Benefits of bokashi for Welsh beef producer

Farmyard manure is a valuable resource in any grassland system.

For an organic farm whose only other input sources are magnesium lime and granular calcium lime, it is even more important, as it must be the sole nutrient supply for growing all grass and crops on the farm.

At Penrhiw Farm, near Llandysul, Phil Cowcher turns his farmyard manure (FYM) into bokashi, a fermented material produced by adding microbes to digest the manure.

See also: Why calcium is critical for soil, plant and animal health

This coming winter will be the third that he has made bokashi, and he is convinced it offers a good return on investment from a process that costs him about £500 a year.

Phil produces bokashi by applying a product containing a broad spectrum of bacteria, yeast and fungi twice weekly to bedding using a knapsack sprayer.

He does this when cattle are housed, adding fresh straw after each of those applications.

“It’s an anaerobic process because the cattle trample it down and that seals it, keeping the air out,” he explains.

The microbes multiply as nitrogen proteins within the muck and bedding mix, increasing its nitrogen content.

Ease of handling

When the cattle are turned out – the youngstock in March and the cows as they calve in April – the bedding is left in situ for about six weeks.

This gives time for the composting process to progress and saves moving the bedding twice.

“We then clean out the sheds and fill the Rotaspreader at the same time,” says Phil.

The bokashi is spread on the fields after the animals have grazed, or after silage has been cut.

Because the material has already decomposed through the fermentation process, the nutrients are immediately available to the soil.

© Charlotte Cunningham

He notices a difference in its consistency even as it is removed from the sheds.

“Instead of the bedding being like a mat, this breaks up easily so we can clean out the sheds with a loader bucket.”

The smell is noticeably different, too, compared with untreated manure, he adds: “There is no bad smell because the microbes colonise the bedding and [prevent the organisms that produce gas and smells from forming],” he explains.

“One of the people who introduced me to bokashi was a pig farmer, who told me it got rid of any bad smells, and he was right, it does eliminate those.”

Calf health

Phil believes using the bokashi process helped prevent any sickness in calves that he had to rehouse last spring during persistent wet weather.

“We always turn out from the sheds as we calve, but the ground conditions were so wet in April that we had to bring a lot of stock back in.

“I was concerned that because of the poor weather, the calves would pick up some bugs [in the damp conditions], but we had no issues at all with ill health, no scours, and I think a big part of that was the bokashi [producing fewer emissions].”

The main reason he went for bokashi was for the benefits it is said to bring to soil health.

Research has shown that, while field-stacked FYM loses 40-60% carbon in 12 months, and aerobic composting and turning, 75% carbon in as little as eight weeks, bokashi losses are 1-3%, depending on conditions.

This allows maximum levels of carbon to be utilised by the soil when the material is applied.

Nutrient cycling

Bokashi does not typically result in bigger crop yields, but the return on investment comes from a reduced requirement for other inputs – especially for non-organic farmers – and easier and quicker spreading.

In addition, Phil says that when the bokashi is spread in the fields, it disappears at a much faster rate than untreated manure.

“That is a good sign, because it means the earthworms are taking in the muck quickly and returning more nutrients and carbon to the soil, because it is not releasing methane and carbon dioxide.

“The cost is quickly offset by not having to apply other nutrients, as the muck maintains production without having to buy in fertiliser and cycles nutrients more effectively.”

Soil nutrient status varies between his owned and rented land, with pH ranging from 5.8 to 6.2, and phosphate and potash mostly at index 2.

The bokashi is applied in light dressings once or twice a year, at about 5-7.5t/ha.

Grazing management

The grass that the bokashi helps to grow is grazed on a rotational system by his cattle and sheep.

In 2023, Phil trialled “total grazing” by moving cattle four times a day and grazing residuals as low as 1,400kg dry matter (DM)/ha.

He also deferred a block of land for winter grazing by the cows.

However, the exceptionally wet conditions, in combination with his clay loam soils, resulted in poaching, and this impacted on spring and summer grass growth.

As a result, he has reverted to housing all cattle at the end of October, a move he says will not only protect soil and spring grass production, but allow him to produce more bokashi.

Rotations have been shortened to keep grass leafy and palatable to enhance animal performance.

A leader-follower system, with cows and calves following finishing lambs into paddocks and grazing to a residual of 1,500-1,600kg DM/ha has also aided lamb performance.

Phil, who farms with his parents, Tom and Eva, is always keen to trial systems that could make the business more efficient, particularly when it comes to soil health.

“You have to experiment to work out what works in your climate and for your soils,” he suggests.

Better than compost

Before going down the bokashi route, he had been producing an aerobic compost by turning stored muck with a telehandler during the composting phase.

This kept it within the correct temperature range to produce an aerobic compost.

Once it cooled and had been left to mature, it was spread on pasture following grazing or silage.

Some of the compost was added to vermicompost, created by introducing specific breeds of composting earthworms, a mix of “red wigglers” and tiger worms, to composted manure.

© Charlotte Cunningham

The worms ingest the manure, then excrete casts, producing a soil conditioner that is spread as a thin layer on poorer performing fields as a biological stimulant.

Although this produced a good product for the soil, the process required labour, machinery and diesel to turn the compost and is a reason why Phil believes bokashi offers a better solution.

“Because you are not turning it, you are not releasing gases, so that retains a lot more of the nutrients,” he says.

Once he has gained a greater understanding the bokashi process, he believes he will have the confidence to make his own product to apply to the bedding, reducing cost.