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Plants and Their Relationship to the Soil
submitted by LuAnn Rolling, District Conservationist, Allamakee County

As we dive deeper into the topic of healthy soil we have to understand the relationship that plants create with the soil.  As a plant grows it excretes “food” called exudate into the area around the root.  Exudates are secretions of sugars along with a little protein and carbohydrates.  A plant can release as much as 50% of the sugars they make from photosynthesis to attract bacteria and grow fungi which eat the exudate.  One very important fungi is called mycorrhizal fungi.  This fungi actually grows with the roots and in return delivers nutrients and trace minerals back to the plant.

Mycorrhizal fungi form networks between plants and colonies of soil bacteria.  Plants can actually communicate what they need through these networks, making the fungi both a highway and the Internet of the soil.  In the lab it has been shown that a plant with healthy mycorrhizal fungi will photosynthesize much faster than one next to it that does not have the fungi.

This fungi performs many functions, including the uptake of phosphorus.  As soon as there is any free phosphorus in the soil it forms a chemical bond with another element like iron or calcium, making it unavailable to plants.  Certain bacteria produce an enzyme that can break that bond and release the phosphorus.  Once released the mycorrhizal fungi transport it to the plant.

The mycorrhizal fungi can extend far from the plant root and in dry times can greatly expand the ability of the plant to reach water stored in the soil.

Back to the root exudates – bacteria in the soil eat this and grow and reproduce.  There are also protozoa in the soil, which “eat’ bacteria.  As they eat the bacteria they leave behind excretions.  The nutrients in the protozoa excretion are plant available, so through the process of bacteria eating organic matter and then being consumed by protozoa they are making unavailable nutrients available to the plant.

In addition to protozoa there are nematodes in the soil.  Not all nematodes are bad and in fact there are many more “good” nematodes than bad in the soil.  Nematodes eat bacteria, fungj, some protozoa and other nematodes and occasionally plant roots.  When nematodes eat they also excrete plant available nutrients.  Some nematodes eat other nematodes so in a healthy system, root-eating nematodes are eaten by other nematodes and are typically not an issue.

Bottom line – soil microorganisms are so important to a plant they spend up to 50% of the food they make to grow them. A plant root alone can only directly take up 20% of applied fertilizer.  All the rest of plant nutrient uptake passes through soil biology to be made plant available.  Also crop roots touch 1-2% of the soil.  By forming relationships with fungi soil contact can expand up to 100 times more surface area than the root alone.

How do humans impact soil biology: tillage, pesticides, commercial fertilizers and growing the same one or two crops year after year.  Tillage decreases microbial diversity, increases compaction, reduces soil organic matter and reduces fungi.  Excess synthetic fertilizers cause plants to not create normal relationships with fungi and bacteria.

Bacteria consume excess fertilizer and cause a huge bacteria growth and create an imbalance in the soil. Lack of crop diversity creates fewer species of soil biology to flourish and results in an unhealthy system.

What can we do: less tillage, very careful use of herbicides, fungicides and insecticides, not over apply fertilizer and diversify crop rotations by the addition of cover crops and small grains.

Stop in Soon to Sign Up for the 2019 and 2020 ARCPLC Program
Producers now can enroll in the Agriculture Risk Coverage (ARC) and Price Loss Coverage (PLC) programs for the 2019 and 2020 crop year.  ARC provides income support payments on historical base acres when actual crop revenue declines below a specified guaranteed level. PLC provides income support payments on historical base acres when the effective price for a covered commodity falls below its reference price. The 2018 Farm Bill reauthorized and updated both programs.

Signup for the 2019 crop year closes March 16, 2020, while signup for the 2020 crop year closes June 30, 2020. Producers who have not yet enrolled for 2019 can enroll for both 2019 and 2020 during the same visit to an FSA county office.
 

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