How We Grow

2021 July/Aug How We Grow

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AROUND THE WORLD able to reduce applications of synthetic nitrogen by up to 20% due to increased water holding capacity. This helps keep nitrogen where roots have a greater chance to take it up, making nitrogen less likely to leach into groundwater. Cover crops: a climate-smart practice with multiple benefits In Colusa, grower Ben King has been a long-time advocate for the use of cover crops in and around almond orchards. He says their strategic use adds organic material to the soil, with the added benefit of providing much-needed habitat for wild and managed pollinators. 3 King planted cover crops in all 350 acres of his almond orchards this past year to reap the soil and pollinator benefits offered by the practice. As the cover crops grow, King welcomes all pollinators into his orchard, noting that "what's good for a bumble bee is good for a honey bee; there's not a bad pollinator." After the cover crops have done their job of feeding pollinators – and soil microbes from their roots – it is mowed in the spring, where it will breakdown to return organic matter to the soil. "We planted what's called a soil builder, which has some mustard, legumes and some barley," King said. "The stuff we planted earlier turned out pretty good, without much precipitation. Going into May, we had a stand that was about four feet high from just rain. I see the difference in the water holding capacity of my soils where I've had cover crops more regularly from year to year." To help with the cost of planting his cover crops, King leveraged the California Department of Food and Agriculture's (CDFA) Healthy Soils Program, which provides financial incentives to farmers to implement various practices that sequester carbon. Since 2017, more than $9 million dollars has been awarded to almond-specific projects. "The Healthy Soils Program covered my seed costs and some of the costs to plant it," King said. "We need this kind of program at a much larger scale." Climate-smart agriculture: more than organic matter According to an ABC-funded lifecycle assessment 4 of California almonds, nitrogen and water use are the top two contributors to the almond industry's carbon footprint (all of agriculture in California accounts for 8% of greenhouse gas emissions in the state). When synthetic nitrogen fertilizer arrives for use in an orchard, it brings with it a carbon footprint due to the fossil-fuel based energy used in its production. ABC's Ludwig noted that growers have little control over that process, however, some fertilizer companies are working to decarbonize the energy used to produce nitrogen fertilizer, which may allow growers to choose lower carbon footprint fertilizers in the future. Once applied, nitrogen can be converted by soil microbes to nitrous oxide, a greenhouse gas with a global warming potential nearly 300 times greater than carbon dioxide. However, practices that improve nitrogen use efficiency can also help reduce nitrous oxide emissions. For almonds, such practices include matching the amount of nitrogen applied (from both synthetic and organic sources) to projected yield, 5 using April leaf sampling, applying nitrogen in more frequent and smaller amounts, 6 and making sure the irrigation system is functioning as advertised to avoid over- or under-irrigation. According to the almond life cycle assessment, greenhouse gases associated with water are from the energy it takes for pumping it. That includes moving it around the state and into the orchard, pumping ground water and/or pressurizing the water for micro-irrigation systems. Thus, efforts to ensure that pumps and irrigation systems are functioning efficiently are also climate-smart practices. Another aspect is the form of energy used for pumping and pressurizing. Moving from diesel to electric motors reduces greenhouse gas emissions both by avoiding the use of fossil fuels and 5 Growers can use the free Nitrogen Calculator in the California Almond Sustainability Program (CASP): https://bit.ly/3zMD4KA 6 "Nitrogen Best Management Practices" Almond Board of California (2020): https://bit.ly/3vGbtYx Almonds.com/CoverCrops Almonds.com/WOR Cover crops can offer benefits ranging from forage for pollinators to reduced nitrogen losses and increased soil organic matter to improved water infiltration. Download ABC's Cover Crop Best Management Practices at: WOR provides a solution that addresses how to dispose of old trees and provides a sustainable alternative to co-generation burning that can be integrated into standard orchard replanting practices, potentially improving soil health and increasing yields in the next orchard. Download ABC's Whole Orchard Recycling Grower Guide at: 3 See California Pollinator Coalition article in this edition of How We Grow. 4 "Greenhouse Gas and Energy Footprint of California Almond Production" Kendall A, et al. (2015) J. of Industrial Ecology: https://bit.ly/3gUZsJl Continued from page 2 NEW 3

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