Agriculture Reference
In-Depth Information
(a)
(b)
2%
3%
5%
7%
37%
24%
19%
48%
24%
32%
Cattle
Swine
Poultry
Sheep
Other
Fig. 8.1.
Contribution of species of livestock to global production of (a) manure N and (b) manure P
(adapted from Sheldrick
et al
., 2003).
Table 8.1.
Whole farm nutrient balance in different countries. Adapted from
Vitousek
et al
. (2009) and Nkonya
et al
. (2005).
Annual nutrient balance (kg ha
−1
)
Country
Region
Nitrogen
Phosphorus
China
Northern
+227
+53
Kenya
Western
−52
+1
Uganda
Eastern
−48
−11
USA
Midwest
+10
−9
livestock farms, and protection or restoration of
riparian vegetation. To maintain and improve
the modern agriculture system, it is important
for national agriculture agencies to evaluate the
effects of changing system and to provide incen-
tives to encourage the farmers to adopt nutrient-
conserving practices.
Manure is one of the major contributors to
nutrient inputs in all countries, and virtually the
only contributor in some (Sheldrick
et al
., 2003).
Most countries, developed and developing, find
manure a less expensive alternative to mineral
fertilizers, but frequently commercial fertilizer is
preferred because of its ready supply and easy
application. From a global perspective, the use of
manure as nutrient source has decreased with
increasing use of synthetic fertilizers (Fig. 8.2).
Two countries with widely differing agri-
culture industries demonstrate changing ferti-
lization practices and remaining opportunities
(Sheldrick
et al
., 2003). In Kenya, livestock pro-
duction plays a major role in the agriculture
industry, and since 1961 nutrient excretion by
livestock has increased gradually. A relatively
small portion of excreted N and P are captured in
manure available for land application, suggesting
great opportunity for improvement in productiv-
ity without reliance on additional commercial
fertilizer. In the Netherlands, livestock manure has
also been the key source of nutrient inputs but the
majority of excreted nutrients are managed (con-
tained, stored and applied in a managed fashion).
Thus, they have been able to meet crop needs with
reduced application of synthetic fertilizers.
