A recent Canadian demonstration project to determine if variable rate (VR) fertilizer techniques work for manure was featured in the recent National Hog Farmer magazine.
Producers were impressed with the concept, but found current manure application technology fell short of the challenge. The potential agronomic/economic benefit would be increased yields in more productive areas of the field by applying more nutrients to these areas and, therefore, decreasing the environmental risk of nutrient leaching to bodies of water.
In the study, manure was applied using the drag hose application method. Application rates were varied based on global position satellite field maps indicating different nutrient requirements for different parts of the fields. Satellite imagery identified zones using different light bands to create a vegetative index of better growing parts of the field. The zones were then individually soil tested to determine the reasons for the variability across zones and establish the optimal nutrient application rate.
Project leader Scott Dick with Agra-Gold Consulting, Ltd. says an increasing number of producers are adopting VR application with commercial fertilizer to tailor application rates to the varying nutrient requirements on different sections of a field. That technique can produce better nutrient utilization by the crop, higher yields, lower costs and reduced environmental risk of excess nutrients contaminating water supplies.
While adapting variable-rate techniques to manure application would seem to have good potential, there still needs to be some refinement in the application of the technology, he says.
“Producers accepted the methodology used in creating the different management zones, but they weren’t ready to embrace this precision approach yet,” Dick reports.