nitrogen availability for turning organic matter into humus. It erases wheel tracks and ruts from harvesting equipment. It controls many perennial weeds and delays the growth of others until spring. It accelerates spring soil warming and water evaporation due to lower residues on the soil surface. It facilitates seeding with a lighter seed, controls many crop enemies (slugs, crane flies, seedcorn maggots-bean seed flies, borers), and raises the number of "soil-eating" earthworms (endogic), but deters vertical-dwelling earthworms (anecic). Ploughing leaves little crop residue on the surface that might otherwise reduce both wind and water erosion. Over-ploughing can lead to the formation of hardpan. Typically, farmers break that up with a subsoiler, which acts as a long, sharp knife slicing through the hardened layer of soil deep below the surface. Soil erosion due to improper land and plough utilisation is possible. Contour ploughing mitigates soil erosion by ploughing across a slope, along elevation lines. Alternatives to ploughing, such as a no-till method, have the potential to build soil levels and humus. These may be suitable for smaller, intensively cultivated plots and for farming on poor, shallow or degraded soils that ploughing would further degrade. Depictions See also Boustrophedon (Greek: "ox-turning") — an ancient way of writing, each line being read in the opposite direction like reversible ploughing. Conduit current collection Foot plough Furrow profilometer Headland (agriculture) History of agriculture Railroad plough Ransome Victory Plough Silviculture has a technique for preparing soil for seeding in forests called scarification, which is explained in that article. Snowplow Whippletree References Further reading Liam Brunt, "Mechanical Innovation in the Industrial Revolution: The Case of Plough Design". Economic History Review (2003) 56#3, pp. 444–477 P. Hill and K. Kucharski, "Early Medieval Ploughing at Whithorn and the Chronology of Plough Pebbles", Transactions of the Dumfriesshire and Galloway Natural History and Antiquarian Society, Vol. LXV, 1990, pp 73–83 V. Sankaran Nair, Nanchinadu: Harbinger of Rice and Plough Culture in the Ancient World Steven Stoll, Larding the Lean Earth: Soil and Society in Nineteenth-Century America (New York: Hill and Wang, 2002) External links The Rotherham Plough — the first commercially successful iron plough History of the steel plough — as developed by John Deere in the United States Breast Ploughs and other antique hand farm tools "Tractor Guide Saves Labor for the Farmer", Popular Mechanics, December 1934 Articles containing video clips Chinese inventions Farming tools History of agriculture