CULTIVATING SUSTAINABILITY
Cover Crops: Worth the Water? This year the entire West and Northern Midwest is experiencing drought, leaving some growers with barely enough water to keep their crops healthy. Beekeepers are also struggling in places like North Dakota, where honey bees are preparing for almond pollination in February and some beekeepers are reporting record low honey crops. When nectar dries up, bees struggle to produce the honey they need to survive winter.
PAm Clover Mix, for example, requires more moisture than the PAm Brassica Mix which can perform well with average seasonal rain, no irrigation needed. Recent trials conducted by University of California Cooperative Extension researchers Shulamit Shroder and Jessie Kanter give some insight as to what growers can expect from a cover crop that is grown in drought conditions. During the 2020/2021 season, a variety of cover crop mixes were evaluated at the Shafter (Kern County) research station. Most of the irrigated seed mixes were more successful than the non- irrigated ones by providing about twice as much biomass, with the brassica mix being the exception as seen in Table 1 (Shroder, Shulamit and Kanter, Jessie 2021). However, they conclude “all of the non-irrigated plots contributed some amount of biomass. This means that even if you cannot irrigate your cover crops, you can still reap some soil health benefits.”
Blooming cover crops benefit both beekeepers and growers by providing better nutrition for bees, increasing the soil’s water-holding capacity by adding organic matter, increasing water infiltration, reducing erosion, and providing natural weed control. Having forage available when bees arrive for pollination can help colonies build up strength after a tough year and ensure good pollination. On an exceptionally dry year, some cover crop plantings may not flourish as well as a year that sees average or above average rainfall. Even if your cover crops are not as robust as you might like them to be this year, the benefits are still valuable and are worth the effort. What to Expect Water is precious and promoting cover crops raises some important questions about water use. Seed blends intended to be planted in California’s Central Valley should contain species that have low moisture requirements. Sowing seeds in the fall is a great way to take advantage of fall and early winter rains. If planted early, to utilize the seasonal rains, robust, well-growing cover crop stands are possible without the use of irrigation. Early planting also encourages an early bloom which provides nutrition for honey bee colonies pollinating almonds. Planting September 10 through November 10, while soil is still warm (above 55⁰) is an appropriate time to plant any cover crop in California. However, to ensure species like canola, mustard, and radish will bloom before almonds, it must be sown and germinated before November 1. While not necessary for an adequate stand, irrigation can be used to ensure a more robust cover crop for some mixes. Enrollees of Project Apis m.’s (PAm) Seeds for Bees ® program receive seed mixes designed to be successful in harsh conditions like the non-irrigated middles of orchards. If water availability is a concern, select seed mixes that are the most efficient at growing successfully in droughts. The
Table 1. Comparing Irrigated vs Non-Irrigated biomass collected in Shafter on March 17, 2021. (Shroder and Kanter 2021)
How Cover Crops can IncreaseWater Use Efficiency Growers who participate in Seeds for Bees receive technical advice specific to them, and our team will help
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A L M O N D F A C T S
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