Diversity in Application

by Erik Biksa

A crop may respond as diversely to the range of environmental factors that may occur relative to the diversity of the building blocks that are available to it. Often the most complex of the building blocks are found in the soil chemistry. There are volumes of research that demonstrate that all plants require source(s) of carbon, oxygen, hydrogen, nitrogen, phosphorus, potassium, sulfur, calcium, magnesium, iron, zinc, copper, manganese, boron, and molybdenum. However, there has also been a considerable amount of research conducted on the benefits of sub-micro nutrients, the interactions of beneficial soil life with nutrient sources, and the composition and range of the nutrient sources themselves.

How all the different components interact with one another is of significant importance. When there is a greater level of diversity in the soil composition, there are considerably more possibilities in terms of nutrient availability and uptake. The quantity of nutrients in the soil environment is only as effective as the availability of those nutrients in the soil solution through a range of conditions.

This article will likely be the first in a range of articles that stresses applying diversity to the root environment. For starters, let’s look at macro and micronutrients (listed above). In nature each nutrient has distinct characteristics in how it is cycled in the root environment. For example, the nitrogen cycle is very complex and may produce more than one form of plant-available nitrogen (N) for crop uptake. It is understood that N is typically the nutrient required in the greatest abundance for plant growth. In the nitrogen cycle, soil life may produce the following:

• Ammonium (NH4). This form of N is highly available and mobile in the soil and root environment. Over-applications of this form of N by indoor growers can lead to serious cropping problems.
• Nitrate (NO3). This form of N is also available to the plant, but tends to be leached away easier from the plant and soil environment. This helps to make it a preferred source of nitrogen for indoor growers.
• Urea (CO(NH2)2). This is an unavailable form of nitrogen, but is a source of potential plant-available N.
• Ammonia (NH3). This is also an unavailable source of nitrogen. However, ammonia is typically more readily converted to plant-available nitrogen than urea. Often soil life stores potential N in this form.
• Nitrite (NO2). This is a precursor to plant-available NO3.
• N2 and N2O (nitrogen gases). In the soil environment these are forms of nitrogen lost as gases. In nature, they may re-enter the soil environment as a source from the atmosphere.

From this small and brief example we can see that nature has intended that plant nutrients be supplied in diversity. Synthetic nutrients help growers to ensure that there is a high level of nutrient availability for the crop in the correct forms and ratios. Products that offer a diverse range of plant-available nutrients are typically going to be more effective than those products that have a limited diversity, particularly where trace elements are concerned. Make no mistake: just because trace elements are used by the crop in much smaller amounts relative to macronutrients such as nitrogen, this by no means lessens their significance in achieving the full genetic potential of a crop. Organic nutrients by nature typically contain a wide array of nutrient sources, due to the various parent materials used in the composition of the product blend/formulation. The availability of nutrients from purely organic sources is largely dictated by the soil life. In some instances, the source nutrients have been “pre-digested” by organisms to produce a diverse range of nutrients that are more available (i.e., NO3) compared to undigested organic sources (i.e., NH3), but they may be slightly less available than synthetic nutrient sources.

Historically, synthetic nutrient sources used a very limited range of ingredients or “parent materials” (from a strictly chemical sense) because of the relative availability of the synthetic nutrients to the crop versus their organic-based counterparts. In short, these formulations are of the school of thought that diversity found in organics can be replaced by improved availability of a single source. While in a sense this holds true, today’s growers who push the boundaries of conventional yields have realized the importance of supplying their crops with a more diverse range of nutrients that are highly available to the crop through a range of conditions.

Let’s look at iron (Fe), a trace element required in greater quantities than most trace elements. Typically, levels ranging from 5 to 7.5 ppm are considered ideal in the soil solution. As you may or may not be aware, iron (Fe) is relatively unavailable to the plant due to the electrical charge that it carries and its reactions with the chemical composition of the root environment. That is why nutrients, particularly synthetic nutrients, are said to be supplied in “chelated” or “complexed” forms.

Almost every synthetic nutrient on the market contains Fe EDTA, the most common form of chelated iron. This form holds the iron in a relatively tight bond with the complexing agent. If the bond is too tight, it will not be released at absorption; if it is not held tight enough, it will be lost to the soil environment and not be made available for absorption by the crop. The availability of micronutrients including chelated formulations is largely dependent on pH levels. There is more than one form of chelating agent, and some chelating agents work better than others at certain pH levels. For example, Fe EDTA is more available at lower pH levels while another more common chelate Fe DTPA is more available at slightly higher pH levels. One of the highest-quality synthetic chelates is Fe EDDHA. This synthetic chelate is held in a bond up to 100 times tighter than DTPA because it has six molecular bonds rather than five points of bonding, while EDTA chelates have only four points of bonding.

In nature, soils that produce healthy crops have a wide spectrum of naturally occurring chelates present. Among these chelates are citric acid, malonic acid, gluconic acid, fulvic acid, and amino acids.

Chelates that are the most active often are lower in molecular weight. Proteinates can be very effective chelating agents and in some instances have a strong influence on the availability of a range of nutrients. Glycine is an amino acid with a molecular weight of 75. Compared to Fe EDTA (the most common synthetic chelate), with a total molecular weight of 382.1, this organic chelating agent offers greater activity on a molecular level. Studies have demonstrated the following:

1. Organic chelates increase the availability of micronutrients compared to common synthetic chelates.

2. Crops tend to have greater yield when micronutrients are supplied with a wide range of complexing agents, both organic and synthetic.

There are nutrient formulations on the market that contain all of the above-mentioned chelating and complexing agents, including proteinates. To improve the availability and range of nutrients available using conventional nutrient formulations, the grower may choose to supplement his or her feeding regimen with nutrient additives containing organic and inorganic chelating compounds. Some additives will also contain other beneficial carbohydrates, vitamins, and growth promoters, in addition to organic and inorganic chelating agents.

Some formulations based on current research supply both the macro- and micro-elements they contain with a range of complexing agents. Elements such as magnesium and calcium are arguably considered macro-elements due to the abundance in which they are required by modern-day croppers. These elements may also be chelated or complexed with organic chains such as proteinates and fulvic acids.

So, for now let’s leave off with the sense that by supplying the necessary nutrients in available forms, formulated in ratios using a diverse range of sources (organic and inorganic), we can ensure that our crops have all the resources available to help them achieve their maximum genetic potential. Remember that the growing environment will drive the growth of the crop; the nutrients you apply are the building blocks.