- (Focus Area) Agriculture
Satellite-based irrigation tools to manage irrigation water more precisely in avocado groves
Ali Montazar, UCCE Irrigation and Water Management Advisor
in San Diego, Riverside, and Imperial Counties
The water requirement of a crop must be satisfied to achieve optimum potential yields. The crop water requirement is called crop evapotranspiration and is usually represented as ETc. By combining reference evapotranspiration (ETo) and the proper crop coefficient (Kc), crop water use (ETc) can be determined as ETc = ETo × Kc. ETo is an estimation of evapotranspiration for short grass canopy under a well-managed, non-stressed condition. ETo is the main driver to estimate or forecast crop water needs. There are user-friendly satellite-based irrigation tools available that may assist growers to schedule irrigation more effectively. These tools provide ETo forecast for up to six days in the future or/and actual ET at the scale of individual fields. This article introduces three satellite-based irrigation tools including FRET, IrriSAT, and OpenET. A comparison of the estimated daily crop water needs utilizing OpenET tool and actual ET measured for a period of 150-day is also presented for an avocado grove in the San Pasqual Valley, Escondido.
Read more about this study: https://ceventura.ucanr.edu/Com_Ag/Subtropical/?newsletteritem=100493
A screen dump of cumulative ET (inch) for the entire western states in 2021. You may zoom on the OpenET map to find your orchard for a specific time (daily, monthly, yearly) and explore the data.
![OPEN ET map OPEN ET map](/blogs/blogcore/blogfiles/107466.jpg)
- Author: Ben A Faber
Microirrigation systems include microsprinklers for tree crops, drip emitters for trees, vines, and some row crops, and drip tape for row and field crops. Microirrigation systems apply water to the soil through emitters that are installed along drip lines and contain very small flow passages. Microirrigation systems can apply water and fertilizers more uniformly than other irrigation methods. This uniformity results in potentially higher yields, higher revenue, and reduced irrigation operating costs.
Uniformity, a performance characteristic of irrigation systems, is a measure of the evenness of the applied water throughout the irrigation system. Distribution uniformity (DU), sometimes called emission uniformity (EU), is an index that describes how evenly or uniformly water is applied throughout the field. A uniformity of 100% means the same amount of water was applied everywhere. Unfortunately, all irrigation systems apply water at a uniformity of less than 100%, and thus some parts of a field receive more water than others. Field evaluations have shown that microirrigation systems have the potential for higher uniformity than other irrigation methods. However, clogging reduces the uniformity of applied water in microirrigation systems, thus increasing the relative differences in applied water throughout a field.
The small flow passages in the emitters and microsprinklers make microirrigation systems highly susceptible to clogging. Clogging reduces the uniformity of the applied water and decreases the amount of applied water. Clogging also decreases the amount of salt leaching around the lateral line in saline soils.
The objective of this web site is to provide information to irrigators about the causes of clogging and the methods for preventing or correcting clogging problems in microirrigation systems. Among the topics covered are the sources of clogging, chlorination, preventing chemical precipitation, filtration, flushing, and monitoring microirrigation systems.
This web site is divided into sections to allow the users to more quickly access the information they want. For example, if you already know you have a clogging problem and you want to solve it, go to the section Solutions to Existing Clogging Problems - "I have a problem and I want to solve it".
https://micromaintain.ucanr.edu/
![avocado irrigation 2 avocado irrigation 2](/blogs/blogcore/blogfiles/107783.jpg)
- Author: Ben A Faber
Hot off the internet, a new edition of Topics in Subtropics, articles from UC subtropical horticulture folks
Topics in Subtropics Volume 25 Spring 2024
Jul 9, 2024
Fatemeh Khodadadi, Editor
Topics in this issue:
- Effectiveness of Asian citrus psyllid management in huanglongbing treatment zones in residential Southern California
- Managed honeybees in a wet year
- Threats to citrus orchards in California by synergistic effects of dry root rot and phytophthora root and crown rot
- Microbial Safety in Avocado Farms
- How Much Fruit is Up there?
- Tiny Troublemakers: How Geminiviruses are affecting California's Crops
- Citrus Leprosis Disease – Staying alert on potential threat to California's citrus industry
Download (3,620KB PDF)
https://ceventura.ucanr.edu/Com_Ag/Subtropical/
AND THERE"S LOTS MORE TO READ FROM THE ARCHIVES
https://ceventura.ucanr.edu/Com_Ag/Subtropical/?newsletterlist=3197
![topics in sub masthead topics in sub masthead](/blogs/blogcore/blogfiles/107742.png)
- Author: Whitney Brim-DeForest
- Author: Luis Espino
- Author: Roberta Firoved
- Editor: Taiyu Guan
- View More...
At our last meeting, we had some questions about the approved uses of pendimethalin in California rice. There are several products labeled for use on rice with pendimethalin as the active ingredient. As of June 2024, pendimethalin registered products (on rice) include Prowl H2O, Prowl 3.3, Harbinger, Satellite Hydrocap, Stealth, Helena Pendimethalin, Pavilion H2O, Pavilion 3.3, and a few others. Please make sure to always check the product label, as not all pendimethalin products allow use for the below-listed timings. Furthermore, labels are updated regularly, so it should not be assumed that the same use pattern applies from season to season. For the most currently-registered products, refer to the California Department of Pesticide Regulation website, product label databases, as well as manufacturers' websites for reference. Please remember the container label is the deciding point for pesticide use enforcement.
The mode of action of pendimethalin is disruption of mitosis (WSSA Resistance Group 3). In California rice, there is no other herbicide registered with this mode of action. The herbicide binds to clay soils, with residual activity of between 1 to 4 months, depending on environmental conditions. Pendimethalin can be readily absorbed by young roots, and thus, weeds are controlled as they germinate. Damage can also occur to rice or other crops as they germinate. Weeds are not controlled by this product once emerged and established.
Labeled controlled weeds are: junglerice, barnyardgrass, and sprangletop. Barnyardgrass and sprangletop are the two most abundant grass weeds in dry- or drill-seeded California rice, also causing the most yield loss. Rotating with pendimethalin can help to manage herbicide-resistance biotypes, as well as preventing the selection of herbicide resistance in these species.
Pendimethalin Rice Timings (product-dependent):
Preflood, preemergence: In drill- or dry-seeded rice, pendimethalin can be applied to the soil surface AFTER rice has been dry-seeded and lightly incorporated or drill-seeded. The product should be tank-mixed with a safener adjuvant. Water should be flushed across the field AFTER herbicide application (within 7 days).
Delayed preemergence: NOT a currently labeled use for any pendimethalin product registered in California.
Early postemergence: Only for dry-seeded rice and into fields with no standing water. Pendimethalin is usually applied with a tank-mix partner. Timing should be based on the leaf stage of the rice or weeds as appropriate for the tank-mix partner. Field should be flooded or flushed within 7 days after application.
Postemergence: For water-seeded rice (California ONLY) between the 4-6 leaf stage. Field must be completely drained with no standing water at time of the pendimethalin application and should be reflooded within 7 days after application.
- Author: Ria DeBiase, UC Giannini Foundation
How policies affect emissions, land use, and the prices of fuel and vegetable oils
Over the last two decades, both the federal government and state governments have enacted policies to reduce greenhouse gas (GHG) emissions in the transportation sector. In a new Special Issue of ARE Update, University of California agricultural economists explore how these federal and state renewable fuel policies have affected biofuel production for motor and aviation fuels and consider how these policies have affected land use and food prices. Their research shows that as U.S. demand for renewable diesel began to outpace supply, consumer prices for vegetable oil—which is used as a feedstock for renewable diesel—surged.
The national Renewable Fuel Standard (RFS) and California's Low Carbon Fuel Standard (LCFS), implemented in 2006 and 2011, respectively, have led to an increase in the amount of biofuels consumed and produced in the United States. While the RFS mandates that a minimum volume of renewable fuels be blended into U.S. transportation fuels, the LCFS sets an annually increasing targeted reduction in transportation-related carbon emissions. The LCFS set a 2030 target date to reduce GHG emissions by 20% through the development of a carbon trading program that requires refiners who produce ‘dirtier' fuels to buy credits from those who produce cleaner (e.g., renewable) fuels.
The authors show that after 2020, whenLCFS credit prices (i.e.,biofuel subsidies) were high, California saw an increasing volume of motor fuel coming from renewable diesel — which previously only made up around 5% of the state's diesel blend. Currently, the retail diesel blend in California is 35% conventional diesel and 65% renewable diesel.
By 2023, renewable diesel was the most consumed renewable fuel in California and also generated the most credits under the LCFS. Because renewable diesel is a perfect substitute for “conventional diesel,” it does not need to be blended with conventional diesel, unlike biodiesel which is chemically different from renewable diesel.
The agricultural inputs used to make renewable diesel can be used not only in the production of motor oil, but also in the development of sustainable aviation fuel (SAF). Additional tax credits set forth in the 2021 Inflation Reduction Act aim to bring about a 100-fold increase in the production of these fuels by by the end of decade. However, the authors of the second article show that current incentives to produce SAFs are not large enough to overcome the opportunity cost of instead using these fuels for on-road use.
After the drastic increase in demand for renewable diesel (up 500% over the last five years), a higher percentage now comes from edible vegetable oils. This increased demand almost certainly plays a role in increasing inflationary pressure on foods such as cooking oils.
“From 2018 to 2024, food-at-home inflation was 24%, but over the same period, fats and oils inflation was 83%,” said UC Davis professor and co-author Jens Hilscher.
The increased demand for these oils from the United States has also led to booms in production in countries such as Brazil and Indonesia, and some of the land conversion into these vegetable oil crops could result in deforestation. Greenhouse gas emissions are a global challenge. The authors show that local biofuel mandates often succeed in moving U.S. consumption of these fuels from one product or region to another without necessarily decreasing emissions at the national level. Their research emphasizes the importance of a coordinated effort to target emission reductions with a careful eye to the indirect consequences that inevitably result from ambitious policies.
To learn more about how federal and statewide renewable fuel policies have affected the demand for biofuels, read the full Special Issue of ARE Update 27(5), UC Giannini Foundation of Agricultural Economics, online at https://giannini.ucop.edu/filer/file/1719507310/21010/.
ARE Update is a bimonthly magazine published by the Giannini Foundation of Agricultural Economics to educate policymakers and agribusiness professionals about new research or analysis of important topics in agricultural and resource economics. Articles are written by Giannini Foundation members, including University of California faculty and Cooperative Extension specialists in agricultural and resource economics, and university graduate students. Learn more about the Giannini Foundation and its publications at https://giannini.ucop.edu.
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