Supporting Biology for Optimal Reproduction

April 10, 2023

As we think about the importance of biology and microbial activity for good nutrient release from the soil, better soil structure, and improved plant growth – the question we should be asking is “What does biology really need in order to multiply fast?

Or ask it another way. Considering that biology is the biggest limiting factor in most soils, and that most minerals are in the soil, but dependent upon biology for release to plants, how can we harness the potential of the microbial activity and get it working in our soils?

Here’s the deal: Biology can reproduce every 7-20 minutes, which is incredibly fast, but it is dependent upon them having the complete environment that they need. Think of biology as a living organism just like us – they breathe in oxygen and expel carbon dioxide, they need water, and they need food. They also need a good environment.

Oxygen: Oxygen is one of the most limiting factors in biological life. Humans can live several weeks without food, several days without water, but only several minutes without oxygen. Soil biology is the same. So one of things that we often recommend when we start working with a grower is to subsoil their fields if they have compaction. This is not the complete long-term answer, but it does give a short term response. The long-term answer is to start getting living cover crops that have deep tap roots into the cover crop mix and then have them photosynthesizing as much as possible so as to feed microbes, which create soil structure and build soil aggregates.

In addition to hardpans, crusting on the soil surface can also be very detrimental to soil biology. Limit tillage events as much as possible and make those as light and gentle as possible to prevent crusting and then follow up with a soil protection (mulch or living crop) as soon as possible.

Another more long-term approach for breathable, structured soil is to get the calcium to magnesium ratio right – calcium having the ability to loosen soil when not overused, and magnesium having the ability to tighten soil. Having the right calcium to magnesium ratio is very helpful although biology is much more important.

I have been asked what effect plastic mulch has oxygen and soil breathability. My answer is that I observe good crop responses from using plastic mulch, so I don’t consider it a problem. On the other hand, I don’t like to see the black woven ground cover used because I notice that it usually hardens the soil if there is no cover crop or mulch hay underneath. I know it sounds counter-intuitive, because the black woven ground cover absorbs water and plastic mulch does not. BUT look underneath both, and you will notice that soil typically does not get hard underneath plastic mulch, nor does it get a film. So biology can breathe better.

All this is important, but an additional piece is to not over-saturate your soil when watering as this pushes out the oxygen from the soil.

Water: Microbes also need enough water. So when you want to use something like the Rejuvenate program, you want to make sure that you have moisture present in order to get the best response.

As the soil biology increases, your soil will also improve its water holding capacity, which will be very helpful for long-term response.

For vegetable production, try to keep the soil moist enough to allow the biology to thrive.

Food: One of the big limiting factors today is that most soils don’t have enough digestible carbon to serve as food for microbes. This digestible carbon comes from the root exudates of plants, and the higher the plant brix, the more food / digestible carbon is produced for the microbes.

Of course, you can always use a carbohydrate source such as Rejuvenate or even plain sugar to help along, but remember that plant brix is the most important and most efficient source of energy for microbes. By extension, it also means that we want to keep the soil covered as much of the year as possible, including using cover crop mixes with plenty of diversity. And then feeding those cover crops to maximize brix levels.

The right environment: It is also important that soil biology has the right environment to thrive in, which is not an environment where a lot of chemicals are used or where the soil has an excess of carbon dioxide that is trapped in the soil because of soil crusting. Rather, the soil should be free from these toxins. We frequently use some Santerra with the Rejuvenate program to stimulate biology and help with chemical residual.

The bottom line is that the system was designed to work, given the right environment, water, food, and oxygen. Your job is to find ways to support that cycle and to enhance it. Management practices play a big role.