Organic matter focus yields surprising results – Arable Farming

Few farmers would expect yields of up to 12 tonnes per hectare from their wheat on the back of only 167mm of rain since January. But ensuring soils have an optimum level of soil organic matter has meant Doug Taylor’s crops performed well even in a year of drought on his sandy down-land soils.

It has been the cumulation of almost 20 years of work on the 400ha he farms at Hope Farm, near Folkestone in Kent. Before then, the family ran a dairy too, with dung going onto the lighter arable soils. But when they stopped dairying and also stopped burning straw, Mr Taylor says the land soon became less resilient as a result. Windblow on the sandy soils caused crop damage, shearing off new plants.

“We could see how dung had transformed the soil in the past, so looked for another source of organic matter and found composting.”

Back in 2003, the business started composting 3,000t of green waste for the local council, pioneering kerbside collections. Today, it processes 35,000t, using most of the resulting compost on-farm and selling up to 5,000t. Compost is spread after harvest and kept as near to the surface as possible, with the soil just ‘tickled’ to ensure the fine compost material disappears.

The focus on increasing soil organic matter over a long period has had some surprising results, as attendees at a recent meeting discovered.

Using an excavator to dig soil pits meant it was easy to see the soil structure to a depth of 1.5 metres, and to notice that wheat roots had grown down worm holes to this depth. The worms had also pulled compost that far down into the soil as their holes were lined with black compost.

According to Matt Ward, services leader at Hutchinsons, the farm’s use of Omnia – which started about 18 months ago – will help backup decisions about variable rates. The information from both systems means there is a discussion about whether low yielding areas could be improved or whether they should be managed for a much lower yield potential.

Mr Ward adds: “For nitrogen application in particular, there is the potential to stop feeding a 7.5t crop as it if was going to be a 10t crop. That would be a significant N saving.”

Composts are regularly tested for nutrients before spreading, with the last application (at 26t/ha) calculated as supplying 98kg/ha phosphate, 192kg/ha potash, 73kg/ha sulphur and 689kg/ha of calcium. According to RB209, green composts supply only very small amounts of crop available N but repeated long-term use will increase supply of soil nitrogen.

The compost has a pH range of 8.2 – 8.4, so the farm has not spread any lime for about 15 years, though this used to be an annual occurrence at 2.47t/ha.

However, the high pH does mean crops have to work hard at the root zone to acidify the soil, using a lot of energy which would be better spent growing, says Mr Robertson.

“A plough and power harrow is very simple, even when it rains. But with direct drilling, you have to stop after about30 minutes of rain as it starts to smear, which creates a superhighway for slugs. Stop-ping can also create issues with variable germination times.”

The farm still has a plough, which has not been used for a few years, but Mr Taylor would use it if needed.

“I’m not fixed in a mantra – we just need to do the best for the crops we grow. Luckily, our organic matter levels mean we can direct drill, and all our winter oilseed rape and cover crops have gone indirect.”

This winter, Mr Taylor plans to spend time interrogating his data in Omnia and doing more on carbon monitoring.

“It’s simple to set up, so every activity on-farm will have a carbon cost. So we will know our cultivation carbon cost, for instance, and want to better understand what we are doing.”

Farmers who are seeking more land should instead think about farming vertically – down into their soil to get it functioning better, says Mr Robertson.

“A lot of what I do is old-fashioned, but a lot of people have forgotten how much soil can do and have always reverted to a bag or can.”

But he says changing the way you farm should be done cautiously. Many people have gone too quickly from massive inputs to a regenerative approach and he warns that soils need to be weaned off the old system over a period of years.

“People often tell me farming like this takes time and costs more, but there doesn’t have to be a yield penalty. If you have done things right, there should be a reduction in input costs, leaving a better margin.

“It does require more management though, and I like clients to do something on their farm every year which makes them feel uncomfortable.”

Trialling different ways of doing things on your own farm, even in a small area, can bring about surprising results, he says.