Introduction

Background information

Canadian Western Red Spring (CWRS) Wheat is the most widely grown wheat class in Western Canada. CWRS requires many nutrients, with nitrogen (N) typically being its most limiting. In Western Canada, N is most commonly applied as granular urea [CO(NH₂)₂] fertilizer that is banded during seeding or broadcast during the growing season. Granular urea banded at seeding, is considered the conventional method of N fertilization where the fertilizer band is in near proximity to the seed row band. Any application method of N fertilizer can result in N loss from the crop via volatilization, denitrification and/or leaching (Thapa et al., 2015). Lost N can create environmental problems such as eutrophication caused by nitrate leaching and runoff (Finaly et al., 2010), as well as increased greenhouse gas emissions depleting the ozone layer and increasing global temperatures (Khalil et al., 2008; Ravishankara et al., 2009). Economical implications of lost N are primarily reductions in growth parameters of yield and protein content.

Enhanced efficiency fertilizers have been developed to mitigate N loss from fertilizer applications. There are many versions of them, but the three most common types are urease inhibitors, nitrification inhibitors, and polymer coatings. Urease inhibitors are designed to stop the urease enzyme from hydrolyzing urea, which hinders ammonia volatilization (Ferguson, 2019). Nitrification inhibitors aim at reducing nitrifying bacteria populations, hindering the conversion of ammonium to nitrate and subsequent nitrate leaching or denitrification (Ferguson, 2019). Polymer coated fertilizers release N slowly based on increased temperatures whereby the plant can uptake the N more readily as it develops (Nutrien, n.d.). Both urease and nitrification inhibitors are chemical coatings applied to urea granules, while polymer coatings are plastic coatings. These enhanced efficiency fertilizers can increase costs of urea by roughly 10-30%.The importance of using enhanced efficiency fertilizers can be distilled down to increasing crop N availability and reducing environmental impacts.

In this research, five enhanced efficiency fertilizers will be investigated.

Their method of N stabilization and active ingredients include:

•Agrotain (urease inhibitor)

-N-(n-butyl) thiophosphoric triamide (NBPT)

•Instinct impregnated urea (nitrification inhibitor)

-Nitrapyrin

•SuperU (urease and nitrification inhibitor)

-N-(n-butyl) thiophosphoric triamide (NBPT)

-Dicyandiamide

•NBPT-DMPSA (urease and nitrification inhibitor)

-N-(n-butyl) thiophosphoric triamide (NBPT)

-3,4-dimethylpyrazole succinic (DMPSA)

•Polymer-coated urea (Environmentally Smart Nitrogen (ESN))

-Urea granules coated in polymer

Figure 3: Images of Urea¹, SuperU² and ESN³ to show the visual differences of three common N fertilizers (left to right). Urea is the most commonly used granular form of N fertilizer. SuperU are Urea granules coated in a chemical mixture containing urease and nitrification inhibitors. ESN (Environmentally Smart Nitrogen) are polymer-coated Urea granules. The purpose of this figure is to simply show how different EEF's appear differently.

Research objectives

The main research objective of this study is to determine whether or not enhanced efficiency fertilizers can improve grain yield and protein content of CWRS wheat compared to conventional urea. There is a cost differential between urea and any enhanced efficiency fertilizer, and determining if they can provide additional yield or protein to warrant those costs is important to determine. Additionally, we want to determine what N rate is optimal for CWRS production as well as whether split applications are beneficial.

Expected results

I'm anticipating that plots grown with enhanced efficiency fertilizers will have higher grain yields and/or protein content compared to plots using urea. This reasoning is such that enhanced efficiency fertilizers are reducing N loss and would theoretically provide more N to the crop. The crop would then assimilate more N and relay that into growth in yield and/or protein. An alternative result to this could be that some or all enhanced efficiency fertilizers yield or result in less protein than urea. The results observed here could help growers in Western Canada to chose what N fertilizer option is best for them.

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