The idea of organic farming is to focus on entire ecosystems, particularly the soil environment, rather than just the above-ground plant environment. The farmer must include air, water, soil, plants and all organisms in his agricultural practices. The goal is to stimulate biological activity in the soil and use natural organisms as our fertilizers, pesticides, and herbicides. These microorganisms in the soil are the key to our survival as a species.
Beneficial microbes have numerous benefits for plant growth. These microbes can attach themselves to large minerals and break them down into smaller pieces for the plant to absorb. They can also increase the nutrient efficiency of the plant by providing the right nutrients at the right time during growth. This leads to increase the vigor and growth of plants increasing yields and germplasm.
Soil microbes can also break down soil organic matter (SOM) to release minerals and nutrients into the soil over a long period of time. This forms an improved soil structure that gives rise to numerous pore spaces to be occupied by air and water. Taken together, these effects will be transferred and replicated in the natural environment, allowing the land to heal. To start organic farming, soil amendments must be added to jump-start the biological activity.
These soil amendments are of organic origin. That is, they are free of synthetics and are completely natural. This includes green manure, brown manure, seaweed, compost, and worms (also waste), just to name a few. These materials provide microbial inoculants (compost and worms) and nutrients (seaweed, manure) to start the process. Each farm will have different requirements based on the farm’s history, soil quality, crop choice, local climate, etc., but everyone can benefit from this step.
The key to success is to cease all, or in some cases almost all, use of farmicides (pesticides, herbicides, etc.). Farmicides kill their target, but they also kill beneficial microbes in the soil. Adding soil amendments and stopping the use of farmicides will allow beneficial microbes, such as mycorrhizae and rhizobia, to repopulate the soil.
Mycorrhizae are beneficial fungi that increase plant growth by supplying the plant with nutrients in exchange for sugars. Mycorrhizae form a fibrous network of hyphae to collect water and nutrients that are far from plant roots. This helps increase plant growth and reduces the need for direct fertilization.
These fungi also create symbiotic relationships with specific plant species to perform this nutrient exchange. Mycorrhizae have been shown to have a strong positive influence on plant growth, yield, and vigor. Another well understood symbiosis is with plants and rhizobia.
Rhizobia are bacterial organisms responsible for nitrogen fixation in soils. These bacteria convert nitrogen gas into a usable form of organic nitrogen for other organisms. Rhizobia form nodules on plant roots, which contain rhizobia bacteria. This is where nitrogen fixation takes place.
Nitrogen fixation is an incredibly energy and resource intensive process for us, and yet these bacteria do it for just a few sugar molecules. Available nitrogen is often a major limiting factor in agricultural operations where the climate and water have sufficient quality and quantity. This is the biggest benefit and it is well studied and established. However, there are more advantages to creating and allowing a complete microbial community to thrive.
Maintaining a healthy population of microbes in the soil allows the organic material to continue throughout the recycling process creating a reserve of nutrients. These nutrients are slowly released by decaying bacteria and fungi (previously killed by fungicides) present in the soil. Other soil organisms will transport heavy metals to the plant, which may be important for normal plant growth or soil remediation. Adding SOM to a soil provides the necessary elements for a healthy microbial community.
With SOM, microbes can break down large particles into smaller soluble forms required for plant uptake. SOM also adds carbon to the soil. This improves the soil structure and promotes the growth of additional microbes. A soil with high SOM has a healthy microbial community, which then helps plants take up various nutrients.
Farming operations today are increasingly dependent on inputs of fertilizers and pharmicides, and unfortunately those inputs are becoming more expensive and are required in higher doses. Using soil microbes to improve nutrient efficiency in the field will not only reduce production costs, but also produce healthier plants and crops. These microbes have the ability to seek out specific nutrients required during various stages of plant growth.
Supplying the right amount of nutrients at the right time allows the plant to grow rapidly while maintaining healthy, natural vigour. Plants can grow extremely fast when fed with a high nitrogen fertilizer. However, a high nitrogen environment can block the uptake of other nutrients, weakening the plant overall. The plant cannot maintain its defenses during this rapid growth and therefore farmicides are applied.
The application of high nitrogen fertilizers also changes the pH of the soil. This also affects the ability of plants to absorb a balanced supply of nutrients. Fortunately there is a solution. A healthy population of microbes can solve this problem.
As soil organic matter (SOM) and microbial populations begin to increase in a given soil, the pH of that soil will gradually equilibrate to around 6.5. This is important because a soil with a pH of 6.5 to 7 provides optimum nutrient availability for the plant. Coincidentally, this is also the optimum pH for soil microbial activity.
So the microbes (and the farmer) have twice the incentive to balance the pH of the soil. Microbes do it because it promotes plant growth. Strong, healthy plants provide enough food for microbes. As all these changes begin to come together, the natural suppression of diseases increases and pests no longer become a significant problem.
Once the farmer has stopped the farmicide applications, the beneficial microbes not only invade the soil, but also the aerial parts of the plant. Research has shown that healthy plants can have a minimum 60% of its leaf surface covered with fungi and bacteria! These microbes create a physical and chemical barrier on the leaf in the same way that soil microbes do.
Soil microbes have a variety of tactics they use to prevent disease in your parent plant. Soil microbes can prevent disease by excreting chemicals or creating a physical barrier around the root. Once again, your life is at stake if the plant becomes infected and can no longer provide sugars.
Organic farming also helps to improve the soil structure, which leads to more water retention in the soil. A biologically active soil creates pores to store organic matter. This is generated by root expansion and microbial growth. As plant roots grow and enlarge, they die and wither, leaving pore spaces that are used to retain air and water. Microbes also create humus: highly nutritious, highly porous, carbon-rich organic matter.
Humus is very porous and can hold a lot of water. As soils become more enriched with MOS, humus will develop from microbial activity. This allows the soil to retain much more water than industrial agriculture. Higher water retention will not only save on irrigation requirements, but can also allow a crop to survive drought conditions. Higher water capacity soils have the ability to continuously supply much more water than their industrial counterparts.
All this biological activity also increases soil carbon. Soil carbon benefits microbial communities, traps CO2 from the air, and helps clean water as it passes to the groundwater table. Plant material and sugars that feed microbes are two ways carbon is easily stored in soil under organic farming. This can effectively remove carbon from the atmosphere and offset the use of mechanical equipment on the farm. Organic farming is the key to successful agriculture and a healthy planet.
Since we must not forget through all this that microbes have populations. There may be high populations, such as those found in established biological and organic operations, or they may be low, such as those found in industrial agriculture. Varying degrees of biological activity can generate different crops in neighboring fields.
Any comparison between organic agriculture and industrial agriculture must include population counts of microorganisms. Bringing this statistic into the world of management would give scientists and farmers a basis for measuring and managing. So we can begin to understand In fact how much microorganisms can affect our agriculture and change our future.