Cover crop biomass samples from our demofarm’s field show high numbers

A mix of buckwheat, phacelia, peas growing on our trial field.

Cover crops are part of regenerative farming practices and they come with many benefits. Keeping the soil covered and living roots in the ground during a period when the field would be otherwise bare, helps to reduce erosion and nutrient leaching, suppresses weeds, improves soil structure etc. 

Different species of cover crops have various benefits to the soil - some of them are especially good for restoring soil structure, some are best for capturing nutrients. Also, it is really important to use mixes instead of single species to combine benefits of different species and reduce the risk of crop failure when relying on only one species.

 eAgronom’s demo farm tries to get the most out of cover cropping. Our aim is to avoid bare ground and we try to have a green cover on our trial field close to a year round. This helps to increase the amount of carbon in the soil - to maximise the sequestration and also minimise the loss of it. In order to achieve this, we plan to grow winter crops and add cover crops to the rotation before spring crops, plus sow everything by direct drilling. 

What was grown on our trial field?

One single and a mix of different cover crops was grown on our Estonian trial field in autumn 2023. White mustard (10 kg/ha) was sown on 4 ha and a mixture of peas, phacelia and buckwheat (45 kg/ha) to 12 ha. Cover crops were drilled on 4th of August with Horsch Avatar.

The active growth period lasted until the last quarter of October when temperatures were above +5 degrees Celsius. Cover crops’ growth period was approximately 2,5 months. 

Aboveground and belowground biomass samples were gathered from both types of cover crops by METK (The Centre of Estonian Rural Research and Knowledge) scientists at the end of October. The samples were dried and weighed.

Aboveground and belowground biomass sample results.

Carbon sequestration potential

White mustard grew an impressive amount of biomass - average 6,1 t/ha of dry matter (DM) aboveground and close to 0,9 t/ha DM belowground. Cover crop mix also performed well with 4,4 t/ha DM aboveground and close to 0,5 t/ha DM belowground. 

To give those numbers a bit of context, let’s look at the rough carbon sequestration calculation. All plants consist 〜45% of carbon. Rule of thumb is that 〜20% of carbon in aboveground biomass will become part of soil carbon content.

Estimated carbon sequestration calculations.

To get the amount of CO2 that is removed from the atmosphere and stored in soil as organic carbon, we have to multiply the sequestrated carbon value with 3,67 (this factor is explained here).

Estimated calculations on how much CO2 was removed from the atmosphere.

It is important to note that the table represents rough calculation as actual sequestration that takes place depends on multiple factors like soil type, soil organic carbon level etc.

Experimenting with biofumigation

Biofumigation is a strategy which uses plants, mainly belonging to the Brassica family, that produce chemicals called glucosinolates. When the tissues of these plants are damaged, glucosinolates are broken down by an enzyme to release various substances - including isothiocyanates (ITCs). ITC’s are known to suppress numerous pest and disease organisms. This means that brassica cover crops might have an additional benefit. In order to test this strategy, one part of the white mustard crop on our trial field was rolled at the beginning of October. This area will be monitored by our agronomical team in the spring. 

White mustard being rolled on our trial field in October.

About eAgronom’s demo farm

In autumn 2023, eAgronom and Rannu Seeme signed a cooperation agreement in which our trial farm was born. eAgronom is responsible for farming 20 hectares of land in Rannu, Estonia. Our farm is managed by following conservation agriculture practices and our aim is to get real hands-on experience about adopting new practices to a farm with the goal of increasing profitability. Our field is going to be direct drilled with control plots of 1 ha plowed and 1 ha minimum cultivated each year. In addition, we grow cover crops before spring crops and we surround the field with a strip of wildflowers and green fallow crops. We are following a 5 year rotation of: winter oilseed rape → winter wheat → peas → winter wheat → barley. 

You can find more results and info about eAgronom's demofarm here.