Agriculture Reference
In-Depth Information
Why is Humus Important?
Most people think they would like to have high humus in the soil, but
Albrecht's work in this area revealed that even humus cannot completely
annihilate all the problems. With soils that are high in humus always ex-
pect copper deficiency problems. Peat and muck-type soils generally
mean production problems because of copper deficiency.
The term humus is not used on most soil audits, but there is the desig-
nation, organic matter percent. Humus and organic matter are often used
interchangeably. Humus is made up of decomposed residues which have
been completely broken down in the soil by microorganisms. The organ-
ic matter or humus terms notwithstanding, when talking about a long-
term reservoir for nitrogen, phosphorus, sulfur, boron and zinc, I am not
talking about undecomposed residues. This is referring to the humus
(that is, completely decomposed organic residues) — without it, the
reservoir function wouldn't happen.
Why does humus hold nitrogen, phosphorus, sulfur and boron while
clay does not? Because humus is “stronger” than clay. If you could take a
handful of clay in one hand and a handful of humus in the other hand,
and measure the nutrients, humus has three times the nutrient-holding
ability of the clay.
Humus improves the physical properties of soil. It helps hold water
better. It certainly adds to the tilth and friability of soil.
Next, it aids in micronutrient nutrition of plants through chelation re-
actions. It encourages microorganisms in the soil because it serves as a
good source of food for microbes.
Humus aids in solubilization of plant nutrients from insoluble miner-
als. This means that it helps break down fertilizers that are on-scene in
the wrong form and tied up or complexed.
— Neal Kinsey and Charles Walters in Hands-On Agronomy
