GHGMP News Releases

Multiple benefits make spring soil tests worthwhile

Truro, N.S. September 14, 2004

Minimize nutrient waste. Save crop input costs. Reduce the impact of farming on the environment. Three strong arguments in favour of spring soil nitrogen testing.

"Evaluation of results from five on-farm demonstration sites in 2003 showed that a spring soil nitrogen test can be a valuable tool for matching nitrogen fertilizer applications with plant requirements," says Rob Michitsch, regional co-ordinator of the federal Greenhouse Gas Mitigation Program for Canadian Agriculture (GHGMP).

The demonstration sites, located throughout Nova Scotia, were used to compare the benefits of pre-plant soil nitrate testing in barley, wheat and corn crops. The demonstrations are among a number of projects funded in part by the GHGMP. Further information on the demonstration projects can be found on the Soil Conservation Council of Canada's Web site at www.soilcc.ca.

"Many producers follow nitrogen fertilizer recommendations produced by governmental sources, which tend to recommend higher-than-required levels of nitrogen and do not consider residual nitrogen that becomes available to the crop during the growing season from past manure applications or crop residues," says Michitsch, (pronounced Mikitch).

Through this and other demonstration projects it was hoped that the reliability of these tests could be demonstrated and convince more producers to adopt spring soil testing as part of their overall crop and nutrient management plan. The demonstration projects continue through 2004 and 2005.

On-farm demonstration sites in western Nova Scotia had no recent history of manure application, while those in the eastern part of the province had received manure regularly over the course of several years. Soil nitrate tests were done on each plot just prior to planting, during the growing season and after harvest. Fertilizer rates ranged from 25 to 100 percent of recommended rates. There were also control plots at each location that received no additional nitrogen. In 2004, soil sampling was increased to gain a better understanding of nitrate levels over the course of the entire growing season.

"Sites that received little or no manure in previous years showed a positive yield response when we applied fertilizer," says Michitsch. "However, results at the site that received two manure applications in past years showed no significant yield differences when additional nitrogen fertilizer was applied."

This means if the soil has a high nitrogen content from prior manure application, no added fertilizer is needed. "That's the benefit of the spring soil nitrogen test," Michitsch adds. "It will indicate the level of nitrogen already present in the soil, allowing producers to adjust their fertilizer rates and avoid application of more nitrogen than the crop requires."

Reducing fertilizer rates not only reduces input costs to producers, it also means more efficient use of the nitrogen that is available, and reduced risk of nitrogen leaching through the soil to groundwater or being lost to the atmosphere through denitrification. Under the right conditions, surplus nitrogen can convert to nitrous oxide, a powerful greenhouse gas.

Plots at the eastern sites showed similar barley yields whether or not nitrogen fertilizer was applied. At the sites in western Nova Scotia, wheat yields increased when up to 50 percent of the recommended fertilizer rate was applied. Beyond that, there was no additional yield benefit to increased fertilizer application.

"These demonstration sites show that with a spring soil test, producers can more easily match nitrogen applications with crop requirements," says Michitsch. "On previously manured land, we showed that additional nitrogen may not be needed to achieve maximum crop yields. On non-manured land, we showed that reduced levels of the recommended fertilizer rate were sufficient to meet crop requirements for maximum yields. However, our results are specific to individual sites; a producer must test their own fields in order to properly adjust their rates of fertilizer application."

Results from the 2004 demonstration projects will be available later this fall.

The GHGMP supports a broad range of projects across Canada with the goal to promote awareness of agricultural practices that reduce greenhouse gas emissions. Soil Conservation Council of Canada (SCCC) administers the delivery of the soil and nutrient management sector component of the program. For more information on activities, visit the SCCC's Web site at www.soilcc.ca.


For more information, contact:

Rob Michitsch, Regional Co-ordinator
Greenhouse Gas Mitigation Program for Canadian Agriculture
Truro, Nova Scotia
Phone: (902) 896-7092

Jerome Damboise, Project Co-ordinator
Eastern Canada Soil and Water Conservation Centre
Grand Falls, NB
Phone: (506) 475-4040
Email: info@soilcc.ca