Everyone's Concerned About Water... But What About Soil?

As climate change intensifies and its impacts become more visible, water use in agriculture has justifiably held its place in the national spotlight. Droughts across the American West in recent years have made this spotlight even brighter, to the point where water has become the foremost issue for many investors considering adding farmland to their portfolios.

Yet as water takes center stage, another equally urgent issue is playing out in the background: soil degradation.

Soil is the medium through which our food is grown, and is as fundamental to farming as any natural resource. Plants’ and animals’ nutrition begins in the soil, and we rely on healthy soils for a healthy food supply. However, the advent of commercial fertilizers and the pressure for farms to maximize crop yields over the last century has led to widespread losses of nutrition, biodiversity, and organic matter from our agricultural soils. If this trend continues, according to one senior UN official, the world would only have 60 years’ worth of topsoil left to farm.

Given the urgency to conserve and regenerate the health of our soils, the agricultural sector at large is busy looking for solutions, and a range of promising ones has emerged in recent years.

What Is Soil?

Soil is a collection of minerals, organic matter (i.e. recently dead and decaying vegetation), and living organisms feeding off of the organic matter. Unto themselves, soils are ecosystems that support the health of the plants growing in them. Healthy soils are alive with microbes, insects, animals, fungi, and plant matter, all of which interact with the water and mineral matter within the soil to enable nutrients to be available to the plants we grow.

The availability of nutrients and the suitability of soil for growing crops is impacted by many factors that humans cannot control, such as geological processes and weather patterns. However, there is one factor within our control that can improve and regenerate soils for generations to come: sustainable farmland management.

Where has all the soil gone?

Before understanding how soils can be regenerated, it is important to understand where the soil went.

In the 20th century, farming intensified significantly across the United States. Crops’ “yields”, or the amount that a given planting produces per acre, skyrocketed thanks to technological advances that completely reshaped conventional farming methods. These included new approaches to crop breeding and the advent of synthetic fertilizers. The productivity these advances unlocked even led to policy changes that reinforced these trends. In the 1970s, Former Secretary of Agriculture Earl Butz infamously told farmers to plant their crops “fence row to fence row,” and to “get big or get out,” forcing farmers to prioritize economies of scale in order to remain profitable.

The increased reliance on synthetic fertilizers, in particular, has proven to be a significant driver of the problem. The availability of extra nitrogen supplies to apply to fields at the farmer’s discretion pushed farming toward repeated plantings of the same commodity crops, such as corn, soybeans, and wheat, all of which could be grown in high volume year after year if enough synthetic fertilizer was applied. Whereas farmers may have previously managed their soils’ fertility through crop rotations or even simply leaving a field fallow, these new norms intensified annual growing cycles and left little time for exhausted soils to recover. In fact, beyond amplifying soil loss, synthetic nitrogen production has been linked to climate change and worsening air and water quality.

Today, the decades of soil depletion are catching up to American farms. In the Corn Belt, recent estimates show that about 35% of topsoil has been eroded, meaning that lower layers of soil, which are lacking in nutrients essential for growth, are now responsible for growing 75% of our nation’s corn. Poor soil quality leads to stunted plants, depressed yields, and higher rates of plant disease and infestation.

What Can Be Done?

While no agricultural conundrum has a single solution, there are several important tools that farmers can employ today to restore their soils, which in turn can improve fertility, water retention, and eventually, crop yields.

The soil microbes in healthy topsoil do much of the work that synthetic fertilizers have done, providing the ecosystem with valuable services such as nutrient cycling. In turn, a healthier soil structure is more porous, providing valuable pockets for holding onto water and other nutrients, making these available to plant roots.

Thus, increasing soil organic matter is one solution farmers are turning to.

Soil organic matter increases when farmers lower tillage and other soil disturbances, add compost, intercrop, or practice a variety of other soil-building farming techniques. However, increasing soil organic matter is a long-term process and cannot be done immediately

Today, farmers are finding innovative ways to restore their soil organic matter, from integrating perennial crops into their farmland to minimize soil disturbance to utilizing farm tools such as roller crimpers and seed drills; this allows farmers to plant new crops directly into last season’s farm residue. As an added bonus, farmers who utilize these practices aren’t only restoring their own soil fertility for the long term, they are also potentially sequestering carbon from the atmosphere.

Cover cropping is another technique that not only improves soil fertility but also prevents erosion. Cover crops are any crop planted in a field for benefits other than harvest for sale. Often, farmers plant cover crops in fields to add nitrogen, attract pollinators, add biomass, or just keep topsoil from being eroded by wind and rain. Cover cropping has been shown to increase soil organic matter by 4%-114%, depending on the variety of crop used.

Additionally, farmers often implement minimal tillage or no-till practices to complement cover cropping. By knocking down cover crops and planting directly into plant residue, rather than tilling the residue into the fields, farmers are able to prevent erosion, keep soil nutrients in place, and add to soil organic matter.

Although farmers have been adding soil amendments, such as animal manure or other forms of compost, to their fields for thousands of years, the science is now catching up with millennia of farmer observations. By some calculations, adding compost to fields is between 1 to 5 times more effective than cover cropping for increasing soil carbon.

Seed and input companies are also joining the fight against soil degradation. Indigo Ag has developed natural microbial seed coatings that make plants more resistant to pests and drought, meaning that farmers can irrigate less and therefore, prevent erosion. Additionally, companies like Ascribe Bio are developing biopesticides that can be used as a seed coating, limiting a farmer's need to apply potentially-harmful pesticides on a large scale.

To Grow Farms, Grow Soil

A farm can only be as healthy as its soil. Growing soil improves plant health, crop yields, and long-term profitability. However, while there are a host of innovative technologies and research efforts in play to combat soil degradation, farmers need the financial backing to invest in their own soil. This is step one.