Blue Diamond Almond Facts March-April 2021

IN YOUR ORCHARD then the set run time would be just over 14 hours under a strategy of 60 percent water application. Wait, a little, before starting the irrigation season. This is especially true if water availability is limited and the goal is regular stress through the season. Current suggestions are to wait for a SWP of -1 to -2 bars below baseline before irrigating. If using soil moisture sensors to schedule irrigation, wait until the sensors show enough soil water depletion so that all water applied in the first set stays in the soil without saturating the root zone. Small, short irrigations to deliver fertilizer, especially in a drought year where the rootzone isn’t saturated with spring rain, are a different story from first full irrigation. Watch your salt(s). Limited irrigation and/or moderate to poor water quality can lead to increased root zone salinity and eventually decreased yield. The threshold for salinity yield impact in almonds is 1 .5 dS/m in the rootzone (0–5'). With each 1 .0 dS/m increase in salinity beyond 1 .5 dS/m, yield is reduced roughly 20 percent. When needed, additional irrigation water should be added (where available) to reduce root zone salinity. Consult with your CCA about leaching requirement for a particular orchard based on irrigation water quality, soil salinity and target yield. When planning irrigation this season, consider the long term consequences on soil and orchard health of using very poor quality irrigation water. It is possible that applying more (cheaper), poor quality irrigation water this season will cost more in yield loss and reclamation costs over time than smaller amounts of better quality water. It could also reduce land value. To check root zone soil salinity, soil samples should be taken at one foot intervals to a depth of five feet, analyzed separately (not lumped) and the resulting salinity values averaged across the five depths to determine “root zone salinity”. Consult with an experienced CCA regarding sampling sites and timings through the season. Good salinity management can inadvertently result in poor nitrate management; see information about efficient nitrogen application in the next section. Rootstocks differ in their tolerance for chloride, the major toxic element in saline ground water up and down the state. (Boron is a major issue on the west side, but generally not on the east side of the Central Valley.) Lovel, Nemaguard, and Krymsk 86 showed the lowest cumulative yield (4th–7th leaf) in a replicated trial assessing Nonpareil performance with different rootstocks using poor quality irrigation water (high levels of everything bad, including chloride) in western Stanislaus County. This trial was set up and is being conducted by Roger Duncan, UCCE Orchard Advisor. Groundwater and surface water quality can change from year to year and within a year. Regular irrigation water sampling and lab analyses help inform irrigation management through the season. Including nitrate in the analysis helps with nutrient management. What doesn’t work to reduce drought stress and water use ? Removing crop or heavy pruning (scaffold removal to reduce leaf area and water use) has not reduced water use in UC studies. Crop removal and heavy pruning can increase shoot growth and leaf area and so increase water use. Nutrition: The primary nutrient concerns in almond production, especially bearing orchards, are nitrogen (N) and potassium (K), in that order. The primary goal of a fertility program is to deliver the amount of nutrient needed for the growth of crop (and the tree) as it is needed by the crop through the year. This limits waste and cost. A new best management guidelines for nitrogen in almonds was published this past winter and can be found at: almonds.com/almond-industry/orchard-management/ soil-health-and-nutrients/nutrient-management. Potassium: Most of the potassium in the trees is found in the nuts, so only limited amounts of K are needed before 3rd leaf. However, once a good crop is set early in the life of the orchard, potassium deficiency symptoms can appear (see photo) quickly if soil K is low. Nitrogen: Orchards with at least adequate leaf N levels in summer, 2020 (greater than 2 .5 percent leaf N) should 3 8 A L M O N D F A C T S