Maybe you’ve experienced the iron shortage symptom: Young foliage goes pale between the veins but retains its green along the veins. Maybe it’s stunted maize plants with bronze leaves, especially on the bottom or sunflower plants with empty seed heads. If this is your situation, it isn’t necessarily that soil lacks iron, but rather that one of several micronutrients has been locked away. Rather, soil chemistry has locked up the nutrient, preventing the plant from getting it.
The chart provide a grid of visual symptoms for each missing nutrient and the solution.
How to Fix Missing Nutrients in Your Plants
Nitrogen, phosphorus, and potassium: Most growers test these three macronutrients, but what about micronutrients? The trouble is that unless you see signs of damage, you tend not to notice them which means a loss in yield. Because trace elements govern early-season activity, waiting till you notice symptoms waste precious time.
Iron, manganese, and zinc is all involved in making chlorophyll. Boron supports cell wall formation and sugar transport during flowering. Molybdenum helps legumes fix nitrogen from the air. If any one of these actions falters, the rest of the plant will slow even if the major nutrients are abundant.
The most common culprit? The soil’s pH level. When your meter registers higher than 7.5, the compound iron, among other nutrients such as manganese, copper and zinc, become unusable to the roots because it has joined with others in a state that cannot dissolve. Another issue is sandy soil which allows nutrients to be washed out between irrigations or rainfall. The high water table also alters the chemistry of manganese and iron making them either toxic or unusable by plant. Additionally, excess phosphorus application ties up zinc before the crop can access it.
None of those issues shows up on the typical NPK analysis, which is why the chart links symptoms with conditions in the soil that bring them about.
To correct a deficiency, select the approach that’s best for the time and crop. Soil applications (using chelated or sulfate forms) is longer lasting and suited to pre-plant decision-making. Seed treatments provide an early reserve supply of zinc or molybdenum in seedlings which is particularly valuable with maize and other legume. Foliar sprays hit the leaves’ surface within hours, making them ideal if the issue arises mid-season. Match the fix to the situation by following the chart, listing some practical choices beside each nutrient different than guesswork.
The old adage is true: prevention is cheaper than cure. Maintaining a slightly acidic soil (pH in the range of 6.0-6.8) ensures that most micronutrients are all available at once. Rotating legume crops with deep-rooted ones redistributes nutrients in the profile. Adding manures and compost slowly adds their elements to the soil. These elements are gradualy released, which also makes the soil better able to retain them. The natural nitrogen cycle also help replenish cobalt and molybdenum. All of these tactics don’t take much doing once you get into the habit of including them as part of your year-round routine.
The chart also provides a starting point if you’re seeing tip burn or some other yellowing that doesn’t seem to be related to lack of nitrogen. It takes a vague “something’s amiss” feeling and makes it into: Here are several possible causes, here’s what I can do about them, and that kind of clarity prevents small problems turning into costly ones by harvest time.
You should of used the chart earlier to avoid this.