Grape pomace-based organic fertilizer for calcareous soils
Novel organic fertilizer derived from grape pomace waste that reduces soil pH, increases soil fertility, and improves nutrient uptake in calcareous soils such as those found in Arizona. Converts a major agricultural waste stream into a value-added soil amendment.
Overview
This research proposes the development of organic fertilizers formulated from grape pomace, a significant agricultural waste product from winemaking. Grape pomace constitutes approximately one-third of total grape harvest by weight, consisting of seeds, skins, pulp, and stems. For every 30 tons of grape harvest, roughly 10 tons of grape pomace remains after juice extraction. Currently, most grape pomace in Arizona is discarded in landfills with no productive use.
The nutrient composition of grape pomace includes approximately 2% nitrogen, potassium, and calcium, along with 0.5% phosphorus, and a naturally acidic pH of 3.5 to 3.8. This acidic profile makes it particularly well-suited as a soil amendment for calcareous soils, such as those prevalent in Arizona, where high pH limits nutrient availability and plant growth.
Technical specifications
Key features:
- Made from grape pomace, a readily available and currently underutilized agricultural waste stream
- Contains essential macronutrients: approximately 2% N, K, and Ca, and 0.5% P
- Naturally acidic pH of 3.5 to 3.8, suitable for neutralizing alkaline calcareous soils
- Targets soil pH reduction, improved fertility, enhanced nutrient uptake, and positive effects on soil microbiome
- Applicable to crops such as tomatoes and other vegetables grown in calcareous soil regions
Technology readiness level
The technology is at an early research and concept validation stage. Future work includes formulating grape pomace-based fertilizers and conducting greenhouse trials to evaluate efficacy on calcareous soils, measuring pH reduction, soil fertility improvement, nutrient uptake in tomato plants, and effects on the soil microbiome. Following greenhouse validation, field testing will be conducted over an estimated two-year period to assess real-world agricultural performance. Funding is sought for materials, greenhouse and field testing, laboratory analysis, and personnel support.
About University of Arizona
The University of Arizona is a comprehensive public research university in Tucson serving a broad research enterprise and statewide impact. Industry collaborates through Tech Parks Arizona, which operates the UA Tech Park at Rita Road and UA Tech Park at The Bridges alongside the University of Arizona Center for Innovation, providing co-located office and lab space with scale-up environments. Partnership with Banner – University Medicine links researchers to major clinical sites, while the region’s Optics Valley cluster and park-based testbeds such as the Solar Zone support prototyping and validation in desert conditions. Faculty secure competitive federal funding from agencies such as NIH, NSF, DOE, NASA, and USDA. A dedicated commercialization office, Tech Launch Arizona, supports IP strategy, licensing, and startup formation.
delivered to your inbox.