Zinc is present in several plant enzymes and is required in photosynthesis.
Zinc deficiency can arise when the soil pH is too high and adversely affects zinc uptake. High phosphorous or calcium levels can impact uptake as well as copper, magnesium, manganese and iron. Deficiency symptoms begin on the lowest leaves and are subtle. There will be slightly paler areas between the veins that become worse over time while veins remain green, the space between where leaves come out of the stem is shortened up and leaves become small.
To correct a deficiency
- Spraying with zinc sulphates can correct a zinc deficiency
Too much zinc can happen from multiple causes including proximity to mines or smelters, runoff water from galvanized building frames and contamination of water from galvanized pipes. Plants in soil with too much of this nutrient will have a very deep dark green vein colour that will eventually become blackened. Young leaves will develop yellow-green colour between the veins, which later turn completely yellow. Growth is stunted then stops, and yellow leaves develop dead patches and fall off. Too much of this nutrient is difficult to correct.
To offset an excess
- adding lime
- adding phosphorous
Soil testing is an important activity for a successful garden. Soil stewardship is an ongoing process, where you test and amend, grow some stuff, then test, amend and grow some stuff….and so on. Focus on building soil tilth so it can really hold and make available to the plants all the important nutrients. You do this in part by adding compost, manure, rock dust, bone meal, kelp & fish emulsions. Read this article series to learn more about each of the 13 key nutrients for your garden.