Agriculture Reference
In-Depth Information
assumptions:
- total capital expenses for N sensing = 46 500
€
incl. taxes
- annual costs for depreciation, interest and repair
amount to 20% of these capital expenses
- additional annual cost of 300 for servicing the sensor.
80
60
additional benefit due to higher capacity in combining (10
€
/ ha)
benefit due to higher yield
or
due to lower nitrogen expenses
40
20
0
0
500
1000
1500
2000
area fertilized annually in ha
Fig. 9.41
Costs of the control technique
versus
benefits of site-specific nitrogen application for
winter-wheat. It is assumed that the site-specific application - depending on the control setting -
provides either for a yield increase
or
alternatively for a saving of nitrogen expenses. With present
market prices for grain or for nitrogen fertilizer, both alternatives amount to approximately the
same financial benefit, hence both are represented by the
green line
. The homogenizing effect of
site-specific nitrogen application on the crop results in a higher capacity of the combine. This
benefit amounts to 10 euros per ha (
brown line
). For details see Sect.
9.4.11.1
9.4.11.2
Comparing Benefits and Costs
The costs of site-specific in-season nitrogen application result primarily from the
capital expenditures for the equipment that is needed for the control of the spreading
machine. These expenditures amount to about 46,500 euros for an implement that is
designed for reflectance sensing by means of artificial light (Fig.
9.25
) including
operational terminal, software, a handheld transmittance meter to assist the calibrat-
ing procedure and taxes. If natural- instead of artificial light is used, the total expen-
diture for the corresponding items is about 31,000 euros. However, the annual area
that can be treated with the latter outfit might be smaller too because of limitations
in operational time.
The control costs per ha that result from the equipment depend heavily on the
annual area that is treated (Fig.
9.41
).
As for benefits that may result from higher
yields
, an average increase of 4 % is
assumed (Fig.
9.40
, right). With a yield level of 8.5 t/ha, the corresponding absolute
increase of 0.34 t/ha represents a benefit of approximately 45 euros per ha, assum-
ing that the unprocessed small grains in the field are valued at 130 euros per t.
Alternatively, the site-specific control can be used in such a way that no yield
increase, but instead a
saving of nitrogen
fertilizer results. From the average effi-
ciencies in Table
9.8
, bottom line, it can be calculated that for the same yield of
