Slurry, Emission and Nutrogen Utilization

Emission and N-efficiency of slurry,

the report every dairy farmer should read ... and actually every arable farmer too

We are proud to present the report of the study "Slurry, Emissions and Nitrogen Utilization".

This study was carried out by Peter Vanhoof and Anton Nigten on behalf of the VBBM and 10 Sponsoring companies, including Napagro.

The great merit of this study is that it looks at the total cycle instead of isolated aspects (such as closed stable floors or emissions when spreading).

Striking results and points for attention in terms of emissions:

- No product or treatment of manure results in a reduction of NH3 emissions in all cases: there is no single, magical solutions to reduce emissions

- A considerably lower emissions of up to -30% is possible through an adapted ration, supplemented with a number of good practices:

  • aim for a urea <20 (see page 14)

  • no chemistry in the manure pit (formalin, cleaning agents)

  • No lime in the boxes (this increases the pH and therefore more NH4 > NH3 conversion)

  • aerating the pit, rock flour in the boxes, impact powder in the ration, ...

In terms of nitrogen utilization on the land (KGs N fertilization converted to KGs protein in 1° cut), the following points stand out:

  • lower dossage workd much better: max 20m³ at a time and preferably less

  • later is better: rather fertilize in March instead of February, due to soil temperature

  • Above-ground fertilization makes it possible to archieve more than 100% utilization: in other words, the soil life provides extra N fertilization and thus makes significant savings on fertilizer possible. (p 21)

  • adding water works better (less damage to soil life)

  • fertilizer use on top of good slurry reduces N efficiency (this is mainly a C/N issue)

  • sufficient Molybdenum and Boron ar important for proper nitrogen utilization

  • high OEB values in the feed result in a lower N utilization (p.26)

We recommend reading and disseminating this report in local study clubs and circles. Also bring it up on the table during consultations with the local government, with nature associations and at meetings of farmers organisations.

Peter Vanhoof has put together a fascinating lecture of approximately 2.5 to 3 hours, which provides insight into the impact of even more variables. A number of slides have been pasted into this email. You can book a lecture through us or directly with Peter.

The intention is to repeat this study in the spring of 2021, on a larger scale and even broader in terms of anaysis:
- Extend N utilization from 1° cut to all cuts in a year
- Adding Kinsey soil analyses
- Leaching of nitrate in the soil


Arable farmers would do well to familiarize themselves with the characteristics of good slurry and to pay a little more for it. We think of pH < 7; EC < 1.5; organic bound N > 55% of total N.

Our tests show that good slurry can deliver +10% more yield compared to 'average slurry'.

In this way, locally closed cycles generate a lot of money for livestock farmers and arable farmers.


A few nice trials in terms of fertilization are in the pipeline for 2020:

- can the combination "improved slurry + compost" help to reduce the fertilizer application by 50% to 75% in potato cultivation?

- how does above-ground fertilization work compared to injection in arable farming (4 years trial)?

- can fertilizer - free arable farming become profitable by actively stimulating soil life at the same time (4 years trial)

Would you like to know more about our approach or are you interested in a lecture? Send me a message

Slurry, Emission and Nutrogen Utilization
Office 1 April, 2020
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