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Foliar nutrition as a management tool

Foliar nutrition as a management tool

Foliar nutrition as a management tool

What is the most important nutrient a plant needs? The answer is the one that is the most limiting, called the ‘law of the minimum’. This law states that growth is dictated not by the total quantity of nutrients available, but by the scarcest nutrient.

Plants require 16 essential nutrients to complete their life cycle which are divided into macro and micronutrients. Plants require macronutrients, such as nitrogen, in greater amounts compared to micronutrients, one of which is molybdenum. All nutrients are equally important for plant growth and should be present in the soil, in adequate amounts and proportion for optimum plant growth.

Plant nutrient deficiencies occur for several reasons: when there is insufficient nutrient in the soil, where pH is significantly high or low, where a significant nutrient imbalance exists, or when they cannot be absorbed and utilised by plants due to unfavourable environmental conditions. Nutrient deficiencies can reduce a plant’s ability to fight pests and diseases, as well as interfering with cell division and the conversion of nutrients into proteins that are necessary for plant growth. Ultimately, if nutrient deficiencies are not remedied, a loss of yield will result.

Usually, crop nutritional needs are supplied via the soil through capital and maintenance bulk fertiliser applications. The quantity of applied fertilisers is usually based on soil test results. However, soils tests are only useful for macronutrients as testing for micronutrients is unreliable. As well, the tests only report what is available for the growing crop, not what was taken up by the crop. Therefore, where the situations arise as previously mentioned, look at alternatives such as foliar nutrition. Foliar nutrition is mainly based on plant tissue tests, which identify nutrient deficiencies in the crop at the time of testing.

The purpose of foliar nutrition is not to replace soil fertilisation, as this is the most effective and economical means of supplying a plant’s macronutrient needs. Foliar nutrition, however, will supply micronutrients, such as manganese, zinc and molybdenum, to the plant while also supplementing macronutrients such as nitrogen, phosphorus and potassium needed for short-term growth. This is also a quick and effective management tool to favourably influence plants that have been compromised by environmental stressors such as adverse growing conditions and/or temporary poor nutrient availability.

Foliar nutrition’s main benefits:
» Rapid correction of nutrient deficiency with immediate uptake of applied nutrients.
» Accurate and even application of small amounts of key elements.
» Providing plants with certain micronutrients that may not be readily available in the soil.
» Foliar nutrition can be combined with other foliar chemicals, thereby minimising application costs.

Contact your local PGG Wrightson Technical Field Representative for advice or assistance with choosing an appropriate foliar nutrition product for your farm.