Summer leaf sampling is serious business

It’s July. Among key orchard activities as harvest approaches, it’s time to sample almond leaves for nutrient analysis. The lab analysis report for a leaf sample serves as part of the “report card” for your fertility program for this growing season for a particular variety in a particular block. A previous post from "The Almond Doctor" covers the practice of summer leaf sampling and shows the University of California critical nutrient levels for almond leaves sampled in July. This post will talk about several additional steps to orchard nutrition assessment in summer and to stress the importance of these practices to the commercial success of an orchard.

Take separate leaf samples for each variety in a block. Crop load is the key factor determining mature almond tree nitrogen (N) and potassium (K) use. Different almond varieties in the same block can produce different yields and nutrient demand based on their genetic potential and conditions at bloom. If you don’t already, consider taking leaf samples for nutrient analysis from each variety. Use the lab reports and crop yield reports from each variety in the block from this year as background information when it comes time to apply N and/or K fertilizer for next year. If you applied the same amount of N and K fertilizer this season to all trees in an orchard, yet the Non-pareil yield was off and the Monterey yield was high, can you see that reflected in the leaf analysis reports? Variety specific leaf analysis and cropload data can help you understand how different varieties use expensive nutrients and how you might possibly fine tune your fertilizer delivery to optimize yield without wasting money. Look up between leaf samples. Adequate tree vigor (growth) is key to good production. Adequate leaf nutrient levels and little to no growth may indicate lost yield potential. When you or an employee is pulling leaf samples, bring a note pad along. Assess and record tree vigor in the different varieties. This information, combined with lab analysis reports and yield data, can help with future orchard fertility planning.Make sure the person pulling your leaf samples is trained and attentive. Leaf analysis reports are keys to orchard fertilizer use decisions that run to hundreds of dollars per acre per year. Don’t let Alfred E. Newman (“What me worry?”) take your leaf samples. Make sure the person sampling knows to take only leaves from non-bearing spurs, sample from similar trees across the block, keep careful notes and ID for each sample, and keep the sample cool after sampling and before mailing. You have a lot riding on the leaf analysis results. Make sure you get good information. That starts with the quality of the samples. Don’t make leaf sampling and who does the work an afterthought to your July almond orchard practices.