Project Title: Nitrogen Management Guidelines for Olive Growers to Improve Soil Health and Sustain Production

The rapid expansion of newly developed high- or super-high-density (SHD) olive orchards in California, critical nitrogen (N) inputs required for olive production, and renewed interest in soil health are leading to a rising demand for developing best management practices (BMPs) for N use in olives. The goal of this project is to assess N recommendations and improve N management guidelines for California olive growers to manage SHD orchards. This will be done by providing information on how soil health parameters, crop N uptake, yield, and fruit quality respond to the use of different N rates and organic amendments in olive orchards.


Project Title: Cover Crop Strategies to Tighten Nitrogen Cycle, Save Water, and Increase Soil C Sequestration and Reduce Greenhosue Gas Emissions

The use of cover crops increases soil carbon (C), nitrogen (N) fertility, and soil productivity, making it an appealing practice for climate change adaptation and sustainable land use. The project goal is to develop management guidelines for walnut growers that use cover crops by providing information on the mineralization, distribution, and uptake of soil N, as well as water use and C sequestration. Such information is needed to predict seasonal N availability. This project will, 1) investigate the effect of cover crops on soil N transformations and water use; 2) quantify the N credits of cover crops in walnut orchards; and 3) evaluate the cost and returns of cover crop use. It is expected that N management guidelines will improve adoption of cover crops to address soil health.


Project Title: Compost Management Guidelines for Tomato Growers to Improve Soil Health and Reduce Greenhouse Gases


The potential for compost (i.e. green waste and food waste/green waste mixture) to improve soil health and productivity while lowering global warming potential makes them appealing to address climate change mitigation and promote sustainable land-use. However, little information is available to growers to utilize compost  and reassess nutrient management plan. Our goal is to demonstrate successful compost utilization and nutrient reduction management for tomato growers to 1) sequester C, 2) reduce greenhouse gases especially nitrous oxide emissions, 3) build healthy soils to enhance system resilience to climate change, and 4) improve overall sustainability and productivity of tomatoes.


Project Title: Liquid and Soil Sample Collection and Analyses of Dairy Digestate and Lagoon Effluent during Storage and Land Application Phases

This study will investigate potential environmental factors that could affect emissions during the storage and field (land) application of effluent from two dairy manure management sources, open lagoons (project baseline) and covered lagoon digesters.  Effluent from a covered lagoon digester is also referred to as “digestate.”  The monitoring and sampling work required for this project will be performed at three or more different dairies in California. This project is in collaboration with Dr. Horwath (UC Davis) and Dr. Zondlo (Princeton University, responsible for GHG and ammonia monitoring).