CEREAL CROPS: ECONOMICS, STATISTICS AND USES yield t/ha), corn meal (2.04 t/ha) and white wheat four The proportion of the total harvested the eight cereals is similar content in k]/g(15.7 for milled rice, 16.61 area 1.72 t/ha by the respective figures for energy contributed by each of for corn to,or greater than, the proportion of the total meal, 16. I for white wheat flour). As regards food production, except for maize and rice(see Table protein yield, rice, producing 0.18 t/ha of protein 1. 1). This is because the yields of wheat, barley, (in milled rice), is second only to wheat, produc oats, rye and sorghum do not vary greatly among ng 0 19 t/ha(in white flour), followed by oats, abour, s(and that for millet is very low), producing 0.15 t/ha(in oatmeal) whereas times the average yield of all the other reals (apart from millet. Taking all the cereals Wheat together, the average yield for the whole world progressively from 18. 1 q/ Cultivation 1969-1971to22.5q/hain1981, and to258 g/ha in 1987-1989. Between 1969 and 1989, the Wheat is grown throughe world, from yield of maize increased by 11. 8 q/ha(from 24.7 e borders of the arctic to near the equator, to 36.5 q/ha), largely through the use of hybrid although the crop is most successful between the maize(cf. p. 99), and that of rice(padd latitudes of30°and60° North and27°and40° increased by 12. 1 q/ha(from 22.6 q/ha in 1969 South. In altitude, it ranges from sea level to 34.7 q/ha in 1989), whereas that of all other 3050 m in Kenya and 4572 m in Tibet. It adaptable to a range of environmental conditions cereals together increased by only 3.9 q/ha on from xerophytic to littoral distribution of the world cereals area and produc Wheat grows best on heavy loam and clay tion and the world average yields for each cereal although it makes a satisfactory crop on light over the period 1987-1989 are shown in Table 1.1 land. The crop repays heavy nitrogenous manuring. TABLE Wheat flourishes in subtropical, warm tempe World Cereal Area, Production and yield for the Period rate and cool temperate climat 1987-1989★ rainfall of 229-762 mm, falling more in spring of total temperature should be 13C (56F)or more. production (q/hat) The seed is sown in late autumn( winter wheat) Wheat 32 23.3 or in spring(spring wheat). Winter wheat can be Barley rown in places, e.g. northwestern Europe, where excessive freezing of the soil does not Rice(paddy) 33. 8 occur. The grain germinates in the autumn and Maize grows slowly until the spring Frost would affect Millet 14.0 the young plants adversely, but a covering of snow protects them and promotes tillering. In ★ ed from F. A.O. Production Year Book(1990). countries such as the Canadian prairies and the t N.B. 1 qha 0.79 cwt/ac. steppes of russia that experience winters too severe for winter sowing, wheat is sown as early s sources of carbohydrate related to land use, as possible in the spring, so that the crop may be rice, producing 38. 1 x 106 kJ/ha, ranks first harvested before the first frosts of autumn. The among cereal grains, followed by maize with 33. 9 area of production of spring wheat is being x 10 k]/ha and wheat with 27.7 x 10 k]/ha. extended progressively northwards in the northern These figures are obtained by multiplying the hemisphere by the use of new varieties bred for 1989 average world yield of milled rice(2.43 their quick -ripening characteristicsCEREAL CROPS: ECONOMICS, STATISTICS AND USES 3 t/ha), corn meal (2.04 t/ha) and white wheat flour (1.72 t/ha) by the respective figures for energy content in kJ/g (15.7 for milled rice, 16.6 for corn meal, 16.1 for white wheat flour). As regards food protein yield, rice, producing 0.18 t/ha of protein (in milled rice), is second only to wheat, produc￾ing 0.19 t/ha (in white flour), followed by oats, producing 0.15 t/ha (in oatmeal). Yield The proportion of the total harvested area contributed by each of the eight cereals is similar to, or greater than, the proportion of the total production, except for maize and rice (see Table 1.1). This is because the yields of wheat, barley, oats, rye and sorghum do not vary greatly among themselves (and that for millet is very low), whereas the yields of maize and paddy rice are about 1.7 times the average yield of all the other cereals (apart from millet). Taking all the cereals together, the average yield for the whole world increased progressively from 18.1 q/ha in Cultivation 1969-1971 to 22.5 q/ha in 1981, and to 25.8 yield of maize increased by 11.8 q/ha (from 24.7 maize (cf. p. 99), and that of rice (paddy) increased by 12.1 q/ha (from 22.6 q/ha in 1969 to 34'7 q/ha in 1989)y whereas that Of a11 Other cereals together increased by only 3.9 q/ha on average (from 13.8 to 17.7 q/ha). The percentage distribution of the world cereals area and produc￾tion and the world average yields for each cereal over the period 1987-1989 are shown in Table 1.1 TABLE 1.1 World Cereal Area, Production and Yield for the Period 1987-1989* Wheat Wheat is grown throughc ! world, from although the crop is most successful between the South. In altitude, it ranges from sea level to 3050 m in Kenya and 4572 m in Tibet. It is adaptable to a range of environmental conditions from xerophytic to littoral. Wheat grows best on heavy loam and clay, although it makes a satisfactory crop on lighter land. The crop repays heavy nitrogenous manuring. Wheat flourishes in subtropical, warm tempe￾rate and c001 temperate c1imates* An annua1 rainfall of 229-762 mm, falling more in spring than in summer, suits it best. The mean summer Cereal area production (q/hat) The seed is sown in late autumn (winter wheat) 29 Wheat or in spring (spring wheat). Winter wheat can be 32 Barley 11 10 22.6 grown in places, e.g. northwestern Europe, Oats 3 2 17.8 where excessive freezing of the soil does not occur. The grain germinates in the autumn and Rye 2 2 Rice (paddy) 21 27 Maize 19 25 34.5 grows slowly until the spring. Frost would affect Sorghum 7 3 14.0 the young plants adversely, but a covering of snow protects them and promotes tillering. In Millet 5 2 countries such as the Canadian prairies and the steppes of Russia that experience winters too severe for winter sowing, wheat is sown as early as possible in the spring, so that the crop may be harvested before the first frosts of autumn. The area of production of spring wheat is being extended progressively northwards in the northern hemisphere by the use of new varieties bred for their quick-ripening characteristics. dha in 1987-1989* Between 1969 and 1989Y the the borders of the arctic to near the equator, to 36*5 q/ha)Y largely through the use Of hybrid latitudes of 300 and 600 North and 270 and 400 Percentage Percentage Average of total of total yield temperature should be 13°C (56°F) or more. 23.3 :!:: 7.8 * Data derived from F.A.O. Production Year Book (1990). t N.B. 1 q/ha = 0.79 cwt/ac. As sources of carbohydrate related to land use, rice, producing 38.1 x lo6 kJ/ha, ranks first among cereal grains, followed by maize with 33.9 x lo6 kJ/ha and wheat with 27.7 x lo6 kJ/ha. These figures are obtained by multiplying the 1989 average world yield of milled rice (2.43