The Dutch foundation SPNA agroresearch has just published a sneak preview of a long-term study on plant-based arable farming without animal manure. This study will serve as a benchmark for other studies addressing similar questions with regard to biocyclic-vegan agriculture.
In the introduction it states:
Sneak preview evaluation Planty Organic 2012-2020
Brief evaluation of Planty Organic, 2012–2019 The Stikstof Telen (Nitrogen Cultivation) project will finish at the end of 2020. In this project, additional measurements are being carried out on the ‘Planty Organic’ trial field, where experimental crop rotation has been carried out since 2012 on the basis of nitrogen generated entirely on the farm. A brief evaluation is given here of the results up to the end of 2019 as input for discussions about possible continuation of the study and new research questions. The measurements in 2020 are expected to be in line with the results so far and should therefore reinforce the conclusions. The full evaluation of the period 2012-2020 will follow in early 2021.
The conclusion so far:
An organic arable farming system without animal manure, that is completely self-sufficient in nitrogen (no external nitrogen supplies) and that uses cut-and-carry fertilizer is quite feasible and delivers sufficient yields. The environmental burden is minimal, energy consumption is low and biodiversity is high.