Agriculture Reference
In-Depth Information
TABLE 15.3
Selected Characteristics of 57 Nutrient Balance
Studies Reviewed by Cobo et al. (2010)
Characteristic
Number of Studies
% of Studies
Country
Kenya
19
33
Ethiopia
8
14
Mali
7
12
Uganda
6
11
Study Type
Agroecosystem assessment
42
74
Experiment
13
23
Scenario/simulation
8
14
Nutrients
N
55
96
P
47
82
K
36
63
Time Frame
1 year
23
40
1 season
11
19
2 years
8
14
Results Showing Negative Balances
N
48
85
P
32
56
K
43
76
Studies Showing Positive Balances
N
14
24
P
25
44
K
9
15
Source:
Cobo, J.G. et al.,
Agric Ecosyst Environ
, 136, 1-15, 2010.
balance estimations especially when results are scaled up spatially and temporally.
These limitations suggest that many published nutrient balance papers seek to pro-
vide an indication of trends rather than precise estimates.
15.2.2 n
utrient
B
AlAnceS
At
i
nternAtionAl
And
r
egionAl
S
cAleS
Net international trade of agricultural food commodities leads to major nutri-
ent transfers (
Figure 15.4
). The analysis by Grote et al. (2005) shows that in 1997,
through net trade, SSA imported the equivalent of 0.266 Tg of NPK, projected to
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