The Rhizosphere & Subsoil Biological Activity
The Rhizosphere is the region of soil that surrounds plant roots; technically, it is just below the top layer of leaf mulch. It is the region where the biology and chemistry of the soil are influenced by plant root growth, respiration, and nutrient exchange. Many interactions occur in the rhizosphere between plant roots, minerals, organic compounds, solutes, gases, and microorganisms.
There are countless microbes in the rhizosphere. These microbes are fueled by root tip exudates (sugars) released from the roots into the rhizosphere and expand into the soil. Mucilage, a water-soluble viscous material from various plants (such as seaweed), is also an exudate that contains protein, polysaccharides, carbon, and sugar. These nutrients stimulate microorganism growth and metabolic activities.
In addition to sequestering nutrients from plants through their roots, soil also absorbs nutrients from food scraps, compost, hay mulch, and other organic matter. This organic matter moves into the subsoil. It then breaks down into components that are more soluble for plants to more easily absorb.
Plant nutrients exist in the soil as cations (positively charged nutrients) or anions (negatively charged nutrients). Most soil particles are negatively charged; the amount of negative charge is dependent on soil texture. Highly weathered soil, such as soil found in the tropics, is positively charged and attracts negatively charged (anions) nutrients.
Negatively charged soil attracts positively charged nutrients (Cations) such as magnesium, calcium, and potassium. The soil holds these nutrients and releases them to plants as needed. Plant roots “tell” the soil what specific minerals they need (iron and phosphorus, for example). The subsoil delivers the nutrients requested by the plants via their roots.
Cation Ion Exchange, in soil, is a chemical process that allows positively charged nutrient ions (cations) such as calcium, magnesium, and potassium to be held and released to plants as needed. Cation Ion Exchange happens when nutrient cations are attracted to negatively charged cell surfaces within the root. The Cation Exchange Capacity (CEC) is the measurement of the negative charge on the soil —the soil’s ability to hold cations. When a cation becomes bound to a plant root cell, the root releases a hydrogen ion. This lowers the pH of the immediate surrounding soil area. Nutrient ions that are not as closely bound to the soil will move more quickly through plant material, and, if there is enough moisture for leaching to occur, the nutrients will pass through and be lost to the plant.
The nutrient content of the soil can also be increased by nutrient layering and by adopting the no-till farming method. These processes minimize soil disturbance and can also increase the nutrient content of the soil. Less soil disturbance gives the soil biology a chance to thrive. For more information on no-till farming, see “Gabe Brown—Brown’s Ranch” on the No-Till Growers YouTube channel and on Advancing Eco Agriculture’s YouTube channel.
Mycorrhizae are symbiotic associations where fungi colonize plant roots, providing the plant with increased water and nutrient uptake, especially phosphorus, in exchange for carbohydrates (sugars) produced during photosynthesis. This mutualistic relationship enhances plant health, growth, and resistance to stress and disease. The fungal hyphae extend far into the soil, exploring a larger area than roots alone, and can help improve soil structure and nutrient availability.
Endomycorrhizae refers to a type of mycorrhizal association where fungal hyphae penetrate the root cortical cells of plants. This association enhances nutrient absorption, particularly of phosphorus, and is common to more than 86% of plant species.
What goals do we all have in common to encourage Nature’s processes?
Generally, we add to the soil and minimize soil disturbance. Of course, proper organic matter and mulch are of key importance. We must acknowledge that our impact does alter natural systems. The question is: How can our impact improve crop yield and the diversity of the soil ecology? Our impact is tangible yet can be of a beneficial nature. Each way is a unique method that is chosen. Each situation is special as we intuit the best direction.
An understanding of the process is needed. This includes testing and having the experience to understand how the application, frequency, and action work. Our observations and methods are subject to constant updates as our understanding grows. Every situation is as unique as its biology. What we observe is important, but there is no fully objective understanding due to the are many subjective inputs.
The application of Mineral MAX AG Biostimulant affects plant roots, soil, and their interactions. The entire chain of geological forces, compost, mulching, plant activity, and Rhizosphere, with full biological activity of the bacterial, fungal, and mycelia networks, and the process of decay and breakdown contribute to the interchange between the soil reservoir and plant, securing their nourishment.
Thanks to Nature.com and traceandsave.com