Soil Health is a relatively new phrase in agriculture that describes the important role soil plays in the long-term sustainability of crop land. Soil health involves a productive balance of soil chemistry (nutrients), soil physics (structure), and soil biology (soil microorganisms). The potato industry needs productive, healthy soils to remain competitive. Therefore, it is good to ask the question, “How does soil health relate to my operation?”.
Sometimes it is easier to understand a new concept by saying what it is not. Farmers know the opposite of soil health and they have a word for it. Problem, low yielding, unresponsive fields are referred to as “tired”. Tired fields are fields in which the potato crop struggles to reach its yield potential and/or potato yields decline over time. Farmers respond to tired fields by increasing inputs such as fertilizers and pesticides to improve production. Tired fields are a problem because they increasingly cost more to farm and inevitably provide the least return on investment. Farming tired fields, one feels as if they are on a treadmill fighting the problems with little hope of finding a way to improve the situation. Collectively, the potato industry has many thousands of acres of tired fields that, as a whole, reduce the sustainable footprint of the industry.
Poor soil health and the resulting tired fields develop through intensive farming practices including short rotations, use of harsh chemicals, and/or planting disease susceptible varieties. Over time, these practices lead to a substantial build-up of disease, a reduction in native soil biological activity, and stagnant or declining yields. Often, the potato rotation cycle includes other intensely farmed cash crops that provide little organic matter back into the soil. In response, potato farmers actively search for new fields, usually further from the packing shed, to replace the worst of the tired fields. However, often higher production costs on tired fields are just replaced with travel and transport costs to and from new fields. This constant search to find new farmland does little to fix the soil health on tired fields.
The first step in improving soil health in tired fields is to stop doing the cultural practices that caused the problem. That is as blunt as it gets. There will not be improvement until changes are made. One has to make the choice to step away from current production practices and invest in new ideas that build long-term sustainable yield improvements. Start by building soil health on the land you own and then branching out to land partners to build soil health on rented ground in the community.
The first step in improving soil health in tired soils is to jump start the native soil biology. This is accomplished by feeding the soil micro-organisms. Cover crops are a proven way to feed soil microbes. The second step to improve soil health is to reduce soil borne disease. The fungal potato pathogen, verticillium (early die, verticillium wilt), and the traditional chemicals used to suppress verticillium are often associated with tired fields. First, let’s dive deeper into the benefits of cover crops.
The standard responses to the benefits of cover crops are that they stabilize topsoil, recycle nutrients and build fertility, suppress soilborne diseases and pests, reduce weed pressure, add organic matter to the soil, and promote biodiversity or create a reservoir for beneficial organisms. The benefits of the cover crop don’t end when the cover crop is incorporated into the soil. The long-term soil health benefits are just beginning. Healthy soils are teeming with countless numbers of bacteria and fungi. The organisms that feed on organic matter in the soil are called saprophytes. Through the breakdown of organic matter in the soil, like cover crops, saprophytes cycle nutrients, compete with and prey upon soil borne pathogens, and produce unique compounds that improve soil structure. Additionally, saprophytes are known to associate with living plant roots in a beneficial relationship that promotes plant growth.
Saprophyte growth is critical to building the physical, chemical, and biological health of a soil. Saprophytes are allies in crop production. Don’t fixate on the percent organic matter in the soil. Instead, think about the flow of organic matter through your soil. Organic matter is the food used to farm the beneficial bacteria and fungi in your soil. To bring back soil health, the saprophytes have to be sustainably farmed as much as the potato crop.
A cover crop is only the first component to solving the tired soil puzzle. The second component of improving soil health is the inclusion of Strike soil fumigation in the rotation sequence. One might ask how the use of a soil fumigant can improve soil health? The answer is that not all soil fumigants act the same way in the soil. Strike soil fumigants suppress several important potato soilborne pathogens including verticillium. However, Strike applications also stimulate the growth of native soil saprophytes in the soil. By promoting the growth of saprophytes post-application, Strike use helps cover crop organic matter cycle through the production system.
A solution to improving soil health is within easy reach. Potato rotations should include a cover crop that produces a large amount of biomass but that does not host potato diseases. Ideally, this cover crop would be incorporated into the soil late summer the year before the potato crop is planted. Strike soil fumigant is applied as an in-row application the fall before the potato season. Potatoes are planted directly into the Strike treated rows in the spring. Strike suppresses potato soil borne diseases and stimulates the growth of native soil saprophytes. During the season, the soil microbes that feed on the cover crop literally breath life back into the soil contributing to processes like cycling nutrients, reducing disease pressure, and building soil structure. These benefits build over time as soil health rebounds.
Many may be thinking this Cover Crop/Strike system won’t work on their farm. Well, it is working to improve potato production on many farms in many parts of the world. It requires adapting to a new soil fumigant and a few new sustainable crop production practices. Improvements in soil health cannot be expected until beneficial changes in farming practices are made. Better soil health builds land value and should be embraced by both those growing the crop and those buying the crop. The future environmental and financial sustainability of each farm and the potato industry is dependent on adopting practices that improve soil health.