Apple growers look at fertilizer alternatives

Monday, May 12, 2008

By MARIBETH FITTS

Ontario Ministry of Agriculture, Food and Rural Affairs nutrition lead, Christoph Kessel, showed some hard numbers related to types of nitrogen fertilizers used in apple orchards at an Apple Information Meeting at Horticultural Experiment Station, Simcoe on May 8.

Fertilizer prices rose by about 20 percent in 2007 and Agriculture and Agri-food Canada is predicting another 20 percent rise again in 2008.

Extrapolating from a research study which was conducted in British Columbia, Kessel compared costs of spring soil-applied urea or ammonium nitrate with seven applications of foliar urea and with trees fertigated through the season with calcium nitrate or potassium nitrate.

He showed that either the soil applied urea or ammonium nitrate was the most economical to use with foliar applications of urea costing about 1.5 times that of the soil-applied over the season. Fertigation was the most expensive option, costing about three times that of soil-applied fertilizer.

The products were compared based on the actual amount of nitrogen content.

Kessel explained that foliar applied urea is a different grade than that used on the soil and therefore is a more expensive product to purchase.

Yields were similar among all treatments in the trial, he stated, but were greater than the control trial where no fertilizer was applied.

He suggested that growers might also take another look at organic nitrogen sources such as manure to save on fertilizer costs. His calculations showed that manure would cost about half that of the soil-applied inorganic fertilizer.

Kessel stressed the importance of soil and tissue analysis in apple orchards for determining the exact amount of fertilizer the trees need. BF