hi all. i have a 25-15-15 fertilizer for my citrus. it also has trace minerals - 0.02%iron (is this enough for the tree or should i add more in the spring?) 0.01%maganese and 0.01%copper. i know what the iron and the maganese are for, but the copper? i have only ever seen it as used for antifungal preparations. is this its purpose in the fertilizer, or does it have some other benefit to the citrus i dont know of? thanks in advance for any help :) dan
Yes, Cu is an essential element for citrus trees--In some commercial orchards, there is enough Cu from foliar sprays that has accumulated in the soil that they do not need to supply additional. In addition, there are several others not listed--Magnesium, Zinc, Sulfur, Boron. These can be added as a foliar spray or a soluble mineral mix added to the soil (S.T.E.M. by Peters is one, Essential Element mix by So Ag. Industries is one that I use).
As with all fertilizers it is assumed everything in the product you have bought will be needed by your specimens and in the amounts provided. This is, of course, not necessarily the case at all as soils and potting media vary in mineral content. Fertilization is also affected by minerals in irrigation water. Soil sampling and testing is used by farms, nurseries and other seriously interested parties to get an idea of what the mineral situation in their soils is like. The next level is to actually have the leaves of the crop itself analyzed. Home gardeners here can get assistance with soil sampling and testing from the USDA Cooperative Extension Service network. I do not know what may be available in England at present.
thanks for the great replies :) i am slowly but surely building up more knowledge of how to grow and care for citrus :) these forums are a gold mine!!
