Agriculture Reference
In-Depth Information
considering the rapid escalation of natural gas
price and the adverse environmental effects
of irresponsible N use. This importance is ampli-
fi ed by the yield and nutritional penalties from
not having applied suffi cient N. The key to suc-
cessfully introducing these technologies and
scientifi c developments to farmers in the devel-
oped and developing world is the creation and
extension of a comprehensive package of technol-
ogy, science, education, and fi nancing. In the
absence of an entire package or system these
technologies and scientifi c breakthroughs will
not be adopted. The optical-sensor-based systems
further described can provide the agronomic
science and sensing technology components of
this package.
target when accusations of mismanagement arise.
An examination of fertilizer consumption and
production data from Sub-Saharan Africa (SSA)
and the US illustrate the importance of address-
ing the problem of imprecise use of N fertilizer
(Table 10.1).
Today, SSA has a population exceeding 699
million persons. In 2005, SSA produced
97,317,420 t of cereal grain on 88,435,068 ha, or
a mean of 1.10 t ha −1 . A total of 26,801,040 ha of
maize was harvested in SSA, with a total produc-
tion of 40,473,062 t, or a mean maize yield of
1.51 t ha −1 (Food and Agriculture Organization
2007). Wheat, sorghum ( Sorghum bicolor L.), rice,
and millet ( Pennisetum glaucum L.) comprise the
majority of the remaining cereal production
(Table 10.1). Alternatively, the US produced
364,019,526 t of cereal grain on 56,404,000 ha,
resulting in 6.50 t ha −1 . Fertilizer N consumption
for SSA in 2005 was 1,307,443 t, of which 60%
was estimated to be consumed for cereal produc-
tion (Alexandratos 1995, p. 190). This translates
into an anemic average N rate of 4 kg ha −1 for
more than 88 million hectares of cereals produced
in SSA. In the US, 6,526,998 t of fertilizer N was
consumed for cereal production, and the average
annual N rate was 52 kg ha −1 for all cereals. While
SSA represents 10% of the world population, it
CASE STUDY: WHAT DEFINES
DIVERSE ENVIRONMENTS
Improved N management has never been more
important than it is today, whether or not the
environment is diverse and challenged in some
way. Because fertilizer N used in cereals accounts
for more than 60% of the total N (Alexandratos
1995, p. 190) used worldwide (90 million tonnes),
maize, wheat, and rice farmers are the obvious
Table 10.1 Production and nitrogen
use statistics for cereal production in
Sub Saharan Africa (SSA), the US, and
worldwide.
SSA
US
World
Population
699,813,000
300,000,000
6,600,000,000
Cereal production (ha)
88,435,068
56,404,000
657,085,620
Maize (ha)
26,801,040
30,081,820
138,163,504
Wheat (ha)
2,631,932
20,226,410
210,247,188
Sorghum (ha)
25,829,881
2,301,470
41,689,272
Rice (ha)
8,477,895
1,352,880
147,455,159
Millet (ha)
20,480,119
200,000
34,242,897
Cereal production (t)
97,317,420
364,019,526
693,427,825
Maize production (t)
40,473,062
280,228,384
601,815,839
Cereal yields (t ha −1 )
1.10
6.45
1.06
Maize yields (t ha −1 )
1.51
9.32
4.36
Fertilizer N (t)
1,307,443
10,878,330
84,746,304
Fertilizer N, cereals (t)
784,466
6,526,998
50,847,782
N rate, cereals (kg ha - 1 )
3.99
52.07
34.82
N fertilizer costs ($)
706,019,220
5,874,298,200
45,763,004,160
Source: Food and Agriculture Organization (2007).
 
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