2018 ASHS Annual Conference

Fertigation is an effective method to quickly deliver nutrients to crops, matching application timing with crop needs. Organic fertilizers can be expensive, especially for fertigation. In this study, commercially available fertilizers in small quantity (e.g. up to 1 gal for one-time purchasing) and bulk-quantity (e.g. >256 gal) in the U.S. were tabulated, and cost per unit (lb) of nitrogen (N) was calculated. The price of N per lb varied significantly between fertilizers within the two categories. For fertilizers sold in small quantities, the cost per lb of N ranged from $13.27 to $269.50. For fertilizer sold in bulk, the cost per lb of N ranged from $8.70 to $36.00. Other considerations for selecting an organic fertilizer for fertigation include solubility, viscosity, and other characteristics that can impact the ease of injecting the fertilizer solution as well as drip tape maintenance (clogging of emitters). Thus, costs for labor and supplies associated with injection and maintenance must also be considered. Another consideration is the odor of the fertilizer, as many soluble organic fertilizers are fish-based. Especially when applied in confined spaces (e.g., tunnels or greenhouses), the odor may have a negative human impact. The amount of time to apply three different organic fertilizers will be presented, and the risk of clogging the drip line and emitters will be discussed. The three fertilizers selected for this study were: 1) fish-based and low price per lb N, 2) corn-based, 3) fish-based and commonly used in our region.