Farm­ing

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The plough en­dures whereas stub­ble burn­ing has had its day. Tim Field pon­ders the fu­ture of an in­her­ent part of the farm­ing land­scape

FROM his pink­foot-grazed stub­ble on the East Neuk of Fife, my cousin Pa­trick cap­ti­vates an un­wit­ting vis­i­tor with an­other hu­mor­ous yarn. Iden­ti­fy­ing dis­tant burn­ing stub­ble across the Firth of Forth he ex­cit­edly de­ci­phers the plume as smoke sig­nals… a warn­ing from clan to clan… in­va­sion was im­mi­nent!

Of course, a fond mem­ory from the last cen­tury as, his­tor­i­cal ac­cu­ra­cies notwith­stand­ing, stub­ble burn­ing has been as­signed to a by­gone era. Since the pass­ing of the Crop Residues (Burn­ing) Reg­u­la­tions in 1993, plough­ing has played an in­creas­ingly vi­tal role to sup­press weeds and pests, and to pre­pare a seed bed.

As en­dur­ing as the iron at the forge, our land­scape and cul­ture are moulded by the mighty plough, not least through pub names, star con­stel­la­tions and a legacy in horse breed­ing. How­ever, the more we un­der­stand about soil ecol­ogy, em­bed­ded car­bon and modern cul­ti­va­tion tech­niques, could the plough be head­ing the same way as stub­ble burn­ing?

Healthy soils main­tain air space for root devel­op­ment, meta­bolic ac­tiv­ity and mois­ture re­ten­tion. This is hard to achieve where sev­eral tonnes of plough­ing ma­chin­ery grunt back and forth, in un­pre­dictably wet sea­sons. Un­der the fur­row, a trial pit re­veals where years of com­paction by a weighty mould­board leaves an in­creas­ingly im­pen­e­tra­ble and im­per­me­able hori­zon, of­ten known as the “plough pan”.

At the sur­face, bare soils are sus­cep­ti­ble to rain­wa­ter runoff caus­ing ero­sion and leach­ing of hard-earned nu­tri­ents.

As Bri­tish agri­cul­ture evolves, more of our land­scape ap­pears to be es­cap­ing the scars of the plough in a move to re­duce tillage. In com­bi­na­tion with other ef­forts to en­hance soil health, the no­tice­able out­come is an abun­dance of earth­worms and im­proved yields. The worms help to se­quester car­bon high in the soil pro­file by drag­ging down or­ganic mat­ter from the lit­ter layer, whilst their casts and tun­nelling im­prove soil struc­ture. In an ev­er­more cost­sen­si­tive and car­bon-con­scious in­dus­try, fewer trac­tor hours with less horse power drag­ging a heavy plough is also a ma­jor sav­ing.

In the ab­sence of heavy plough­ing, the soil struc­ture re­mains rel­a­tively undis­turbed, root sys­tems re­tain a hold of the valu­able top­soil and an ecosys­tem of ben­e­fi­cial micro­organ­isms is sus­tained. The in­com­ing seed has a re­cep­tive bed from which to ger­mi­nate. Fur­ther­more, where the stub­ble and lit­ter re­main, a more com­plex habi­tat layer across the field sur­face has broader con­ser­va­tion ben­e­fits than a bleak blan­ket of bare soil.

Is the mighty plough des­tined for the his­tory books? Not so fast. Not all fea­tures of a stub­ble field are wel­come when try­ing to cul­ti­vate a crop; what about weed bur­den, over­win­ter­ing slugs or the con­crete sur­face of sun-baked clay? For­mer head of the Soil As­so­ci­a­tion, Pa­trick Holden, is of­ten heard ex­tolling the virtues of the plough, and he has a point.

The in­ven­tion of heavy plough­ing in the Mid­dle Ages un­locked vast tracts of fer­tile clay soils that were pre­vi­ously im­pen­e­tra­ble for cul­ti­va­tion. Those needs re­main, cap­tured in the idyl­lic win­ter scene of a hard frost grip­ping a ploughed field, qui­etly break­ing down the sods with freeze-thaw ac­tion. Re­duced tillage is all very well in light and loamy soils; on heavy clay the plough is in­valu­able to build­ing a tilth. Turn­ing the soil does not au­to­mat­i­cally re­move or­ganic mat­ter, it merely places it deeper in the soil pro­file – much im­proved if turn­ing fol­lows a dress­ing of well­com­posted muck.

How­ever, savvy farm­ers are too shrewd or im­pa­tient to wait all win­ter for a hard frost to bite whilst watch­ing their hard­earned soil fer­til­ity wash away. As a re­sult, there is a grow­ing move­ment to fol­low tillage with green ma­nures, such as mus­tard, to de­velop soil struc­ture and or­ganic mat­ter. These catch crops can also help the con­trol of pests and weeds, and sup­port other con­ser­va­tion in­ter­ests. Like­wise, in­vert­ing a fer­til­ity build­ing ley or stub­ble is a valu­able method of non-chem­i­cal weed man­age­ment. That’s not to say her­bi­cides are crit­i­cal to min­i­mum tillage, as or­ganic farm­ers have a wealth of tricks at their dis­posal; from new weed­ing ma­chin­ery to the act of graz­ing sheep dur­ing early ce­real es­tab­lish­ment.

Soil is a liv­ing ecosys­tem and no one farm­ing method can be pre­scribed to all. Suc­cess­ful agri­cul­ture sys­tems re­flect the con­di­tions of the land and there will long be a niche for the plough to carve a fur­row in the land­scape.

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sthoanpneds oth­few­choeuant­tirny2s0id1e5 Fol­low Tim and Agri­col­ogy on In­sta­gram: @agri­col­ogy

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