I like the analogy of an engine when talking about soil health. What is the size of your soil engine? Have you checked lately? Just like you use a dynamometer to measure the horsepower on a tractor you can use Solvita soil respiration to measure the horsepower of your soil.
The better-tuned an engine the greater the horsepower and efficiency. I believe soil is similar and by improving the quality (tuning) and building the biological factory (modifying and supercharging) your soil engine can produce more horsepower.
Over the past couple years, I have recognized that soil is probably more of a limiting factor than we realize. When I talk to farmers, crop contest winners and crop researchers they never mention the soil as a limiting factor, – that is, beyond fertilizer. Is it because they don’t think of it as a living entity that plays a significant role in yield?
Liebig’s “Law of the Minimum” states that a crop’s yield will be determined by the most limiting factor. We see this illustrated as staves of a barrel with water leaking out of the shortest stave, signifying a limited factor such as nitrogen, zinc, etc. Of course this could be weather, weed competition, pest infestations or even (and maybe more often than we think) soil health.
Farmers know how to manage crops: how to select a variety and plant it; how to control weeds, pests and diseases; and feed and water it. If seems that the soil is primarily a surface to drive over, put seed and chemical in it and apply fertilize over the top of it. Yet with all these factors optimized and in a perfect season, yields can still be limited by something else. Maybe it’s the soil that isn’t optimized biologically and that is limiting yield?
So maybe it is time to start farming the soil and starting measuring the size of your soil’s engine. This need not be complicated and involves measuring the CO2 output from soil respiration – just like measuring engine horsepower with a dynamometer. But there is more to it, you need to know the quality of your soil because you can’t have health without quality and you also want to know what all that CO2 output is doing for your soil and crop in terms of mineralizing nutrients and creating soluble carbon.
The first step is to evaluate soil by monitoring critical soil indicators such as organic matter, salinity (EC), bulk density, water infiltration, aggregate stability and nutrient availability. Field kits can be assembled to measure many of these indicators and there are values to target. If the soil is impeded physically or chemically, you can’t optimize biology.
Second is monitor the health of your soil because this is the engine that drives productivity. Run tests like the Solvita CO2 field or burst test. A CO2 burst of 12 to 30 ppm in 24 hours is low, 40 to 60 ppm is average by today’s standards. Very healthy soils will have bursts of 100 ppm or more. Remember microbes actively feed on carbon and recycle nutrients to feed roots and humic compounds to improve the soil. And the bigger the burst the bigger the engine.
Third is build the soil like you would a race engine. Don’t settle for a simple service as that is what’s done when you till, lime and fertilize. Instead build yourself a high performance engine. Adopt tactics that optimize soil indicators, improve aeration, increase organic matter and enhance microbial activity. It’s the microbial activity that will take your soil and crop production to new levels.
So maybe it is time to start farming the soil itself. It’s time to start thinking of soil as the little engine that could. You have to be positive, keep trying and know you can do it.
You can send a question, comment or topic to our guest blogger Dan Davidson CCA at: ddavidson @ woodsend.com. Dan also accepts calls at 402-649-5919.