CASE STUDY

Biochar increasing Yields from Grassland on Dairy Farms

Black Bull Biochar set up field trials in collaboration with UKCEH, SRUC and Arla, trialing our tailored biochar products as an additive to organic fertilisers on dairy farms in the UK. Biochar is a carbon-rich soil additive that can improve nutrient retention, soil health, and crop productivity.

In this field trial, we assessed soil changes resulting from low dose biochar application, when used as an additive to organic fertiliser. This allowed us to quantify the benefits of using biochar - particularly our flagship biochar product, PinChar - on dairy farms.

Increase in third cut yield

Increase in plant available nitrogen

Increase in annual grassland yield

Increase in soil organic carbon

The trials were conducted on both grassland and arable plots. Biochar was applied to slurry and farmyard manure, and the resulting mixes were applied to grassland and arable land respectively. These were compared against control plots, where manure was applied without added biochar. We conducted crop, soil, and slurry analyses to measure the impact of biochar application on physical and chemical properties. The field trials are located at SRUC’s Dairy Research and Innovation Centre in Dumfries, Scotland.

Both trials will be continuing this year, and results for the arable trials will be available after this growing season. Results to date show the greatest positive impacts of biochar when applied to grassland in combination with slurry.

Preparing the biochar and manure

We tested our flagship biochar product, PinChar, in slurry systems on dairy farms. Before application to land, we prepared the slurry-PinChar mix and stored it for 6 weeks to give the nutrients time to bind to the biochar’s surface. PinChar was added at a rate of 1% to slurry, by dry weight (10 kg of biochar to 1 ton of slurry).

The slurry was sampled, before and after adding PinChar, to analyse its nutrient content.

Applying to the fields

Slurry was applied to grassland at a rate of 50 t/ha (20 t/ac). In the trial plots with PinChar, the slurry-PinChar mix was applied at a rate of 53 t/ha (21 t/ac), adjusted for the weight of the biochar and added water. Through the amended slurry, PinChar was applied at a rate of 500 kg/ha (200 kg/ac).

The slurry and slurry-PinChar mix were applied using a precision slurry equipment with a dribble bar.

Harvest and sampling

The slurry-PinChar mix and slurry were applied to grassland plots in April 2023, followed by top-up slurry applications (without PinChar) in June and July. The first silage cut was in May, followed by second and third cuts in July and September respectively.

Soil samples were taken in March (before slurry or biochar application), May, and August. These were analysed by UKCEH for total soil carbon, total soil nitrogen, nitrate and ammonium concentration, and pH.

CASE STUDY

Crop yields

The results show significant increases to grassland yields with low-dose biochar application of just 500 kg/ha. Third cut silage yield from the PinChar plots was 41% compared to the plots with only slurry, and annual results showed a significant yield increase of 16%.

This significant improvement is likely the result of synergies in the interactions between the plant, biochar and the soil, including:
- Enriched soil microbial and fungal communities
- Increased adsorption and exchange of ammonium
- Enhanced root development
- Improved soil structure, water properties, and aerobicity

Importantly, this increase in yield did not cause a drop in silage quality, with crude protein, ash, modified acid detergent fibre staying the same across silage from the biochar and non-biochar plots.

CASE STUDY

Slurry nutrient content

Analysis of the slurry showed that using 10kg of PinChar in 1 ton of slurry significantly enhanced its nutrient retention. In particular, plant available nitrogen increased by 30%, with ammonium increasing by 59%. Total organic carbon in the slurry with biochar was also 43% greater than without biochar, indicating improved retention of organic matter.

CASE STUDY

Soil carbon

Biochar significantly increased soil carbon content over the baseline. The increase in carbon is greater than just the carbon content of the biochar, suggesting that the biochar slows the decomposition of carbon in the manure.

CASE STUDY

Paving the Way for Biochar in the UK

These farm-scale trials mark our pioneering efforts in integrating biochar into UK farming systems, highlighting its role as a pivotal tool in sustainable agriculture. While many biochar field trials have been conducted in tropical regions, fewer have been done on temperate soils. Our trials show that when used effectively, biochar can significantly improve crop yields on British farms even with a low application rate per hectare.

PinChar is designed specifically to work with manure managements systems, and tailored for nutrient retention. Its effectiveness was validated through the grassland crop yield and slurry analysis results, achieving a 16% increase in annual yield and 30% increase in plant available nitrogen in the slurry.

It is crucial for farmers to use biochar products tailored to their specific requirements, so their desired effects can be achieved. If you would like to find out more about different types of biochar and use cases, get in touch with the team. Or, join the waitlist to indicate your interest in using PinChar on your farm!