Growing pulse crop as protein feed improves beef farm’s carbon footprint

Replacing a bought-in protein blend with home-grown beans and peas is helping a Pembrokeshire beef farm reduce its carbon footprint, while capturing significant savings on fertiliser and feed costs, too.

The pulse crop grown on eight hectares (ha) at Pantyderi Farm, Boncath, has the ability to fix nitrogen; this means that the crop of winter wheat that followed it in the field will likely see a reduction of 2.32 tonnes (t) of nitrogen fertiliser use as a result.

At current ammonium nitrate prices, this means a fertiliser cost saving of £1,508. However, the benefits extended beyond the financial, a recent Farming Connect webinar was told. By not using the 2.32t of fertiliser, the Farming Connect demonstration site removed a potential 2.72t of CO₂ equivalent from its carbon footprint

This benefit was also seen by eliminating bought-in feed. The crop replaced 40t of protein concentrates – a CO2 equivalent of 60t, said Farming Connect Technical Officer Dr Delana Davies, who managed the project.

“These figures are based on the carbon footprint of rape and maize distillers mix into a feed mill,’’ she told the webinar

The project was featured on a Welsh Government stand at the Low-Carbon Agriculture event in Stoneleigh Park on 8-9 March, with others from Farming Connect demonstration sites.

“Not only has growing the peas and beans required no fertiliser and eliminated any purchased feeds for the beef cattle, it has also fixed nitrogen – reducing the amount of fertiliser required for the following cereal crop,’’ said Dr Davies.

The pulses replaced a 36% protein concentrate blend that had been fed at a rate of 1-1.5kg/head/day with grass silage and home-grown urea-treated crimped barley in the growing and finishing rations of 400 head of cattle.

Eurig Jones, who farms at Pantyderi with his father, Wyn, said it is an important step toward a goal to become self-sufficient in protein in the beef enterprise.

The crop, which he harvested on 3 September 2021, analysed at 26.6% protein and 13.6 ME in the dry matter (DM) and 61.7% DM, and achieved a protein yield as fed of 860kg/ha as a crimped feed.

Costings calculated by the project’s nutritionist, Hefin Richards, priced the feed at £242/t, compared to £275/t for bought-in beans delivered and milled.

The crop favours free draining soil, and responds well to plentiful moisture, which made it a good match for the conditions at Pantyderi.

Lime was applied to the trial field at a variable rate of 937kg/ha to lift the pH from 5.8 to 6.5 (the ideal pH for beans and peas is higher than 6); farmyard manure was applied at 25t/ha; there was no requirement for nitrogen inputs.

The growth habits of beans and peas are very complementary: the beans provide a strong scaffold that helps keep the peas standing later in the season; they also benefit from the same agronomy approach, said Dr Davies.

“Double cropping also tends to synchronise any varietal differences with regard to time to maturity, and the peas fill the air gaps between the larger particle size of the beans in the clamp,’’ she explained.

The seed was planted in two passes on 22 April. The beans were sown first, at a rate of 308kg/ha and a depth of 60mm, followed by the peas at 225kg/ha and at a depth of 30mm. These seed rates were calculated using an app available through the Processors and Growers Research Organisation (PGRO). A fungicide was applied twice to tackle chocolate spot.

Mr Jones harvested the crop with his own combine, fitted with a side knife. “The side knife is a must – an essential bit of kit for the job,’’ he said.

Getting the timing right was a balance between having the crop dry enough to go through the combine, but at above 30% moisture for crimping. The crop yielded 5.25t/ha – 42t from 8ha – and also produced 22 bales/ha of haulm (the fibrous part of the plants, which is nutritionally superior to straw).

Dr Davies said the project had been very successful on several counts: “It is a win-win situation, and has ticked a surprising number of boxes.’’

Farming Connect is delivered by Menter a Busnes and Lantra Wales, and funded by the Welsh

Government and the European Agricultural Fund for Rural Development.