Grant: Impact of Traditional and Enhanced Efficiency Phosphorus Fertilizers on Canola Emergence, Yield, Maturity and Quality

Date: March 2013
Term: 3 years
Status: Completed
Researcher(s): C. Grant, Agriculture and Agri-Food Canada (AAFC), Brandon MB, J. Relf-Eckstein and R. Zhou, AAFC, Saskatoon SK
SaskCanola Investment: n/a
Total Project Cost: n/a
Funding Partners: n/a

Project Summary

Phosphate fertilizer is a major input cost for canola production. Researchers with Agriculture and Agri-Food Canada conducted a three-year study (2008-2010) at two locations in Western Manitoba to evaluate the effect of various enhanced efficiency P fertilizers on seedling toxicity, yield and quality of canola. Overall, there was little difference among P sources in their effects on canola seed yield, although a benefit may occur from the use of polymer coated product (CRP) due prevention of seedling damage.

Phosphate fertilizer is a major input cost for canola production. A number of enhanced efficiency P products have been developed that may improve the effectiveness of seed-placed P fertilizer, by reducing the risk of seedling damage and/or maintaining the P in an available form for a longer period to enhance crop uptake. While these enhanced efficiency fertilizers may have an advantage over traditional MAP, their price is higher. Therefore, it is important to determine if any increases in crop yield, quality, fertilizer use efficiency or simplification of field operations are large enough to justify the extra fertilizer costs.

Researchers with Agriculture and Agri-Food Canada conducted a three-year study at two locations in Western Manitoba starting in 2008. The objective of the field study was to evaluate the effect of various enhanced efficiency P fertilizers on seedling toxicity, yield and quality of canola. A second study compared the P response of black- and yellow-seeded canola cultivars.

Field studies were conducted at two locations in Western Manitoba, on a fine sandy loam (FSL) and a clay loam (CL) soil, in 2008, 2009 and 2010. Soil analysis was conducted to select sites low in P to increase the likelihood of seeing a P response. At each location, nitrogen (N) and sulphur (S) were applied before seeding to ensure an adequate nutrient supply for optimum yield, based on soil test results. Pre-plant banding was used to avoid any risk of seedling damage from the N. Plots were seeded using a Seed-Hawk type plot seeder equipped with narrow hoe openers. Seeding rate for the canola was 5 kg/ha.

The following P sources were seed-placed in replicated trials:

1. Control – no P application

2. MAP – standard monoammonium phosphate

3. CRP – a polymer coated MAP product formulated for broad acre agriculture

4. Avail MAP – MAP with treatment to sequester antagonistic ions and reduce soil P reactions

5. Liquid P – ammonium polyphosphate

6. Avail Liquid P – liquid P with treatment to sequester ions and reduce soil P reactions

7. Polyon – a polymer coated MAP product formulated for horticulture.

Each of the P sources was applied at four application rates (10, 20, 40 and 80 kg P2O5/ha), plus one control plot with no P applied, for a total of 25 treatments per site. In a second study, plots of black-seeded Argentine canola (Brassica napus species) InVigor hybrid cultivar were compared with plots of a yellow-seeded, open-pollinated breeding line of AAFC cultivar using the same treatment methods.

Over the three years of the study, canola yield generally increased with moderate rates of P application. Decreases in seed yield occurred where high rates of application decreased stand density below critical levels. The results showed seedling damage occurred with high rates of applied P unless soil conditions were very wet, with damage being particularly evident with liquid P. Where damage occurred, use of polymer coated MAP reduced the risk of seedling damage. Canola could compensate for seedling damage if stands were not reduced below critical levels, but where stand density was low, seed yields declined and maturity was delayed due to seedling toxicity.

Overall, there was little difference among P sources in their effects on canola seed yield, although a benefit may occur from the use of polymer coated product (CRP) due prevention of seedling damage. The enhanced efficiency phosphorus (P) fertilizers evaluated provided little economic benefit as compared to traditional monoammonium phosphate (MAP) or ammonium polyphosphate (APP) fertilizers. The polymer coated CRP product may provide the benefit of reduced risk of seedling toxicity if it is necessary to exceed safe levels of seed-placed P fertilizer to optimize crop yield.

In the second study, the yellow-seeded cultivar showed very poor emergence and vigor, resulting in low seed yield at the end compared to the black-seeded cultivar. Seedling damage in the black-seeded cultivar occurred with P rates of 40 and 80 kg P2O5/ha. Yields tended to increase to between 20 and 40 kg P2O5/ha and then decline, reflecting the seedling damage at higher application rates. Differences were larger in the black- than yellow-seeded cultivar, primarily because the yellow-seeded cultivar had very poor initial stand density than the black-seeded cultivar, leading to a lower yield potential and lower ability to respond to applied nutrients.

Full Report PDF: n/a