Balancing Soil Nutrition for Sustainable Weed and Pest-Insect Management
Project Director
William E. Snyder
Year Funded
2019
Award Number
2019-51106-30188
Funded Institution
University of Georgia
Grant Program
ORG (Organic Transitions)
USDA NIFA Report
Project Overview
Reliance on manure compost as the primary source of nitrogen (N) can lead to nutrient imbalances, especially a buildup of excess phosphorus (P), which may lead to increased weed and pest pressures or other production problems. This project surveyed more than 50 organic farms in Georgia and the Carolinas to identify correlations among soil test N and P levels, soil health parameters, and weed and insect populations. Zucchini plants were grown in soils taken from each of these farms in a side-by-side trial.
Farmer Takeaways
(1) Providing sufficient N to optimize crop vigor does not aggravate pest problems.
(2) Omnivorous arthropod predator populations increase with soil N and plant quality.
(3) Elevated soil P levels resulting from reliance on poultry manure to meet crop N needs can stimulate weeds at the expense of crops.
(4) High P levels can also reduce the crop’s capacity to attract natural enemies and thereby allow pest numbers to increase.
(5) Reducing poultry litter rates and substituting cover crops and low-P compost can mitigate P accumulation and the associated pest and weed problems.
Project Outputs
Blubaugh, C. K. 2023. “An Omnivore Vigour Hypothesis? Nutrient Availability Strengthens Herbivore Suppression by Omnivores across 48 Field Sites.” Journal of Animal Ecology 92 (3): 751–59.