Sustainable Soil fertility Management for Organic Vegetable Farms
Small-scale organic vegetable production is on the rise across the nation and Montana is no exception. However, managing soil fertility and soil health more broadly in these systems can be challenging. According to a recent survey of Montana organic vegetable growers conducted by the Organic Advisory and Education Council, less than a third of growers felt that their fields had adequate fertility and methods for improving soil quality and fertility was the second ranked educational need behind educating consumers about the benefits of organic food. Organic production practices can promote tillage and require soil amendments (e.g. composted manures) that can be difficult to find in needed quantities, expensive and or potentially threaten soil health and water quality if over applied. For example, reliance on animal manures for fertility can result in over-application of nutrients such as phosphorus (P) and potassium (K) and also must be applied prudently to avoid potential herbicide contamination.
With these concerns in mind, the objectives of several projects at the Center are to:
1.) Evaluate soil health (nutrients, microbial activity, and weed seed banks) in organic vegetable farms in Montana
2.) Improve growers' ability to manage soil fertility/health and
3.) develop alternative practices that integrate cover crops and livestock to provide more balanced soil fertility, better economic returns, and reduced risk of herbicide contamination.
Soil Health survey in Organic Vegetable Farms:
Balanced Fertility for Vegetable Production in collaboration with Dr. Mac Burgess, MSU-Bozeman
Integrating Pasture Poultry for Fertility and Profits in Rotation with Organic Vegetable Production
Useful Links: WSU-Puyallup has conducted similar trials
Green Manure Mulch in Tomatoes
Results: As expected, yields were lower in green manure treatments than reference treatment (black plastic mulch). The difference in yield between the plastic and living mulch (~30%) were due to changes in the number of fruit per plant rather than changes in fruit size (see table). We had predicted that planting the clover later would reduce competition between clover and the tomatoes and increase tomato yields, but this was not supported by the results, which showed it didn’t matter when the cover was planted.