Post-harvest Nutrition of Almonds
POST-HARVEST NUTRITION OF ALMONDS
In periods of uncertainty, investments should be done with the help of safe and proven methods and materials. Some post-harvest fertilizer additions (Boron, Potassium, Zinc) when needed it has been proven that they increase tha production. In properly managed almonds, Nitrogen, when applied in autumn, does not increase production.
Autumn boron applications can increase the outputs by hundreds of pounds per acre if analyzes on almond bone show inefficiency or marginal sufficiency of this spesific element. This sharp increase has been demonstrated in several research studies by the University of California. The recommended doze is 100-200 g. Solubor® per 100 liters of water per acre. Lower boron doze may not provide the expected results. Higher doze may decrease output per acre. Autumn application of boron through the ground increases boron levels in the tree at next year’s “flower drop petal’s” stage.
The key to effective autumn nutrition with Boron is its presence in flowers until blossoming begins. Autumn foliar application of Boron increases the vitality of pollen for the next spring and consequently increases the fruit setting compared to trees with low levels of Boron. The “pink peak” stage is also a relevant point for the effective application of foliar boron in order to increase the almond production as opposed to the application of boron at the “full bloom” stage where fruit setting reduction has been observed. Due to the difference in blooming time between different varieties in an almond tree, autumnal applications at the right doze increases the boron content of the blossoms without risk for fruit setting.
Consequently, autumnal boron application is, in best circumstances, a maintenance application. Do not expect to change the boron levels of almonds with just one application in autumn. If the production fluctuates at 250 kg kernel/ ha, about 50 grams of Boron are removed from the almond tree. This equals with 200 grams of Solubor® / acre if the whole sprayed quantity is absorbed by the foliage of the trees. If the shell content is sufficiently low, in conjunction with a specialized geotechnical, the boron level of the almond tree should be increased by spring and summer by soil applications. It should be taken into account that even increasing the boron content to a satisfactory level, an autumn spraying at a lower doze than recommended, can contribute to increased outputs.
The adequate of Zn in fruit trees is necessary for the expansion of new vegetation during the “breaking” of lethargy. Due to its easy fixation to the soil, foliar sprays are usually the most effective method of replacing Zn. Autumn foliar applications of Zn in high proportion (for example, 2.5 kg of zinc sulphate / acre) can help defoliation by supplementing the trees with the required amounts of Zn. This was a common autumn application (November) in California almonds. Recent studies have revealed that lower doses of zinc sulphate (600 g / ha) applied in October were equally effective in supplying trees with adequate amounts of zinc without promoting defoliation.
Autumn application of potassium in the soil acts as a storage method for years to come. This method was applied before the introduction of new technologies such as hydrolysis and water-soluble potassium fertilizers. Targeted fertilizer microdrops through the irrigation system are now the most effective technique to meet these needs. Only in fields where no water lubrication system can be installed does it make sense to apply it with granular fertilizers. The need for potassium should not be neglected. If the application of potassium is not incorporated into a water lubrication program then production will suffer.
Time and money in the autumn period is not enough, so careful management of the producer’s resources needs to be done. Low levels of zinc, boron and / or potassium should lead to autumn applications before the relevant periodo of flowering season.
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