Agriculture Reference
In-Depth Information
Chapter 9
Site-Specific Fertilizing
Hermann J. Heege
Abstract
Fertilisation aims at providing soils with nutrients for high crop yields
without adversely affecting the environment. Since in most cases the properties of
soils as well as of crops vary within individual fields, site-specific fertilization is
needed. The challenge is to find
sensing methods
that provide suitable signals for
the site-specific control of fertilizer application. Feasible approaches to meet this
challenge are based on
•
recording the yield of previous crops and the nutrient removal derived from it
•
electrochemical indication of nutrients in soils by ion-selective electrodes
•
sensing the nutrients either in soils or in crops via optical reflectance.
The best choice depends on a variety of factors such as
e.g.
nutrient type, proper-
ties of soils, properties of crops and climate. The last listed method - sensing via
optical reflectance - can be used in a proximal mode from farm machines or also in
a remote mode from satellites provided clouds do not obstruct the radiation. Its use
for in-season nitrogen application with proximal sensing from farm machines is
becoming a leading technology.
Keywords
Bending resistance • Benefits • Control algorithm • Crop-reflectance
• Fluorescence • In-season crop properties • Ion-selective electrodes • Nutrients
removed • N-sensor • Reflectance of soils