Agriculture Reference
In-Depth Information
N
electr. conductivity
in mS per m
< 10.0
10.1 - 12.5
12.6 - 15.0
15.1 - 17.5
17.6 - 20.0
> 20.1
vertical thickness
of loess-layer in cm
< 30
31 - 60
61 - 90
91 - 120
121 - 150
> 150
risk of leaching
for isoproturon
very high
high
medium
low
0
100
200 m
Fig. 13.3
Map overlay for the control of herbicide leaching by site-specifi c application. The soil
is a silt-loam of aeolian origin that is resting on sandy gravel deposits from the Rhine river and is
located near Cologne in Germany. The herbicide Isoproturon is a frequently used chemical for
pre-emergence as well as for post-emergence weed control (From Mertens
2008
, altered)
areas of high leaching risk, choosing a herbicide that is better absorbed would be
necessary. A similar adaptation to the absorption of herbicides would be feasible
based on
soil organic matter
, which can easily be sensed by visible and infrared
refl ectance (Sect.
5.3
). However, in humid regions it can be assumed that a positive
correlation between the clay- and the organic matter content of a soil exists. So with
soils that contain some clay, either sensing by electrical conductivity or sensing by
refl ectance for organic matter may be suitable, whereas for sandy soils the sensing
based on organic matter seems more reasonable.
The most frequently mapped crop property is the yield. For modern combines,
grain yield sensors
have become a standard accessory. In fact, maps about a spa-
tially resolved yield are indispensable for the determination of the site-specifi c
need of phosphorus and - with the exception of sandy soils - also of potassium.
Because for these nutrients no other sensing methods - that are well developed -
are available.
And there may be additional sensible uses for grain yield maps. From records
about the local grain yield mass, maps about the site-specifi c residue mass easily
can be obtained. The mass of crop residues is positively correlated to the mass of
