Biofertiliser assessment

A biofertiliser assessment measures the material that is going on the crop, and what the crop does with it. Digestate, dewatered sludge, and a graded product such as Bio-NPK are not interchangeable because they share a name. Moisture, nitrogen, phosphorus, potassium, and contaminants come from the sample. The agronomic rate comes from the crop, not from the label on the load.

The assessment can run in parallel with an agronomic crop trial. Same site, same season, same visits. The trial measures biomass yield. This work measures the fertiliser side of that yield: what was applied, at what rate, and how the harvested tonnes sit against that application. The two scopes stay separate. A yield without the analysis does not say whether the fertiliser was the cause. An analysis without the harvest does not say whether the material grew anything on that site.

It is not a claim that every sludge is a fertiliser. A material that fails the analysis is reported as failing. The result is an input to the feedstock assessment and to the design, where the nutrient return and the biomass tonnes both have to be numbers from the site.