Agriculture Reference
In-Depth Information
Umweltbundesamt
2011
; Wolter
2004
). In agricultural areas, the main cause for this
is fertilization. Reducing this by generally accepting lower yields is no worldwide
solution of the problem when taking into consideration that still about 800 million
people are starving. Instead, technologies that provide a high efficiency of nitrogen
use should be aimed at. Because nitrogen that is taken up by a crop is prevented
from leaching into groundwaters. Hence more precision in application is needed.
Important means for improving the efficiency of nitrogen use are site-specific appli-
cations (Table
9.8
) as well as temporally split dressings. In other words, the applica-
tion should be at the right place, in the right time and with the right rate
.
The thus
obtained higher efficiency in nitrogen use results in two-sided advantages: both
higher yields or lower nitrogen expenses and in addition better qualities of water
resources.
For small grains, also the effect of site-specific nitrogen application on the
conditions for harvesting
the crop should be considered. Nitrogen application
for high yielding small grains can result in crop canopies that at harvest time are
lodging
partly. This nuisance for harvesting is mainly caused by disregarding
site-specific differences in soil qualities, hence by a local oversupply with nitro-
gen. Site-specific nitrogen application is oriented at local differences in the con-
dition of the crop, therefore can remove this local oversupply and thus can
homogenize the canopy. If the site-specific control is well adjusted, the lodging
problem is gone.
However, there is a homogenizing effect via site-specific fertilizing also if no
lodging occurs. This is due to the fact that this technique provides more
even shoots
.
At harvest time of small grains, this means for shoots of a low order that the ears are
located higher from the soil level. Hence harvesting by a combine is facilitated even
if no grain lodges (Feiffer et al.
2005
).
For combines there exists a relationship between throughput in tons of har-
vested product per time unit on the one hand and losses in % of the grain on the
other hand. Generally it holds that when -
ceteris paribus
- the throughput or the
travel speed is increased, the losses get higher and this in a more than propor-
tional manner. Farmers try to keep the losses at a level of approximately 1 % of
the small grain harvest and adjust the travel speed accordingly. Under this prem-
ise, the site-speciically fertilized and hence more uniform crop allows for a
higher throughput. In extensive trials by Feiffer et al. (
2005
) in Eastern Germany,
the field capacity of combines in ha/h for strips of small grains that had been
homogenized by site-speciic nitrogen application was on the average about
10 % higher than for strips that had been fertilized uniformly. With average costs
for combine operations including the driver of 100 euros per ha, this means a
saving of 10 euros per ha.
Another potential benefit from site-specific nitrogen application can result from
better qualities of the harvested product, especially a more precise control of its
protein content
(see Sect.
9.4.9.3
). Perspectives in this direction might exist for
many crops, not only for small grains. However, much more knowledge about con-
trol algorithms for site-specific quality control is needed.
