farmers with some modifications. The hydraulic parameters and structural design of the CPIS were designed using IrriExpress and SAP2000 software, respectively. An economic analysis of the modified CPIS was carried out. The results revealed that in one complete revolution of the whole system, its span slope varied from 2.98 to 0.1%, and the wheel slope varied from 2.35 to −2.4%. The timing setting was 60% for one revolution, and the irrigation depth was 10 mm. When the time setting was reduced from 100% to 10%, the irrigation hours per cycle and irrigation depth both increased. Variendeel type-II trusses were designed for structural purposes using SAP2000 software. This design led to a 17% reduction in weight by lowering it from 1.916 to 1.5905 tons and a 44% reduction in joint count, decreasing it from 32 to 18. Our economic analysis revealed that the structural part of the system is more expensive than the hydraulic, electric and power parts for small-scale design. So, it was suggested that CPIS is suitable for land holdings from 100 to 250 acres, because when the area increases to more than 250 acres, there is no significant change in the cost. A towable system is more economical for small-scale farmers due to its lower cost per acre. This study will be helpful for the optimization of CPISs to improve water use efficiency and crop yield.

Evapotranspiration of Palmer amaranth (Amaranthus palmeri) in maize, soybean, and fallow under subsurface drip and center-pivot irrigation systems

AbstractPalmer amaranth (Amaranthus palmeri S. Watson) is a major biotic constraint in agronomic cropping systems in the United States. While crop–weed competition models offer a beneficial tool for understanding and predicting crop yield losses, within these models, certain weed biological characteristics and their responses to the environment are unknown. This limits understanding of weed growth in competition with crops under different irrigation methods and how competition for soil moisture affects crop growth parameters. This research measured the effect of center-pivot irrigation (CPI) and subsurface drip irrigation (SDI) on the actual evapotranspiration (ETa) of A. palmeri grown in maize (Zea mays L.), soybean [Glycine max (L.) Merr.], and fallow subplots. Twelve A. palmeri plants were alternately transplanted 1 m apart in the middle two rows of maize, soybean, and fallow subplots under CPI and SDI in 2019 and 2020 in south-central Nebraska. Maize, soybean, and fallow subplots without A. palmeri were included for comparison. Soil-moisture sensors were installed at 0-0.30, 0.30-0.60, and 0.60-0.90-m soil depths next to or between three A. palmeri and crop plants in each subplot. Soil-moisture data were recorded hourly from the time of A. palmeri transplanting to crop harvest. The results indicate differences in A. palmeri ETa between time of season (early, mid-, and late season) and crop type across 2019 and 2020. Although irrigation type did not affect subplot data, the presence of A. palmeri had an impact on subplot ETa across both years, which can be attributed to the variable relationship between volumetric soil water content (VWC) and ETa throughout the growing season due to advancing phenological stages and management practices. This study provides important and first-established baseline data and information about A. palmeri evapotranspiration and its relation to morphological features for future use in mechanistic crop–weed competition models.

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 &amp;gt; 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 &amp;lt; 0.0001). Non-fiber carbohydrates were greater for non-sterile over sterile sorghum hybrids (P &amp;lt; 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 &amp;lt; 0.0001). Compared with non-sterile hybrids, male sterile hybrids DM was decreased (28.4% and 40.8%, respectively; P &amp;lt; 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.