Agriculture Reference
In-Depth Information
Fig. 2.1 Aerial view of a farming area in Schleswig-Holstein, Germany
density and morphology of crops
crop content of water and of various minerals
infestation of crops by different weeds and by various pests.
Nowadays, many of these soil- or crop properties can be detected and recorded
within a field in a site-specific way via modern sensing techniques. Yet before these
techniques are dealt with in detail in subsequent chapters, the question arises, how
in principle variations of these soil- or crop properties can show up.
These variations of soil- or crop properties within a field can occur in different
ways. They can show up in a complete random pattern , i.e. in a similar manner as
raindrop spots within a field. All locations within the field are affected by the rain in
a similar way.
Yet the variations can also show up in a nested pattern . This is the case, if the
respective property, e.g. the clay content of the soil, is not uniform on the whole
field, but instead there are parts in various directions where it is lower and vice versa
higher. The respective property in this case varies with the distance.
Thus the spatial variation can be uncorrelated or correlated (Fig. 2.2 ), depending
how it presents itself in a graph with a distance scale. However, the distance scale
too can change. And if it does, the appearance of variations can be different. What
looks as random arrangement or noise at one scale can be recognized as structure at
another scale. This is why looking through a microscope can be so fascinating.
Therefore, we have to deal with resolutions . What is meant is not a resolution
taken by a political assembly. Here the term resolution stands for the “resolving” or
the dividing up of physical properties involved, such as the area of the field, the time
or the measurement units that belong to the signals of a sensor (Fig. 2.3 ).
The temporal resolution that is required depends very much on the respective
soil- or crop property. Textures and organic matter contents of soils hardly change
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