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Abstract California’s Central Valley is one of the world’s most productive agricultural regions. Its high-value fruit, vegetable, and nut crops rely on surface water imports from a vast network of reservoirs and canals as well as groundwater, which has been substantially overdrafted to support irrigation. The region has undergone a shift to perennial (tree and vine) crops in recent decades, which has increased water demand amid a series of severe droughts and emerging regulations on groundwater pumping. This study quantifies the expansion of perennial crops in the Tulare Lake Basin, the southern region of the Central Valley with limited natural water availability. A gridded crop type dataset is compiled on a 1 mi2spatial resolution from a historical database of pesticide permits over the period 1974–2016 and validated against aggregated county-level data. This spatial dataset is then analyzed by irrigation district, the primary spatial scale at which surface water supplies are determined, to identify trends in planting decisions and agricultural water demand over time. Perennial crop acreage has nearly tripled over this period, and currently accounts for roughly 60% of planted area and 80% of annual revenue. These trends show little relationship with water availability and have been driven primarily by market demand. From this data, we focus on the increasing minimum irrigation needs each year to sustain perennial crops. Results indicate that under a range of plausible future regulations on groundwater pumping ranging from 10% to 50%, water supplies may fail to consistently meet demands, increasing losses by up to 30% of annual revenues. More broadly, the datasets developed in this work will support the development of dynamic models of the integrated water-agriculture system under uncertain climate and regulatory changes to understand the combined impacts of water supply shortages and intensifying irrigation demand.
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Effects of Deficit Irrigation in Pepper Plants (Capsicum annuum) Grown Under Greenhouse Conditions
Water is a vital component for agricultural productivity; however, freshwater supplies are limited and are dwindling worldwide. Water for agriculture is an extreme issue for the southern region of Texas, where water supplies from reservoirs are used for municipal, industrial, and agricultural purposes. Due to intensive and prolonged intermittent droughts in south Texas, freshwater sources can deplete rapidly leaving growers on water restrictions. One potential solution of reducing the amount of water for crops is by applying less water than recommended crop evapotranspiration requires. Deficit irrigation (DI) is the practice of applying lower amounts of water than general crop requirements to increase water use efficiency for economic benefit. Deficit irrigation practice has been shown to be beneficial to some fruit and vegetable crops, but to a lesser extent in south Texas for mild heat pepper plant production. The purpose of this project was to analyze how watering jalapeño and serrano pepper plants at different levels of DI would impact plant growth and fruit yield in a greenhouse study. Deficit irrigation treatments were performed by irrigating pots at increasing the number of days between irrigation events (water application: 2, 4, 8, and 12 days) to create increasing water stress levels to plants. Plant growth and biomass data was collected to determine the impact of increasing deficit irrigation on plant shoot productivity. In both varieties, plant biomass steadily decreased as water application decreased. Serrano peppers grown at both 4d and 2d between water application events produced identical yields, however, increased water stress immediately impacted jalapeño peppers with lower yield. The encouraging results from serrano peppers suggest a potential economic benefit for deficit irrigation water use practices applied to this pepper variety.
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- Award ID(s):
- 1914745
- PAR ID:
- 10517207
- Publisher / Repository:
- Iris Publishers
- Date Published:
- Journal Name:
- World Journal of Agriculture and Soil Science
- ISSN:
- 2641-6379
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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