ASHS 2025 Conference

Agricultural runoff can contaminate surface and groundwater through the accumulation of nitrate-nitrogen (NO3-N) and phosphate-phosphorus (PO4-P). The Gray Water Footprint (GWF) estimates the volume of freshwater required to dilute pollutants to achieve target water quality standards. GWF can be used to compare the environmental impact of agricultural practices, such as irrigation and fertilization. In this project, we estimated and compared the GWF of three irrigation systems and two fertilizer rates in the production of Petunia milliflora F1 (Picobella Pink) in greenhouses. The experiment was a split plot design with two factors: irrigation (overhead, drip irrigation, and subirrigation) and control released fertilizer (CRF) rates (2.1gN-1.26gP-1.68gK or 1.8gN-1.08gP-1.44gK per pot). Plant growth and leachate were measured weekly. GWF was estimated with nitrate or phosphate from the leachate recovered from the containers. Significant differences were observed by irrigation system, but not by CRF rate or the interaction between the factors. In general, GWF (L of water to dilute the pollutant) of phosphate was higher than nitrate. The subirrigation, closed irrigation system had zero GWF because it does not release any leachate. Fertilizer inputs can be reduced while effectively maintaining the quality of petunia in container-production; however, it did not affect pollution rates. In contrast, the choice of irrigation system had a significant effect on nitrate and phosphate runoff rates.

Improving irrigation efficiency is essential for sustainable agricultural production. Smart irrigation technologies enhance water-use efficiency by integrating wireless communication, advanced sensors, and adaptive scheduling based on actual plant water requirements and weather conditions. Unlike traditional fixed-schedule timers, smart controllers dynamically adjust irrigation to optimize water use. This study aimed to compare three commercially available smart irrigation controllers: Hunter® Hydrawise (Hunter Industries, San Marcos, CA, USA), Orbit® B-hyve (Salt Lake City, UT, USA), and Rachio (Rachio Inc., Denver, CO, USA). The experiment was conducted at the Utah State University Greenville Experiment Station in Logan, Utah, USA. The experimental site (18.5 m x 6.4 m) comprised 12 plots (1.8 m x 1.8 m each), arranged in a completely randomized block design with three blocks, each containing four treatments (three smart controllers and one control). The control plot operated on a fixed timer: 20 minutes of irrigation daily managed by Rachio, whereas the other three smart controllers operated independently utilizing the weather data to schedule irrigation. Each plot was equipped with four sprinkler heads positioned at the corners. Controllers were installed and configured following manufacturer guidelines, utilizing Wi-Fi-enabled communication with their respective software applications. Each controller was configured, ensuring similar settings for a fair comparison, adhering to their respective technical features. Plugs of sage plants were transplanted in 7.5 L containers filled with Metro-Mix® 820 substrate. Initially, plants were irrigated daily for 20 minutes for two weeks to ensure proper establishment. Subsequently, the smart controllers managed irrigation based on real-time weather data, maintaining substrate moisture between 25-30% volumetric water content. Results showed significantly higher total water use in the control plots compared to those managed by smart controllers. Among the smart controllers, Hunter Hydrawise consumed significantly more water than Orbit and Rachio. Growth parameters including plant height, growth index, biomass, and visual appearance did not differ significantly across treatments. However, flower dry weight was significantly higher under Orbit compared to the control and Hydrawise, and similar to Rachio. Physiological parameters such as assimilation rate, stomatal conductance, maximum photochemical efficiency (Fv/Fm), Soil Plant Analysis Development (SPAD), Normalized Difference Vegetation Index (NDVI) remained consistent among all treatments. This study will be replicated during the upcoming summer to further validate the findings and enhance the reliability of the results.

Dona Ana County is one of the largest producers of pecans in the nation, making this area one of the most significant pecan production regions in the world. However, it is facing a shortage of water due to prolonged drought in the region. Management of water to grow crops, including pecan, is crucial to sustaining the agricultural industry in the region. This study assesses the evapotranspiration (ET) of a flood-irrigated young pecan orchard planted in 2021 in the Valley. This orchard has a partial canopy cover of pecan and pasture as a cover crop above the soil. In this orchard, ET was measured using an eddy covariance system and calculated as a residual using the energy budget method. Results indicate that ET primarily varies between 2.5 and 5.5 mm/day from June to August in the years 2021 and 2022.

Climate change, including rising average global temperatures, prolonged drought, and irregular weather patterns, presents significant challenges to landscape plant communities. Urban green spaces are vital to support mental health, mitigate urban heat island effects, and foster community cohesion. The objective of this project is to evaluate the drought-tolerance and ecosystem services of several ornamental plants. We hypothesize that, compared to other species, slow-growing broadleaf deciduous plants will exhibit superior drought resilience by sustaining greater biomass, attracting more pollinators, and preserving aesthetic value in the landscape. The trial was established April 20204, at Oregon State University’s Lewis-Brown Research Station in Corvallis, Oregon on a Chehalis silt clay loam. Experimental design is a randomized complete block with four replications. The single factor is plant taxa, which include 17 unique taxa of monocots, broadleaf deciduous and broadleaf evergreen, and conifer. From May 15, 2024 to Aug 30, 2024 date individual plants received an average of 1 gallon of water per week applied using a 0.5 GPH emitter. Their performance was assessed using leaf area index (LAI), plant height and width, presence of living leaves, pollinator activity, and volumetric water content (VWC). All plants survived the initial establishment in spring of 2024 and subsequent summer irrigation of 0.5 gallons per week per plant. Allium, Muscari armeniacum, and Narcissus exhibited vegetative growth in spring, fall, and winter, and summer dormancy or drought avoidance. Ceanothus, Cornus stolonifera, and Physocarpus opulifolius, being deciduous plants, retained foliage in spring, summer, and fall, and winter dormancy. After the first year, we found that broadleaf deciduous species tolerated drought while increasing in height and width, while enhancing urban green spaces during the spring and summer months. Juniperus squamata, Rosmarinus officinalis, and Arctostaphylos coloradoensis maintained year-round green vegetation. In summer of 2025 no irrigation will be applied, and data will be collated until July and presented at the this conference. After the first year, we found that broadleaf deciduous species tolerated drought while increasing in height and width, while enhancing urban green spaces during the spring and summer months. Findings from this study will provide data-driven recommendations to improve ecological management and guide the landscape industry in selecting climate-adapted species for the Pacific Northwest.

Salinas Valley is a major U.S. production region for cool-season vegetables. As regional producers work to achieve groundwater sustainability, there is a growing need to improve irrigation efficiency while sustaining crop yields. Recent advancements and availability in satellite-derived evapotranspiration (ET) data provide opportunities to inform on-farm water management. Quantifying the accuracy and limitations of these methods, however, remains important to build trust for increased operational adoption. This is especially the case for short-season vegetable crops, where performance evaluations of satellite-derived ET have been limited to-date. OpenET is a free, publicly-available platform that uses an ensemble of six satellite-based models to monitor and archive daily-to-monthly ET throughout the western U.S. at 0.25 acre resolution. In this study, daily OpenET values were compared with in-situ ET data from an eddy covariance system deployed in commercial broccoli fields during 2023 (66 days) and 2024 (76 days). Applied water was measured by an on-site digital flow meter, and precipitation was recorded by a nearby weather station. Cumulative totals from the OpenET ensemble mean were within 8.2% and 0.7% of in-situ data during the 2023 and 2024 deployment periods, respectively. Summary performance metrics were within previously published ranges for cropland sites during 2023 (mean bias error: 0.27 mm/day, mean absolute error: 0.65 mm/day) and 2024 (mean bias error: 0.02 mm/day, mean absolute error: 0.61 mm/day). Ensemble ET totals represented 88% of the 344 mm of total water received from irrigation and rainfall for the full crop cycle in 2023 (92 days), and 67% of 518 mm water received during 2024 (101 days). Results indicate OpenET quantified crop water consumption at these two sites with reasonable accuracy, while revealing differences in irrigation application efficiency. Additional discussion will address potential sources of satellite model uncertainty, challenges of collecting eddy covariance data in commercial plantings of short-season horticultural crops, and future verification efforts planned for regional high value specialty crops.

The Plants in ambient conditions are subject to dealing with biotic and abiotic stresses. Water deficit, being an abiotic stress, causes changes in plants that make them respond in several ways, such as reduced growth, leaf senescence and lower fruit growth rate, production of Reactive Oxygen Species (ROS), caused by a deficiency in the dissipation of energy due to impaired photosynthesis. The application of silicon becomes an alternative to mitigate the effects of this stress on plants, being deposited in the cell wall, providing rigidity, and increasing the plant's defense enzymes. The study aimed to understand the morphological, physical, and post-harvest responses of mini watermelon according to different soil humidity associated with the foliar application of silicon. The study was conducted in a greenhouse using the mini watermelon cv. Sugar Baby. The experimental design was in randomized blocks, in a 3x2 factorial scheme, with three water tensions in the soil (-35 kPa without water deficit, -50 kPa moderate water deficit, and -65 KPa severe water deficit) and two doses of foliar Si (0 and 1.5 g L-1), with four repetitions. The variables plant length, stem diameter and shoot dry mass, root dry mass, total soluble carbohydrates, proline, gas exchange, and post-harvest analyses were analyzed. There was a significant difference for the variables (p>0.05), but there was no interaction between tension and Si. Proline levels were not statistically significant. The water deficit promoted shorter plant length, aerial part dry mass, root dry mass and Si provided greater stem diameter. For biochemical variables, water deficit caused a higher carbohydrate content in the leaf and lower gas exchange rates. Si influenced skin thickness and average fruit weight. Thus, SI proves to be a strategy for cultivating mini watermelon in conditions of deficient water application.