Deena Murphy

Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School



Precision farming methods have been introduced to increase profitability and reduce environmental impacts. Among the basic principles of precision farming are: (i) intensive soil sampling, (ii) variable-rate fertilization, (iii) yield monitoring, and (iv) the global positioning system (GPS) (Schepers and Francis, 1998). As these new technologies are developed, sound interpretation methods are needed. Yield monitors allow farmers to calculate the profitability of different areas of the field, and to identify yield limiting factors. However, it is difficult to compare rotational crops with differing yield potentials. Transformation of yield into relative yield makes it possible to compare yields from one year with yields from another. Standardization, or normalization, is the process that rescales the data to values between O and 1. This transformation helps to identify limiting yield factors, yield potentials, and management zones within the field allowing precision application of inputs. After within-field variation is identified, variable-rate fertilization can be implemented (Sawyer, 1994). Traditionally, farm fields were fertilized using a single rate across the field, which resulted in the over- and under-fertilization of many areas. Variable-rate technology (VRT) has the ability to manage production reducing environmental risks. Much research has been conducted comparing conventional application to variable-rate application but the results are mixed. The potential downfalls of VRT include the increased reliance on computerized technology and the increased cost of application. This may result in improper application of agricultural products and loss of yield and profits. With proper calibration (pan-collection) accurate dispension of these products can be achieved.

Library of Congress Subject Headings

Precision farming
Crop yields
Fertilizer equipment



Number of Pages



South Dakota State University