That purple-stained leaves on a stunted tomato? That’s no case of neglect; usualy it’s over-fertilizing. Too much of something can be toxic, just like starving, plants needs to be balanced.
The above is a map to what nutrient overload looks like in the plant itself. Knowing that map mean managing your plants before things go wrong. Not after. Toxicity doesn’t manifest one way, and so the chart are broken down according to symptom and type of nutrient.
How to Fix Too Much Fertilizer in Plants
For instance, too much nitrogen makes the foliage go dark-green, which look healthy. However, the plant will not flower because it is focused on making leaves rather then fruit. Too much potassium cause the marginal edges of leaves to burn, as if they were scorched. That resemblance fools the gardener into watering harder! But the added water only make the soil-salting issue worse. Knowing these particular clue helps you avoid addressing incorrect issue.
Too many ions upset osmotic pressure in the root zone. This mean the area no longer pulls water into the roots and instead pull it outward. This damage occur on a cell-by-cell basis. Flushing with clean water remove excess ions from the soil, but sometimes doesn’t correct the imbalance; some nutrients inhibits the uptake of others. If you have too much of one, you will be deficient in another. For example, high levels of phosphorus inhibits the uptake of zinc and iron, resulting in yellowing of the leaves despite supplementing with iron. This is where people makes the mistake of not understanding the basic nutrient competition.
The soil pH regulates this system; that’s what governs nutrient availability to plants. If the soil pH moves outside optimal 6-7 range, it greatly change how available any nutrient is. Regardless of what fertilizers might be applied, metals such as aluminum and manganese becomes soluble in acidic soils, damaging root tips and slowing growth. In alkaline soils, micronutrients becomes unavailable, but depending off water quality, there is a risk of having too much of certain element like boron or molybdenum. To manage effectively, you must test your soil for pH to see if it require lime to increase it or sulfur to decrease it prior to applying nutrients.
It’s not enough to cut out fertilizers; we need to do things that fix the toxicity, too. We can incorporate organic matter to tie up excess metals, particularly copper and zinc. We can also grow cover crops, like cereal rye, in offseason to capture leftover nitrogen to help set the soil right again. There are special plant, too, that will gradually leach heavy metals from a polluted piece of ground over time. They all work by treating entire soil ecosystem, not just its chemistry.
An ounce of prevention is worth a pound of cure. Don’t apply too much fertilizer all at once; it can causes toxicity or nutrient imbalances. Break up applications through the season. Less is better than more; for example, potassium toxicity can lead you to overwater, which only worsens salt buildup in the soil.
Don’t guess about the fertility of each crop. Some are less tolerant of certain nutrients then others. Strawberries? Lettuce? Barley? What’s good for one may be bad for another. Get advice from local experts on how much and what types of inputs to apply, based off your soil profile. Use the chart as a diagnostic tool, but avoid creating issues by using it carefuly.
Too much food isn’t always good; provide the correct amount of nutrients at the correct time for healthy plants. Learn to read what they do tell you, rather than assume what they “should of” had.