My goal is to solve problems related to food production, the environment, and climate change. I use field experiments, simulation modeling, and analysis of existing datasets to address a set of related questions:
- What productivity and environmental goals does agriculture need to meet by 2050?
- How does cover cropping affect maize drought stress, and can cover crops be used to adapt cropping systems to more frequent drought?
- Can cover crop mixtures provide a wider range of benefits than cover crop monocultures, enhancing both production and the environment?

Agriculture in 2050: Recalibrating Targets for Sustainable Intensification
How much food do we need to grow in 2050? What will it take for agriculture to be environmentally sustainable? These are complex questions, but sometimes simple answers can provide a broad outline of the direction we need to go. Along with colleagues, I have reviewed the main projections of food demand in 2050 and updated them for recent production gains. I have also selected proposed environmental goals for agriculture that illustrate the scope of the challenges we face if we are to maintain functioning ecosystems - for instance, a stable climate and vibrant coastal fisheries. Together, our analysis points to a two-part challenge for agriculture: production needs to rise ~25-70% between 2014 and 2050 to meet food demand, while environmental impacts must plummet. At the same time, agriculture needs to adapt to changing climate conditions. This means that as we pursue "sustainable intensification" (or ecological intensification, or climate-smart agriculture, or conservation agriculture, etc.) sustainability must be a priority on par with production. Meeting both of these goals is a daunting challenge, but it motivates me to keep learning, asking questions, and working toward innovative solutions.
Read our recent publication or watch my talk on this subject from the 2016 Agronomy Society meeting.
How much food do we need to grow in 2050? What will it take for agriculture to be environmentally sustainable? These are complex questions, but sometimes simple answers can provide a broad outline of the direction we need to go. Along with colleagues, I have reviewed the main projections of food demand in 2050 and updated them for recent production gains. I have also selected proposed environmental goals for agriculture that illustrate the scope of the challenges we face if we are to maintain functioning ecosystems - for instance, a stable climate and vibrant coastal fisheries. Together, our analysis points to a two-part challenge for agriculture: production needs to rise ~25-70% between 2014 and 2050 to meet food demand, while environmental impacts must plummet. At the same time, agriculture needs to adapt to changing climate conditions. This means that as we pursue "sustainable intensification" (or ecological intensification, or climate-smart agriculture, or conservation agriculture, etc.) sustainability must be a priority on par with production. Meeting both of these goals is a daunting challenge, but it motivates me to keep learning, asking questions, and working toward innovative solutions.
Read our recent publication or watch my talk on this subject from the 2016 Agronomy Society meeting.

Effects of cover crops on maize drought stress
Using custom-built rain exclusion shelters and a wide range of ecophysiological research tools, I assessed how cover crops affect drought stress in the following maize crop. I installed the shelters in select treatments of the Cover Crop Cocktails organic cropping system experiment, which includes a rotation of maize, soy, and wheat. The cover crops were terminated with moldboard plowing following application of manure.
I found that short-term (1-3 year) effects were mostly due to nutrient availability. Cover crops that supplied nitrogen (N) to the maize, such as clover, were beneficial under both drought and ambient conditions. Those that immobilized N, such as a relatively mature stand of rye, were harmful under both conditions.
Going forward, I am interested in exploring the potential drought-mitigation benefits of retaining cover crop mulches on the soil surface and of soil improvements due to long-term cover cropping and other soil health practices. I am currently investigating these questions using cropping system simulation modeling.
Watch my talk on this subject from the 2016 Agronomy Society meeting.
Using custom-built rain exclusion shelters and a wide range of ecophysiological research tools, I assessed how cover crops affect drought stress in the following maize crop. I installed the shelters in select treatments of the Cover Crop Cocktails organic cropping system experiment, which includes a rotation of maize, soy, and wheat. The cover crops were terminated with moldboard plowing following application of manure.
I found that short-term (1-3 year) effects were mostly due to nutrient availability. Cover crops that supplied nitrogen (N) to the maize, such as clover, were beneficial under both drought and ambient conditions. Those that immobilized N, such as a relatively mature stand of rye, were harmful under both conditions.
Going forward, I am interested in exploring the potential drought-mitigation benefits of retaining cover crop mulches on the soil surface and of soil improvements due to long-term cover cropping and other soil health practices. I am currently investigating these questions using cropping system simulation modeling.
Watch my talk on this subject from the 2016 Agronomy Society meeting.

Multifunctional Cover Crop Mixes
Farmers across the country are planting cover crop mixes, or "cocktails," to improve their soils, enhance their crops, and reduce impacts on the environment. The benefits speak for themselves on many farms (not least the satisfaction of seeing an explosion of green when the ground is usually bare) but it is still important to understand the whys and hows of cover crop cocktails.
I am working to answer these questions with colleagues in the Cover Crop Cocktails experiment. We have produced a farmer-friendly factsheet and a recent publication, with more publications to come. In general, we find that cover crop mixtures can diversify the benefits that cover crops provide, making cover crop stands more multifunctional. However, we also find that individual species are often as good as mixtures--or better--when it comes to providing individual services. This is certainly true of weed suppression, where monocultures of oats or rye typically limit weed growth at least as effectively as the most weed-suppressive mixtures.
Read our recent publication, which was featured in this article in the CSA News magazine. Or, watch my talk on weed suppression with cover crop mixes, my SARE training talk on using mixes, my webinar on optimizing seed mixes for soil health and nutrient retention, or the original Cover Crop Cocktails project eOrganic webinar on managing mixes.
Farmers across the country are planting cover crop mixes, or "cocktails," to improve their soils, enhance their crops, and reduce impacts on the environment. The benefits speak for themselves on many farms (not least the satisfaction of seeing an explosion of green when the ground is usually bare) but it is still important to understand the whys and hows of cover crop cocktails.
I am working to answer these questions with colleagues in the Cover Crop Cocktails experiment. We have produced a farmer-friendly factsheet and a recent publication, with more publications to come. In general, we find that cover crop mixtures can diversify the benefits that cover crops provide, making cover crop stands more multifunctional. However, we also find that individual species are often as good as mixtures--or better--when it comes to providing individual services. This is certainly true of weed suppression, where monocultures of oats or rye typically limit weed growth at least as effectively as the most weed-suppressive mixtures.
Read our recent publication, which was featured in this article in the CSA News magazine. Or, watch my talk on weed suppression with cover crop mixes, my SARE training talk on using mixes, my webinar on optimizing seed mixes for soil health and nutrient retention, or the original Cover Crop Cocktails project eOrganic webinar on managing mixes.