Planty Organic evaluation 2012-2024

The Planty Organic experimental field was started in 2012 at the SPNA research farm Kollumerwaard with the question what the features are of an organic arable crop rotation based exclusively on farm-own produced nitrogen. In order to be able to answer that question as precisely as possible, a set-up without any external supply was chosen. It concerns a six-year crop rotation in which one year, with a clover-lucerne mixture, fixes a large part of the required nitrogen that is applied as Cut&Carry fertilizer on other plots. From 2021, the plots have been split into a part (continued) without external supply, and a part with 15 tons of green compost applied per year, aimed at an absolute phosphate balance. In 2022, a small change took place in the crop rotation and spring wheat/field bean was replaced by green bean. This report discusses the soil development with an emphasis on nitrogen and organic matter, and the nitrogen use efficiency is determined. The yields are also evaluated. The changes in nitrogen dynamics due to the change in the crop rotation and the compost application are discussed. The system without external supply is stable and can be simulated well in the NDICEA model. The annually measured organic matter content is almost stable or increases very slightly, and the measured soil N-total is stable or decreases slightly. The new crop rotation appears to be less efficient with nitrogen than the old one. According to the model calculations, the compost supply hardly provides more nitrogen in the first six years; the organic matter content and N-total do increase in the meantime. The new crop rotation is less efficient in nitrogen utilization and organic matter build-up.