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ARS Home » Pacific West Area » Davis, California » Crops Pathology and Genetics Research » Research » Research Project #434994

Research Project: Documentation of COMET-Farm and Greenhouse Gas Accounting for Specialty Crops

Location: Crops Pathology and Genetics Research

Project Number: 2032-21220-008-07-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Sep 1, 2018
End Date: Sep 30, 2020

This scope of work supports a collaborative project among the University of California at Davis, USDA Agricultural Research Service, Colorado State University (CSU), and the USDA Natural Resource Conservation Service (NRCS). The first objective is to support completion of a scientific review of these processes in Almonds, Strawberries, Walnuts, Pistachios, Processing tomatoes, Grapes, Lettuce, Cole crops (broccoli, cauliflower, related crops), Citrus, Cotton, Alfalfa, and Corn. The second objective is to focus on publishing the development and verification of the DayCent model for these specialty crops, which was executed in the recent expansion of COMET-Farm for specialty crops. These publications on the development of DayCent for specialty crops will include documentation on the changes in parameters that may include 1) soil characteristics, 2) crop characteristics and factors that control root or shoot death, 3) tillage intensity as it relates to soil C storage, and 4) soil water availability and other factors that highly influence nitrous oxide production. This work will inform efforts among other entities to identify soil conservation practices that mitigate greenhouse gas emissions and improve soil health and carbon storage within California’s working lands, including agriculture. In summary, key products that are anticipated from this work include a review of this scientific literature that was used to expand DayCent for specialty crops and two to three peer-reviewed publications documenting the parameterization, calibration and validation process for specialty crops. Amendment 1-Expand scope of work to include: to improve COMET-Farm’s representation of these practices for specialty crops by: 1) modifying the water balance routines in DayCent to simulate drip irrigation, 2) conducting a literature search to compile data on soil water dynamics under drip irrigation, impact of drip irrigation on surface evaporation and impact of drip irrigation on plant root depth and distribution, and 3) gathering CA regionalized default data on practices standards for irrigation timing/amount/methods and fertilization amounts/timing for major CA specialty crops. By doing so, we can add specialty crops and standardized (default) drip irrigation and fertigation practices to the Drag ‘N Drop feature in COMET-Farm to facilitate ease-of-use for California users. We anticipate that this work will be adaptable to other regions in the future given that specialty crops commonly grown in California are also found in other regions in the U.S.

This effort is intended to leverage all existing and ongoing research efforts in which available data published in the scientific literature was used to parameterize the DayCent model for the crops listed above. The current work will leverage this effort to report the model development for specialty crops in California and examine scenarios to evaluate conservation practices for cool and warm season vegetables, and woody perennials such as orchard crops and grapes. No new field-based research is required in this project. Compiled content on Specialty Crops that was used to expand DayCent for specialty crops within the COMET-Farm tool will be used in a written synthesis of existing research, knowledge gaps, and voluntary conservation-based GHG mitigation and carbon sequestration opportunities for these cropping systems. This analysis will be published in the peer-reviewed scientific literature as a review article and several research articles. Amendment 1: Modify, parameterize and test the DayCent model to account for different water dynamics associated with drip irrigation. From a whole soil perspective, the use of drip irrigation systems radically alters water fluxes involving surface evaporation, percolation, root distributions and drainage, relative to conventional (e.g. sprinkler) irrigation. To account for this differences, we will introduce empirical adjustment factors in DayCent to modify the specific fluxes and processes on the basis of experimental data sets and publications, from existing studies. Compile information on typical irrigation and fertilization practices for specialty crops in California, to enable implementation of default one-click or two-click features to specify data inputs for crops that are grown with various irrigation/fertilization methods: Surface drip irrigation: allowing users to indicate crops like grapes, tomatoes, and lettuce are receiving irrigation water at set intervals (e.g. daily, every other day, weekly, etc.). Subsurface drip irrigation: This would be implemented as with the “Surface drip irrigation” feature described herein, but would be implemented with co-developed improvements to the DayCent model allowing water application directly to the root zone rather than to the soil surface, reducing surface evaporative losses. Surface furrow/flood irrigation: allowing users to indicate crops are receiving fixed quantities of irrigation water at set intervals (e.g. weekly, every other week, etc.). Fertigation: Users will be able to associate fertilizer application directly with irrigation events, in quantities and chemical types (e.g. UAN, etc.) appropriate for this practice. Like with irrigation practices currently described in the tool, this will streamline the data entry process for users and allow more direct uptake. Other practices as revealed through interviews with producers and extension personnel, and discovered in literature reviews.