2017 ASHS Annual Conference

In order to assist berry and vegetable growers with managing irrigation and nitrogen (N) for the specific growth stage of their crops and field conditions, the University of California Cooperative Extension developed an online decision support tool. CropManage (cropmanage.ucanr.edu) is a free web-based app that uses data from multiple sources to customize water and N fertilizer recommendations on a field-by-field basis. The software estimates crop evapotranspiration from daily reference evapotranspiration from a network of weather stations, and crop coefficients that are based on models of canopy cover. Nitrogen fertilizer rates are estimated using models of crop N uptake and soil nitrate quick test. The objective of this study was to assess the effectiveness of CropManage’s recommendations in four experiments conducted between 2015 and 2016. Three experiments were conducted in celery (Apium graveolens L.) and one in strawberry (Fragaria x ananassa) in commercial fields located in Ventura County, California. Each experiment was followed a randomized complete block design with four replications and consisted of two treatments: CropManage’s recommendations for water and N fertilizer (CM), and the grower standard water and N fertilization practices (GS). All other cultural practices were performed equally in both treatments. Overall, yields of the CM treatment were either greater or similar compared to GS for the four studies; water and N fertilizer amounts varied according to each field. For the celery experiments, the CM treatment resulted in either similar or greater (although not statistically significant) yields compared to GS: 5.8%, 0.7%, and 13.5% greater (P = 0.286, 0.864, and 0.448, respectively). Water use for the CM treatment was 1.2% greater, 22.0% lower, and 2.4% greater for CM compared to GS. Nitrogen fertilizer use was 24.1%, 10.6%, and 22.5% lower for the CM treatment, compared to GS. For the strawberry study, CropManage recommendations resulted in 22% greater yields (P = 0.0008), 11.4% greater water use, and 34.6% greater N fertilizer use compared to the GS treatment. The plants of the GS treatment were noticeably under-fertilized, which consequently resulted in less water use and lower yields. Seasonal average soil nitrate of the CM treatments was slightly greater for the strawberry experiment, and lower for all celery experiments. The results of this study are encouraging and indicate that CropManage’s recommendations did not decrease yields while substantially reducing fertilizer use in all celery fields; strawberry yields were significantly greater with increased N fertilizer use.