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Farm North East - Opinion 9.20

Can there be a more virtuous activity than applying lime to agricultural land?  If there is, I cannot think of it. It is strange then that it has become a sort of Cinderella activity when it comes to looking at climate change and the tough drive towards zero carbon. So why is support for liming constantly overlooked  as an environmental measure? 

I guess it is because it lacks a certain trendiness. It is “old hat” for sure. To check up on the science behind liming I went straight for my well-thumbed copy of the “farming bible” – my Watson and More , the Science and Practice of Farming. First written in 1924 (mine is an eleventh edition from 1962) the first chapter is about the soil and its management and it wastes no time in going straight to the vital matter of liming to neutralise  soil acidity. By this simple activity nitrogen uptake by plants is improved,  as is nitrification, nitrogen fixation and bacterial activity. Not a bad deal.

The application of lime also improves flocculation , not a word which trips off the tongue admittedly , but it describes the crumbling  process of making making clay soils more workable.

None of these things have changed over the 100 years  since Watson and More wrote about them but looking at the illustrations in their book the equipment used to apply lime  certainly has. Instead of three- tonne  spreaders on old army wheels, modern spreaders make the job precise and easy on the soil. And of course GPS sampling beforehand makes variable rate application a cinch. It always amazes me how much lime can be saved by only applying it where it is needed.

So why is support for liming not at the top of every list of greening measures? More food produced from less land by more efficient use of inputs is surely exactly what Scotland’s Rural Affairs Minster  Fergus Ewing is aiming to achieve.

Balancing soil acidity across all land types is absolutely central to what is now called “regenerative farming.” It is an intriguing concept but the move to restore soil fertility and condition by regenerative methods is really just a modern take on the sort of mixed farming which was common until the 1970s or thereabout. Until then every farm in the Scottish lowlands operated a rotation which included a two year, or sometimes three year, ley in a seven course cycle. It maintained fertility without doubt but at a cost. Farmers did the sums and realised that the cost of stocking these leys with cattle and sheep and the investment needed in buildings and associated machinery didn’t  balance with the meagre returns on offer for finished stock. The tail was wagging the dog in that the cost of building fertility organically outweighed the benefit. Much better then to rely on bagged fertiliser and increase the cropped area.

The doomsters and gloomsters, as Boris would style them, said it would lead to disaster in short order, but in fact it has been quite sustainable bar an insidious loss of organic matter content and of course an increase in soil acidity. Rectifying that trend appears to me to be what regenerative agriculture is about. It is not a case of turning the clock back though, because the economics would be no better that they were. The initiatives we are reading about now are more innovative although some do involve reintroducing livestock, especially over winter.

The story  from  the group of Scottish farmers making up the  Farming for a Better Climate Soil Regeneration Group is about establishing cover crops in clever ways which suit the Scottish climate and its restricted window between harvest and the onset of winter. As long as it can be done at reasonable cost it sounds good and thanks to the equipment now available it is perfectly possible to sow cover crops into standing cereals to give them a head start.

I visited a dairy farm in the Borders recently where the practice is to sow ryegrass into standing wheat which is then harvested as whole crop for silage. The ryegrass by then is poised for a real growth spurt and goes onto provide winter grazing for a large sheep flock, before being ploughed in the spring ready for another cereal crop.  A very neat system and hopefully typical of the sort of productive agriculture we will see in the future.

All it needs is a liming support scheme to help it along.

Article by Ewan Pate, Farmer and Freelance Agricultural Journalist. The article first appeared in ‘Farm North East’.

[Note:  James Scott Watson, joint author of Watson and More was brought up at Downieken, Carnoustie where his relatives still farm. He left school to work on the farm at 14 before embarking on a distinguished academic career which culminated in his appointment  as Professor of Agriculture and Rural Economy at Edinburgh University in 1922. His friend and colleague James (Tony) More was a  highly regarded lecturer in agriculture and Director of Studies at Edinburgh during the same era.]

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