Project Overview
Commodities
- Vegetables: celery
Practices
- Crop Production: nutrient management
- Production Systems: organic agriculture
Abstract:
Organic agriculture emphasizes the improvement of soil organic matter and stresses the foundation of maintaining healthy soil structure and diverse biological activity. With a fundamentally unique approach to soil fertility, the avoidance of many synthetic inputs leaves the organic grower much more dependent on soil biological processes that govern nutrient pools and transformations. Differences in fertility management and the challenges associated with navigating site- and season-specific variations in nutrient release and availability may result in different tissue nitrate contents in vegetable crops. Previous studies have indicated that nitrate content is often lower in organic foods than their conventional counterparts. Celery is known as a nitrate accumulator, and celery powder has been utilized as an alternative to traditional food preservatives. Regardless of the controversy associated with nitrates and human health and the restriction on maximum nitrate levels of certain leafy greens in Europe, the USDA National Organic Program currently places conventional celery powder on the National List for non-organically produced agricultural products allowed as ingredients in processed products labeled as Certified Organic. Concerns have recently been expressed questioning the use of conventional celery powder in the production of organic processed meats, although a lack of consistent, research-based recommendations for organic growers to meet the needs of the processing industry remains a significant barrier. To date, little research-based information is available regarding varietal differences in celery nitrate levels, and the impact of soil fertility management on nitrate accumulation in celery.
In addition to the inherent variation of tissue nitrate content between species and within organic and conventional counterparts, there are also other factors that can influence the accumulation of nitrate. Intraspecific variation among different cultivars is common and has been observed in species including celeriac and lettuce. Diurnal fluctuation in nitrate content has been observed in several species, likely due to the influence of light quality and intensity on the activity of nitrate reductase. Given the lack of information on nitrate accumulation dynamics in organically grown celery, this project focuses on the examination of cultivar, harvest time, and nutrient management factors affecting nitrate contents in celery under organic production. Findings from this project will help to improve our understanding of celery nitrate accumulation and will also provide meaningful information toward promoting timely soil nitrogen (N) availability, minimizing N losses, and enhancing crop productivity under organic management.
Project objectives:
Objective 1: Assess commercially available celery cultivars in terms of their yield performance and capacity to accumulate tissue nitrate throughout the growing season under organic production.
Objective 2: Determine the effect of early morning and afternoon harvesting on the accumulation of tissue nitrate in organic celery.
Objective 3: Compare different rates of total seasonal N application using various preplant and liquid organic fertilizer types to quantify effects of fertilizer source and rate on crop yield, soil N availability, and tissue nitrate content.