Balancing soil nutrition for sustainable weed and insect management

Manure fertilizers bring many benefits for plant and soil health. However, because manure is not composed with an ideal balance of macro/micronutrients for crops, meeting the needs for nitrogen can lead to accumulations of surplus phosphorous. Nutrient imbalances, in turn, may exacerbate weed and insect pest pressure, bringing unexpected and unwelcome management costs to growers (Fig 1).


With a new USDA-funded research project, we hope to help farmers use fertility inputs to achieve balanced soil nutrition that maximizes profitability and optimizes pest management, focusing on zucchini crops (Cucurbita pepo subsp. pepo), due to their economic importance and challenging weed and insect problems. Starting in summer 2020, we will begin by searching for links between soil nitrogen, phosphorous, and densities of weeds and pests, on a network of more than 50 collaborating organic mixed-vegetable farms across the Southeast. Then, we will experimentally define how different manure compost application rates impact Picture2.pnginteractions between weeds, insects, and crop yield (Fig 2). Finally, we will optimize combinations of cover crops and different compost fertilizers that improve nutrient balance while promoting natural pest suppression. Complementary economic analyses will allow growers to confidently ensure profitability while minimizing labor investments, while on-farm work with our large network of cooperating growers will ensure real-world applicability of our findings while facilitating outreach efforts. We will extend our findings to a broader audience through workshops, field days, and electronic media. Altogether, our project addresses critical needs to refine organic fertility management by quantifying costs and benefits of organic manure composts for biodiversity, soil health, and natural pest control.  

If you’re an organic farmer interested in joining our on-farm survey network, contact us here! This means that our students and/or faculty will visit your farm twice annually to collect soil samples, weed samples, and insect samples, and we’ll always share all our data and all our discoveries with you.

If you’re a prospective student interested in how soil fertility interacts with plant growth, plant chemistry, and pest resistance, we’re currently recruiting a team for spring 2020! Check out our prospective student info here.