GHGMP Project Reports by Region

If applied nitrogen is not in the plant and not in the soil, then a lot of the nutrient is simply being wasted

Standard fertilizer recommendations may be more than the crop needs and more than the environment can handle

Less is better? That philosophy may not apply in all aspects of life, but when applied to winter wheat fertility rates it could help eastern Canadian farmers save money and minimize the impact of their operations on the environment, says an Ontario producer monitoring an ongoing research project.

Greg Kitching isn't talking about supplying fewer nutrients than the crop needs, but instead, fine tuning fertilizer management, which might lead to lower than traditional application rates.

The first year of a three-year research/demonstration project, at three sites across Ontario, showed a spring soil nutrient test with a mid-range fertilizer application rate produced top yields and minimized the amount of residual nitrogen in the soil that could be lost to leaching or denitrification. The three sites are part of the federal Greenhouse Gas Mitigation Program (GHGMP) research and demonstration initiative.

"If your standard fertility program is leaving behind too much nitrogen, that represents wasted nutrients and dollars," says Kitching a dairy producer and cash crop farmer who farms at Moffat, south of Guelph. Being able to better judge crop fertility requirements, could save producers between $7 to $10 per acre in reduced fertilizer costs. Kitching is helping co-ordinate research jointly funded by the Ontario Soil and Crop Improvement Association (OSCIA) and GHGMP.

"In the first year of this project we have sites where we can't account for 45 to 50 pounds of nitrogen," he says. "It's not in the crop and it's not in the soil. So it's just missing, which suggests the nitrogen either leached from the soil or was lost as nitrous oxide, a harmful greenhouse gas."

Crop use

Many winter wheat producers follow traditional fertilizer rates, applying 100 to 125 pounds without a clear picture of what the crop actually uses.

Admittedly, nitrogen soil tests over much of Eastern Canada create challenges, says Harold Rudy, co-ordinator for the GHGMP in Ontario. Because of high soil moisture levels at certain times of the year, nitrogen can be lost between the time a soil test is taken and the time crops are seeded or growing. Many producers simply apply a traditional fertilizer rate, to ensure nutrient bases are well-covered.

"The soil tests aren't perfect but at least they provide some reference," he says. "Producers also need to realize that fertility is not always the yield-limiting factor. Adequate moisture during the growing season and disease also play a big role."

The Ontario project is based on what's known as a nitrogen budget, says Kitching. The idea is to measure all the nitrogen that goes into producing the crop, and then measure nitrogen levels in the output - the grain and straw - to find the remainder. Ideally, nutrient levels should meet crop requirements, without mining the organic nitrogen in the soil, or without leaving a lot of surplus nitrogen that can be harmful to the environment.

Winter wheat was planted in the fall following a soybean crop at three sites: near Ottawa in Eastern Ontario, the Milton area in Halton County and the London-area in Middlesex County. Spring soil tests provided a reference line of existing nitrogen prior to the start of the growing season.

Various rates of fertilizer were applied at three different spring dates - March 31, April 15 and May 10. Rates applied were 30 pounds, 60 pounds, 90 pounds and 125 pounds of actual nitrogen per acre all applied in the form of a 28 percent urea-ammonium nitrate (UAN) solution.

The total nitrogen input included the residual nitrogen as indicated by the soil test as well as the fertilizer rates applied. To determine how much was actually used by the crop, whole plant samples were collected and analyzed at harvest. A fall soil test was also done to determine how much residual nitrogen remained in the soil.

Surprising data

So far, the data is surprising, says Kitching. The mid-fertilizer rate, about 90 pounds of added nitrogen, came the closest to meeting crop needs, without leaving a huge surplus of nitrogen in the soil or unaccounted for.

Lower nitrogen fertilizer rates, forced the crop to "rob" nitrogen from the soil. And higher nitrogen fertilizer rates, at some sites, supplied considerably more nitrogen than the crop required. In the fact tests showed in some cases more than 50 pounds of nitrogen per acre were unaccounted for, suggesting it was lost through leaching or to the atmosphere.

"As producers we need to fine-tune fertilizer rates to the needs of the crop," says Kitching. "Depending on growing conditions, in some areas, the higher fertility rates may be appropriate to achieve higher yields. But there's no point from an economic or environmental standpoint to apply fertilizer that's just going to be wasted.

The nutrient balancing project continues for two more years with the aim of demonstrating to producers the value of fine-tuning fertilizer requirements and applications. The University of Guelph is providing technology this year, which will improve nitrogen tracking during the crop production cycle.

"We need to get a better handle on crop nitrogen utilization," says Rudy. "That means using whatever tests are available and developing better ways to track these nutrients."

Regional reports will be posted as information becomes available. Please check back regularly for updates.