Understanding the differences between conventional and regenerative approaches is the aim of a research trial by Harper Adams University post-doctoral student, Joe Collins.

The systems-based research compares 24m tramlines – five from each management system – on two fields in North Shropshire, explained Joe, during the BASE-UK conference.

Entire management system

In contrast with conventional research methods which isolate one variable such as tillage or use of a cover crop, and make no other changes, his research looks at the entire management system and allows for multiple adjustments.

Consequently, the work reflects what happens on-farm when growers introduce a regenerative system, said Joe. “You don’t just buy a new drill, you change your management approach – your whole farm ethos. And it gets away from the problem where practitioners look at trials and say you’d never drill a crop on that day in a particular system or manage the crop that way.”

Each approach is managed by a separate agronomist. In the conservation agriculture approach, three principles are followed: minimal soil disturbance with no cultivation, maintenance of soil cover by chopping straw residue, and a diversified rotation including use of cover crops and companion crops.

In contrast, the conventional system uses tillage when deemed necessary, removes straw when financially beneficial, and doesn’t grow cover crops.

Cropping rotation

For the first two years, the rotation has been the same in both systems – spring beans followed by winter wheat. Yields favoured the conventional system in both years, but expenditure – both machinery costs and inputs – were also higher, explained Joe.

That meant for the spring beans, gross margins were virtually identical, while for winter wheat there was a statistically significant higher margin for the conventional system. For year three, oilseed rape was the intended crop.

“Unfortunately, in the conservation ag plots, we had poor seed-to-soil contact and the OSR was written off pretty quickly to be replaced by spring barley. In hindsight, it might have also been better to have written off the conventional crop as it underperformed,” he commented.

Both systems made a loss from these crops but it was higher in the conventional system, wiping out some of the gains made in the previous wheat crop. During the three-year period, both systems had similar gross margins.

Monitoring

As well as the economics, yields and input costs, Joe is also monitoring soil properties and biology, available nutrients and greenhouse gas emissions.

“So far, we’ve seen no significant differences in pH, soil biology, soil carbon or soil nitrogen. Bulk density within the conservation treatment has been steadily rising, while there have also been significant increases in the availability of P and K in that treatment.”

In-field greenhouse gas emissions from the wheat suggest a higher global warming potential from the conservation ag system, especially when taking into account the lower yield, reported Joe.

“But this is only half the dataset, and doesn’t include the manufacture of the products and fertilisers used. I’m now conducting a life cycle analysis to take those into account – my hypothesis is that it’ll reverse these results.”

The trial is continuing with funding from BASE-UK into a fourth cropping season and potentially beyond, added Joe. “It’s important to keep trials like this going to provide the long-term trend data that help farmers with their businesses,” he concluded.

This story is linked to another feature from the BASE-UK conference which can be found here.