Soil applications of nutrients are necessary and the most common practice in crop fertilization, but it has many limitations with respect to nutrient bioavailability for plants. Plants use different inorganic nutrients in addition to CO2 and water for their growth and production. Most of these nutrients inherently exist in soil but can be depleted by the high crop loads and monolithic crops that we produce today. Nutrients such as phosphorus (P), potassium (K) and most of the micronutrients, have relatively low soil availability given their insoluble forms. The more soluble nutrients such as nitrogen (N) are easily leached down into the soil, especially in soils low in organic matter. Concerns about nitrate leaching dominates news headlines these days, with reports of contaminated aquifers, groundwater and environmentally sensitive areas.
It’s well known that leaves can absorb nutrients as a natural process by which plants obtain nutrients from rainwater. This principle is utilized in agriculture by spraying the foliage with diluted solutions of the desired nutrients, called foliar fertilization. It’s generally recommended to foliar feed additional N (1 lb. of foliar fed N is equivalent of 4 lbs. soil applied N), magnesium (Mg) and micronutrients as well as P, K and sulfur (S). The importance of nutrients, especially micronutrients, in plant nutrition is still one of the crucial areas of study for plant biological sciences. We’re learning that small deficiencies in micronutrients have large consequences, and the interactions among elements is crucial to their availability to the plant.
Foliar applications of nutrients are fairly common, yet many growers don’t use them so as to derive the most benefit. For one, we believe that frequent foliar applications are better than fewer, more concentrated foliar applications. Nutrient availability from the soil to the plant is a much more delayed process than foliar applications, which can deliver nutrients to plants when they’re most needed in adequate concentrations. Foliar fertilization improves plant nutritional status as well as increasing crop yield and quality (Smoleń 2012). Foliar sprays stimulate nutrient uptake from the soil through the release of sugar (carbon) in exudates that stimulate microbial life, which in turn releases more nutrients to the plant and expands root systems.
Foliar applications also have the additional important benefit of mitigating the damaging effects of many stresses (e.g., heat, drought, frost, etc). Finally, there is a good deal of flexibility in the ability to spray selected plant nutritional compounds (i.e., simple sugars, disaccharides), growth regulators and stimulators, amino acids, peptide chains, pesticides and nanomaterials (Smoleń 2012; Shalaby and El-Ramady 2014; Simões et al. 2017). These foliar applications can turn things around very quickly when plants aren’t doing well, or conversely, further contribute to a healthy crop.
Foliar biostimulant applications are essential for moving agricultural production to the next level. However, biostimulants need to be applied at the right time, and only foliar applications can take advantages of those strategic windows. Foliar applications should be part of any grower’s program.
Andaman Ag sells an array of foliar sprays, including our premium foliar fertilizers like Agrostimand Agroprime, and biostimulants like Aquasap, a seaweed extract of 0-0-35, CropBioLife, a flavonoid nutrient synergist and Sea-Crop, containing a broad, complex range of natural sea minerals and active organic substances that provides everything a plant needs to function properly.