Updated: Mar 13
The reason for releasing the beginners guide to plant nutrition is to help you from making wrong decisions in your indoor grow room. Visualize... by the end of this blog, you will be able to understand plant nutrition.
Plants are able to take in essential plant nutrients through leaves, a fact known for years. Foliar fertilization has been used for years mainly with high valve crops such as vegetables and fruits. Early uses of foliar fertilization were mainly used to balance micronutrient deficiencies such as iron deficiency with blueberries, or to boost the appearance and shelf life of foliage plants and cut flowers. Foliar applications of nutrients can balance nutrient deficiencies caused by diseases, insect damage and help plant recover from other stress conditions. Both quantity and quality of yield can be increased by foliar application of deficient nutrients regardless of cause.
Nutrient Mobility and Foliar Fertilization
Foliar fertilization is especially important for nutrients that are poorly mobile in the plant. A endless supply of these nutrients is needed to provide that plant has sufficient nutrition for acceptable growth and yield. If the supply of these nutrients from the water or growing media is unable to keep up with demand, then new growth will suffer from nutrient deficiency. The application for moderately mobile or very mobile nutrients is also important when the crop cannot take and deliver adequate nutrients to the growing points of the plant, but mobile nutrients have the benefit of being able to taken for older plant tissue and translocated to the new growing points. Foliar application of mobile nutrients will help prevent the depletion by older tissue by these mobile nutrients. One frustration in using foliar sprays to supply nutrients to plants is that intake and translocation of the applied element may not be rapid enough for growing crop yields if foliar application is the major source of a nutrient. This problem is greater for macronutrients. Foliar application of plant nutrients continues to gain increasing widespread acceptance. The mobility of nutrients generally is classified into three categories of mobility: very mobile, moderately mobile and poor or slightly mobile.
Nitrogen is a very mobile element within the plant, and foliar sprays using urea, nitrate salt and ammonium have been used to supplement the nitrogen levels in plants.
Urea is the most effective form of foliar nitrogen followed next by ammonium ion and then by nitrate ion. Urea is easiest to traverse the cutin layer to enter the plant, and is considered the most suitable form of N for foliar application because of its non polarity, rapid intake, low phytotoxicity and high solubility.
Ammonium application effectively boosts growth and yield for many crops through foliar application. Like urea, the plant assimilates most of the ammonium within 48 hours after application. Ammonium, once inside the plant cell has a similar effect on plant nitrogen, as does urea.
Nitrate, through adsorbed by the plant effectively, is less effective as a foliar source of nitrogen than urea or ammonium because it must first be convert into ammonium through nitrate reduction.
Phosphorus is a very mobile element within a plant and its application through foliar application is an effective means of supplying phosphorus. Phosphorus foliar application can increase the concentration of phosphorus in the foliage and is more effective method of delivering phosphorus to the plant via water.
Potassium is a very mobile element, and applications as foliar sprays utilize potassium polyphosphate, potassium sulfate, potassium nitrate, potassium thiosulfate, or potassium hydroxide. Many of these sources have low salt index, are highly soluble, and can provide potassium to plants in situations where a deficiency of this element will reduce yield or is needed for foliar plants going to market.
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