Almost all diesel-powered trucks built since 2010 are equipped with Selective Catalytic Reduction (SCR) that utilizes Diesel Exhaust Fluid (DEF) to help reduce the production of Nitrogen oxide (NOx). This regulation by Environmental Protection Agency (EPA) aimed at reducing air pollution as much as possible.

However, not every tractor manufacturer has embraced the EPA changes. And even the ones that have adopted the changes do not apply it to all their high horsepower (hp) brand series. 

I checked 9 tractor brands to find out whether they use DEF; which of their series use DEF and the year it was adapted. But first, let’s clarify how the DEF regulation came along. 

Non-road Engine Emission Standards

The ramp-up to the point where tractors were required to use DEP has been gradual. The Tier 3 standards phased in between 2006 and 2008, then came the Tier 4 Interim from 2008 to 2012, and now the Tier 4 Final that requires the use of DEF.  

Tier 3 standard regulation

Some of the after-treatment systems added to the diesel engine to help meet this regulation include:

Exhaust Gas Recirculation (EGR)

Tier 3 engines do not require DEF fluid. To meet the Tier 3 regulation, most engine manufacturers added an Exhaust gas recirculation (EGR) circuit to their engine to reduce the amount of oxygen in the combustion chamber. As a result, the exhaust contains less NOx. 

Diesel Particulate Filter (DPF)

These filters help reduce diesel particulate matter (PM) to the required levels in high horsepower 3 Tier engines.

DPF is coated with metal catalysts that trap particulate matter in the exhaust stream. As a result, the exhaust is free of particulate matter and therefore less harmful. 

Tier 4 Standard Regulation

Diesel Oxidation Catalyst (DOC)

These are simply filters with catalyst coating on the filter media. The catalyst on a DOC enhances a chemical reaction that transforms carbon monoxide, diesel particulates, and hydrocarbons among other pollutants into water and carbon dioxide. 

DOC can be used in conjunction with DPF in higher horsepower. But in lower horsepower, DOC is sufficient to meet Tier 4 Final regulations without the need for a DPF. 

Selective Catalytic Reduction (SCR)

The tier 4 final regulation called for a drastic reduction in NOx – something that EGR alone could not handle.

In an SCR system, the exhaust passes through a DPF or a combination of DPF and DOC first, then doused with a mist of water and urea commonly referred to as diesel exhaust fluid (DEF).

The exhaust and DEF in the presence of the catalyst turn the NOx into mostly water and nitrogen.

Though this process does add another layer of complexity, there are several advantages to this. The main advantage of using DEF is that engines run cooler since they can meet emissions standards with less aggressive use of exhaust gas recirculation (EGR).

However, this new innovation also comes with one key disadvantage that makes some tractor users somewhat sceptical. The disadvantage is that you have to keep DEF in stock to refuel your tractor when it runs out of DEF.

The new high-horsepower tractor engines that are equipped with SCR are programmed to stop working when your tractor runs out of DEF. That said, let’s find out if the following popular tractor brands use DEF.

Do Kubota Tractors Use DEF?

Kubota 75-100 horsepower series diesel engines were certified in September 2014 as Tier 4 final compliant. The tractors in these series use an SCR system, where the exhaust is doused with DEF to help further reduce NOx. 

The good news is, Kubota tractors use very little DEF. I have tested a 135 hp Kubota tractor and it really uses little DEF unless under load.

According to Kubota, their new track loader can run 8 to 10 hours without refueling and 4 to 5 days before a DEF tank refill is needed. The track loader is equipped with a 28.8-gallon fuel tank and a 5-gallon (DEF).

Do Kioti Tractors Use DEF?

Kioti introduced tier 4 compliant engines on several models in 2014. With Tier 4 Final emissions standards in place, DEF is required for Kioti diesel engines over 74 hp series. 

To be precise, only some of their PX series use DEF fluid. This is the brand’s most powerful series with engines from 93 to 110 hp. 

Do Mahindra Tractors Use DEF?

Mahindra has a new innovation that enables them to meet the stringent Tier 4 final standard without the use of SCR which uses DEF and DPF. The new Mahindra Common Rail Diesel (mCRD) engines are only equipped with a DOC component.

Mahindra introduced Tier 4 interim for above 75 HP, emission compliant mCRD engine in 2012. The Mahindra mCRD engine is an eco-friendly and fuel-efficient high-performance engine that lowers greenhouse gas emissions by over 360 tons per year.

Do John Deere Tractors Use DEF?

The 4-cylinder 5Ms ( 5100M, 5115M, 5085M) have a DOC/SCR solution using DEF to meet Final Tier 4 emissions standards.

These models also feature a compact cooling package and a new, low-sloping hood that will improve efficiency in loader applications.

John Deere made this highly anticipated announcement in 2012 that it will add DEF to its engines in order to meet Final Tier 4 emissions standards. However, there are some John Deere Tier 4 engines that meet regulations without using DEF. 

Do LS Tractors Use DEF?

The Tier 4 final tractor from this brand includes the 2015 100 horsepower models. These models are equipped with common rail fuel injection and DOC components.

The new models in the range 50-60 horsepower series are equipped with Mitsubishi common rail. 

That said, none of the LS tractors engines require diesel exhaust fluid (DEF) to meet EPA standards. However, some of the models are equipped with DPF. But LS engines below 32 horsepower can meet the standard without DOC, DPF, or DEF. 

Do TYM Tractors Use DEF?

TYM tractors built since 2010 are equipped with SCR and require DEF. The RK74 engines are all EPA Tier 4 compliant. The high horsepower engines are equipped with the SCR and therefore can use DEF. 

TYM makes several tractor brands including Mahindra and RK. However, most of these brands made by TYM are always treated independently. 

Do RK Tractors Use DEF?

Just like the parent company, TYM, high-horsepower Rural King (RK) tractors are EPA tier 4 final compliant. The high-horsepower engines are equipped with SCR and require DEF. 

Even their 19-55HP series tractors are powered by EPA Tier-4 compliant Yanmar diesel engines. However, these lower horsepower engines don’t require DEF to meet EPA regulations. 

Do Branson Tractors Use DEF?

Though Branson claims to be free of electronics, they still use DEF somehow to achieve the final Tier 4 compliance in some of their high horsepower series (78hp-80hp).

However, most of their tractors fall just under the threshold for emissions requirements. So most of their tractors don’t use DPF and DEF. 

Do New Holland Tractors Use DEF?

New Holland tractors started using DEF in 2011 to meet governmental mission regulations. This is the only practical way this brand employs to meet governmental regulations. However, DEF is reserved for their high-horsepower tractor equipment. 

Conclusion

DEF is necessary to make sure that what exists in the diesel tractor engine is harmless when released into the environment.

However, not all tractor brands and series use this technology. Out of these nine that I have tested, you can easily have your pick if DEF is what you have been looking for in a tractor. Please feel free to contact us if you want more clarification. 

Reference

Kioti Products

Parts and Service.pdf

Diesel Engine Technology