IN YOUR ORCHARD
Chico, CA on January 12th, 2023. Standing water can be seen where no cover crop is present. Photo credit: Project Apis m.
Diving in: Below the Orchard Floor Compaction
Soil Microbes Cover crops support a diverse variety of soil dwelling organisms that can benefit tree crops. Cover crops in perennial agriculture systems increase arbuscular mycorrhizae — a type of fungi which colonizes tree roots and helps provide almond trees with greater access to nutrients and water. Greater diversity in the soil environment may also decrease soil-borne pathogens. Organic Matter The decomposition of plant matter, particularly roots, increases soil organic matter. The bulk of the chemical composition of organic matter is carbon. Because of this, sequestering carbon from the atmosphere through cover crops is a major potential environmental service that is actively being studied in almond systems. Currently, it is suggested to add compost along with cover crops to reliably build soil carbon levels.
Cover crops can reduce soil compaction by simply forcing compacted particles apart through root growth. This root growth helps build stable soil pores and channels, improving soil aeration and water infiltration, thus reducing run-off of fertilizer material and pesticide residues. In one study, it was shown that soil compaction could be reduced by almost 40% using cover crops. Soil Water There is some concern that cover crops might compete for, or increase overall water use. Recent research has shown that cover crops can have a minimal impact on total water consumption. In some vineyards cover crops have been shown to increase water content in deeper soil levels. This is thought to be due to increased water infiltration. Cover crop evapotranspiration and soil evaporation have not been fully studied in almonds and further research is needed to understand all its effects. In particular, drip irrigation systems and how they relate to cover crop growth and soil water conditions is under investigation. Some of these water-related research questions are currently being studied at UC Davis, funded by Project Apis m .²
Seeing the Action: Above the Surface Suppression of Weeds
Cover crops may suppress weed growth in the areas of the orchard they are grown by outcompeting and shading weeds or reducing weed seed germination via the cover crop termination process.
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ALMOND FACTS
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