From Cover Crop Charts to Living Systems: How Diversity Builds Resilient Soil
- kloot1
- 6 days ago
- 5 min read
In early September 2013, just before the Atlas storm swept across the Dakotas, I met Dr. Mark Liebig at the USDA-ARS laboratory in Mandan, North Dakota. He handed me a single laminated sheet — the now-famous Cover Crop Chart — a visual guide to plant diversity that still feels timeless, like a periodic table for living systems. Each square on that chart represented not just a species but a function in the soil ecosystem.
I’d first encountered the idea of crop and cover crop diversity three years earlier, in Burleigh County, ND, and it changed how I thought about diversity. The pattern was simple yet profound: four great functional groups — warm-season grasses, cool-season grasses, cool-season broadleaves, and warm-season broadleaves. Within those quadrants lay nearly every cover-crop decision a farmer could make. Diversity, I realized, wasn’t random mixing; it was design — the deliberate arrangement of contrasts in growth habit, rooting depth, and seasonality that keeps a system balanced.
When Liebig and his colleagues at Mandan began articulating what they called Dynamic Cropping Systems or DCS (Liebig et al. 899–903), that principle found its scientific footing. A dynamic system isn’t a fixed rotation but an adaptive one — a sequence that responds to precipitation, market signals, soil conditions, and opportunity. It’s diversity over time and space: a living experiment that evolves with each season.
That same theme echoes in Natalie Sturm’s recent essay, “It’s Not Just No-Till: Why Crop Rotations Matter More Than You Think”. Sturm argues that no-till practices alone can’t deliver resilience unless they’re paired with thoughtful crop rotations — a claim that mirrors Liebig’s research from the northern Great Plains. Both contend that diversity, not uniformity, is the real driver of soil health.
Liebig’s long-term research at Mandan confirmed that principle in practice. His team found that dynamic cropping systems improved both yields and soil health, with higher organic matter content and infiltration rates than in static three-year rotations (Liebig et al. 2007). Flexible sequencing also reduced disease and weed pressure while improving precipitation use efficiency and nutrient use efficiency (Tanaka et al. 2007). As weather variability increases, such adaptable systems become not just beneficial but essential — enhancing resilience by allowing producers to seize environmental and market opportunities, increasing adaptability “amid an uncertain future” (Hanson et al. 2007).
Fast-forward to September 2025, when I spoke again with Ray Archuleta—this time in the Carolinas. Ray calls living plants “the mouth of the soil.” His language of green bridging—keeping living roots active between crops—reminded me of Liebig’s data-driven insight. While Liebig quantifies dynamic systems, Ray personifies them. One speaks in charts and yield curves, the other in parables of living roots and “liquid sun.”
While Ray speaks evocatively of living roots and “liquid sun,” it’s important to be precise: “green bridge” is also a pathology term. A green bridge forms when living plants — volunteers, weeds, or poorly chosen cover species — persist between cash crops, providing pathogens or insect pests with continual living tissue in which to survive and multiply. That continuity can increase disease carryover from season to season. The flip side, which Liebig’s dynamic-sequencing logic supports, is that thoughtful sequence and species choice can break that bridge: terminating a host cover before pathogen buildup, selecting non-host covers, timing grazing or termination to interrupt lifecycles, and building a microbial community that suppresses disease. In short, green bridging can be a problem — or, if managed deliberately, a problem prevented. (Liebig et al. 2007; Tanaka et al. 2007).
When we speak of “context,” the sixth soil-health principle, this is what we mean. What works in one system may falter in another. Liebig’s 2006 paper on long-term DCS trials stresses that such research must evolve with local conditions; static experiments risk losing relevance as environments and markets change (Liebig et al., 2006).
So here’s the takeaway. A cover crop isn’t just a pause between cash crops, or an erosion stopper—it’s a service crop, a connection of life that carries energy from one season to the next. Liebig’s science and Archuleta’s storytelling both remind us: if the soil stays green, it stays alive.
Works Cited
(Please get in touch with us if you have any problems accessing these works.)
Hanson, Jonathan D., Mark A. Liebig, Stephen D. Merrill, Donald L. Tanaka, and Joseph M. Krupinsky. “Dynamic Cropping Systems: Increasing Adaptability amid an Uncertain Future.” Agronomy Journal, vol. 99, no. 4, 2007, pp. 939–43. USDA ARS.
Liebig, Mark A., Donald L. Tanaka, Joseph M. Krupinsky, Stephen D. Merrill, and Jonathan D. Hanson. “Dynamic Cropping Systems: Contributions to Improve Agroecosystem Sustainability.” Agronomy Journal, vol. 99, no. 4, 2007, pp. 899–903. USDA ARS.
Liebig, Mark A., Donald L. Tanaka, Joseph M. Krupinsky, Stephen D. Merrill, and Jonathan D. Hanson. “Dynamic Cropping Systems: Implications for Long-Term Research.” Proceedings of the Great Plains Soil Fertility Conference, vol. 11, 2006, pp. 132–36. Kansas State University.
Sturm, Natalie. It’s Not Just No-Till: Crop Rotations Are Key to Improving Soil Quality and Grain Yields at Dakota Lakes Research Farm. Master’s thesis, South Dakota State University, 2022. Open Prairie, https://openprairie.sdstate.edu/etd2/366.
Tanaka, Donald L., Joseph M. Krupinsky, Stephen D. Merrill, Mark A. Liebig, and Jonathan D. Hanson. “Dynamic Cropping Systems for Sustainable Crop Production in the Northern Great Plains.” Agronomy Journal, vol. 99, no. 4, 2007, pp. 904–11. USDA ARS.
Summaries of Liebig’s Works
Liebig et al. (2007), “Dynamic Cropping Systems: Contributions to Improve Agroecosystem Sustainability.” Introduces the DCS concept, emphasizing adaptability in crop sequencing. Reports yield and soil improvements from flexible rotations compared with fixed systems. Advocates for managing cropping decisions annually based on environmental and economic factors.
Tanaka et al. (2007), “Dynamic Cropping Systems for Sustainable Crop Production in the Northern Great Plains.” Field data from no-till DCS experiments show that prior crop and residue strongly affect yield, residue cover, and precipitation-use efficiency. Demonstrates that legumes and diverse rotations enhance system stability.
Hanson et al. (2007), “Dynamic Cropping Systems: Increasing Adaptability amid an Uncertain Future.” Argues that DCS prepares producers for future climate and market variability. Calls adaptability the new cornerstone of sustainability and encourages long-term monitoring of DCS impacts.
Liebig et al. (2006), “Dynamic Cropping Systems: Implications for Long-Term Research.” Examines how to design meaningful long-term DCS trials. Suggests that research must adapt to remain relevant and that flexible experimentation better mirrors real-world farming decisions.
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