29 Nov 22

Did you know that soil science is more complicated than rocket science? Here to help break it down is Matt Duncan, CPSS/CPAg/CCA, with 25 years’ experience in soil science and agronomy. Matt is Senior Sustainability Science Lead with Truterra, LLC. His passion is working at the field level to help troubleshoot yield-limiting issues while improving soil health and climate resilience at scale.

Why is soil science so important?
When it comes to agriculture, soil guides everything – what types of crops you should grow and how you should manage them. You need to know what your soil is capable of, so you can produce a profitable crop over time, despite extreme weather events. Soil health practices can make your farm more efficient and profitable while improving your resilience to extreme weather. The solution isn’t always removing or reducing inputs. It’s about thoroughly thinking through the entire system of the farm operation and soil characteristics and understanding which practices could be adjusted, added, or eliminated.

What are the components of soil health?
Soil health has three components – chemical, physical and biological. For decades in the ag industry, we've been focused on the chemical side. Things like measuring soil pH and nutrient levels and correcting them, to feed the crop whatever it’s short on.

In recent years, though, we’re looking at soil health more holistically to make improvements. For example, on the physical side, we know that compacted soil restricts oxygen and water storage and makes it hard for roots to grow. You’re not going to fertilize your way out of a compaction problem; you need to figure out how to break up the compacted soil to allow water to penetrate and roots to grow. Maybe we add some radish cover crops to create extra channels and break through some of that compaction. Or maybe we need to deep-rip the soil if the compaction is too severe.  

Then, on the biology side, even if you have a lot of organic matter in the soil, if it’s bone dry and excessively hot, the microbes won’t be able to break down that organic matter and release nutrients for the plants to take up. The question is, what can we do to encourage a healthy and diverse microbial population? Maybe a reduced tillage practice would help by conserving soil moisture.  Keep in mind, soil biologic health requires adequate chemical and physical health, too. 

It’s all about balance. Hitting the target on all three components is when we’ve truly maximized the potential of the soil – making practice changes that tilt the equilibrium towards the better each time.

You like to say, “Soil science isn’t rocket science; it's harder.” Why is that?
To understand soil health, you need to understand agronomy, biology, microbiology, geology, chemistry, physics, hydrology, climatology and a bit of ag history – basically every type of science except, ironically, aeronautics. It’s really complex because they’re all intertwined. You can have a great understanding of one science, but if you don't know how it interacts with some of those other sciences, you're going to have a hard time solving the problem that might be occurring in that field.

What does a soil scientist do?
My job is to see though the complexity to help focus on what’s most impactful and important. What can we do – as a business, crop advisor or farmer – to maximize the farm’s productivity, minimize environmental impacts, improve soil health, reduce emissions, and increase efficiency and ROI? Basically, our job is to evaluate the plant, soil, water and climate interactions to determine which piece of the puzzle is holding us back. And then figure out what we can do to compensate or correct, from the soil health side of things. It’s exciting; kind of like detective work.

How do you evaluate the soil health on a farm?
The first thing to understand is the achievable soil health level for the field in question. This is challenging because it’s relative to the inherent capabilities of the soil environment.  In other words, a numeric value that may be considered healthy for one soil in one climate might not be considered healthy in another.  Good examples of this are soil bulk density and CO2 respiration, which are used to in part to quantify physical and biological health, respectively.  The numeric value of those measures that are considered “good” is different in various soil textures and climates.  So, we need to locally benchmark soil health measures with inherent soil health potential. 

I also like to understand the history of the farm and its current practices – crop rotation, tilling and fertility management. I use SSURGO to understand the natural characteristics of the land (texture, drainage and topography), as well as historical weather data. We also collect soil samples to quantify the three soil health components in that farm and compare them to local benchmarks to better understand where the soil health level is and where it could go with improved practices.

Can you share some practical examples of addressing soil health issues?
We can't control the weather, but we can manage soil moisture through conservation methods, irrigation management, or by adjusting water table heights within that drainage system to help keep water around longer. We can’t eliminate steep slopes, but we can manage surface erosion on that slope, by adding terraces or strip-cropping perpendicular to the slope.

Soil type is important, too – how you manage a sandy soil is going to be very different than a clayey soil. Management practices that work well for one soil may not be a good option in another soil. That's where some of the complication comes in. There’s no one-size-fits-all. 

In thinking about regenerative agriculture, what’s your approach to change?
Regenerative ag is managing in a way that increases the quality of the soil and larger environment. But regenerative ag also needs to be sustainable. We need to look at enacting changes in a way that works from a financial, production and environmental standpoint. It isn’t sustainable if it isn't also economically sustainable. We can do all kinds of things just for the environment, but if the farm goes out of business or we lose 20% of our food production, that didn't help anybody in the long run.

What advice do you have for farmers?
Soil health management is complex, but it doesn’t need to be scary. It’s about going back to the basics of science and agronomy and focusing on the biggest things first. Some farms and farmers aren’t comfortable committing to selling their carbon just yet.  This is one of the advantages of Truterra’s offerings, you can get started where you’re comfortable.  

  • The Truterra™ carbon program is for the farmers that recently made, or are ready to make, practice changes and dive into selling their carbon.

  • For those who aren’t ready or comfortable with the carbon market concept yet, or for those just wanting to improve their operations, we have numerous other entry points into sustainable, regenerative management and environmental markets.  The Truterra™ sustainability tool helps them to understand where their operation ranks from a sustainability perspective, with low effort on the farmer’s part.

  • Our new Truterra™ soil health assessment includes specialized soil sampling to quantify your individual field’s soil health status and provide locally relevant recommendations on the best ways to improve it.

  • And our Truterra™ market access program allows the farmer to get their feet wet in the realm of carbon markets without being required to sell their carbon rights up front.

Bottom line: Don't be afraid to take the next step, explore and try it out.