Soil

The Soil Enjoys Our Company

Whether you’re a commercial grower or a backyard hobbyist, there are three things that will never lie to you: your soil, plants, and animals. When we are willing to observe their simple truths, we gain a tremendous amount of understanding and a new appreciation for the world around us.

Soil is the foundation.

The soil is a living organism; a complex network of macro- and micronutrients, microbes (bacteria, fungi, nematodes), water, air, and earthworms to only name a few. A healthy and vibrant soil is responsible for providing a suitable environment for capturing and transforming energy to plants, animals and microbes. What is added or subtracted from this complex network has great consequences on the ability of these key players to perform or operate.

A comprehensive description of soil quality includes a diversity of microorganisms. Choosing soil amendments or practices that support this living organism is critical to its survival! Unfortunately, many products on the market today are only concerned with yield…not quality. Because soil quality is so crucial, products should not only feed the plants, but they should also feed the soil.

Soils that are biologically active will contribute to overall plant health, yield, and quality year after year. To feed the plants, we must first feed the soil! Effective application of plant-available, soil nutrients during high demands is essential for optimum crop performance and environmental protection (23, 39).

Many other factors affect the availability of nutrients already present in your soil.

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Soil pH. Chemistry in action. pH can affect availability of several essential nutrients needed for plant growth. Extremes in soil pH can tie up nutrients or cause toxicities. The key to excellent root growth is a soil pH between 5.8 and 6.4.

Compaction. In compacted fields, roots remain shallow and are usually not well anchored. Shallow roots are at greater risk of lodging and drought stress. They are unable to tap into deep-soil nutrient or moisture reserves. Essentially, a compacted soil cannot “breathe”. Thus, gas exchange is very important to soil health.
Organic Matter. Organic matter is a key characteristic of soil and environmental quality (12, 17, 36). Plant debris breaks down and eventually becomes available for the next crop. It is a rich nutrient resource and has many exchange sites for nutrients to attach. A soil with 1% organic matter content could be expected to mineralize approximately 40 lbs nitrogen/acre/yr (32).

Microbes and earthworms. To maximize results, we MUST recognize the role of living organisms in the soil; we can no longer look at a field as a lifeless storage bin for water and inorganic nutrients (40). Soil is so much more!

Read MoreMicrobes (e.g., fungi and bacteria) and other soil organisms (e.g., earthworms and beneficial nematodes) help to neutralize pH, reduce soil compaction, increase organic matter and contribute to soil complexity. For example, earthworms turnover soil organic matter, help create and maintain good soil structure, and increase nutrient availability and nitrogen content (18, 26).

Earthworms act like garden tillers by mixing soil matter and dead, decaying plant material, thus increasing the amount of organic matter in the soil. In fact, earthworm castings are loaded with microbial activity (13).
When one soil component is enhanced, a cascade of effects occurs. Soil bacteria and fungi make use of this new environment created by earthworms. In many cases, an increase in soil fauna can increase nitrogen mineralization by up to 25%. Also, plant biomass (i.e., leaf and root tissue) is increased in the presence of microbes resulting in higher yields (33).
Fertilizer inputs can dramatically affect these communities. High nitrogen inputs found in many conventional production systems can reduce the abundance of soil microbes, whereas organic production systems can enhance biological communities (14). Regardless, the soil will respond to all inputs in some way, however, it is up to us to listen to its needs!

Fertilizer inputs. Timing, rate and placement all influence nutrient availability. Making fertilizer accessible to roots at critical growth periods is essential for establishing healthy, vibrant plants. However, too much nitrogen can potentially create environmental problems.

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For example, nitrogen applied in acidifying compounds have direct, adverse effects on soil chemical properties (27, 35) and earthworm populations (20). The use of alternative soil amendments result in a higher quality soil and a greater plant disease suppression (6). Soils in organic production systems lose less nitrogen into water sources than conventional production systems (19).

As stewards of the soil we must understand the impacts of our agricultural decisions:
– Potassium chloride or KCl, commonly applied as 0-060, contains high levels of chlorine (~48%), a great disinfectant!
– Anhydrous ammonia can adversely affect soil structure, increase soil pH, and dry out soil organic matter. Availability and composition of organic matter are key factors affecting microbial biomass and community composition (3, 11).
– Chemical pollutants (i.e. pesticides and heavy metals) have been inflicted on the biosphere at an alarming rate. Unstable nutrients and pesticides can be directly transported into water reservoirs (2, 5, 28).