Principles of Soil Management - Principles of Sustainable Soil Management in Agroecosystems - page 5

show that the relative yield of maize ( Zea mays ), with reference to the highest yield
of 9.34 Mg/ha in North America, is only 14.6% and 17.3% in eastern and western
Africa, respectively. Compared with the highest yield of 10.84 Mg/ha of rice (paddy)
in Australia, the relative yield is merely 19.3% in eastern Africa. In comparison with
the highest soybean yield of 3.2 Mg/ha in southern Europe, the relative yield is 30.9%
in eastern Africa and 40.5% in western Africa (Table 1.4). The low relative yields of
major crops (e.g., wheat, maize, rice, soybean) can be mostly attributed to misman-
agement of soil and water resources under the prevailing harsh and uncertain climate.
Global energy use (primarily based on coal, oil, and gas) increased by a factor
of 19 from 28.6 EJ in 1850 to 542.8 EJ in 2008 ( Table 1.5 ). Whereas the energy-
based input (fertilizer, irrigation, machinery) must be increased in Africa and South
Asia, the importance of enhancing the use efficiency of inputs (e.g., fertilizer, water, farm
operations), by minimizing losses and conserving energy, cannot be overemphasized.

TABLE 1.4
Current Relative Yield Levels of Major Crops in Different Regions

Region Wheat Maize Rice Soybean

Western Europe 100 (6.85 Mg/ha) - 45.9 85.3

Northern
Europe

94.3 - - -

Southern
Europe

45.3 - 63.0 100 (3.20 Mg/ha)

Australia and
New Zealand

19.3 - 100 (10.84 Mg/ha) 59.3

North America 38.7 100 (9.34 Mg/ha) 69.6 91.3

Eastern Asia 65.4 55.6 60.0 54.6

Southern Asia 36.6 25.4 31.9 33.6

Northern Africa 30.2 - 385.8 85.2

South America 35.6 35.4 42.3 89.6

Eastern Europe 34.5 44.5 47.9 45.3

Central
America

- 24.4 35.0 39.0

Southeastern
Asia

- 34.6 38.2 44.0

Eastern Africa - 14.6 19.3 30.9

Western Africa - 17.3 - 40.5

Caribbean - - 32.7 -

Eastern Africa - - 24.4 -

World 40.1 65.4 36.3 72.5

Source: Recalculated from Hengsdijk, K.H. and J.W.A. Langeveld. Yield trends and yield gap analysis
of major crops in the world. Wageningen Wettelijke Onderzoekstaken Natuur & Milieu, wOt-
werkdocument 170 blz. 57; fig. 15; tab. 13; ref. 40, Wageningen, Holland, 2009.
Note: The minimum yield of a specific crop in a region (given in parenthesis as Mg/ha) is considered
100. Yield for all other regions are relative to 100.