Soil Analysis By Leaf Testing For Correct Fertilization

Tasteless food is a good measure of the micro-mineral concentration in your soil. ASAP Plant Minerals is the effective way to assure biosynthesis of phytochemical nutrients in crops. Nitrogen, potassium and phosphorus work in synergy with micro-minerals and need them present to grow not just plants, but plants with nutrition. The strong fragrance in flowers and rich taste in food is due to micro-nutrients present during photosynthesis of phytochemicals. Testing leaves is an easy way to see what’s going on underground.

Plants need two distinct groupings of fertilization. The well known type of nitrogen, potassium, phosphorus and sulfur applications that are adjusted depending on season. In the spring, the nitrogen and phosphorus with a lower potassium combination is applied to stimulate root and green growth, then as photoperiod shortens after the summer solstice, potassium is high, with nitrogen and phosphorus delivered at a lower concentration to stimulate fruit maturation. The other type is the micro-mineral elements, which are poorly understood and mostly neglected having not as obvious an effect on growth as NPK. Minerals stimulate photosynthesis of phytochemical nutrients inside the chloroplast cells at the microscopic size frame and their effects are less apparent until the crop is harvested and can be tasted. The major difference between the two is that the first type produces the size of food, the second type puts the nutrition into food. ASAP understands these two areas of soil and plant nutritional requirements and can offer some clear thinking on the subject.

It is extremely important that the right amount and kind of the first group fertilizer is applied to fruit trees and grape vines. For example, too much nitrogen (N) can result in oversized, poorly-colored fruit which does not keep well. If growth continues late in the season (because of excessive N), trees fail to harden properly and are more subject to winter injury. Diseases such as fireblight of pear and apple, or canker of peach, can be more serious if N levels are too high. Too little N also causes problems such as poor fruit set, small fruit, pale foliage and stunted growth. N control is the most common and serious nutritional problem in Ontario orchards and vineyards. Excessive levels of N occur more frequently than deficient levels.

Micro-nutrient stripping in the soils in the United States is more common. K deficiency and excess are also frequently encountered. Grapes, for example, often show K deficiency as the crop matures, even though the clay loam soils on which they are grown test high in K. This is more serious in dry years or with heavy crops.

Soil pH should be checked every 2 to 3 years. Micro-nutrients are very sensitive to acid or base conditions and incorrect pH can produce unavailability or toxicity. Excesses or deficiencies of micro-nutrients also can result in serious metabolic functional problems in crops. This is where ASAP Plant Minerals has its greatest effects, micro-minerals are essential for the utilization of the big three and even more important if you are growing food for nutrition. With increased fertilizer costs and environmental concerns, proper fertilizer use becomes even more important.

Excessive potassium can lead to magnesium deficiency. Low magnesium levels particularly in vineyards and apple orchards are becoming more common. Without understanding the intricate link between NPK and micro-minerals Zn, Mn and B deficiencies are created in orchards when micro-minerals are not replenished. When the big three are used year after year; these minerals are simply removed. All disorders, however, can be most readily identified by leaf analysis to evaluate what is missing in the soil by identifying what is found in the leaf tissue. In many cases, growers have found that the cost for each leaf sample has been returned many times over in reduced fertilizer costs and/or in better crops of higher quality fruit.

Leaf Analysis:

The Ontario Leaf Analysis Service for fruit, initiated in 1958, was one of the first to be introduced in North America. An analytical service is now available from accredited private laboratories for apple, peach, pear, plum, cherry, grape, strawberry and blueberry. Growers of these crops have an effective method of predicting fertilizer requirements and of measuring responses to their fertilizer and cultural programs. Each lab has a basic and complete two tier analysis.

The best method of determining the kind and amount of fertilizer to apply to fruit trees is by leaf analyses. It effectively measures macro and micro-nutrients and indicates the need for changes in fertilizer programs. Leaf analyses integrates all the factors that might influence nutrient availability and uptake and shows the balance between nutrients. For example magnesium (Mg) deficiency may be the result of a lack of Mg in the soil or from excessive K levels or both of these conditions. Leaf analyses can indicate the balance between K and Mg and show hidden or incipient deficiencies. Adding N, for example, when K is low may result in K deficiency because the increased growth requires more K.

An example of how leaf analyses data might be interpreted:

A Fuji apple leaf sample taken the last 2 weeks of July tests 2.30% N. This is at the low end of the optimum range and suggests a need for slightly more fertilizer N. If the trees had been heavily pruned the previous spring a greater increase in fertilizer N might be applied since pruning would have increased leaf N concentrations. On the other hand, if the trees are to be pruned heavily next spring, the same rate of fertilizer N might be applied this year since growth and N uptake will be stimulated by the pruning. If the trees are on M26 or M9 rootstock, an even greater increase in N rate should be applied since the leaf N is no longer in the optimum range. If the leaf K is 1.4% an increased rate of K fertilizer is needed since this is the bottom of the optimum range and an increase in N fertilizer rate will increase the need for K. The increased K rate may increase the need for Mg if the Mg concentration is below .25%.

Testing fruit and leaf is an easy and safe way to investigate the condition of the minerals in your soil to assure the growing medium of your plants. But applying ASAP Plant Minerals in fall and spring will always provide the stripped micro-nutrients back to your soil for the big three to work.

August Dunning is the head Research Director at

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