Project Grant 20195110630190

KEEPING WEED PRESSURE LOW AND BUILDING UP SOIL ORGANIC MATTER AND FERTILITY LEVELS ARE TWO OF THE MOST IMPORTANT OBJECTIVES FOR GROWERS TRANSITIONING GROUND FROM CONVENTIONAL TO ORGANIC MANAGEMENT. WHILE LITTLE INFORMATION HAS BEEN AVAILABLE TO GROWERS IN THE PAST, RECOMMENDATIONS FOR THE TRANSITION PERIOD HAVE TRADITIONALLY EMPHASIZED HIGH ORGANIC MATTER INPUTS FROM HIGH-BIOMASS CROPS AND/OR APPLICATION OF ORGANIC MATERIALS LIKE COMPOSTS OR MANURES. ALTERNATIVELY, SOME EXPERIENCED GROWERS RECOMMEND USING PERENNIAL CROPS LIKE ALFALFA DURING THE TRANSITION PERIOD. UNCERTAINTY REMAINS REGARDING THE RELATIVE EFFICACY AND PROFITABILITY OF ANNUAL VERSUS PERENNIAL APPROACHES TO TRANSITION, ESPECIALLY IN CALIFORNIA TOMATO PRODUCTION SYSTEMS.PROCESSING TOMATOES ARE AN IMPORTANT CROP IN NORTHERN CALIFORNIA, A REGION THAT PRODUCES OVER 95% OF THE TOMATOES THAT ARE USED FOR KETCHUP, SAUCES, SALSA, AND CANNING IN THE NATION.DEMAND FOR ORGANIC PROCESSING TOMATOES HAS BEEN GROWING STEADILY THROUGHOUT THE LAST DECADE BY ONE TO TWO PERCENT PER YEAR,AND DECREASING REVENUES IN THE CONVENTIONAL TOMATO INDUSTRY COULD DRIVE MORE PRODUCERS TO CONSIDER TRANSITIONING THEIR TOMATO PRODUCTION OPERATIONS TO ORGANIC.DESPITE THE STEADY GROWTH IN ORGANIC PROCESSING TOMATO PRODUCTION IN CALIFORNIA, LITTLE INFORMATION TAILORED TO THE PROCESSING TOMATO INDUSTRY HAS BEEN MADE AVAILABLE TO INFORM MANAGEMENT PRACTICES AND DECISIONS DURING THE TRANSITION TO ORGANIC PERIOD. PARTICULARLY, NORTHERN CALIFORNIA GROWERS HAVE EXPRESSED A NEED FOR INFORMATION ON CROPPING STRATEGIES AND ROTATION OPTIONS, INCLUDING COVER CROPS, ANNUAL CROPS, AND PERENNIAL FORAGES, AS WELL AS A MORE DETAILED UNDERSTANDING OF SOIL ORGANIC MATTER, NUTRIENT, AND SOIL MICROBIAL COMMUNITY TRENDS AS THE TRANSITION-TO-ORGANIC PERIOD PROGRESSES. THIS STUDY AIMS TO PROVIDE CALIFORNIA TOMATO GROWERS WITH INFORMATION THEY HAVE REQUESTED ON THE I) TIME SCALE OF CONVERSION OF SOIL FERTILITY AND STRUCTURE DURING THE TRANSITION TO ORGANIC PRACTICES, II) THE OPTIMAL ROTATIONAL CROPS FOR N RELEASE AND SOIL CARBON BUILDING IN MEDITERRANEAN CROPPING SYSTEMS, AND III) COMPREHENSIVE FINANCIAL ANALYSES OF INCREMENTAL COSTS AND BENEFITS TO MAXIMIZE NET REVENUES (OR MINIMIZE COSTS) FOR GROWERS DURING TRANSITION AND SUBSEQUENT CERTIFIED ORGANIC PRODUCTION. THESE RESULTS WILL BE DISSEMINATED THROUGH INNOVATIVE EDUCATIONAL AND EXTENSION METHODS, INCLUDING HANDS-ON SOIL HEALTH AND WINTER COVER CROP MANAGEMENT WORKSHOPS AND AUDIO PROGRAMMING FOR RADIO AND PODCAST DISSEMINATION.