Most of a farmer’s fertilizer dollar should be spent on nitrogen but there are variables to consider before it ever hits the ground, says an Alberta Agriculture agronomist.
Nitrogen’s effectiveness depends on soil moisture, the kind of fertilizer that is used and how it is applied, Ross McKenzie told the recent Western Barley Growers Association annual meeting.
The first step is to soil test.
“Probably 15 percent of Alberta farmers soil test on a regular basis,” he said.
When input costs are high and commodity prices are low, soil tests can show how much fertilizer is needed.
Read Also
Anaerobic digestion seen as possible emissions solution
Cattle manure is one of the feedstocks that can be used in anaerobic digestion systems.
Last year’s record rainfall also affected fertility needs.
Leaching was suspected in much of southern Alberta but farmers may see enhanced microbial activity with more organic matter breakdown and higher levels of nitrogen.
Various types of nitrogen fertilizers perform differently under different circumstances.
Ammonium is rapidly oxidized to nitrate through the nitrification process in soil that is warm, moist and well aerated.
Banding slows the nitrification process by creating an environment near the band that inhibits the activity of the bacteria that convert ammonium to nitrate. Therefore, if urea or anhydrous ammonia is banded in late fall, most of the nitrogen is retained in the ammonium form until the soil warms up in the spring.
McKenzie recommended comparing fertilizer prices and types.
“The bottom line is, make sure you price out the cost of urea and liquid nitrogen and buy on price and ease of handling,” he said.
Losses due to volatilization, denitrification and leaching may occur, adding further to a farmer’s costs and yield losses.
Volatilization means the nitrogen has converted to gas and is lost into the atmosphere.
Nitrates are mobile but move only in sandy soil under high rainfall conditions. Leaching is less problematic in clay loam.
Denitrification is the loss of nitrogen when a soil becomes saturated with water and the oxygen is depleted. Soil microbes strip oxygen from nitrate compounds.
For improved results, McKenzie suggested improving the odds that roots will intercept fertilizer by applying it with the seed or to the side.
When it comes to other nutrients, soil tests indicate whether phosphorus, potassium or other trace minerals are needed. Producers should consider adding more phosphorus if there is less than 30 lb. per acre in the top 15 centimetres of soil.
More potassium could be added if a soil test finds less than 200 lb. of potassium per acre, but not if the soil contains more than 300 lb. per acre.
McKenzie recommended caution if considering yield boosting fertilizer products that include micronutrients because there is little documented evidence to show they help. Producers who are considering these products should ask for scientific evidence to show they work.
“Don’t waste your money on products that don’t work,” he said.
“Make sure you get a second or third opinion so you can make informed decisions.”
For further information, Alberta Agriculture has developed a conversion program on its website to determine how much fertilizer is needed. The Alberta Farm Fertilizer Information and Recommendation Manager includes location, soil group, year, date, crop, crop price and whether irrigation is used.
The variables can be filled in and a fertilizer recommendation is calculated. The program is also available to farmers in other provinces.
