Reserach and Outreach Activities

The research and outreach activities of our lab focus on nutrient turnover and plant nutrition in agricultural systems. We are interested in the effects of different management practices on nutrient use in California crops and how nutrient use efficiency can be improved, particularly with nitrogen.

Applying the right amount of nitrogen to crops is challenging. Limited nitrogen availability can decrease crop yields, while excess nitrogen can leach into groundwater in the form of nitrate. One focus of our research is on nitrogen turnover in soil and ways to improve our ability to quantify the temporal availability of nitrogen from organic sources, such as soil organic matter, crop residues and animal manure. The goal of these efforts is to develop accurate, user-friendly tools for growers to support their nutrient management decisions.

An important part of our outreach activities is to create online nutrient management guidelines for various crops grown in California, ranging from alfalfa to walnuts.

Reserach Projects

• Reducing nitrate leaching to the groundwater by accounting for the soils' capacity to supply nitrogen through mineralization
• Nitrogen requirements and release rates of organic amendments in organic fresh market tomato production
• Developing a decision support tool for processing tomato irrigation and fertilization in the Central Valley based on CropManage
• Evaluation of nitrogen uptake and applied irrigation water in Asian vegetables
• Assessment of harvested and sequestered nitrogen content to improve nitrogen management in crops
• Determining the relationship between soil health and stress indicators for plants and soil microbial communities

Outreach Projects

• California Fertilization Guidelines