Issue link: https://www.e-digitaleditions.com/i/1349956
Percent of seasonal nitrogen uptake from soil STORED NITROGEN IN THE TREE STORED NITROGEN * For late harvest cultivars, cold temperatures or harvest stress can limit post-shaking uptake. Nitrogen uptake from the soil is used to support new growth and fill the nitrogen storage pool in the tree. Dormancy Bloom 70% Leaf Out 100% Hull Growth Hull Split to 3 Weeks Post-Shake* Kernel Fill Nearing Completion Early Leaf Senescene to Leaf Fall 100 80 60 40 20 0 Remobilization to support new growth Uptake and storage into perennial wood Remobilization to perennial wood within the tree starts to occur earlier than we used to think – the tree starts to move nitrogen to the buds and flowers that are going to be responsible for next year's crop as early as the kernel filling period. So, as early as June, the tree starts to mobilize nitrogen for next year's crop." From dormancy through 70% leaf out, almond trees do not take up any nitrogen from the soil. As such, fertilization should begin just prior to 70% leaf out, followed by frequent fertigation during the growing season to reduce instances of high nitrogen concentration. Nutrient demand decreases as plants approach fruit maturity and diminishes completely once the trees' leaves begin to turn yellow. (See the figure above for more details.) "There are benefits to not overfeeding early in the season and saving some nitrogen for later in the year," said Brown. "Further, growers can benefit from assessing if yields will be higher or lower than expected, and then having the flexibility to respond accordingly." In the past, logistics were a limiting factor for timing nitrogen applications. Today, the advent of drip and micro-irrigation systems and the use of injectable fertilizers have allowed for fertigation, which enables growers to easily divide fertilizer across multiple applications throughout the growing season. This flexibility gives growers more options and allows for true optimization of nitrogen management and placement. Receive your Nitrogen BMPs today! "It's exciting to organize everything we've learned over 15 years of nitrogen research into guidance that is presented in such an actionable, grower-friendly way," said Saa. Growers are encouraged to visit Almonds.com/NutrientManagement to view the Nitrogen BMPs. Industry members may also request a physical copy by emailing industry@almondboard.com with their name and mailing address. Individual management plans are best devised in conjunction with PCAs, CCAs and other field experts. For help implementing the Nitrogen BMPs contact ABC's Field Outreach and Education team at fieldoutreach@almondboard.com, or reach out to your local UC Cooperative Extension. Nitrogen Dynamics Throughout the Growing Season Almond Board of California 10 Nitrogen Management and Whole Orchard Recycling (WOR) Nitrogen application recommendations are different for orchards in which WOR takes place, which growers must consider when estimating annual inputs of nitrogen in soil organic matter. For more information on how nitrogen recommendations differ in this scenario, view pages 7 and 8 of the Nitrogen BMPs. Almonds.com/NutrientManagement