# Empirical View
# Land Use Change in the Very Long Run
Navin Ramankutty and Jonathan A. Foley have reconstructed the change in global agricultural land usage. In their very highly cited (>800 times) publication, Ramankutty and Foley (1999) have reconstructed the change between 1700 and 1992. In the equally famous update, Ramankutty et al. (2008) have presented estimates on global agricultural lands in the year 2000.1
# The changing global landscape of crop production, 1700-2000 – Alston, Babcock, and Pardey [eds.] (2010) [based on SAGE data]2
There are two beautiful animations that show the change of agricultural land since 1700. Bill Rankin mapped the change between 1700 and 1990 at Radical Cartography (here). And on Navin Ramankutty’s personal academic website there is a video that shows the change between 1700 and 2000 (online here).
# Agricultural Land Use Change in the Last 50 and the Next 50 Years
The following graph includes a projection of global arable land for the period 2010-2060. While the authors of this paper forecast a slight decline of global farmland, the before-cited research by the FAO projects a slight increase of total global farmland.
Ausubel, Wernick, & Waggoner (2013) argue that ‘peak farm’ is already a reality, saying ‘while the ratio of arable land per unit of crop production shows improved efficiency of land use, the number of hectares of cropland has scarcely changed since 1990. Absent the 3.4 percent of arable land devoted to energy crops (Trostle 2008), absolute declines would have begun during the last decade.’4
# Peaking farmland: extent of global arable land and permanent crops, 1961-2009, and our projection for 2010-2060 – Ausubel, Wernick, & Waggoner (2013)5
# Global Agricultural Land Use Today
# World map of cropland and pastureland – SAGE7
# Land Use Change by Crops
# Agricultural Land Use Today by Crops
# World maps of crop areas (maize, rice, wheat, and soybeans) – Monfreda, Ramankutty, Foley (2008)10
# Land use in the USA – percent of land devoted to each crop by county, 2007 – Radical Cartography11
# Correlates, Determinants & Consequences
The following graph shows that to produce an equivalent aggregate of crop production (PIN) in 2012 required only about 32% of the land needed in 1961. The agricultural production index (PIN) is the sum of agricultural commodities produced (after deductions of quantities used as seed and feed). It is weighted by the commodity prices. The FAO explains the construction of the PIN in detail here.
The idea for this chart is taken from Ausubel, Wernick, and Waggoner (2013).12 The authors write: ‘A combination of agricultural technologies raised yields, keeping downward pressure on the extent of cropland, sparing land for nature.
Countering the global rise of population and affluence by parents and workers, consumers and farmers restrained the expansion of arable land by changing tastes and lifting yields. The noticeable shrinkage in the extent of cropland as a function of the Crop Production index since 1990 (Figure below) provides encouragement that farmers will continue sparing land.’
# Area harvested and production for wheat in France 1820-2010, rice in China 1920-2010, and wheat in Egypt 1890-2010 – Ausubel, Wernick, & Waggoner (2013)14
Quotes from the paper for following graph: ‘The thick “impact” (im) line sums the other five. Population (p) and affluence (a) raise impact, while technology (t) lowers it, and forms of consumer behavior (c) may lower or raise it. When the value of the impact line falls below zero, cropland is released for other uses.
Im = Impact = P · A · C1 · C2 · T
Im = Cropland (in hectares) taken as the amount of arable land and
permanent crops5 (representing land currently used for crop cultivation, not land that is potentially cultivable), as defined and reported by the Fao.Jesse h. ausubel / iddo k. Wernick / Paul e. Waggoner 227
P = Population (persons)
C1 = Consumption 1 (in kcal/GdP), where kcal refers to the annual
national or global food supply in kilocalories from both vegetal and animal sources. C1 tracks the dietary response to affluence in calories, an indicator of both hunger and excess.
C2 = Consumption 2 (in Crop Production index [Pin]/kcal) using the Fao Crop Production index, which measures the relative level of aggregate volume of agricultural crop production indexed to a base year. C2 tracks the ratio of crop production for food, feed, fuel, fiber, and tobacco to the supply of food calories. it monitors farmers’ planting choices relative to caloric sup- ply.
T = technology (in hectares/Crop Pin) tracks how much land farmers use relative to total crop value.’
# Annual change of ImPACT factors in global cropland shown by ten-year moving averages, 1961–2010 – Ausubel, Wernick, & Waggoner (2013)15
# Data Quality & Definition
The Land Area of the World is 13,003 million ha. 4,889 million ha are classified as ‘agricultural area’ by the FAO (this is 37.6% of the Land Area).
The agricultural area use is divided into 3 categories: arable land (28% of the global agricultural area), permanent crops (3%) and permanent meadows and pastures (69%) which account for the largest share of the world’s agricultural area.16
What do these words mean?
The agricultural area is the sum of arable land, permanent crops, permanent meadows and pastures.
The FAO definition for arable land is land under temporary agricultural crops (multiple-cropped areas are counted only once), temporary meadows for mowing or pasture, land under market and kitchen gardens and land temporarily fallow (less than five years). The abandoned land resulting from shifting cultivation is not included in this category. Data for “Arable land” are not meant to indicate the amount of land that is potentially cultivable.’17
The same source defines permanent crops as follows: ‘Permanent crops are divided into temporary and permanent crops. Permanent crops are sown or planted once, and then occupy the land for some years and need not be replanted after each annual harvest, such as cocoa, coffee and rubber. This category includes flowering shrubs, fruit trees, nut trees and vines, but excludes trees grown for wood or timber.
And again from the same source the definition for permanent meadows and pastures is ‘land used permanently (five years or more) to grow herbaceous forage crops, either cultivated or growing wild (wild prairie or grazing land).’
The FAO definition for fallow land is ‘the cultivated land that is not seeded for one or more growing seasons. The maximum idle period is usually less than five years.’
# Data Sources
The FAO Land Use Database is online here. It includes several datasets on land use for countries and world regions since 1961.
Through Gapminder (here) it is possible to visualize data on agricultural land (as % of land) for the period from 1961 to 2009 and to plot this data against a second variable.