Economic and Agricultural Geography: Spatial Organisation of Economic Activities, Natural Resources and Energy Crises, Land Capability, Crop Combination, Von Thünen and Agricultural Productivity

The land capability classification of the US Soil Conservation Service (Klingebiel and Montgomery, 1961) grades land by the degree of its limitations for sustained use without degradation. Classes I to IV are suitable for cultivation, with limitations that increase from none (I) to very severe, requiring careful management (IV); classes V to VIII are generally unsuitable for cultivation — V is wet or stony but not erodible and suits pasture, VI and VII have severe limitations and suit grazing or forestry, and VIII is fit only for wildlife, recreation, water supply or aesthetic purposes. Subclasses name the limitation: e erosion, w wetness, s soil in the root zone, c climate. Land-use planning matches use to capability; in India it starts from the nine-fold land-use classification of the land records — forest, land put to non-agricultural uses, barren and unculturable land, permanent pastures, land under miscellaneous tree crops, culturable waste, current fallows, other fallows and net sown area.

A crop-combination region is defined by the group of crops that together dominate its cropped area. J.C. Weaver (1954, for the American Midwest) compared the actual percentage shares of the leading crops with theoretical curves — 100 per cent for monoculture, 50–50 for two crops, 33.3 each for three, and so on — and chose the combination with the lowest variance, σ² = Σd² ÷ n, where d is the difference between actual and theoretical shares and n the number of crops. Worked example: wheat 60 per cent, rice 30 per cent, maize 10 per cent. One crop: (60 − 100)² ÷ 1 = 1,600. Two crops: [(60 − 50)² + (30 − 50)²] ÷ 2 = (100 + 400) ÷ 2 = 250. Three crops: [(60 − 33.3)² + (30 − 33.3)² + (10 − 33.3)²] ÷ 3 ≈ 1,266.7 ÷ 3 ≈ 422. The minimum is 250, so the region is a wheat–rice combination. K. Doi (1959, Japan) simplified the procedure, using Σd² with a ready-reckoner table of critical values so that the combination can be read off without computing every variance. S.M. Rafiullah (1956) proposed the maximum positive deviation method, which treats positive and negative deviations separately and selects the combination with the largest positive value, to avoid Weaver's tendency to yield combinations with too many or too few crops in some settings.

Crop diversification is the opposite of specialisation — the number of crops grown and the evenness of their shares. It is commonly measured by the Gibbs–Martin index (1962), 1 − Σx² ÷ (Σx)², where x is the area under each crop: 0 means monoculture and values approaching 1 mean many crops in similar proportions; Bhatia (1965) used the share of cropped area under crops each occupying at least 10 per cent, divided by their number. Diversification spreads risk and supports soil health; specialisation raises efficiency and market income.

Johann Heinrich von Thünen, a Mecklenburg landowner, published Der isolierte Staat (The Isolated State) in 1826. He imagined a single city at the centre of a uniform, fertile plain cut off from the outside world, with farmers who carry produce to the city by horse and cart at a cost proportional to distance and who maximise profit. The key quantity is locational (economic) rent per unit of land: R = Y(p − c) − Y f k, where Y is yield per unit of land, p the market price per unit of produce, c the production cost per unit, f the freight rate per unit per kilometre and k the distance to market. Rent falls with distance, and each crop has its own rent line; at every distance the land goes to the use with the highest rent. Example: Y = 10 tonnes a hectare, p = 100, c = 50, f = 2 per tonne-kilometre and k = 10 km give R = 10 × 50 − 10 × 2 × 10 = 500 − 200 = 300; rent falls to zero at k = 500 ÷ 20 = 25 km, the margin of cultivation for that crop.

The model survives as a way of thinking about distance and rent. Olof Jonasson (1925) found von Thünen-like zones around the industrial core of north-western Europe at a continental scale; Robert Sinclair (1967) argued that around growing modern cities the pattern is reversed, because land near the urban edge is held for speculation and farmed extensively. Around Indian cities, belts of vegetable, flower and milk production are the recognisable first ring.

Agricultural productivity is output per unit of input — usually per hectare, sometimes per worker. Because regions grow different crops, geographers use composite indices. M.G. Kendall's ranking coefficient (1939) ranks each areal unit by its yield of each crop and averages the ranks — the lower the average rank, the higher the productivity. Other indices were proposed by Enyedi (1964), Jasbir Singh and Mohammad Shafi, among others, many weighting yields by the share of area under each crop. The determinants are physical (soil, water, climate, relief), technological (high-yielding varieties, irrigation, fertilisers, mechanisation), institutional (land tenure, size of holdings, credit, extension, markets and prices) and infrastructural (roads, storage, power). Regional variations in India follow them closely: productivity is highest in the irrigated north-west (Punjab, Haryana, western Uttar Pradesh) and in the deltas, and lowest in the rainfed plateaux.

The classic classification of agricultural systems of the world is Derwent Whittlesey's (1936). He used five criteria — the crop and livestock combination, the intensity of land use, the processing and marketing of farm produce, the degree of mechanisation, and the types and associations of farm buildings — to define thirteen types: nomadic herding; livestock ranching; shifting cultivation; rudimental sedentary tillage; intensive subsistence tillage with rice dominant; intensive subsistence tillage without paddy rice; commercial plantation crop tillage; Mediterranean agriculture; commercial grain farming; commercial livestock and crop farming (mixed farming); subsistence crop and stock farming; commercial dairy farming; and specialised horticulture.