Why Soil should be Covered

February 26, 2024

Healthy soil is soil that has an abundance of life in it. To promote soil life, you need to treat it like it should be treated – the same basic needs that we have: oxygen, water, food, and a good environment.

One of the key principles in regenerative agriculture is to keep the soil covered. A soil that is covered will have much less temperature fluctuation:

• Soil that is bare in the hot summer, with air temperatures approaching 100 degrees, can reach 130-150 degrees, while covered soil remains closer to 80-85 degrees. 130 degrees is a cooker for microbes. Many of them will die. Even at 108-110 degrees, many of them will shut down and no longer function or produce glomalin – biotic glues that help the soil aggregation that is so critical for soil breathability.
• Soil that is bare in the cold winter will also reach lower temperatures that soil that is covered – it may be may be as much as 10-20 degrees colder than soil that is covered with a heavy mat of residue. In a sense, this may seem like a good thing because we want the soil to freeze and thaw, right? But remember that biology really slows down the colder the soil gets.

From these two examples, you can hopefully begin to grasp how much temperature fluctuation can occur in a day’s time, especially from the morning to the middle of a hot summer day. But its not just temperature fluctuation – a hot soil will deplete its water resources very, very quickly, making the crops very drought susceptible, and also slowing down the nutrient cycle. A lot of negative happens just from that simple act of having the soil exposed during the hot summer sun.

Three other reasons why you should keep the soil covered are:

• Preventing soil crusting
• Weed suppression
• Reducing soil loss in rainy or windy conditions

While any mulch or dead cover will work for the above examples, the ultimate is a living crop, with many diverse species. A living crop can do all of the above just as well or better than a dead mulch, but it also brings new energy into the system through the process of photosynthesis. A living crop acts as a solar panel, capturing energy from the sun and producing sugars and carbohydrates which are used to fuel practically everything else in the whole ecosystem.

This is important because without a living crop that is photosynthesizing, you don’t have living roots in the soil. Without living roots in the soil, biology isn’t well fed. Without biology and mycorrhizae fungi, no glomalin or biotic glues are being produced. Without glomalin and biotic glues, soil will not remain aggregated. And then the soil will become compacted and plated. NOT what we want to have happen.

Soil aggregation, the structured soil that we all desire, does not happen if you don’t have roots deep into the soil. Biology feeds at the roots. Biology and mycorrhizal fungi then produce glomalin and biotic glues, which then produces soil aggregates. This is then repeated over time to create deeply aggregated soils – deeper every year until the roots no longer go deeper.

In summary, think of it this way: Living crop > root growth > biological growth > soil aggregation > REPEAT.