1) Agro-ecological intensification: We quantify the benefits/tradeoffs of agroecological management approaches on system productivity and provision of ecosystem services

Agroecological practices are part of the solution to sustainably intensify annual and perennial cropping systems. The basic principles are well known: minimum soil disturbances, permanent soil cover using residues or cover crops, natural soil fertility building practices and higher structural, temporal and functional field and landscape diversity. Yield advantages of more diverse crop rotations/landscapes and their synergistic effects with reduced disturbance are well documented; however, the underlying crop physiological and developmental mechanisms remain unclear, especially when yields stability to extreme weather events and variations in temperature and soil moisture are considered.  We are also interested in measuring a large suite of ecosystem services along management gradients in annual and perennial systems to provide a balanced assessment of the environmental and economic benefits of farming for ecosystem services. Finally, we have a growing interest in the study of how land-based livestock integration can benefits growers and sustainability and carbon footprint of the whole value chain. Understanding the role of soil health and diversity-based management options on agroecosystem functioning will help design of sustainable and
resource efficient production systems. 

Current Research Activities

  • Assessing ecosystems services provided by organic amendments and cover crops in almond production and potential tradeoffs (Emad Jahanzad, Cynthia Crézé).
  • Impact of sheep integration into vineyard on productivity, soil-based ecosystem services and C sequestration (Kelsey Brewer) 
  • Benefits and tradeoffs of drip irrigation for organic system productivity and long-term soil ecosystem services (Jennifer Schmidt, Caitlin Peterson, Meng Li)

 2) Building Resilience: We apply resilience theory to study the impacts of management options on yield stability and soil functioning under stres

Agriculture is a source of global warming but also provides solution to decrease cropping systems vulnerability to changes in climate if adequate production measures that hold substantial mitigation and adaptation potential are adopted.  Climate-smart agriculture represents a set of management strategies that 1) help adapt agroecosystems to changes in climate by increasing resilience to weather variations and changes in resource availability while 2) mitigating drivers of global warming by sequestering carbon and decreasing greenhouse gas emissions. Using integrated long-term approaches, we study the impact of management practices that sequester carbon and promote biodiversity on system stability and crop ecophysiology and soil biological functioning under stress in a diversity of agroecosystems. We apply resilience theory to crop production systems to identify biophysical indicators of resilience and their relation to systems sustainability  to inform shifts in management practices and land use.  

Current Research Activities

  • Potential of conservation practices to mitigate drought in rainfed cropping systems and the underlying mechanisms (Leah Renwick)
  • Coping with water shortages in California: how healthy soils can help? (Leah Renwick, Meng Li, Emad Jahanzad)
  • Improving resilience through integration of crop and livestock production in Brazil (Caitlin Peterson)
  • Impact of soil health building management practices on insect resistance: Development of next generation IPM for California specialty crops (Jennifer Schmidt) 

3) Root and rhizosphere ecology: We explore the potential of root traits and the rhizosphere to enhance acquisition and uptake of soil resources

Although yields have steadily increased since the mid-20th century, additional gains are critically needed
to meet projected demands from rising population, diet shifts, and increasing biofuels consumption. Efforts to increase crop yields using limited resources can benefit from a better understanding of 1) how root system adapt to their environment, 2) functional root traits instrumental to maintain nutrient and water acquisition under stress, 3) root traits contribution to ecosystem processes such as nutrient and carbon cycling and 4)  beneficial synergies in the rhizosphere.  In addition, little is known about root systems of crop wild ancestors, yet, promising targets for future genetic improvement lie underground as wild ancestors used to grow in nutrient-variable environments with large interspecific competition. One of our hypothesis is that centuries of domestication and decades of breeding under optimal conditions have selected for root traits decreasing plant fitness in challenging environments.  We study how root traits drive ecosystem processes and take an evolutionary approach to elucidate historical changes in crop morphology, developmental plasticity and yield responsiveness to water and nutrients.

Current Research Activities

  • Uncover the effects of domestication and breeding on maize and tomato root eco-physiology, rhizosphere processes and resource acquisition strategies (Jennifer Schmidt, Meng Li, Vanessa Brisson) 
  • Elucidate how management practices shape rhizosphere community and processes (Jennifer Schmidt, Meng Li) 
  • Understand plant control and stability of microbiome recruitment across management and biotic/abiotic stress gradients (Jennifer Schmidt, Meng Li) 
  • Belowground niche complementarily of cover crop stands and feedback to soil ecosystem services (Cynthia Crézé)