Chemistry Reference
In-Depth Information
as a framework for boosting crop productivity through reliance upon soil
fertility management technologies, with emphasis on increased availability and
use of mineral fertiliser. ISFM is defined as 'A set of soil fertility management
practices that necessarily include the use of fertiliser, organic inputs, and improved
germplasm combined with the knowledge on how to adapt these practices to local
conditions, aiming at maximising agronomic use efficiency (AE) of the applied
nutrients and improving crop productivity. All inputs need to be managed following
sound agronomic principles'.
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Conceptually, ISFM can be sketched as shown in
Figure 1 which explicitly addressed the need for non-responsive soils to be
rehabilitated, e.g. through the use of organic resources, before an increase in
fertilier AE can be expected (Paths B to C in Figure 1).
d
n
1
r
2
n
g
|
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Figure 1
Conceptual relationship between the agronomic efficiency (AE) of fertiliers
and organic resource and the implementation of various components of
ISFM, culminating in complete ISFM towards the right side of the graph.
Soils that are responsive to NPK-based fertiliser and those that are poor and
less-responsive are distinguished. The 'current practice' step assumes the use
of the current average fertiliser application rate in SSA of 8 kg fertiliser
nutrients ha
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. The meaning of the various steps is explained in detail in the
text. At constant fertiliser application rates, yield is linearly related to AE.
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