Improving US soil health supercharges ag productivity and locks-in global food security---it’s reverse causal.

The impacts of soil and land degradation on agricultural productivity also reveals grim results. According to Otuk and Daniel (2015), estimates for the magnitude of global crop yield reduction caused by soil degradation range from 12.7% (Oldeman, 1998) and 13.4% (Crosson, 1997) to 19% (IIASA, 2000), and even as high as 30% (Pimentel, Allen, and Beer, 1993). A review by Eswaran, Lal, and Reich (2001) found that at the field and plot level, degraded soils reduced harvests by up to 40% in rowcrops in the U.S. Midwest (Fahnestock, et al., 44 1995; Schumacher, et al., 1994); by between 30% and 90% in west Africa (Mbagwu, et al., 1984; Lal, 1987; Charreau, 1972; Kayombo and Lal, 1994); by up to 50% in some parts of Europe (Ericksson, et al., 1974); and by 20% in India, China, Iran, Israel, Jordan, Lebanon, Nepal, and Pakistan (Dregne, 1992). Soil erosion causes economic losses to the U.S. agricultural sector of $44 billion per year (Eswaran, Lal, & Reich, 2001). A 100-year analysis of a continuously cropped field in the U.S. Midwest found that, even with fertility management, degraded soils had 60% lower corn yields than at the start of the 100-year period (Gantzer, Anderson, Thompson, & Brown, 1990). The worsening of soil quality threatens global food security and livelihoods in developing nations and exacerbates climate change (Sulaeman & Westoff, 2020).

Increasing SOM through regenerative management represents the reversal of the soil erosion process: adding SOM builds soil structure and aggregate stability and makes soil less vulnerable to erosion by wind and water. Research on the impact of regenerative agriculture implementation on crop yields generally shows that crop yields stabilize or increase, with a smaller number of studies showing yield declines after implementation. It is postulated that the increase in soil fertility and the resilience that allows soil to withstand shocks and stabilize yields is mediated by the increase in SOM (Soil Health Institute, 2018).

The Soil Health Institute reviewed some of the literature on the impacts of regenerative agriculture practices on crop yield. Of the 8 studies that had sufficient data, crop yield volume remained the same or increased in 7 (Soil Health Institute, 2018). The average change in crop yield in these studies was +17.6%, while the change in the one remaining study was -6.2% (Soil Health Institute, 2018). Six of the 8 studies showed that yield variability was the same or smaller from year-to-year (Soil Health Institute, 2018).

Van Es and Karlen analyzed 3 long-term field experiments in North Carolina, which primarily differed by tillage intensity and management disposition (organic or conventional). They found that tillage intensity was the most important variable in predicting soil health levels, with minimally tilled soils having the best scores for each variable at each site (van Es & Karlen, 2019). Especially important were levels of plant-available C and N, as well as manganese (which helps break down organic matter and 45 make it available to plants). Soil health indicators were correlated with increased crop yields (van Es & Karlen, 2019).

A meta-analysis that compared conventional to organic crop production systems found that organic farms produce around 80% of the yields of conventional farms (de Ponti, Bert, & van Ittersum, 2012).8 The study does not include data on farm profitability, which can be higher in organic operations due to premium pricing and reduced input costs, even if yields are lower. A global meta-analysis that analyzed the relationship between SOM and yields of maize and corn found that increasing SOM levels increase the yields of both crops (Oldfield, Bradford, & Wood, 2019). They found that the yield benefits started to level off after SOM levels reached 2%, a threshold also found in other studies (Oldfield, Bradford, & Wood, 2019). Since about two-thirds of wheat and maize cropland globally are below 2%, small increases in SOM levels could have major yield benefits. Indeed, according to the authors, “potential yield increases of 10±11% (mean±SD) for maize and 23±37% for wheat amount to 32% of the projected yield gap (the difference between observed and attainable yields) for maize and 60% of that for wheat” (parenthetical statement my own) (Oldfield, Bradford, & Wood, 2019). The increase in SOM would also reduce the fertilizer requirements by 7% for maize fields and by 5% for wheat fields (Oldfield, Bradford, & Wood, 2019). Fertilizer reductions may be even greater in some scenarios, as a 1% increase in SOM roughly equates to 20 pounds of N that a producer does not have to apply.9

Another global meta-analysis examined the impact of cover crops on crop yield and found that with a biodiverse mix of cover crops that includes legumes and non-legumes, primary crop yield improved by 13% (when cover crops were not biodiverse, primary crop yield dropped by 4%) (Abdalla, et al., 2019). While cover crops can negatively impact yield in water-scarce regions, livestock integration with cover crop grazing offers higher profits than monoculture crop production.10

A large-scale set of field experiments in China showed that without any increase in fertilizer application, adopting agroecological and integrated crop management methods can increase rice, wheat, and maize yields by 18%, 24%, and 35% respectively (Chen, et al., 2014). The experiments also reduced nitrogen losses and GHG emissions.

In sub-Saharan Africa, intercropping of a legume tree in a maize monoculture and application of the tree’s prunings as a soil amendment tripled maize yield (Makumba, et al., 2006). A country-wide study over dozens of farms in Malawi showed that a crop rotation that incorporated semi-perennial legumes allowed farmers to halve fertilizer use while maintaining the same yield and improving yield stability (Snapp, Blackie, Gilbert, Bezner-Kerr, & Kanyama-Phiri, 2010). Field trials in Botswana also showed that reduced tillage and manure application doubled maize yields (Falkenmark, Fox, Persson, & Rockström, 2001).

According to Lal, improving SOC levels by 1 Mg/ha globally would “increase crop yield by 20 to 70 kg/ha for wheat, 10 to 50 kg/ha for rice, 30 to 300 kg/ha for corn, and 10 to 20 kg/ha for beans,” and by 0.5 to 1 kg/ha for cowpeas (2010, p. 717; 2004).

The benefits of regenerative management to crop yield and yield stabilization increase profitability and decrease economic risk for farmers. This service also improves global food security and fights climate change.

Improved Farm Profitability and Livelihoods

By transitioning to regenerative management practices, farms can become more profitable. This often occurs through some combination of yield increases, yield stabilization, reduced input costs, and/or premium prices due to high quality products. Some studies indicate that an increase in costs due to regenerative management, such as input expenses or time investment to learn new methods, are offset on a net basis by cost reduction elsewhere and/or revenue growth. Research and case studies offer insight into the possibility of increased farm profitability through regenerative management.

The American Farmland Trust compiled case studies of the economic impacts of switching to regenerative management on 8 farms across the U.S. (2019). The farms are in California, Ohio, Illinois, and New York, and represent a diversity of crop and livestock production. The case studies identify which practices on each farm created an increase or decrease in income and costs.

The most striking success stories come from two almond farmers in California. In the first, the 47-hectare Okuye Farms, additional financial outlays were more than made up for by increases in income. Okuye Farms reports an annual increase in per acre net income of $657 and an annual change in total net income of $76,155 (AFT, 2019).

The 71-hectare Rogers Farm reports even more significant gains, with an annual increase in per acre net income of $991, a return on investment of 553%, and an annual change in total net income of $173,345 (AFT, 2020). Both Okuye and Rogers Farms report increases in their crop yield as well.

The almond farms are the most dramatic of the 8 case studies. These remaining 6 farms ranged in size from 445 to 1821 hectares. These still reported meaningful growth in net per acre income, with increases ranging from $22 to $56 per acre and growth in net annual income of between $25,000 and $102,000 (see example in Figure 4).

[Figure 4 Omitted]

These case studies show that while the switch to regenerative management can sometimes entail greater costs for expenses like compost amendments, cover crop seeds, and added educational and labor commitments, they are typically more than offset by decreases in cost like reduced pesticide use and machinery usage, and/or by increases in income from improved yield.

South Dakota State University surveyed farmers to compare the profitability, resilience, and optimism of regenerative vs conventional farmers and ranchers. The poll found that 31% of regenerative practitioners increased their profitability in 2019, compared to just 12% of conventional practitioners; 83% of regenerative practitioners expected their operations to be more resilient to extreme weather, compared to 60% of conventional practitioners; and 69% of regenerative practitioners compared to 36% of conventional practitioners expected increased profits over the next 3 to 5 years (Griekspoor, 2020).

One study compared the profitability of several dozen conventional corn plots to regeneratively managed plots. It found that while regenerative plots had 29% smaller yields than conventional plots, they were 78% more profitable, due to reduced input costs and greater overall revenue (LaCanne & Lundgren, 2018).

According to a modeling study by Wang and colleagues, AMP grazing will improve both ecological outcomes and long-term profit for commercial scale ranches (2018). The study by Snapp and colleagues mentioned above showed that the incorporation of a semi-perennial legume rotation in Malawi not only stabilized yield and halved fertilizer use but also substantially increased farm profitability (2010).

It is an unfortunate truth that farming is a profession that can be exhausting, thankless, and hazardous. Many farmers scrape by on the margins of profitability. Opportunities to improve livelihoods in the industry that feeds the world are essential undertakings. In the U.S., farmers have the highest suicide rate of any profession; they commit suicide at a rate 5 times higher than the general public (McIntosh, et al., 2016). Studies have even linked depression to pesticide exposure, which is a sine qua non of conventional farming methods (Beard, et al., 2014).

Given this data, improving farm profitability and reducing chemical application are more than pathways towards climate mitigation, pollution reduction, and food security. They are vital strategies for improving the wellbeing of those practicing what is arguably one of the most important jobs on the planet.

Water Infiltration and Holding Capacity and Resilience to Drought and Extreme Weather

According to the IPCC, atmospheric warming around the globe is likely to lead to altered patterns of rainfall (Collins, et al., 2013). Some regions will get wetter, and some drier, though in both cases it is likely that precipitation events will be less frequent but more intense (Collins, et al., 2013). Climate change and growing water scarcity mean that between 5 and 6 billion people could live in water-scarce regions between 2050 and 2100 (Gosling & Arnell, 2016; Hanasaki, et al., 2013).

These trends speak to the need for society more broadly, and agriculture in particular, to adapt to different resource use patterns in coming years. Soils will need an expanded capacity to infiltrate and retain the water they receive. If water resources are more limited and costly, while farmers face greater demands than ever before in feeding a population of ~10 billion, then operations that use water most efficiently increase their chances of success.

A fundamental claim by proponents of regenerative agriculture is that as SOM and soil health increase, soil structure improves. As soil structure improves, it infiltrates water more quickly throughout the soil profile, retains more water for longer time periods, and reduces vulnerability to flooding and erosion. Each of these adaptations would make soil more resilient to extreme precipitation events and drought. Ability to infiltrate and store more water will be crucial for agriculture productivity in the semiarid regions of the U.S. Great Plains.

As with soil fertility, the improvement in soil’s water holding capacity (WHC) and infiltration rate is mediated by SOM (FAO, 2005). According to soil scientists working with Natural Resources Defense Council, every 1% increase in SOM allows an acre of soil to hold an additional 20,000 pounds of water (Bryant, 2015). Hudson found that as SOM grew from 0.5% to 3%, the available water capacity (AWC) of soil more than doubled (1994). Studies support the claim that cover crops, green mulch, and other regenerative practices increase SOM, WHC, and food security (Falkenmark, Rockström, & Karlberg, 2009).