Some farmers are using soil probes to test land they might farm—not just land they already do.
That’s because a probe can explain more about the land than the eye can see, including what’s beneath the surface and what happened on that tract in the past. Without testing and research, it’s difficult to know whether farmland is a good investment.
While modern agricultural techniques and supplies can push even subpar fields to produce crops, the right question for prospective buyers to ask isn’t always, “Can I farm it?” but rather, “Should I?”
With one-third of the world’s soils already in fair or poor conditions, according to a 2015 report by the U.N. Food and Agriculture Organization, there’s a good chance that land you’re considering doesn’t have top-quality soil and that more intensive management will be needed. And if no amount of management can ameliorate the land, it’s best to know that, too.
The right question for prospective buyers to ask isn’t always, “Can I farm it?” but rather, “Should I?”
The Past Is Present in the Soil Structure
In many places, annual planting and intensive agricultural practices have taken a toll on soil structure and composition. The same type of soil management which has increased productivity per hectare has also depleted the land, according to experts at the Food and Agriculture Organization of the United Nations.
For farmers looking at prospective land, examining the soil using probes and other research provides a glimpse into types of crops and management approach that preceded them.
First, it’s worth looking at the government data. The U.S. Department of Agriculture’s National Resources Conservation Service keeps track of the type of soil on 95 percent of national farmland, with measurements about the soil’s acidity, drainage, and physical attributes, like location on a steep hill or preponderance of large stones.
These are a good reference, but potential buyers still need to do their research on the ground. Soil sensors can reveal nutrient levels, microbial activity, acidity, and salinity, all signs not just of what the soil is like today, but of what went on during previous cultivation. Some common practices that can deplete soil are:
Years of tilling can wreak havoc on the soil aggregates—the soil particles that bind to each other more strongly. When soil is turned over with heavy equipment, it degrades the habitat for microbes by changing the oxygen level in the soil and disturbing the environment in which microbes flourish.
Monocultures. Microbe populations thrive when a mix of plants are on the fields. That’s because a variety of crops are conducive to a similarly diverse population of soil microbes, a boon to the soil. Crop rotation can help keep microbe populations thriving.
Chemical fertilizer changes the environment of the soil, because it supplies particular nutrients in abundance. Not only does that change the nutrients available, but over the long term, it can alter other metrics like pH. By comparison, when farms have intact organic matter, soil retains more water, keeps its structure, and supports an important microorganism population.
When the top layer of a field remains exposed to wind and rain, the elements take a toll not just on the top layer, but down below as, well. Surface erosion can indicate a deeper problem with soil texture, then the lack of surface aggregates result in erosion at the surface and poor soil structure down below.
While there are many ways to detect evidence of soil’s path—including asking county agents, neighboring farm businesses, or previous owners—going underground to measure CO2 levels can indicate one clear sign of soil fertility: an active microbe population. Soil teems with living things, which are responsible for turning nutrients in the soil into elements that can be taken up by plants. When microbial activity is high, soil health follows, since the microbes can make nutrients usable not just in the present moment but in the future, as well.
But when it’s low, that can be confirmation of the intensive management practices mentioned above.
Difficulty of Remediation
Both erosion and weak microbial communities are signs of poor soil structure. Heavily tilled, frequently fertilized soil crumbles between a farmer’s fingers, evidence that it cannot hang onto as many amendments regardless of if it comes from a synthetic fertilizer or compost.
That said, the U.S. has made strides towards preserving or ameliorating soil health since 2012, when the National Resources Conservation Service launched initiatives to help farmers improve soil health. As farmers adopt standard conservation practices like cover cropping, for example, there have been slow-and-steady improvements, both to soil health, as measured by short-term outcomes like increased microbial activity or long-term changes like higher proportions of organic matter in the soil, and to crop yields.
Sometimes, the ecological and economical approach is to give the land a break from intensive agriculture. When American farmers first started farming the land, it had been untouched for years beneath forests and prairies, allowing a rich ecosystem to thrive on its own. That presents a conundrum for farmers looking for new land: to remediate the soil can take time, and after making an upfront investment, that may be a luxury farmers don’t have. On the other hand, for farmers excited to do the work of remediating soil, improving soil structure and rebuilding microbial populations can pay off, both for crops down the line and for the environmental stewardship itself.