jan-feb-2021

Franz Niederholzer, UCCE Farm Advisor, Colusa and Sutter/Yuba Counties IN YOUR ORCHARD Fertilization Prebloom is a key time for nitrogen planning. Cropload drives nitrogen use in mature orchards. For this year, consider factoring in the possible impact of water stress on production and perhaps a lighter crop than last year, maybe even lighter than average, due to the size of the 2020 crop. The annual target nitrogen rate for an orchard should be set before buds start to move and applications planned for the season. Almonds remove 68 pounds of nitrogen per 1,000 pounds of kernel crop (hulls, shells, and kernels) from the orchard at harvest. For planning purposes, multiply (68 pounds per 1,000 pounds) by average kernel crop yield from a block to get expected average crop nitrogen use in that orchard. Adjust that number upwards to account for inefficiency of soil application (divide expected crop nitrogen use by 0.70 to 0.80) and you have a target fertilizer budget for the year if no other sources of nitrogen inputs. “Other” sources of nitrogen include irrigation water nitrate-nitrogen, so include nitrate in the irrigation water analysis this spring/summer so nitrogen from this source can be used in the nitrogen budget. For every one part per million of nitrate-nitrogen in an irrigation water source, there are 2.7 pounds of nitrogen per acre foot. Reduction in fertilizer nitrogen rate due to irrigation nitrate levels will be most significant when Evapotranspiration is highest – late spring and summer. Consult with your Certified Crop Advisor (CCA) about a cost-effective program to maintain adequate orchard potassium fertility. If you have been matching crop potassium use annually or applying some on a maintenance basis, this might be a year where easing up a bit helps your bottom line without harming this or future crops. For example, work in Dr. Patrick Brown’s lab at UC Davis showed that using 220 pounds per acre per year of potassium sulfate fertilizer (not the 440 pounds per acre that is the usual maintenance rate for potassium sulfate) was sufficient to provide adequate potassium nutrition if an early season soil analysis shows 100 to 150 parts per million exchangeable potassium. To avoid any chance of deficiency, spot checking leaf potassium levels once or twice through the summer ($1 to $2 per acre for lab analysis of a leaf sample from a 50 acre block) is a good idea and a July leaf sample key confirming the orchard is not potassium deficient. Don’t fall behind on potassium. This might be a year to be a little stingy if you can. Planning Consider a meeting with your PCA/CCA to plan out economically sustainable crop management programs under several nut price scenarios for the coming year. To help with planning, there are free downloads of the updated (2019) UC Ag & Resource Economics Department’s almond cost and return studies for the south San Joaquin, north San Joaquin and Sacramento Valleys available. In addition, the “Facts and Figures” section of the annual Almond Almanac from the Almond Board of California includes data on planted acres, production history by years and varieties plus estimated non-bearing acres that provide an excellent background for developing budgets for the coming year. Successful growers I have talked with generally budget based on low nut prices to reduce the risk of bad news as the season progresses. I hope there are good bee hours at bloom in orchards up and down the state in 2021. 5 2 A L M O N D F A C T S