Precision ag = sustainable ag?

We had phosphorus for Christmas dinner. I had phos. You had phos. Everybody filled up on phos. It’s an old tradition among people who eat — any time, anywhere and not just at Christmas.

If you went south for Christmas and ate tacos in Tijuana, you had phos. If you went north to Baffin Island for deep-fat-fried whale blubber, you had phos. Same deal if you stayed home for ham and scalloped potatoes.

Phosphorus is a component in all food. Every life form requires phosphorus. Without phosphorus, there is no food. Without food, the human race expires. Not a pleasant thought at this time of year, but it’s an issue that deserves discussion as we sit around the dining room table drinking coffee and digesting our phosphorus.

The discussion is especially important because there’s a finite amount of phosphorus on our planet — only enough to last 100 to 250 years. When it’s gone, it’s gone for good, and so are we.

That’s why we need to figure out how to recycle the phosphorus we mine out of the earth every year, says University of Manitoba soil scientist Don Flaten.

He recalls a reporter interviewing him recently after he finished making a presentation on phosphorus.

“He asked me what the synthetic substitute is when we run out of phosphorus. I tried to explain to him that there is no replacement for phosphorus. That’s why it’s so important that we start recycling phosphorus now.

“The whole concept of sustainable agriculture demands that we employ precision farming technology to make the most of the fertilizer we apply. Precise fertilizer placement means nutrients are located where the roots can easily access them. If no excess fertilizer is going into the soil, then there’s no overflow into the environment.”

Mitch Rezansoff, executive director at the Canadian Association of Agri-Retailers and previously the precision ag specialist for Enns Brothers John Deere dealerships in Manitoba, said emerging technology has already made a big difference in reducing the volume of fertilizer going into the ground. The evidence is obvious when driving around and seeing field after field of perfectly straight rows.

“GPS and autosteer have dramatically reduced the amount of overlap and over-application. We’ve dramatically reduced the amount of seed, fertilizer and pesticides,” said Rezansoff, adding that it’s rare today to find a field where the rows are not perfectly straight. He figures 95 percent of fields in Western Canada are seeded with autosteer.

“We’re talking an inch of overlap, so the reduction in inputs is tremendous,” he said. “The same thing is happening in the headlands with automatic shutoff systems and section control. Precision agriculture technologies are letting farmers squeeze the inefficiencies out of their operations. That’s good for the farmer and it’s good for the environment.

“Farmers are moving more and more into variable rate seeding, fertilizer application and crop protection products. You only apply what you need and when you need it. That’s good from a sustainability point of view. In the long run, I think the technologies will allow farmers to maintain yield without damaging the environment.”

He said variable rate is not catching on yet in areas such as the Red River Valley, where the land is flat and the soil is fairly consistent throughout a field. However, the big payback comes in the rest of the Prairies where topography and soil variability is a factor.

Carl Larsson’s “Ett hem åt solsidan” from 1904 depicts his own home at Christmas. They had no way of knowing that every food item in the painting contains phosphorous. | Larsson collection image

John Heard, a soil fertility specialist with Manitoba Agriculture, said there’s an easy answer to the challenge of fertilizer application, but it’s too outrageous so it isn’t going to happen.

“We could take all the excess manure from eastern livestock operations and precision apply it to the impoverished soils out here on the Prairies, but that’s not going to happen,” he said with a laugh.

Heard says providing crops with sufficient nitrogen in a sustainable manner is not difficult. It means taking a field out of production to grow a nitrogen-fixing crop for one year. However, managing phosphorus in a responsible manner is a totally different issue because it is not a renewable resource.

“We have to get serious about recycling the phosphorus we apply to our fields. We’re already doing that on a small scale with Crystal Green or struvite.”

He said Crystal Green is a fertilizer product that provides a continuous release of phosphorus. It’s made by extracting 85 percent of the phosphorus and 25 percent of the nitrogen from livestock waste water.

While most people think of reducing commercial fertilizer inputs when they think of sustainability, Heard said Manitoba doesn’t agree.

“We’re going the opposite way with our recommendations in Manitoba now. We feel that long-term sustainability with phosphorus involves bringing levels up to a good working range,” he said.

“We’ve changed our way of thinking. We used to use the sufficiency approach, and now we know how much trouble that got us into. We depleted our soils. So now we offer farmers the option of replenishing phosphorus levels, rebuilding those soils.

“Now, that runs counter to your story line about reducing fertilizer inputs, so I’m not with you on the idea that sustainability means cutting way back on fertilizer. We’re going different paths now. Sustainability does not always mean putting on less. We’re telling farmers to put on more phosphorus. That’s our story and we’re sticking to it.”

Heard said that if a farmer is convinced that sustainability means he should apply less commercial fertilizer, then he should apply triage management and allocate the available commercial nutrients to the spots on the farm that need it most. This applies not only to phosphorus, but also to the other nutrients.

He speculates that if social pressure should ever force farmers to apply less fertilizer, then we should expect a drop in food production and an increase in food prices. He said farmers would likely take some land out of commercial production in order to grow their own nitrogen. This would exacerbate the drop in production.

“Precision agriculture technology will not bale us out if major cutbacks become necessary,” he said.

“Precision ag will help us make best use of what we have, but it will only buffer the collapse of farming. By stretching available resources, it will slow the decline in food production.

“Limiting the supply of fertilizer will also have the effect of raising the price. When that happens, farmers will turn to precision technology as a means to spoon feed expensive fertilizer.”

Frank Larney, a soil specialist with Agriculture Canada in Lethbridge, said he has doubts about the value of precision agriculture.

“Precision ag has been around for decades now, going way back to the 1980s, but at the end of the day has it really made a big difference? I’m not so sure,” he said.

“We have remote sensing technology and the ability to gather all kinds of information and produce all kinds of maps, but then how and when would we use it?”

It would likely be used if mainstream society ever scrutinized agriculture to the degree that government mandated an overall reduction in the use of fertilizer and crop protection products.

Larney said it takes the same amount of nitrogen and phosphorus to grow a bushel of wheat, regardless of how sophisticated the seeding equipment. If those nutrients should ever become limited, that’s when farmers will pay serious attention to precision ag seeding systems in order to place nutrients to get the biggest bang for the buck.

That’s the day when this vague concept of sustainable agriculture will call on precision ag to turn sustainability into a reality.

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