ASHS 2024 Conference: Full Schedule

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11:59am HST

Water Utilization and Management (WUM)

Friday September 27, 2024 11:59am - 12:30pm HST

Evaluating Saline Irrigation Management Strategies Under Drip Irrigated Pistachio - Mukesh Mehata
Lysimetric Determination of Crop Water Requirements for Sorghum - Florence Cassel
Evaluating the distribution uniformity of spray-stakes using pressure compensating emitters - Chris Shogren

Moderator

Chris Shogren

UCCE Los Angeles

Friday September 27, 2024 11:59am - 12:30pm HST
Nautilus

Poster Session, Water Utilization and Management

SUBJECT Water Utilization and Management

12:00pm HST

WUM - Evaluating Saline Irrigation Management Strategies Under Drip Irrigated Pistachio

Friday September 27, 2024 12:00pm - 12:10pm HST

Nautilus

Over 85% of California's bearing pistachio acreage is located in soils with moderate (4 dS/m) to extremely high (16 dS/m) saline. Several previous studies have demonstrated that pistachios can be grown profitably even in moderately saline soils, with optimal soil salinity (ECe) maintained at approximately 4.5 - 6 dS/m. One common practice to reduce the salinity level in rootzone is to apply good quality water during dormant season. As the availability of good quality canal water for in-season irrigation and dormant season leaching declines, growers are relying more on semi-saline pumped groundwater, particularly in the San Joaquin Valley Westside. It would be beneficial to understand if the volume of dormant season leaching could be reduced, if in-season methods of leaching could be effective, and how to use moderately saline water most efficiently for both dormant and in-season leaching. Current methods for managing salinity through dormant leaching rely on one-dimensional models assuming complete surface wetting. We are exploring alternative approaches, investigating the effectiveness of single and double drip lines in managing root zone salinity using in-row, in-season leaching fractions and small volume pulsed dormant leaching. Preliminary results showed that generally, all leaching treatments, (in-season leaching, dormant leaching and the combination of both, applied with both single and double hose lines, significantly decreased soil ECe relative to the control, reducing ECe values of 13-22% relative to their respective controls. All the leaching treatments also effectively prevented boron from accumulating in the soil relative to the control. No clear effects of line configuration, double versus single line, were detected in soil levels. These findings indicate that treatments are effectively reducing salinity or at least preventing the increases observed in the control. Leaf analysis showed that in-season leaching, with/without dormant leaching, significantly increased leaf nitrogen and phosphorus, and reduced leaf boron accumulation.

Speakers

Mukesh Mehata

University of California, Davis

Co-authors

Blake Mccullough Sanden

University of California Davis

Clay Beck

Maricopa Orchard

Donald Williams III

CSU Fresno

Giulia Marino

University of California, Davis

Joseph Coehlo

Valley Orchard LLC

Louise Ferguson

University of California, Davis

Mae Culumber

University of California, Davis

Marta Saludes

Universidad de Salamanca

Friday September 27, 2024 12:00pm - 12:10pm HST
Nautilus

Poster presentation (individual talk), Water Utilization and Management

SUBJECT Water Utilization and Management

12:10pm HST

WUM - Lysimetric Determination of Crop Water Requirements for Sorghum

Friday September 27, 2024 12:10pm - 12:20pm HST

Nautilus

Accurate estimation of crop water requirements (CWR) is essential to optimize water use efficiency and develop efficient irrigation scheduling practices. This is particularly important in California where frequent droughts have accentuated the need to conserve water and improve on-farm water management. The most accurate method to determine CWR is with precision weighing lysimeters, which measure actual crop evapotranspiration (ETa). Thus, the objectives of this study were to determine ETa data, develop new crop coefficients (Kc), and evaluate the relationship between Kc and crop fractional ground cover (Fc) for forage sorghum grown under drip irrigation. Being drought and salt tolerant, sorghum has been considered as an alternative crop to corn in regions of water scarcity and marginal soils. Daily ETa measurements were collected over three years on a clay loam soil using the precision weighing lysimeter available at the University of California Westside Research and Extension Center in Five Points, CA. Crop coefficient (Kc) estimates were derived from the ETa measurements and reference ETo data were obtained from a CIMIS weather station located at the study site. Weekly Fc measurements were also performed to derive relationships between Kc and fractional ground cover. Results from our study indicated that the seasonal ETc ranged from 665 to 870 mm, with average peak ET of 7.0 mm/day and midseason Kc spanning from 0.90 to 1.1. A strong correlation (r2 > 0.95) was also observed between crop Kc and Fc. This study represents the first experiment determining ETc and Kc for forage sorghum grown under drip irrigation in California. Findings also demonstrated the variability of CWR due to seasonal differences.

Speakers