Variable rate fertilizing
Variable rate fertilizing simply means applying different rates of fertilizer to different parts of the same field. Recent research suggests that soil nutrient status varies considerably across a field. At the same time, advances in technology are making it easier to assess soil nutrients and apply variable fertilizer rates.
The easiest place to consider this practice is on rolling and moderately hilly landscapes.
Soil fertility will often be similar for similar landscape positions.
Some farmers in the Biggar, Sask., area have sampled upper, mid and lower slope positions separately, to come up with three different fertilizer recommendations. The custom-applied fertilizer is adjusted on-the-go via a switch in the spreader cab.
Read Also
VIDEO: Green Lightning and Nytro Ag win sustainability innovation award
Nytro Ag Corp and Green Lightning recieved an innovation award at Ag in Motion 2025 for the Green Lightning Nitrogen Machine, which converts atmospheric nitrogen into a plant-usable form.
Researchers with the University of Saskatchewan have found relative amounts of fertilizer required for different slope positions will vary from year to year, depending on previous growing conditions.
Most air seeder manufacturers are beginning to provide variable rate fertilizer capability on new machines. Yield monitors on combines help assess nutrient removal from different parts of a field and determine required fertilizer rates for the next year.
Researchers are also beginning to discover that soil nutrient levels vary even on fairly flat landscapes. They are testing sophisticated and more expensive technologies such as global positioning and digitized computer mapping.
Fertilizer rates are controlled by a computer, and can be changed automatically, even though no visible features such as landscape position are evident.
It is possible for producers with rolling or hilly landscapes to apply variable rates of fertilizer, without expensive computer technology. This simpler approach may prove economical. However, farmers need to be confident about the relationship between landscape position (as they see it from the tractor cab) and soil nutrient status in their field.
With fertilizer prices high, most producers are hoping they don’t need to increase fertilizer use. At the same time, they want net yield increase that will make the practice economical.
Many farmers apply less fertilizer than recommended by soil tests. Applying variable, but lower than recommended rates, could also prove more beneficial than a single lower-than-recommended rate.
– PFRA
Identifying wheat midge risk
A survey of 1994 wheat midge populations in Saskatchewan was released in February.
It indicated high levels of this overwintering insect in some parts of the province, particularly in an area that extends diagonally from the southeast to the northwest corners of the province.
“This survey was based on a limited number of samples containing midge cocoons taken from around the province last September,” says Lloyd Harris, senior pest management specialist with Saskatchewan Agriculture.
Farmers within the infested areas are asking how they can get detailed information on midge populations on their farms. Harris suggests they contact Agri-Pest Research in Saskatoon, which will analyze soil samples for wheat midge larvae and for larvae parasitism. The cost is $30.
“This service may be worthwhile for those farmers who want to know what kind of a risk they’re assuming if they plant wheat this year,” says Harris.
In areas where the density of wheat midge exceeds 1,200 per square metre, Harris said farmers shouldn’t grow wheat in 1995 unless they are prepared to monitor and make timely insecticide applications.
He added producers located in areas of light infestation may want to have their wheat midge population checked if they had an unexplained drop in productivity last year.
For more information, contact Agri-Pest Research, 314 Lansdowne Ave., Saskatoon, Sask., S7N 1C7 at 306-653-1201.
– Saskatchewan Agriculture
