Gerard Finnan (FCG Midwest)

There have been numerous articles written by my colleagues on testing slurry, applying slurry and muck more accuartely, and treating it as a resource and not a waste.

As the table below shows, one of the biggest determinants of slurry nutrient value is dry matter. The more liquid the slurry, the lower the dry matter and the lower the nutrient value.

To get a representative sample for analysis, ideally the slurry needs to be agitated and mixed to ensure the solids are equally distributed in suspension. You tend to do this just before application. If a sample is sent off for analysis then, the slurry is spread before you get the analysis results.

A slurry hydrometer will tell the dry matter of the slurry by dropping it into a bucket of the agitated slurry. You can then read off a table like above, or insert this number into an app like CRAP APP which will adjust nutrient availability for time of year, dry matter, application method, next crop, field nutrient status etc. This means you can decide your application rate at the time of application and get a better targeted application as a result.

To acquire one of these, google slurry Hydrometer or see here for £15 + postage:  https://www.brannan.co.uk/product/slurry-hydrometer/

You can reuse it without any extra cost! I would suggest periodically doing a lab test just to ensure the base N, P, K values are in line with the standard for the given dry matter. By recording the actual nutrient value analysed, it will ensure more accurate compliance with the Farming Rules for Water Regulations. You may be overestimating the dry matter and thus the nutrient density of slurry applied. As I like to say – you can’t manage what you don’t measure!

Contact one of my FACTS registered colleagues at your local FCG office for more detailed nutrient management advice.