Integrating cover crops and organic matter amendments for whole orchard regenerative management

Project Overview

Project Type: Graduate Student
Funds awarded in 2023: $29,811.00
Projected End Date: 06/30/2024
Grant Recipient: UC Davis
Region: Western
State: California
Graduate Student:
Principal Investigator:
Dr. Sat Darshan Khalsa
University of California Davis
Principal Investigator:
Dr. Patrick Brown
University of California Davis


  • Agronomic: mustard, oats, peas (field, cowpeas)
  • Nuts: almonds


  • Crop Production: cover crops, nutrient management
  • Education and Training: demonstration, on-farm/ranch research, participatory research, workshop, youth education
  • Natural Resources/Environment: biodiversity
  • Production Systems: agroecosystems
  • Soil Management: organic matter, soil analysis, soil microbiology, soil quality/health

    Proposal abstract:

    Regenerative agricultural practices in almond orchards include recycling resources, improving soil health, protecting pollinators, improving harvest practices, and minimizing synthetic fertilizer inputs. The complexity of perennial crops requires specific strategies to manage different zones in almond orchards where tree rows are fertigated and irrigated in addition to alleyways which are utilized for growing companion crops or cover crops. Conventional almond orchards typically leave the orchard floor bare and there is a need to use organic matter amendments (OMA) including hulls and shells (HS) as a mulch to protect the soil without compromising profits. Nutshell amendments have been shown to influence soil physical, chemical, and biological properties in almond orchards. Planting cover crops (CC) also have benefits in almond orchards specifically in improving soil quality, nutrient and water preservation, reduced soil erosion risks and weed suppression. Project outcomes will address soil physical, chemical, and biological properties with HS and CC interactions. Nutrient cycling and decomposition of both practices will be analyzed in the first and second years. Field day workshops and demonstrations, articles written on the UCANR Sacramento Valley website, and 4-H college readiness events will disseminate information to stakeholders and engage with community members. 

    Project objectives from proposal:

    Soil Health Objective: Measure soil physical, chemical, and biological properties under HS OMA. Analyze short term effects of HS OMA on CC biomass and nutrient status in the soil. Cover crop aboveground biomass sampling will measure carbon impacts on the soil and nitrogen uptake that will assist in understanding the relationship between HS OMA and CC. 

    Educational Objective: Provide informed data to all stakeholders and members of the industry that include media presentations, conference presentations, and on site field days. Present research findings at UC Davis and with 4-H high school students interested in studying agricultural science in college. Collect data from grower and farm manager surveys to assess current and potential practices using HS OMA and CC.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.