Clay and humus play an important role in soil structure and plant growth, however, too much of one of them is frustrating and too little of the other is a pending death sentence.
What is clay?
Clay in soil is a fine-grained natural rock or soil material and appears in deposits due to weatherization. ( If you are living in Brazoria County, Texas then you are living on a deposit- ha!) Clay can appear in soil in various colors from white to dull grey or brown to deep orange-red. A clay particle is finer than silt and sand and according to geologist and soil scientist, a clay particle is less than 2 micrometer. (a hair strand is about 100 mm in diameter) Due to how small a clay particle is, it has a larger surface area compared to silt and sand and contributes to the chemistry of the soil. Clay mineral is usually negatively charged and attracts water and positively charged elements in the soil, such as calcium, potassium, magnesium, etc. With that being said, clay isn’t entirely harmful because it has some ability to retain water and nutrients, however if there’s too much of it, because of it’s small size, it can choke the soil out of all its oxygen and block soil microbes from encouraging soil structure and nutrient cycling …making the soil hardpan and dead.
Now, what about Humus?
Humus is the end product of decomposed organic matter that was had by soil microbes. It can be seen as the chocolate/black gold of the earth and acts as an anchor for soil nutrients. It appears in color ranging from dark brown to black and smells earthy and is fluffy to the touch. Humus is negatively charged and has a high cation-exchange-capacity (CEC) that helps the soil retain water and positively charged elements that are beneficial to plant heath. Humus appears in soil from organic matter that is left alone and microbes that eat it or each other and releases nutrients. It can also appear in soil by adding Compost with a capital- C and weatherization, but these take either some work and or time. The end result and benefits of organic matter breakdown (humus) are accessible nutrients that can be taken up by plants, improved soil tilth, pest-resistance, and toxin reduction. If there is too little humus in the soil, plants suffers, insects are happy, animals suffer, and we suffer. In the US, the average amount of organic matter in soil ranges between 1-5% and ideal percentages to grow flowers and vegetables are 4-6%.
In other words, there can never be too much humus in our soils, unlike clay, it improves our well-being as well as other life forms. So please. Keep your soils covered with organic matter and add compost! ❤
Links to check out
Soil Components: http://articles.extension.org/pages/54401/basic-soil-components
Percentages of OM in soil: http://homeguides.sfgate.com/ideal-percentage-organic-matter-soil-73408.html
How plants eat: http://organicsoiltechnology.com/cation-exchange-capacity-of-humus.html