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Zero tilage has created soil legacy

The Prairies in the 1970s and early 1980s often resembled the Prairies of the 1930s. Wind and water erosion extracted a huge toll, costing farmers hundreds of millions of dollars.

In one year alone, soil losses were estimated at $430 million in Alberta, $560 million in Saskatchewan and $44 million in Manitoba.

Farmers did not question the need to change their cropping practices. Their only question was how.

In 1973, University of Manitoba researcher Elmer Stobbe convinced Jim McCutcheon to try seeding directly into the residue of his previous crop. The Homewood, Man., farmer became a leader in North America, breaking new ground in a revolutionary new practice without breaking ground.

The new technology was called zero tillage. It was already being tried in Argentina and Brazil. In fact, Allis Chalmers had introduced Brazilian farmers to a revolutionary zero till planter in the late 1950s.

Stobbe and McCutcheon figured that if a profitable zero till crop could be grown on the Canadian Prairies, this method might have potential to address wind and water erosion, loss of organic matter and the ongoing deterioration of prairie soils.

Within five years, a small group of farmers in Manitoba and North Dakota were dabbling in zero till. They soon drew the attention of industry, researchers, the media and farmers from Saskatchewan and Alberta.

Early zero till seed drills include names young farmers today won’t likely recall: HayBuster, Pioneer, Yielder and Great Plains, along with a long list of home-built models.

One unique home-built machine that exemplified the in-depth understanding of the zero till challenge was put together by Dave Lumgar at Thornhill, Man.

He started with a pair of 12-foot disc drill sections that normally would have covered 24 feet per pass. He arranged them so one followed the other. Now they covered 12 feet per pass.

The difference was in the field function performed by each unit. The front drill broke through the residue, buried fertilizer deep and then packed the fragmented soil.

The second unit placed seed shallow into a near perfect seedbed. Lumgar’s concept has been copied by numerous manufacturers over the years.

The seeding technology developed quickly, with much of the initiative and innovation coming from farmers. Researchers and industry leaders concede that farmers were the real leaders in the movement

The Manitoba-North Dakota Zero Till Farmers Association officially came together in 1982, followed by the Saskatchewan Soil Conservation Association in 1986 and Alberta Reduced Tillage Linkages in the early 1990s.

By 1990, zero till was no longer a poor second cousin to conventional seeding. It was the predominant cropping practice in most areas.

Although Alberta farmers adopted zero till at a slower rate than Manitoba or Saskatchewan, the impact on that province has been profound.

When the Alberta Reduced Tillage project wound down in 2009, it produced a 135 page report detailing the effects of zero till over the previous 15 years.

Alberta numbers may not match numbers from the other two provinces, but the general trends are the same.

Yield improvement tops the Alberta list with wheat up 3.5 percent, barley up 6.2 percent, flax up 7.9 percent, peas up 4.6 percent and lentils up 13 percent.

Financial returns to the grower were higher than bushel increases when nutrient management recommendations were followed.

Net returns on wheat were 30 percent higher and on peas 25 percent higher. Net returns on canola were only five percent higher, due to a 14 percent increase in fertilizer costs.

Labour in no till required 3.5 field passes on average. Farmers in minimum till averaged 5.8 field passes, while conventional till required 7.5 field passes.

Fuel savings are always significant when comparing zero till to conventional till.

Alberta data shows that wheat on stubble saved the grower 0.9 gallons per acre. Flax growers averaged a fuel saving of 1.04 gallons per acre. Zero till peas reduced the fuel bill by 1.2 gallons per acre. Seeding wheat into fallow saved 2.1 gallons per acre.

There are two components to reduced fuel use under a zero till regime. Two or more operations are combined into one pass across the field. The other component is a lower draft requirement on equipment, especially after a field has been in zero till for four or five years.

The jury is still out on herbicide use in zero till compared to minimum or conventional till. The Alberta data showed no difference.

However, studies in Saskatchewan indicate herbicide use is slightly higher in zero till.

The Alberta report says any economic benefit from zero till relates to the soil zone.

“In the black and gray soils of Western Canada, no-till and minimum tillage are superior to conventional tillage, says the report. “In the dark brown soils, no-till is equal to or marginally more profitable than conventional tillage.

“In the dry brown soil of Alberta and Saskatchewan, conservation tillage (minimum and no-till) systems are less profitable, especially in continuous cereal and cereal-fallow rotations.”

There are also environment benefits. Zero till allows better water infiltration into the soil. It reduces the amount of sediment, nutrients and bacteria eroding into waterways by 60 to 90 percent.

The report said zero till is responsible for a significant reduction in the loss of particulate phosphorus and total phosphorus in surface runoff.

However, it also says zero till causes greater loss of soluble phosphorus. Long-term research by the University of Manitoba supports that conclusion.

Although the study reported that weeds, plant disease and insect problems can either increase or decrease under zero till, most veteran zero till producers say all three problems become worse.

Other zero till benefits that have been documented in all three provinces include:

• Increased soil organic matter;

• More plant available nitrogen, phosphorus and potassium;

• Higher levels of microbial biomass and earthworms;

• Better tilth, aggregate stability and size distribution;

• Less soil compaction;

• Better water infiltration and retention;

• Less plant stress in hot and dry weather.

When Jim Halford addressed the Saskatchewan Soil Conservation Association in 2010, he said that too many researchers ignore the benefits of increased mineralization of soil nutrients in zero till. He specifically targeted fertilizer companies.

“Fertilizer companies are saying farmers worldwide are going to have to use more fertilizer,” said Halford.

“This justifies their high prices and I believe is mainly aimed at keeping shareholders happy.”

Halford also said the 2009 report from Alberta Reduced Tillage missed an important point.

“These statements miss the potential of increased mineralization of soil nutrients from improved soil and hence the opportunity to reduce fertilizer rates.”

Halford said soils on his farm have been analyzed after 12, 20 and 30 years in zero till by soil scientists from the University of Saskatchewan and Agriculture Canada.

“Nitrogen, which could be annually released or mineralized from soils, was 50 to 63 pounds greater on 20 year zero till soil than on the conventional tilled field.

“Trials with varying rates of nitrogen showed similar yields and higher grain protein in wheat on long-term no till fields. The long-term field had 27 pounds per acre less nitrogen fertilizer than the short-term no till fields.

“Phosphorus trials showed no yield increase from adding P2O5 to the same plots for six continuous years on long-term no till soils in 2009.”

The conclusion is that, if additional phosphorus doesn’t show a yield increase, then the soil must have enough plant available phosphorus.

Soil Organic Carbon (SOC) in the adjacent conventional tilled soils were only 50 to 70 percent of the original SOC levels in a field of unbroken native sod.

“We have increased this (SOC) to about 90 percent of native grass soils with 20 to 30 years of zero till.”

Ten years ago, Halford Farms bought the adjacent field, which had been under conventional tillage for more than a century. Halford could then conduct side-by-side trials comparing the conventional field to a field in zero till for 20 years.

Both fields received the same no-till management and crop inputs. Halford said the trial proved that long-term zero till reduces dependence on commercial fertilizer.

“We produced 43 bushels per acre of 14.5 percent protein wheat on our long-term no till fields.

“Those previously conventional tilled fields yielded only 23 bushels per acre of 13 percent wheat, with the exact same inputs and management.”

Halford has also seen significant reductions in the need for nitrogen fertilizer on his long-term no till fields compared to his short-term no till fields.

Since the late 1970s, zero till and direct seeding have become the accepted methods for dryland crop production on the Canadian Prairies.

Zero till creates a financial benefit when it’s dry because it makes better use of limited moisture, but when that same technology captures too much moisture and puts too much residue on the surface, there are new problems with insects, diseases like wheat streak mosaic and field access.

“In our area, we’ve had excess moisture since 1999,” said Minnedosa grower Bob McNabb, one of the founders of the Manitoba-North Dakota Zero Till Farmers Association and a pioneer in the development of zero till.

“This 180 degree turn in our weather patterns threaten to jeopardize the benefits we’ve gained so far from zero till. It would be good if we had some way to dispose of this excess moisture, which of course, might be tillage.”

McNabb said most farmers in southwestern Manitoba did some kind of fall tillage this year, in the hope it would dry the soil before seeding next spring.

“There was a time I was quite adamant against tillage. But if some sort of tillage is required to make zero till work, then so be it.”

When zero till was in the early stages, technology saved the day. It became possible because of affordable non-selective herbicides and better seeding equipment, most of which was developed on the Prairies.

McNabb said technology may come to the rescue again, possibly with vertical tillage, strip tillage or some other innovation.

Farmers may also have to repeatedly adapt to changing environmental cycles.

McNabb thinks the benefits of zero till go beyond the obvious. Farmers have gained a better awareness of the soil. They now ask questions they wouldn’t have thought of 20 years ago.

Their frequent question is whether farmers are extracting more from the soil than they’re putting back.

“There are fields around here where potash application is showing a net benefit. That generally means there’s a potash deficiency in the soil.”

Ergot on barley is another example. Even with normal nitrogen and phosphorus applications, some barley yields in the Minnedosa, Man., area were down by 20 bu. this year. There was ergot in barley fields where it has never appeared before.

According to Agri-Trend crop adviser Terry Aberhart, ergot in barley can be caused by a copper deficiency. It may go undetected until a growing season when extreme weather plays a role. And 2010 was just such a year.

McNabb said this may be another indication that zero till has allowed growers to take too much from the soil.

Despite its many benefits, zero till is not perfect.

University of Manitoba soil scientist Don Flaten said zero-till has well-known benefits such as better biodiversity, increased carbon sequestration and better wildlife habitat

“But there is no panacea or cure-all. We’ve got to keep the pros and the cons in perspective,” said Flaten, who has been active in zero till related research for more than 30 years.

“Our long-term studies on South Tobacco Creek show significant reductions in soil erosion and sediment loading into water systems. There’s also a significant reduction in nitrogen losses. That’s all good news.”

Studies began in 1993 and show nitrogen loss in zero till fields dropped by 68 percent. Total sediment export from zero till fields into the water system dropped by 65 percent.

“The bad news is that when we compare conventional tillage to zero tillage in the South Tobacco Creek watershed, zero till has a 12 percent increase in phosphorus runoff.”

Flaten said the study underlines the fact that there is no such thing as a beneficial management practice that does everything right for everyone all the time. There are always tradeoffs.

“Unlike nitrogen, phosphorus is strongly retained in the soil,” said Flaten. “It reacts and bonds with calcium in the soil or attaches to soil particles. Once attached, it doesn’t easily wash off and leech down into the soil like nitrogen.”

In most areas of the world, the majority of phosphorus loss occurs when the soil itself erodes into waterways. When soil particles wash into ditches and natural streams, phosphorus goes along for the ride.

That’s not the situation on the Prairies, where the majority of the loss is in the form of dissolved phosphorus released from the soil surface and vegetative residues. This is true on conventional till fields as well as no till fields.

Dissolved phosphorus is highly susceptible to release during spring runoff. On average, prairie watersheds produce 80 percent of their runoff during snowmelt.

There is little soil erosion during spring runoff because snowmelt runs over frozen soil and landscapes are relatively flat.

In the summer, zero till ground absorbs high volumes of water and reduces erosion during heavy rain. If water washes some phosphorus off crop residue, it’s likely to percolate into the soil.

But in early spring, when frozen soil cannot accept snowmelt, soluble phosphorus follows the natural course down the stream and into rivers and lakes.

Zero till has created another problem for phosphorus watchers. Stratification occurs if there’s no tillage to incorporate leftover fertilizers and crop residue into the soil.

Roots bring phosphorus up to the the plant. When the plant dies and decomposes, the phosphorus remains on the surface.

“If there’s no tillage, it remains in the top one or two inches. That’s stratification. From a water quality perspective, it would be better if that phosphorus was buried a few inches into the soil,” said Flaten.

“If it was buried, the next crop could access it so it doesn’t run off.”

Although the mandate of zero tillers everywhere has always been to reduce or eliminate soil disturbance, Halford agreed with Flaten that topsoil might benefit from a certain amount of tillage.

“Some no till farmers have had to till after four or five years because the soil was too hard,” said Halford, adding that drills with the least disturbance may not work the soil enough.

“There is no inversion or mixing, which could assist with deepening the topsoil. This (low disturbance) system relies almost completely on the crop to provide any improvement in the soil’s ability to recycle nutrients.

“A knife opener penetrates 3.5 to four inches deep in the soil and places fertilizer. The knife also lifts, rolls and mixes some soil each year, so the surface of the soils will become softer in time.”

Halford said this small amount of tillage is one of the chief factors allowing him to reduce fertilizer rates.

How significant is a 12 percent increase in phosphorus runoff caused by zero till?

“In the overall scheme of things, when you balance it against the many benefits of zero till, this isn’t a huge problem,” said Flaten.

“We’ve started looking at solutions. First is periodic tillage in a zero till regime. We’ve just started that research, so there’s no results yet.”

The second option is to bale the straw and get it off the field before rain or snowmelt water have a chance to wash soluble phosphorus into waterways.

The third solution is to maintain lower soil test phosphorus values on zero till ground.

Flaten said spring runoff over frozen ground in livestock areas creates another problem, whether on a conventional till or a zero till field.

“Fresh frozen manure applied to the land during the winter is an obvious source of phosphorus runoff during snowmelt.

“We need to balance phosphorus application with phosphorus removal by crops. And we need to avoid winter application of these nutrients.”

Flaten said there’s a message in this for people who worry that phosphorus will kill Lake Winnipeg.

“I’ve heard people taking zero till and runoff data from other regions and freely applying it to the Lake Winnipeg watershed.

“They are saying that zero tillage or conservation tillage can save Lake Winnipeg. Well, it simply won’t work. More zero tillage will contribute more phosphorus to Lake Winnipeg.

“It’s all part of that whole myth that zero till will cure all of our problems. It won’t.”

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