Minimizing Disturbance in Cropping Systems
Agriculture. It is how a large amount of our food, both animal-based and plant-based, is produced. But the systems are not natural and often our systems are broken. This broken system relies on tillage, the use of synthetic inputs, monocultures, not maintaining living plants year round, and improper integration of animals. The goal of regenerative agriculture is to minimize the negative effects of modern agronomy and restore the natural processes in our soils.
Disturbance causes a level of chaos in systems and changes in the environment. In agriculture, the disturbance can be in a few different forms. Tillage, adding synthetic inputs, and monocultures are all forms of disturbance. Each creates stress on our soil ecosystem. How do we manage each to reduce the disruption?
Tillage is the most obvious disturbance. A tillage pass mixes the soil, incorporates plants and plant residues, reduces soil armor, damages fungal hyphae, stimulates bacterial populations, and dries out the soil. The damage is dependent on the intensity of the tillage, the duration of the tillage passes, the timing of the tillage, and the type of opener doing the tillage. Wider openers will cause more disturbance while narrow openers or disk openers disturb the least. The negative effects of tillage can be partially offset if carbon-based soil amendments are being added or if seeds (either a cash crop or a cover crop) are being planted immediately after.
Using synthetic inputs such as fertilizer is a type of disturbance where natural systems of nutrient cycling in the soil, such as free living nitrogen-fixing and microbial phosphate solubilization, are disrupted. Dr. Elaine Ingham suggests that most of the soils in North America have adequate nutrients in the soil, but most of it is not available to plants. Building a functioning soil system will naturally make nutrients available from the soil as the plants and soil biology require it. There may be times where we need to supplement the system to keep things rolling, but we need to know why and when.
Herbicide use can also damage our soil microbial community. Fungicides do exactly as the name suggests: they kill fungi. Most modern agronomic practices reduce our soil fungal populations, causing issues with residue breakdown, nutrient issues, and disease resistance. Adding a fungicide to a growing plant creates a post-harvest condition of slow residue breakdown because of compromised saprophytic fungal growth that is necessary for decomposition. The lack of residue breakdown then leads to more tillage, resulting in less active fungi in the soil and more bacteria, which triggers more weeds to grow. It’s a nasty cycle.
Monoculture cropping is another form of disturbance. The type and timing of the root exudates are limited and mostly occur in the first 40-50 days of growth. The soil ecosystem needs to be fed for more days than that! Dr. Kris Nichols challenges Canadian growers to have a growing root in the soil for 250 days. When Western Canada has a maximum of 110 frost-free days it seems impossible, but by utilizing cover crops, we can greatly extend the growing season and the number of days we are putting liquid carbon into the soil.
Dr. Christine Jones talks about the “legacy effect” of growing a diverse range of different plant families in rotation, both as cash crops and cover crops. By keeping the different species in rotation, we increase the microbial diversity from the different microbiomes in the rhizosheath of the different plant families. As long as the rhizosheath maintains some integrity, the microbiome will be in the soil, allowing the following crops to access the microbial diversity. We do this by maintaining a healthy environment for the microbes and keep plants pumping the carbon into the soil.
Once we learn to minimize the disturbances that keep us from building our soils—or worse, the disturbances that cause our soils to degrade—the quicker we can allow our soils to heal and regenerate. Zero or minimum till, using cover crops, reducing the reliance on synthetic inputs, increasing plant diversity, and properly incorporating livestock into our operations all help to reduce soil disturbance. There are no silver bullets, and it’s not just one single step, but by implementing these practices into our management system, our farming is much more natural and much less “disturbing”.
