Blood, hair, feathers, horn, and bone meal are readily available raw materials for organic commercial fertilizers to supplement the nutrient requirements of organic vegetable cultivation. These products are of animal origin and primarily constitute byproducts of the large-scale conventional meat industry.

This has been a significant factor prompting many organic vegetable growers to opt for Organic Plant Feed (OPF) in recent years. OPF is a plant-based alternative composed of concentrated vinasse, a byproduct of the sugar cane industry. However, the use of OPF in organic farming is under debate abroad (and already prohibited in the Netherlands) due to its relatively high content of readily available mineral nitrogen.

In this project, we aim to map the current range of alternative commercial fertilizers based on these developments. We will investigate fundamental differences in effectiveness and enhance and revise our well-known brochure, 'Guide to Organic Commercial Fertilizers' from 2010, with the newly gathered knowledge.