Chemistry Reference
In-Depth Information
related constraints when concentrated in the planting hole. For instance, the
placement of high quality manure in the planting hole was not only found to
increase climbing bean yields on Ferralsols in East DR Congo from less than
500 to over 1500 kg ha
21
, but also increase the response to NPK fertiliser
application (see Figure 5). Both effects were much less pronounced when the
manure was broadcast over the whole plot surface (Figure 5).
Organic inputs applied as mulch gain prominence nowadays in the context
of the Conservation Agriculture debate.
27,28
Conservation Agriculture
advocates the use of three principles as a pathway towards sustainable
agriculture: (i) minimal or reduced tillage, (ii) retention of surface mulch to
keep the soil covered, and (iii) crop rotation and diversification. While it is not
the intention of this chapter to join this debate, organic resources applied on
the surface have been shown to improve soil moisture conditions, resulting in
higher and more stable yields.
23,29
There is less consensus, however, related to
interactions between surface mulch and fertiliser use efficiency since surface
mulch in the absence of tillage results in higher soil moisture contents and
more continuous soil pores, potentially resulting in larger fertilier N losses due
to enhanced leaching. In lysimeters installed in Nigeria, for instance, it was
d
n
1
r
2
n
g
|
5
Figure 5
Climbing bean (variety AND10) yield in East DR Congo as affected by
fertiliser application (with and without NPK), manure application rates
(medium: 2.5 tonne dry matter ha
21
; high: 7.5 tonne dry matter ha
21
),
manure placement (placed in the planting hole and broadcast), and manure
quality (local and 'quality' manure). Error bars are Standard Errors of the
Mean.
