Area of Focus

Applied Plant Ecology

Research Interests

My lab has interest in a broad range of agroecological issues ranging from the mechanisms of interplant competition to gene flow in sorghum species to ecological weed management in organic production systems to the use of systems simulation to optimize the efficiency and sustainability of our agricultural production systems.

Courses Taught

• PLAS 426 - Invasive Plants. This course is taught every spring semester at UNL. The course provides a background on the identification, biology and ecology of weedy and invasive plants. Principles of invasive plant management by preventive, cultural, biological, mechanical and chemical means using an adaptive management framework. Herbicide terminology and classification; plant-herbicide and soil-herbicide interactions; equipment calibration and dosage calculations.
• AGRO 896 - Interplant Competition in Managed Ecosystems.This course is taught in alternate (even) years during the spring semester. This course will focus on whole plant physiological response to solar radiation, water, and nutrients, and on interplant competition for these resources. Quantitative relationships useful for integrating the interactive affects of these factors on plant growth and interplant competition will be stressed. The course will be a mixture of lecture, discussion of relevant literature, an experiment and its’ write-up, and homework sets.

Major Project Activities

1. Grain sorghum (Sorghum bicolor) and it’s weedy relatives. There has been considerable interest in modifying the quality traits of grain sorghum to enhance its nutritional value to both humans and animals raised for human consumption. There is inherent risk in deploying specific kinds of traits in grain sorghum because related species (e. g. johnsongrass, shattercane) are capable of interbreeding with grain sorghum. There has been little published research on the potential gene flow from grain sorghum to its weedy relatives, both of which are common to sorghum production regions of the USA. We’ve conducted research to to quantify the potential for pollen-mediated gene flow from grain sorghum to shattercane and johnsongrass, and to assess the risk of a trait becoming introgressed into these weedy species. Results of this research have provided valuable science-based information useful for identifying management practices that could minimize the biological risk of deploying specific sorghum traits. Parts of this research were funded by the USDA NIFA Biotechnology Risk Assessment Grants Program, 2010-2015 and 2017-2020; The United Sorghum Checkoff, 2013-2016; and DuPont, 2013-2016.
2. Ecological Weed Management in Organic Agriculture. Many studies have demonstrated the weed suppressive potential and soil health contributions of individual cover crop species, but the value of diverse cover crop strategies has received less attention. The objective of this project is to determine the effects of cover crop diversity on weed populations, soil microbial community composition, soil nutrient availability, soil water content, grain yield and profitability. Various mixtures of cover crops are incorporated into organic crop rotations. Project results will provide innovative solutions for organic farmers seeking to increase productivity, profitability, and system resilience by increasing biodiversity and reducing off-farm inputs. Funded by the Ceres Trust Organic Research Initiative, 2009-2017.
3. Conservation Agriculture. In a collaboration with colleagues at CIMMYT, we have a project on the potential success of conservation agriculture in Nepal. Conservation agriculture is a crop production system that strives to achieve acceptable profits along with high and sustained production while conserving the environment. Key principles of conservation agriculture are 1. Practice minimum mechanical tillage, 2. Keep as much residue as possible, and 3. Rotate crops. Our project involves components of all three of these principles.
4. Mechanisms of Interplant Competition. We’ve recently completed some research on the effects of variable water supply on corn and velvetleaf growth, water use, and interplant interference. The goal of this research was to understand how water supply influences interplant competition and obtain sufficient data to forecast the risks associated with variable water supply in specific environments across Nebraska and the Great Plains. We are currently building this knowledge into an ecophysiological model of interplant competition that can be used to explore the effects of climate change and agroecosystem management on weed competitiveness, potential range expansion of important herbicide resistant weeds, multispecies competition, and soil water and nutrient management to optimize crop production in varying environments, to name a few.

Extension Interests

I'm very interested in applying what we've learned through our research by incorporating results and important concepts about plant ecology into educational programs that aid producers in making decisions about best management practices in specific Nebraska environments.