Performance assessment of a variable-rate fertilizer applicator

Authors: Sui, Ruixiu

Submitted to: Journal of Agricultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2018
Publication Date: 1/15/2019
Citation: Sui, R. 2019. Performance assessment of a variable-rate fertilizer applicator. Journal of Agricultural Science. 11(2): 25-30.

Interpretive Summary: Variable rate technology (VRT) allows crop producers to site-specifically apply farming inputs such as fertilizers and pesticides at variable rates to adjust the temporal and spatial variability of the crops within a field. VRT fertilizer applicator is an important equipment in precision agriculture practices. However, for proper use of such VRT equipment, it is necessary to understand how they perform. A Researcher at USDA-ARS Crop Production Systems Research Unit in Stoneville, MS tested a variable-rate side-dressing liquid fertilizer applicator with a sprayer control system for its performance and application accuracy. The equipment was tested in 5 application rates (30, 60, 90, 120, and 150 lb/ac). Results showed the application uniformity increased as the application rate increased. The absolute error of application rate ranged from 1.3% to 6.5% with an average of 3.76%. There was no significant difference between the selected application rate and actual application rate. This sprayer control system can be used for variable rate fertilizer application in precision farming.

Technical Abstract: A Field-IQ sprayer control system was interfaced with a John Deere liquid fertilizer applicator. The sprayer control system includes Case IH FM-1000 display integrated with DGPS, Field-IQ spray control with full harness, flowmeter and auto-range valve, and the pump. The application accuracy and uniformity of the system were evaluated. Tap water was used to simulate the UAN 32% nitrogen fertilizer solution in the evaluation. A total of 120 samples from 8 rows of the applicator in 5 application rates (34, 67, 101, 135, and 168 kg/ha) were collected, and the data were analyzed for application uniformity and application rate accuracy of the system. Results showed the greatest variation from the application rate baseline among the rows was 10.1% and occurred at a swath-end row with the lowest application rate of 34 kg/ha. The rows in the middle section of the swath had the lower variation than the rows at the two swath-ends. The application uniformity increased as the application rate increased. The absolute error of application rate ranged from 1.3% to 6.5% with an average of 3.76%. There was no significant difference between the selected application rate and actual application rate (p>0.8686).