The Plow and Agricultural Sustainability

Abstract

Settled agriculture began about 10 to 13 millennia ago in the valleys of the Nile, Tigris, Euphrates, and other rivers. Prehistoric tools developed included a short-handled forked branch that evolved into a hoe, and a long-armed hockey-shaped stick with a curved handle called an ard. The ard, which eventually evolved into a plow, won religious sanctions in many ancient cultures such as those of Greece, China, and India. The plow-based agriculture flourished in alluvial and loess-derived soils. These soils are generally coarse-textured, less cohesive, devoid of stones and suitable for growing closely spaced cereals such as wheat (Triticum aestivum). In contrast, hoe-based agriculture dominated in regions where widely spaced roots and tuberous crops, such as cassava (Manihoc esculenta) and yam (Dioscorea spp.), were grown on sloping lands. Mechanization of plowing with the tractor during the early part of 20th century vastly expanded the land area under cultivation. However, plowing also caused erosion and exacerbated environmental problems of non-point source pollution, emission of greenhouse gases (GHGs) and loss of biodiversity. The environmental movement, begun in 1950s and 1960s, led to the development of no-till (NT) farming. After approximately 50 years of its introduction, NT farming is practiced only on about 6% of the global cropland area, mostly in North and South America, and in Australia. Adoption of NT farming by resource-poor farmers of South Asia and sub-Saharan Africa is constrained by removal of crop residues for fodder and animal dung as residential fuel, lack of appropriate seed drill which can sow in an unplowed soil covered by crop residue mulch, and non-availability or prohibitively high cost of herbicides. While use of the plow is unsustainable on erodible soils, its use is essential until alternative sources of residential fuels are available to rural households, efficient seed drills are developed by village blacksmiths, and herbicides become economical and effective against perennial weeds or other viable options of weed control are available.