Growers are increasingly impacted by and/or interested in learning how to prevent declines in the health, quality, or productivity of soils in their high tunnels. More are experiencing or aware that various biotic and abiotic issues threaten crop yield and quality and farm income. As some have learned, increases in nematode populations, disease inoculum, salinity, nutrient deficiencies/excesses/imbalances, and/or compaction or reductions in soil structure can be troublesome. Thankfully, a comprehensive effort is underway to help understand and address soil health/productivity-related challenges in high tunnel production. Sponsored by the USDA Specialty Crops Research Initiative and coordinated by Dr. Krista Jacobsen of the University of Kentucky, researchers with different expertise and extension specialists are documenting grower concerns and practices and charting a path leading to greater grower success. The OSU and five other universities are also currently involved. Team members recently hosted a focus group of eight growers from the Great Lakes (including Ohio) and will hear from more in other regions soon. Growers in the recent focus group represented a range of experience, size of operation, crops grown, typical number of annual production seasons (1-4), and overall farming approach (conventional, organic). Collectively, they shared concerns with issues referenced earlier and gave special attention to others such as the effects of high tunnel soils going extremely dry fall-to-spring unless watered (with or without also being cropped). Interestingly, this observation and concern lines up with the view shared by Dr. Bruce Hoskins of the University of Maine that high tunnel production is like “irrigated desert production in the west and southwest,” and that “failing to realize or take steps to address potential problems because of this” can be detrimental (see VegNet article Feb. 20, 2021). In any case, the recent conversation with growers was a reminder of: (1) potential causes of declines in (high tunnel) soil productivity (examples are listed below), (2) innovative steps growers and researchers are taking to limit the problem, and (3) benefits of addressing the complex problem through partnerships. It also prompted me to ask myself what I am doing to maintain the productivity of soils in my high tunnels. Maybe it will do the same for you!
The health-quality-productivity of soils used in vegetable production, including in high tunnels, can decline for many reasons. Some major ones are listed below in no particular order.
1. Repeated or excessive use of a potentially narrow range of fertilizers, various chemicals, and other soil amendments.
2. Vegetable plants often having relatively small and shallow root systems (compared to other annual crops) and crops returning relatively little residue to the soil.
3. Short rotations with few crops.
4. Placing frequent pressure on and aggressively disturbing soil, especially when it is wet.
5. In high tunnels, relatively unique and potentially extreme temperature and moisture profiles.