agriculture—minimal disturbance (low or no-till), keeping living plants growing at
all times (cover crops), and growing a diversity of crops—work synergistically to
cultivate beneficial life (Montgomery 2017). In addition, microbial inoculants have
been shown to be able to enhance the growth, health, and nutrient density of various
crops (e.g., Lambert et al. 1979), although it can take finding the right microbes to
partner with particular crops because different plants form symbiotic relationships
with different fungi (Smith et al. 2011). A 2014 meta-analysis of the effects of
mycorrhizal fungi on zinc uptake by crops that surveyed 104 articles reporting on
263 field trials (Lehmann et al. 2014) illustrates contemporary interest in potential
agricultural applications.
Recognition of the role of soil organic matter in sustaining fertility also has been
growing (Tiessen et al. 1994). Reviews of the effects of no-till farming on soil
organic matter consistently report increases in the amount of organic matter in
topsoil but mixed results for full soil profiles (Powlson et al. 2014; Haddaway
et al. 2017). However, most such comparisons treat no-till as a stand-alone practice,
while the efficacy of no-till for increasing soil organic matter appears to depend on
integration with other practices, particularly in combination with both cover
cropping and more complex crop rotations.
One long-term study in southern Brazil documented that 25 years of conventional
tillage decreased soil organic matter to less than a fifth of the amount in native soils
(Oliveira Ferreira et al. 2016). But soil organic matter levels recovered almost fully
over two decades after switching to high-intensity, no-till farming using cover crops
and a diverse rotation (Oliveira Ferreira et al. 2016). Similarly, regenerative farms in
Ohio, South Dakota, Saskatchewan, and Ghana have combined practices based on
minimal disturbance, cover crops, and diverse rotations to restore soil organic matter
to levels comparable to native soil in those regions (Montgomery 2017).
But the individual practices don’t work on their own nearly as well. For example,
a recent UC Davis study showed how adding cover crops to regularly tilled fields
does not necessarily increase soil organic matter (Tautges et al. 2019). The 19-year
study compared the effects of nitrogen fertilizers, winter cover crops, and composted
poultry manure in tilled corn-tomato and wheat-fallow crop rotations. Soil organic
matter in conventionally managed fields did not increase and the addition of cover
crops increased carbon in the topsoil, but produced offsetting losses deeper in the
soil profile. Yet soil carbon levels increased overall by about two-thirds of a percent
a year in the field that received both cover crops and composted manure. The authors
attributed this striking difference to compost feeding life in the soil.
Working together the full system of conservation agriculture practices works to
promote the care and feeding of beneficial soil life—and the economic viability of
regenerative farms that rebuild soil health and thereby slash farmer expenses for
diesel, fertilizer, and pesticides (Montgomery 2017; LaCanne and Lundgren 2018).
Agricultural systems that employ all three principles are growing in adoption on
farmland around the world. Global acreage under conservation agriculture rose from
less than 3 million hectares in the early 1970s to about 180 million hectares in 2016,
about 12% of global cropland (Kassam et al. 2019). This new system of farming
holds the potential to regenerate soil health as a consequence of intensive farming
12 The Revolutionary Potential of the Hidden Half of Nature in Agriculture and. . .
199
all times (cover crops), and growing a diversity of crops—work synergistically to
cultivate beneficial life (Montgomery 2017). In addition, microbial inoculants have
been shown to be able to enhance the growth, health, and nutrient density of various
crops (e.g., Lambert et al. 1979), although it can take finding the right microbes to
partner with particular crops because different plants form symbiotic relationships
with different fungi (Smith et al. 2011). A 2014 meta-analysis of the effects of
mycorrhizal fungi on zinc uptake by crops that surveyed 104 articles reporting on
263 field trials (Lehmann et al. 2014) illustrates contemporary interest in potential
agricultural applications.
Recognition of the role of soil organic matter in sustaining fertility also has been
growing (Tiessen et al. 1994). Reviews of the effects of no-till farming on soil
organic matter consistently report increases in the amount of organic matter in
topsoil but mixed results for full soil profiles (Powlson et al. 2014; Haddaway
et al. 2017). However, most such comparisons treat no-till as a stand-alone practice,
while the efficacy of no-till for increasing soil organic matter appears to depend on
integration with other practices, particularly in combination with both cover
cropping and more complex crop rotations.
One long-term study in southern Brazil documented that 25 years of conventional
tillage decreased soil organic matter to less than a fifth of the amount in native soils
(Oliveira Ferreira et al. 2016). But soil organic matter levels recovered almost fully
over two decades after switching to high-intensity, no-till farming using cover crops
and a diverse rotation (Oliveira Ferreira et al. 2016). Similarly, regenerative farms in
Ohio, South Dakota, Saskatchewan, and Ghana have combined practices based on
minimal disturbance, cover crops, and diverse rotations to restore soil organic matter
to levels comparable to native soil in those regions (Montgomery 2017).
But the individual practices don’t work on their own nearly as well. For example,
a recent UC Davis study showed how adding cover crops to regularly tilled fields
does not necessarily increase soil organic matter (Tautges et al. 2019). The 19-year
study compared the effects of nitrogen fertilizers, winter cover crops, and composted
poultry manure in tilled corn-tomato and wheat-fallow crop rotations. Soil organic
matter in conventionally managed fields did not increase and the addition of cover
crops increased carbon in the topsoil, but produced offsetting losses deeper in the
soil profile. Yet soil carbon levels increased overall by about two-thirds of a percent
a year in the field that received both cover crops and composted manure. The authors
attributed this striking difference to compost feeding life in the soil.
Working together the full system of conservation agriculture practices works to
promote the care and feeding of beneficial soil life—and the economic viability of
regenerative farms that rebuild soil health and thereby slash farmer expenses for
diesel, fertilizer, and pesticides (Montgomery 2017; LaCanne and Lundgren 2018).
Agricultural systems that employ all three principles are growing in adoption on
farmland around the world. Global acreage under conservation agriculture rose from
less than 3 million hectares in the early 1970s to about 180 million hectares in 2016,
about 12% of global cropland (Kassam et al. 2019). This new system of farming
holds the potential to regenerate soil health as a consequence of intensive farming
12 The Revolutionary Potential of the Hidden Half of Nature in Agriculture and. . .
199