Top 10 Ways Field Crop Farms can Save Energy

Introduction

Are your field operations as efficient as possible? Or, could you be saving money by changing some aspects of your operation? In most cases, the answer is "yes" to both questions — your operations could be more efficient and you could be saving money. 

Tillage and field operations make up nearly 20% of the total energy consumed by crop and livestock production in the US. The following is a list of ten general measures related to tractor and field vehicle use you could take to improve your farm's energy efficiency. Not all of these tips will work for every farm; some of them might not be economically feasible for you or your operation, or they might not make sense for what you do, so it's important to think carefully prior to making changes. That being said, applying just a handful of these measures could make a difference on your farm. This list focuses on items that improve field operations by saving time and fuel by working smarter, not harder. The points made on this list were selected and ordered with the help of extension educators throughout the Northeast U.S.

10. Harvesting Efficiently

Harvesting your crops in optimal conditions can make your harvest more efficient.  Crops that are too wet or soil that's wet result in more fuel consumption, so by waiting until the conditions are just right, you save energy.

Fuel consumption for combining can be reduced.  When grain combining, increasing the height of your cut will not only harvest less straw and stalks, but also reduce fuel consumption as well.

9. Consistent Wheel Traffic Pattern

The use of GPS guidance or auto-steer technology can result in a regular pattern of machine movement, but even without those tools, you could still set a consistent path for yourself.  Having consolidated soil compaction rather than some compaction all over allows for crops to grow better in the areas with no compaction. However, there is an energy benefit as well: compacted soil is an easier to drive on surface. This can increase machine efficiency and help reduce fuel consumption.

8. Minimize Turning Time

Turning at the ends of a field and going around objects in the middle of it is nonproductive fuel consumption; you aren't getting any return on the fuel you're using in that time. In order to minimize turning time, if it's possible for your farm, fields should be large and long. Any sort of barriers in a field that your tractor is going to have to get around (like fence rows or ditches) should be removed if practical. This practice will save time and fuel, letting you save money. 

7. Use Optimal Gear to RPM, or CVT

An operation strategy for older tractors to maximize fuel efficiency can be condensed into "gear up/throttle down". This means using the highest gear and lowest RPM (Rotations Per Minute) combination that gives the desired speed without straining the engine to the point where it produces visible black smoke. However, if you're working with a newer tractor or thinking of purchasing a new tractor, often they have engines with CVTs, or Continuously Variable Transitions, or IVTs, Infinitely Variable Transmissions.  With a CVT or IVT, there's no need to manually select the gear and RPM, because the machine makes those choices.  A CVT or IVT can also compensate for momentary increases in engine demand (things like hills or heavy soil), so a newer tractor with either a CVT or IVT is a better alternative for fuel efficiency if possible. 

6. Don't Over-Till

Deep tillage uses more fuel than shallow tillage and often isn't necessary.  There are options to save energy, like minimum, strip, or no-till, to reduce or completely rule out tillage.  However, if you decide that tilling (to some degree) is necessary, to make the best use of your fuel and time, secondary tillage should be shallower than primary tillage. Secondary tillage should really only be ½ the depth of the primary till. This reduces compaction, lessens the amount of wet soil and weed seeds brought up to the surface, reduces water loss, and uses less fuel.  With shallower tillage in general, water loss is reduced, leading to a longer period of time before irrigation is needed. 

Plow speed is another factor that is important for being aware of fuel consumption. As plow speed increases, so does the power needed to pull machinery, and the fuel required to complete the task. Double the plow speed, triple the power needed to pull a plow.

5. Machinery and Engine Maintenance

Something as simple as keeping your machinery in good condition and making sure it has regularly scheduled tune-ups can impact your machine's fuel efficiency. Preventative maintenance and tune-ups are especially important when it's possible for your machine to be running under max efficiency without you noticing. The best way to keep a machine running well is to follow the instructions in the operator's manual. For engines, fuel, oil, and air filters should all be changed routinely according to the operator's manual; keeping the engine lubricated and running smoothly improves fuel efficiency.

One study out of the University of Maryland on 50 tractors showed that, after a full tune-up, fuel consumption was reduced by almost 15%.  In addition, the maximum obtainable horsepower of those same tractors increased by an average of about 11% ("Machinery Maintenance for Energy Efficiency", 2019).  For your operations, this could mean a sizeable chunk of savings

4. Technology for Precision Agriculture

Innovations like GPS guidance systems and auto-steer technology are tools that can be used to find the most efficient routes around a field.  The main benefit is that it eliminates skips and overlaps on the field, and can lend to setting a consistent wheel traffic pattern.  Tools for precision agriculture (like GPS and auto-steer technology) can also reduce the amount of time you spend on a field, saving you time, as well as fuel.

3. Optimize Wheel Slip

Every tractor experiences some wheel slip while out in the field.  Because of this, wheel slip should be optimized to get the most effective movement out of a tractor's wheels.  Too much wheel slip indicates that energy is being lost in tire spin, but too little slip means the tires are carrying too much weight.  In both instances, fuel is wasted unnecessarily.  A simple test and calculation can be used to measure wheel slip, which can then be compared to prime wheel slip percentage.  In general, optimum wheel sleep is somewhere between 10% and 15%, although this will depend on several factors, including type of field operation.  Wheel slip can be adjusted by modifying the ballast (weighting) and tire inflation of the tractor - most tractor manufacturers will have detailed recommendations on how to do this on your particular model.

To find what your wheel slip is, you'll need to mark the inside of the tire so that it can be seen from the tractor seat, and you'll need to mark a distance 100 feet into the field. Then, you can use string or measuring tape around the center part of the tire's ribs to find its circumference, or to be more precise, do a quick Google search to find your tire's circumference based on its size.  Count the number of tire revolutions driving that 100 feet- but be sure that the field operation is in progress!  For the calculation, you simply need to multiply the rotations by the circumference, then divide by 100 feet. The resulting number is your wheel slip.

2. Efficiently Drawn Implement Selection and Use

Before buying and using any new equipment for your tractor, you should take a look at the amount of power (horsepower) it needs to do its job. This is because two implements could perform a similar task, but one may take a lot less energy to do its job than the other. For example, a square hay baler might take more energy than a round hay baler.  Whether that stems from a difference in design or better construction, implements that are more efficient will use less fuel to get the job done.

1. Managing Tractor Size

A great way to save on fuel is to use the smallest tractor that can do the job. Larger tractors usually waste more energy, so if you're running a farm that produces a lot of different crops or needs to perform a lot of different field operations, having and using different-sized tractors might be a good investment for you. Generally, small equipment shouldn't be used with a big tractor. Using the most efficient combination of tractor size and equipment for your field operations could save you money in the long run.  If you're looking at buying a new tractor, or wondering which tractor out of the ones you already own would be the most efficient choice for a job, the University of Nebraska houses the Nebraska Tractor Test Laboratory (NTTL), which is the official tractor testing station in the U.S. for OECD (Organization of Economic Cooperation and Development), could be a really useful resource for you.  Alternatively, the American Society of Agricultural and Biological Engineers (ASABE) has a spreadsheet that compiles NTTL Results for a more streamlined comparison. The performance data on the tractors tested by the NTTL and the ASABE Spreadsheet for Matching Tractors and Drawn Implements could help you find a combination that will most efficiently fit your farming needs and help you choose equipment that best complements your machine's capabilities

Hidden Energy

Something else to consider is the ways your farm could be saving on hidden energy, or all the energy associated with a product through its life cycle. A couple of statistics:  almost half of the energy used in agriculture is for fertilizers, and out of that energy, 80% is directed towards the manufacture of nitrogen from natural gas. However, on your farm, some of those energy expenditures might not be necessary, and you could help reduce the amount of energy required by agriculture overall by reducing overconsumption of manufactured nitrogen.

A great first step to conserve energy is to test your soil and see what your soil is lacking.  Do you even need fertilizer?  If your soil's nutrients are low, adding nutrients makes sense, but at high levels, it might make more sense for your farm to use little to no fertilizer.  Make sure that your equipment is calibrated so that you only use the amount that you need.

You could even use legumes or manure as organic alternatives to fertilizer. They still require some energy, but not even close to the amount of energy required to manufacture nitrogen. Once you've applied fertilizer, another way to save energy is by using methods to reduce loss.  Reducing loss reduces the need to reapply fertilizer later.  Soil conservation, and fertigation if possible, could lend to overall energy savings in the long run

Conclusions

Reducing your energy consumption can seem like a daunting task, but it truly is the little things along the way that can make a difference.  Hopefully applying some of these tips can help your farm operation save energy and be more aware of the fuel decisions you are making.

Prepared by Patricia Kline, Department of Agricultural and Biological Engineering.  Reviewed by Daniel Ciolkosz, Jude Liu and Long He, Department of Agricultural and Biological Engineering faculty.  Photos: Mike Houtz, COA Penn State.