2022 California Plant and Soil Conference - Day 3
UC Agriculture and Natural Resources ・21 minutes read
The session led by Bill Green and Michael Khan emphasized effective irrigation practices under drought conditions for farmers, highlighting the importance of monitoring pump efficiency, groundwater levels, and adopting technologies like variable frequency drives and flow meters. Additionally, strategies for prioritizing water allocation in orchards and managing soil salinity were discussed, emphasizing the need for sustainable agricultural practices amidst California's water challenges.
Insights
- The session, co-organized by Bill Green and Michael Khan, focuses on irrigation strategies for farmers facing drought, emphasizing practical applications to enhance water management.
- Bill Green from California State University, Fresno, discusses the impact of drought on pump performance and groundwater levels, highlighting the importance of monitoring these factors for sustainable farming.
- Farmers are encouraged to regularly test their pumps and groundwater levels, using resources from the Advanced Pump Efficiency Program and Southern California Edison to ensure optimal irrigation practices.
- The efficiency of a pumping system is determined by the combined efficiencies of the motor, transmission, and bowl, illustrating that even small inefficiencies can significantly reduce overall performance.
- Variable frequency drives (VFDs) can enhance pump efficiency by adjusting speed to water levels, although they may introduce some inefficiency, which is crucial to consider during drought conditions.
- Accurate flow rate measurement is vital for effective water management; farmers should install flow meters and regularly verify their accuracy to prevent overuse of water resources.
- Changes in groundwater levels due to drought can alter pump operating conditions, necessitating adjustments in irrigation practices to maintain efficiency and ensure adequate water supply.
- Farmers should utilize available resources, such as pump efficiency websites and tool lending libraries, to optimize their irrigation methods and comply with water management regulations.
- The adoption of flow meters among agricultural pumps has significantly increased, reflecting a growing awareness of the need for efficient water management in California's agricultural sector.
- Research indicates that certain crops, such as almond orchards, can yield significantly more with precise irrigation, emphasizing the importance of prioritizing water allocation based on crop responsiveness.
- Effective salinity management and leaching practices are essential for maintaining soil health in semi-arid climates, where understanding soil type and water quality can prevent crop yield reductions.
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Recent questions
What is soil salinity?
Soil salinity refers to the concentration of soluble salts in the soil, which can affect plant growth and agricultural productivity. High salinity levels can lead to poor crop yields, as excess salts can hinder water uptake by plants, leading to stress and reduced growth. Salinity can originate from various sources, including irrigation water, fertilizers, and natural mineral deposits. In semi-arid regions, managing soil salinity is crucial, as it can significantly impact soil health and crop performance. Effective management strategies may include leaching excess salts from the root zone, selecting salt-tolerant crop varieties, and implementing practices that improve soil structure and drainage.
How do I improve irrigation efficiency?
Improving irrigation efficiency involves several strategies aimed at optimizing water use while ensuring adequate crop growth. Key practices include installing flow meters to monitor water usage accurately, utilizing variable frequency drives (VFDs) to adjust pump speeds based on water levels, and regularly testing pumps and groundwater levels to maintain performance. Additionally, farmers should consider implementing precision irrigation techniques, such as drip irrigation, which delivers water directly to the plant roots, minimizing waste. Regular maintenance of irrigation systems is also essential to prevent leaks and ensure uniform water distribution. By adopting these practices, farmers can enhance water efficiency, reduce costs, and comply with water management regulations.
What are the benefits of cover cropping?
Cover cropping offers numerous benefits for soil health and agricultural productivity. By planting cover crops during the off-season, farmers can improve soil structure, enhance nutrient cycling, and reduce erosion. Cover crops, such as legumes, can fix atmospheric nitrogen, enriching the soil and reducing the need for synthetic fertilizers. They also promote biodiversity, providing habitat for beneficial insects and microorganisms. Additionally, cover crops can improve water retention in the soil, helping to mitigate drought effects. Overall, integrating cover cropping into farming practices can lead to healthier soils, increased crop yields, and more sustainable agricultural systems.
What is the role of variable frequency drives in irrigation?
Variable frequency drives (VFDs) play a crucial role in optimizing irrigation systems by allowing pumps to adjust their speed based on real-time water demand. This capability helps maintain pump efficiency and reduces energy consumption, particularly during fluctuating water levels. While VFDs introduce a slight inefficiency, they significantly enhance overall energy and water efficiency by ensuring that pumps operate at optimal levels. By using VFDs, farmers can better manage their irrigation systems, leading to improved water use efficiency, reduced operational costs, and enhanced crop performance during periods of drought or water scarcity.
How can I manage nitrogen in onion production?
Managing nitrogen in onion production is essential for achieving optimal yields and quality. Effective nitrogen management involves applying the right amount of nitrogen fertilizer at the appropriate times during the growing season. Research indicates that a significant portion of nitrogen uptake occurs in the last two months before harvest, so split applications throughout the season can ensure that plants receive adequate nutrients when they need them most. Soil testing is also crucial to determine initial nitrogen levels and adjust fertilizer applications accordingly. By carefully monitoring nitrogen levels and adjusting management practices, growers can enhance onion quality, improve sweetness, and maximize overall crop performance.
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Summary
00:00
Irrigation Strategies for Drought Conditions
- The session focuses on irrigation under drought conditions, discussing practical applications for farmers, co-organized by Bill Green and Michael Khan, an irrigation advisor in Monterey County.
- Bill Green, from California State University, Fresno, manages the Advanced Pump Efficiency Program, addressing how drought affects pump performance and groundwater aquifer levels.
- Farmers should periodically test their pumps and groundwater levels to monitor changes, utilizing programs from the Advanced Pump Efficiency Program and Southern California Edison’s hydraulic services.
- The overall efficiency of a pumping plant combines motor, transmission, and bowl efficiencies, with an example showing a 93% motor efficiency, 95% transmission, and 76% bowl efficiency resulting in 67% overall efficiency.
- Variable frequency drives (VFDs) can assist in maintaining pump efficiency, though they introduce about 4% inefficiency, impacting overall energy and water efficiency during drought conditions.
- Flow rate, measured in gallons per minute, is crucial for managing water usage; farmers are encouraged to install flow meters and regularly check their accuracy for effective water management.
- Total dynamic head (TDH) is calculated by adding suction lift, elevation lift, friction losses, and system pressure, with an example showing a total lift of 385 feet required for a specific pump.
- Pump curves illustrate the relationship between flow rate and total dynamic head, helping farmers identify the best efficiency point for their pumps, which is critical for energy efficiency.
- Changes in groundwater levels due to drought can shift the operating conditions on pump curves, necessitating adjustments to maintain efficiency and output.
- Farmers are advised to utilize resources like the pump efficiency website and tool lending libraries for flow meters to enhance their irrigation practices and comply with water management regulations.
13:20
Optimizing Pump Efficiency for Irrigation Systems
- Current pump efficiency is at 70%, yielding 400 gallons per minute, a drop of 20% in flow rate, impacting irrigation performance and pump runtime.
- Flow meters are essential for monitoring changes in aquifer levels from April to August, especially during drought conditions affecting California's water supply.
- Pumps typically operate slightly right of the efficiency curve; drought conditions shift performance left, necessitating pump replacement for adequate flow and pressure.
- If a pump requires 500 gallons per minute but only delivers 200 gallons, energy waste increases, and irrigation systems fail to operate effectively.
- Fluctuating water tables lead to variable pumping conditions; static water levels drop, affecting the pumping water level and overall irrigation system performance.
- When installing a pump, request the corresponding pump curve to evaluate performance during testing and determine if the pump is operating efficiently.
- Variable frequency drives (VFDs) allow pumps to adjust speed based on water levels, maintaining efficiency and reducing energy consumption during fluctuating conditions.
- Oversizing pumps can prevent frequent replacements; VFDs enable adjustments to flow and pressure, ensuring adequate irrigation even as water levels change.
- Energy savings from VFDs are significant; reducing pump speed from 1800 to 1500 RPM can lower horsepower requirements dramatically due to affinity laws.
- Remote monitoring tools, alongside flow meters, are recommended for precise irrigation management, allowing farmers to optimize water usage and system performance.
25:36
Optimizing Water Use in Agriculture
- Flow meters are essential for efficient irrigation management; without them, farmers may over-irrigate, leading to compliance issues with Sigma regulations.
- Currently, an estimated 35-40% of agricultural pumps have flow meters installed, up from 10% two decades ago, indicating significant but incomplete adoption.
- Incentives for installing flow meters include programs like SWEEP and EQUIP, with potential future requirements for flow meters under Sigma regulations.
- For variable frequency drives (VFDs), maintain operation above 30 hertz to ensure warranty compliance; 60 hertz is full speed, with lower settings potentially affecting performance.
- Water management for tree crops under limited supply requires prioritizing orchards based on their responsiveness to irrigation, as not all respond equally to additional water.
- Research indicates that almond orchards can yield an additional 35 kernel pounds per acre for each inch of water supplied, but responses vary significantly by location.
- Proportional deficit irrigation allocates limited water equally across all orchards, while prioritizing productive orchards can maximize returns but requires more management effort.
- Young developing orchards should be prioritized for water allocation during droughts to promote growth and establish a productive canopy.
- Tools for assessing orchard responsiveness to water include production history, midday canopy light interception, and familiarity with known limitations affecting yield.
- Water productivity can be evaluated in pounds produced per acre-foot of water; for example, one walnut orchard yielded 2,103 pounds per acre-foot, indicating higher efficiency than another yielding 1,364 pounds.
42:14
Optimizing Orchard Productivity Through Light and Water
- Almond orchards yield between 50 to 75 pounds per light interception, while poor orchards yield less than 25 pounds, indicating significant differences in productivity based on light interception.
- A high-yielding orchard can produce approximately 44 pounds per 1% light interception, while a poor orchard may yield only 12.5 pounds per 1% light interception.
- To measure canopy light interception, use digital cameras to capture images of the orchard, inserting grids for scale, and assess shading from noon to 1:30 PM.
- The Lampton Lab has developed an iPad and iPhone app for estimating average photosynthetic active radiation, providing a more accurate measurement of midday canopy light interception.
- Aerial imagery and NDVI can estimate canopy fraction, with tools like CropManage at UC Riverside linking satellite imagery for enhanced assessments of canopy light.
- Monitoring groundwater levels is crucial for prioritizing orchards during water shortages, using manual well sounders or automated remote measurement systems.
- Effective irrigation system design, maintenance, and evaluation are essential, with 20-25% of micro irrigation systems showing less than 70% distribution uniformity, indicating potential water savings.
- Tree water status can be measured using pressure chambers or automated sensors, providing insights into crop stress levels and their impact on growth and yield.
- A walnut orchard study from 2014 to 2019 tested five irrigation treatments based on tree water status, showing significant water savings and improved tree health with delayed irrigation.
- For drought management, focus on real-time crop water needs, evaluate midday canopy shading, monitor tree water status, and understand crop sensitivity to water stress for effective irrigation practices.
01:00:44
Managing Salinity for Crop Health and Yield
- Salinity tolerance thresholds for various crops are published, with resources like FAO48 providing essential guidelines for managing salinity in agriculture.
- Salts originate from parent material, irrigation water, fertilizers, and sea spray, with marine sediments on the west side of the San Joaquin Valley being saltier than granitic soils on the east.
- Soil salinity management is crucial in semi-arid climates, where neutral to alkaline soils may still be affected by salinity or sodicity, impacting crop health and yield.
- Identifying soil type and water quality is vital; high sodium ratios necessitate gypsum or acid amendments, while salinity alone may only require leaching without chemical treatments.
- Leaching involves applying excess water to move salts below the root zone, crucial for managing salinity, especially when nitrogen levels are low to minimize nutrient loss.
- Maintenance leaching prevents salinity accumulation by applying sufficient water over time, while reclamation leaching allows salinity to build up before applying heavier water doses to reclaim soil.
- The leaching requirement calculation considers irrigation water salinity and crop yield loss thresholds, with a typical leaching requirement ranging from 0 to 1, often around 12.6% more water.
- Decision support tools like leaching calculators from UC Cooperative Extension and UC Riverside help determine site-specific leaching requirements based on crop, water quality, and soil texture.
- For example, using a leaching calculator for almonds with clay loam soil and 85% irrigation efficiency may recommend a leaching requirement of 14%, significantly higher than traditional estimates.
- Improved crop varieties and rootstocks with higher salinity tolerance can mitigate yield reductions, emphasizing the importance of selecting appropriate crops for saline conditions.
01:18:15
Optimizing Water Use for Salinity Management
- Maintaining the root zone at 3.5 deciSiemens per meter reduces total water requirements due to a lower leaching fraction compared to the previous 1.5 deciSiemens per meter.
- For tomatoes, the traditional leaching requirement is 19%, while the program recommends 7%, resulting in a total water application of 642 mm for leaching or 755 mm considering irrigation efficiency.
- Lettuce requires a traditional leaching recommendation of 44%, but the program suggests only 11%, indicating a significant reduction in water needed for leaching.
- An Excel-based calculator on the UCCE website allows users to input soil data, including saturation percentage, pH, and electrical conductivity (EC), to determine necessary water applications for desired salinity levels.
- To manage salinity, applying 11.7 inches of water is needed to reduce salinity from 5.5 to 3.0 in the top three feet of soil, while 7.4 inches is required for the top two feet.
- A k factor of 0.15 indicates that 3.6 inches of water per foot of root zone is needed to reduce salinity from 4 to 2 for almonds, and the same applies for pistachios.
- If boron levels are high, the leaching requirement increases, necessitating up to 5.4 inches of water per foot of soil depth to manage salinity effectively.
- The relationship between irrigation water salinity and resulting soil salinity shows that a 15% leaching requirement can reduce soil salinity from 6.3 to 3.2 when starting with irrigation water salinity of 2.
- Dormant season reclamation leaching is beneficial as it minimizes water logging and allows for better timing of leaching when nitrogen levels are low in the soil.
- Soil testing is crucial to assess salinity levels and determine appropriate leaching strategies, especially under conditions of water scarcity, to manage salt and nitrogen effectively.
01:34:51
Soil Carbon Management Strategies for Emissions Reduction
- The analysis focused on soil carbon management strategies for Microsoft Corporation, emphasizing deep-rooted perennials and cover cropping as effective methods for emissions reduction.
- Cover cropping is gaining traction in California, with many counties exceeding a 5% adoption rate, demonstrating its benefits for soil carbon and erosion reduction.
- The addition of compost or bio-waste amendments can complicate carbon accrual, as they may lead to increased nitrous oxide emissions, necessitating careful assessment of their net benefits.
- No-till practices show positive effects on surface soil carbon but may increase greenhouse gas emissions, particularly nitrous oxide and methane, in deeper soil layers.
- Deep-rooted perennials, like switchgrass, are highlighted for their potential to enhance soil carbon storage due to their extensive root systems and associated microbial activity.
- Research using stable isotopes of carbon dioxide (13C) allows tracking of carbon movement from plants to soil, revealing significant long-term carbon retention in mineral-associated forms.
- In a study comparing switchgrass to corn-soy-wheat rotations, switchgrass demonstrated nearly double the soil carbon content at depth, indicating its effectiveness in carbon sequestration.
- The presence of extracellular polysaccharides (EPS) produced by roots and microbes aids in soil aggregation, correlating with increased carbon retention in soils.
- Soil mineral composition affects organic matter retention, with certain poorly crystalline minerals and clays being more effective at storing carbon, particularly in marginal soils.
- Managing soil microbiomes through plant exudates can enhance nutrient availability and potentially increase carbon storage, emphasizing the importance of root-derived organic carbon in soil health.
01:51:22
Enhancing Soil Health Through Carbon Farming
- Growing plants in fertile environments with added nitrogen or NNP fertilizer leads to diverse communities compared to marginal soils, indicating a relationship between soil quality and organism types.
- Arbuscular mycorrhizal fungi (AMF) partner with approximately 80% of land plants, enhancing nitrogen, phosphorus, and water efficiency for plant hosts while increasing soil carbon levels.
- The total length of fungal hyphae in soil is about 100,000 centimeters per square centimeter, vastly exceeding root length, which is around 7 centimeters, enhancing organic matter absorption.
- Soil carbon farming is an emerging concept, with the Healthy Soils Program focusing on greenhouse gas emissions and the potential for improving soil health in various landscapes.
- Opportunities exist to enhance soil carbon in managed landscapes, including agricultural lands like orchards and vineyards, through understanding agroecology and biogeochemistry.
- Implementing deep-rooted perennials, particularly California natives, in underutilized areas can improve soil carbon and health with minimal maintenance costs.
- Encouraging cover cropping is beneficial for soil carbon, providing clear advantages for soil health and agricultural productivity.
- Future efforts may include engineering plant cultivars with deeper roots and beneficial microbe associations to enhance soil carbon storage.
- California's SB 1383 legislation aims to reduce landfill organic waste by 75% and improve food waste management through organized collection systems.
- The state has allocated significant funding, including $75 million for the Healthy Soils Program and $90 million for composting infrastructure, to support composting initiatives and research.
02:07:33
California's Composting Revolution for Sustainability
- The marine carbon project initiated in 2008 has evolved, with 420 cubic yards of compost being delivered to 12 acres in Altamonte Hills for carbon sequestration by 2022.
- California's SB 1383 aims to enhance procurement responsibilities and offset greenhouse gas impacts by promoting compost use, benefiting soil health and microbial activity.
- Composting diverts organic materials from landfills, reducing methane emissions, and improving water retention, crucial for California's ongoing drought conditions.
- The new 1383 requirement is expected to double available compost materials, necessitating robust efforts from composters to ensure market availability and transportation logistics.
- Food waste recovery involves both back-of-house and front-of-house materials, with packaging complicating the identification of compostable versus non-compostable items.
- Legislation is being introduced to clarify standards for compostable packaging, improving the quality of compost produced from municipal food waste collection.
- Contamination in composting programs is addressed through advanced packaging technologies that remove metals, glass, and plastics from food waste streams.
- California's composting infrastructure, primarily focused on green waste, is transitioning to include food scraps, requiring consumer education and behavior change.
- The Healthy Soils Program funds compost application, with increasing support for grants aimed at sustainable agriculture and climate-smart practices.
- The California almond industry spans over 1.2 million acres, with many older orchards being replanted, highlighting the need for sustainable practices in agriculture.
02:26:05
California's Shift from Agricultural Burning
- Agricultural burning has shifted primarily to orchards and vineyards, prompting the state legislature to seek alternative waste disposal methods due to environmental concerns.
- In 2021, California's CARB mandated a near-total phase-out of agricultural burning by 2025, allocating $180 million to air districts for supporting growers and landowners.
- Incentive programs offer up to $600 per acre for orchard chipping and incorporation, with an additional $100 per acre for orchards under 100 acres, and $186 per acre through the Healthy Soils Program.
- Whole orchard recycling requires five machines to grind trees, spread, and incorporate them into the soil, with over 49,000 acres and 1.3 million tons of biomass processed since 2018.
- Research indicates that wood chips can enhance soil organic matter, with microbial decomposition processes crucial for understanding long-term carbon retention in agricultural soils.
- A trial initiated in 2008 by Dr. Brent Holtz showed that grinding and incorporating trees retained approximately eight metric tons of carbon per hectare compared to burning.
- Orchard recycling trials monitor soil health, tree growth, and water use across various locations, with baseline soil organic levels ranging from 1% to 1.5%.
- Current practices produce smaller grind sizes, with ongoing trials assessing carbon storage potential and soil health indicators in replanted orchards.
- Preliminary data shows increased soil organic matter and microbial activity in recycled plots compared to controls, indicating improved soil conditions.
- Greenhouse gas emissions are being monitored to evaluate carbon balance, with a focus on minimizing nitrous oxide emissions in replanted orchards.
02:42:24
Orchard Recycling's Impact on Greenhouse Gas Emissions
- Two research sites were established in 2018 and 2019 to study greenhouse gas emissions from orchard recycling, comparing recycling plots to control plots year-round.
- Daily surface CO2 emissions were monitored, revealing over two times higher emissions immediately after recycling and planting, with an initial carbon application of 61 tons per acre.
- After two years, approximately 66% of the initial carbon application was retained, indicating a significant reduction in CO2 loss compared to the first year.
- A commercial site showed a lower initial application rate of 40 tons per acre, with similar retention rates observed after three years of monitoring.
- A shaker sieve table was developed to analyze wood chip sizes, revealing that the majority of initial applications were in the 1.27 cm size range, indicating rapid decomposition.
- Higher nitrous oxide emissions were recorded in the first season post-recycling, with significant reductions in subsequent years, particularly after fertigation events.
- Growers often apply excessive nitrogen due to high carbon inputs from recycling; a standard recommendation is 28 pounds per acre for first-year trees.
- Emission factors for nitrogen and nitrous oxide losses were calculated, with micro-irrigated almond orchards showing factors between 0.19 and 0.35, indicating efficient nitrogen uptake.
- Orchard recycling demonstrated benefits for soil function, with no significant impact on tree growth or yield from excess nitrogen applications in the first three years.
- Continued analysis of greenhouse gases and soil carbon levels aims to improve predictions of long-term carbon storage benefits from orchard recycling practices.
02:59:43
Impact of Wood Chips on Soil Health
- The grower collaborated with Brent to explore beneficial practices, leaving control areas without wood chips for comparison in their research on soil health and crop yield.
- In June 2019, approximately 70 tons of wood chips were incorporated into an old walnut site, with varying sizes influencing breakdown rates and soil properties like nutrient cycling and water infiltration.
- The grower cover cropped with brassica during the winters of 2019-2020 and 2020-2021 to avoid soil fumigation before replanting, enhancing soil biomass and microbial colonization.
- The study aimed to evaluate soil properties and dry bean yield in the 2020 growing season, hypothesizing that nitrogen immobilization from wood chips could reduce yields, potentially mitigated by additional nitrogen fertilizer.
- Control plots (green squares) covered about half an acre, while recycled plots (orange squares) were sampled to assess the impact of different nitrogen fertilizer rates on bean yield.
- In 2020, the grower applied 116 pounds of nitrogen, aligning with UC guidelines for bean crops needing 80-120 pounds for a 2,000-pound yield; a doubled rate of 204 pounds was also tested.
- In 2021, the grower used a doubled nitrogen rate as the standard due to poor 2020 results, with observations indicating healthier bean crops compared to the previous year.
- Soil organic carbon and total nitrogen were higher in recycled plots over time, while plant-available nitrate initially decreased but improved in the second year after recycling.
- Bean yields in 2020 were negatively impacted by whole orchard recycling, but in 2021, yields returned to higher levels, showing no statistically significant differences across nitrogen rates.
- Whole orchard recycling can enhance soil health but poses challenges for subsequent crops, highlighting the need for careful management of nitrogen and soil practices in annual cropping systems.
03:18:30
Advancements in Whole Orchard Recycling Practices
- Whole orchard recycling research is expanding beyond almonds, with a focus on various orchard crops and their subsequent annual crops, including a study on recycled cherry orchards by Mohamed Nuri.
- Key findings from a walnut recycled orchard include increased soil organic carbon and total nitrogen, indicating potential benefits of whole orchard recycling for soil health.
- Initial observations show lower plant available nitrate in the first year post-recycling, but higher nitrate levels in the second year, suggesting organic nitrogen mineralization.
- Bean yields were lower in the first year after recycling; however, increasing the side dress nitrogen application rate to 200 pounds helped mitigate yield loss.
- The 200-pound nitrogen application is not a universal recommendation; growers should adjust based on their specific soil types, tree sizes, and previous experiences.
- Yields of beans appear to recover by the second year after recycling, indicating a potential long-term benefit of whole orchard recycling practices.
- Michelle's research emphasizes the importance of adapting nitrogen application rates based on historical practices and the specific conditions of the orchard.
- Questions from attendees highlighted the need for monitoring available nitrate levels to fine-tune nitrogen applications during the first year after recycling.
- The presentation transitioned to Wasan Zakiri Hussein, who discussed promoting legumes in California, focusing on fava beans as cover crops and vegetable crops.
- Hussein's research includes evaluating 63 fava bean lines for traits important to growers, emphasizing the crop's nitrogen fixation capabilities and potential benefits for soil health.
03:34:00
Fava Beans: Benefits and Cultivation Insights
- Fava beans exhibit a wide range of flowering dates, seed sizes, yields, and nitrogen fixation, with ndfa indicating nitrogen from fixation and yield representing remaining soil nitrogen for subsequent crops.
- In 2019, fava beans thrived in well-watered conditions, demonstrating significant growth and providing a resource for pollinators during winter, flowering from November to late January.
- A study compared fava beans to bell beans as cover crops in California, Oregon, Arizona, and Nevada, showing fava beans generally outperformed bell beans in biomass production.
- A direct relationship was found between fava bean plant height and biomass, indicating that measuring height can help assess nitrogen benefits from the crop.
- For seed characteristics, visit fava beanresearch.com to explore 63 lines of fava beans, including details on seed size, shape, and color.
- Major challenges in fava bean cultivation include chocolate spot disease in wet conditions and aphid infestations in drier climates.
- Ongoing trials are assessing smaller-seeded fava bean varieties against bell beans in various cover crop mixes across locations like Chico, Fresno, Salinas, Pomona, and Phoenix.
- Fava beans can be harvested for fresh pods and then used as cover crops, with potential yields reaching 80,000 kg per hectare, depending on the variety.
- Varieties such as Aqua Dolce, Garano Violeta, and Windsor show different harvest timings, with early producers like Roma and Garano Violeta yielding better in early seasons.
- Outreach efforts include distributing seeds at farmers' markets and sharing recipes, aiming to promote fava beans as a food crop and enhance public knowledge about their culinary uses.
03:50:00
Imperial Valley's Onion Farming Challenges and Strategies
- Imperial County has approximately 500,000 acres of agricultural land, receiving only three inches of rain annually, relying heavily on Colorado River water for irrigation.
- The region experiences harsh summers exceeding 110°F and mild winters, making it a key off-season salad bowl for the U.S. with over 80 commodities produced.
- The Colorado River has faced a 22-year drought, impacting water allocations; Arizona will see an 18% cut in water, affecting agricultural practices and crop choices.
- California is the largest onion producer in the U.S., with Imperial Valley cultivating about 13,000 acres, generating a market value between $50 million and $100 million annually.
- Onion cultivation involves various irrigation systems, transitioning from sprinklers for germination to drip irrigation, with planting densities ranging from four to twelve lines of onions.
- The onion growing season lasts approximately 200 days, from sowing in late October to harvesting in May, with critical nutrient uptake occurring in the last two to three months.
- Nitrogen management is crucial; 50% of nitrogen uptake occurs in the last two months, with 65% of nitrogen found in the bulbs at harvest.
- Research includes four irrigation treatments with crop transpiration rates from 40% to 130%, and nitrogen applications ranging from 50 to 225 pounds per acre.
- Fertilization is split into three applications during the season, with the first occurring in February, ensuring efficient nutrient management aligned with crop needs.
- Soil moisture sensors monitor water retention, showing that at lower irrigation rates, plants struggle to access water, emphasizing the importance of proper irrigation management for yield.
04:05:22
Onion Production Insights for Improved Practices
- In the 2020-2021 growing season, onion production achieved 20 to 24 inches of water, resulting in high yields of jumbo and colossal onions, despite a 15-ton decrease per acre from the previous year.
- The nitrogen treatments applied ranged from 0 to 225 pounds per acre, with no significant impact on onion yields or sizes observed across the years.
- Initial soil nitrogen was measured at 70 pounds per acre, with a total available nitrogen range of 100 to 350 pounds per acre, showing no significant differences in yields or sizes.
- The 2020-2021 crop rotation followed an alfalfa field, resulting in higher initial residual nitrogen at 100 pounds per acre, yet no significant differences in yields or sizes were found.
- The nitrogen balance indicated a positive range of 40 to 100 pounds per acre, with an estimated nitrogen mineralization of 100 pounds per acre during the growing season.
- Post-harvest analysis showed no statistical differences in onion quality based on irrigation rates, but nitrogen application affected sweetness, with higher nitrogen leading to lower sugar content.
- The study emphasized the need for improved nitrogen management and water efficiency in onion production, highlighting opportunities for better practices in future growing seasons.
