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Cutting energy costs for crop production

Reducing energy inputs may not be as glamorous as generating bio-energy, but it is key to controlling your cost of production.

April 8, 2008
By Carolyn King


“Right now when farmers think about energy, they are thinking about ethanol and biodiesel, and that is fine. But for their farms it’s more important to control their cost of production, and they are paying a lot of money for energy,” says Dr. Martin Entz of the University of Manitoba. “Fertilizer and liquid fuel are energy costs, and together those two account for 80 percent of energy use and 60 percent of their variable costs.”

Along with controlling these costs, reducing energy consumption is valuable because the use of fossil fuels releases greenhouse gases and because fossil fuels are non-renewable. Entz says, “We’re going to run out of fossil fuels. It’s not a question of if; it’s a question of when.”

Entz and others, such as Agriculture and Agri-Food Canada scientists in Saskatchewan, have studied a wide range of cropping and tillage systems over many years. In examining energy use in these systems, Entz considers both direct energy inputs, like gasoline and diesel fuel, and indirect inputs, like the energy used in the manufacture and supply of fertilizers, machinery and pesticides.


The results from these studies point to several key options to lower energy inputs. In a typical crop production system on the prairies, reducing tillage can reduce energy use by three to 14 percent because less tillage means lower fuel and machinery inputs. Entz notes, “Many farmers have already gone to a minimum or a no-till system, so they are capturing some of that. And some farmers are looking at additional places to reduce their energy use. For example, they’re using stripper headers as opposed to straight cut headers. That reduces the amount of energy used because they’re just putting the seed heads through the combine harvester.”

Reducing tillage can lower energy use by about three to 14 percent.

However, to make a big dent in their energy consumption, farmers need to use less fertilizer. Typically, nitrogen (N) fertilizer accounts for about half of the energy inputs for crop production. That is because natural gas is a major component in the manufacture of N fertilizer, both as a raw material and as an energy source.

Entz adds that nitrogen fertilizer has a further drawback in terms of the environment. “In nitrogen fertilizer production, we take nitrogen from the atmosphere, put it through our fertilizer manufacturing process and inject it into the soil, where some of the N is lost as nitrous oxide. So we turn what is essentially an inert gas into a very powerful greenhouse gas.”

A great way to reduce nitrogen fertilizer requirements is to add legumes to the crop rotation. Legumes fix their own nitrogen and leave some nitrogen in the soil for the next crop. According to Entz, growing a grain legume, like field peas, every three years can reduce nitrogen needs in the cropping system by at least 12 percent and perhaps much more. “But I think if you want to cut fertilizer use in half, then you need to do more, like using legume cover crops or adding perennial forages like alfalfa to the rotation.”

But what about the energy savings from fine-tuning nitrogen fertilizer practices to apply it at the right time, place and rate? “Well, it’s not exactly like rearranging deck chairs on the Titanic, but it’s close,” says Entz.

He adds, “Most farmers are already managing their fertilizer to bring N losses as low as is possible.” Even with good fertilizer application practices, nearly half of the nitrogen applied can be lost to the air because urea is easily volatilized. “Nitrification inhibitors could improve it a little bit, but it would be a very small percentage, nothing like the benefit from growing a legume.”

Another approach to lowering energy inputs is to use an organic farming system. The long-term comparisons of organic and conventional cropping systems at the University of Manitoba’s Glenlea Research Station show that organic farming systems typically use about 40 percent as much energy as conventional farming systems.

That difference is mainly because organic systems do not use nitrogen fertilizer. Entz notes, “People say, ‘In organic farming you’re doing more tillage so there’s more energy use.’ Well, organic farmers aren’t doing that much more tillage, and a recent northern US study found that organic farmers use less tillage than many conventional till farmers. And the amount of energy that is consumed in machinery and fuel is small compared to nitrogen fertilizer.”

Energy use can be decreased by integrating crop and livestock production as well. Integrated production would increase the options for adding non-fertilizer nitrogen to the cropping system. Examples of possible practices are adding forages or pasture to a long-term crop rotation, and grazing livestock on swaths and bales on cropland.

Entz sees a couple of ways for integrated production to come about. For farms with specialized crop production systems or specialized livestock production systems, ‘area-wide integration’ is one possibility. An example of area-wide integration is where a feedlot operator partners with farmers in the area so the feedlot gets feed grain from the farms and the farm fields get the feedlot’s manure. Such opportunities for area-wide integration could be further developed and expanded.

Although area-wide integration can be a good first step, Entz points out that intensive livestock systems require a lot of energy. Surprisingly, a traditional mixed farm is actually more energy efficient.

“Going from a specialized system to mixed farming is seen as being nostalgic and going backwards to a way of life that is gone. But in terms of growing food in an energy efficient manner, it is certainly better than being highly specialized and having no integration, and it’s also better than area-wide integration,” explains Entz. “For example, when liquid pig manure is spread within two kilometres of the barn, the energy cost of N from that manure is eight megajoules per pound, compared with 26 megajoules per pound for anhydrous ammonia.”

“With smaller farm units that have both crops and livestock, you are hauling less, which is more efficient – especially if you have the animal actually doing some walking.” He adds, “We like to joke with farmers and say that the universities in Canada have made an amazing discovery: plants like to stand still and animals like to walk! By using the animal’s own horsepower, we can add more efficiency to the system.”

And what about those biofuels that are so much in the spotlight these days? Entz says, “For some time now, farmers have been dropping the legumes out of their rotations so they can grow more biofuel feedstock crops. Rotations are becoming more simplified, dominated by wheat and canola, and barley in certain areas. So the energy efficiency of our agricultural system is dropping.”

This worrying fact emphasizes the need to develop systems that produce biofuels more efficiently for the sake of farm production costs as well as for the environment and society. “A system that has a lot of legumes as part of the rotation and uses that legume nitrogen to produce the biofuel crops will be a much more efficient biofuel production system. Simply doing it with rotations of wheat and canola means you’re probably getting less energy out of it than you’re putting into it,” he notes.

“Here is an example from our Glenlea study. The amount of energy required to produce a kilogram of wheat seed in a wheat-flax-oat-soybean rotation is 1.72 megajoules compared with 1.17 megajoules when wheat is grown in a wheat-flax-two year alfalfa rotation. Agriculture and Agri-Food Canada researchers in Saskatchewan lead by Dr. Bob Zentner of Swift Current found that adding field peas into a cereal-oilseed rotation reduced the amount of energy required per kilogram of wheat from 3.57 to 2.85 megajoules.”

Entz adds, “We should be investing on the energy conservation side. At the very least we should be absolutely serious about energy conservation if we’re going to get into the biofuel business. Getting serious about legumes in cropping systems is a way that farmers can get serious about energy conservation.” -end-

Organic farming, energy and food supply
Data from the long-term rotations at the University of Manitoba’s Glenlea Research Station show that organic farming systems are about 20 percent more energy efficient than conventional farming systems. Here is a closer look.

Adding legumes to a crop rotation reduces fertilizer requirements, which lowers energy consumption. Photos By Bruce Barker.

Energy efficiency is the energy output divided by the energy input. In crop production systems, the energy output is caloric energy. Although organic systems have a lower caloric energy output, they have a much lower energy input than conventional systems. So organic systems are more energy efficient.

Entz puts these facts into the broader context of food supply. “If you only grow grains, you would be lucky if the organic system was perhaps 50 to 60 percent as productive as a conventional system in terms of calories produced. And that’s a problem.”

The caloric output can be improved by adding ruminants to the system. He says, “If the organic system contains perennial legumes like alfalfa harvested by grazing livestock, and you have grains as well, then based on our work, that system produces about 85 percent of the calories of a comparable conventional system.”

Still, there is more to food value than caloric energy. “As far as the nutrient density and health of the food, we have some evidence from our long-term Glenlea work that the micronutrient density is higher in the organic wheat and flax crops,” notes Entz.

“Some of that may be simply because organic crops have smaller kernels and fewer grains so the nutrient concentration would be less diluted than in crops from a conventional system. But some of it may be because of the change in soil health that occurs with a good organic rotation because typically you get more mycorrhizae in organic systems.”

Mycorrhizae are fungi that live co-operatively with a plant host. One of the ways they help to keep their host plant happy and healthy is by sending out long filaments that obtain micronutrients for the plant.

Many soil organisms are important for promoting healthy crop stands and, in turn, the health of the soil organism community is influenced by the crop production system. For instance, “Rhizobia and other bacteria are absolutely critical to the nitrogen fixation process of legumes. There is documented evidence from other parts of the world that soil bacteria can be seriously damaged through herbicide use, for example. That’s something that is kind of insidious and it’s not all that well understood,” says Entz.

A better understanding of the impacts of different agricultural practices on the complex interactions in soil organism communities, and the consequences of those impacts for crop yields, in terms of calories and nutrients, could help both organic and conventional systems become more efficient at producing nutritious food supplies. -end-

The Bottom Line
Over the long-term, the market always has a way of working itself out. As one segment, such as fertilizer prices, reaches a new pricing plateau, more companies are willing to invest more capital into research and development. Eventually new products are brought to the marketplace which either reduce, or even eliminate, the need of that product. The same can be said for production practices.

Our industry is facing the same issues that most other industries face. As more emphasis is put on energy conservation and the environment, the more it will be necessary to reduce our consumption and the ‘footprint’ we leave behind. It will be economics that determines the pace at which this happens. Kenton Possberg, Humboldt, Saskatchewan.

Cutting energy consumption and protecting the environment are synonymous. Any time we as producers can cut an energy cost it contributes to our bottom line. Protecting the environment is also in our best interest, as we are the first in line to benefit from a healthy environment.

The energy cost cutting suggestions in this article are pretty intense in terms of implementation and of measuring. Is there room for the fertilizer manufacturer to reduce the energy required to make fertilizer?

How close is plant breeding in developing other crops with the ability to fix N or with better N utilization efficiency? Organic farming, energy and food supply: Food supply vs. energy efficiency. Take your pick. John and Lisa Huvenaars, Hays, Alberta.

The economics of energy use and farming are tied to the cost of energy and commodity prices. We know energy costs are always going to go up regardless of any increases in
efficiency; unfortunately we are not so sure commodity prices are going to keep up. Survivors in farming will be the ones balancing rotation systems and input costs combined with environmental concerns. Ian McPhadden, Milden, Saskatchewan. -end-