Les Henry: Nitrate down the well

Quit porking on so much N

The photo shows NE26 Township 11 Range 11, west of Meridian 1, three miles east of Austin, Man. The soils are of the Almassippi association. The details of individual soils are all available online at Manitoba Agri-Maps at the Agrimaps website (see link at right).

This song has been sung before in this column. With the death of babies as a possible consequence, it bears repeating.

Nitrate in the environment

In a native grass environment like my grandfather and yours broke up to farm, nitrate was a rare molecule. Native grass evolved by staying brown and doing nothing when it was dry but bouncing up “green as grass” as soon as it rains. Any nitrogen converted from organic to mineral (ammonium and nitrate) is immediately sucked up by a hungry grass root. When the buffalo roamed, the only nitrate would have been where animals or people congregated for some time.

A word about units

Nitrate = 10 parts per million (ppm) means there is 10 ppm of the nitrate ion (NO3-). Nitrate-N = 10 ppm means there is 10 ppm of N in the form of the nitrate ion (NO3-). The conversion factor from nitrate to nitrate-N is 4.43.

In Canada, the limit for potable water is 10 ppm Nitrate-N, which is equivalent to 44.3 ppm nitrate (rounded to 45 ppm). Errors in reporting do happen and are serious. I even found an error in the CCME (Canadian Committee of Ministers of the Environment) guidelines.

Many reports leave doubt as to what they really mean. They will state that the limit for potable water is 10 ppm NO3-N and then show graphs or tables as ppm NO3.

Water well nitrate, 1940s and 1950s

Nitrate in well water is not a new finding. I have seen recent studies where someone surveys water wells and finds nitrates and immediately blames farmers for pouring on all that fertilizer. In the Northern Great Plains, the first account of a farmstead well with high nitrate and blue baby syndrome was in Iowa in 1945.

The finding can be credited to a stubborn farmer. The baby was brought to hospital twice and immediately improved in hospital but got sick back on the farm. On the third trip, the farmer brought a water sample from his well and said, “Test this — it is the only thing different between hospital and home.”

A direct quote from the article in the Journal of the American Medical Association, 1945, volume 129, pages 112-116, is “An open-minded attitude on the part of the latter (admitting physician) in accepting this ‘cock and bull’ theory as plausible, resulted in the father’s bringing the water, which yielded the answer to the problem.” The answer was 140 ppm of nitrate-N.

A 1948 survey of more than 2,000 farm wells from different areas in rural Saskatchewan, found 18 per cent to be contaminated with nitrate. Small towns on sandy soil also had nitrate-contaminated wells. Bounty, west of Outlook and Tugaske, near Central Butte, are two examples.

Bounty, now a ghost town, was where we accessed a locker plant (freezer) in the days before farm power. Tugaske is still a going concern and was the hometown of early Grainews columnist Alf Bryan. Readers long enough in the tooth will remember Alf. It was my pleasure to visit his farm and learn from Alf. His son Shane carries on that farm.

In early days, many small towns had outhouses. Sanitary sewer lines were only constructed in the 1960s. In the summer of 1961, I laid sanitary sewer pipe in Dinsmore and Cupar. Many small towns also housed a few chickens, cows and horses — especially the livery stable.

Manitoba

Nitrate-contaminated wells in Manitoba were very common in the 1940s and 1950s, and particularly in the “wet sands” area of Almassippi soils just east of the Manitoba escarpment.

An important reference for CCA or PAg folks is R.A. Hedlin, Canadian Journal of Soil Science, 1971, Volume 51, pages 75-84. In the late 1960s, pollution was becoming a topic of interest and groundwater nitrate was assumed to be from fertilizer. Bob Hedlin dug out the 1955 MSc thesis of F.P. LeClaire and used that data to make sure the older work was not forgotten. The photo above shows one of the two sites in that thesis.

Thanks to Don Flaten, I learned that University of Manitoba has made many older theses available online. A few mouse clicks later, and I have the MSc thesis of F. Pierre LeClaire as a PDF on my computer. Thanks to readers, I now know that Manitoba soil survey data is also available online and I used it to learn about the sites used in the LeClaire study.

That 1950s farmstead had a house well with 60-70 ppm nitrate-N, a barn well with 100-plus ppm nitrate-N and other sites within the farmstead also high in nitrate. The Almassippi soils are sandy- to medium-textured overlying clay and high water tables are common.

Shallow, hand dug or bored wells were common, as were pit privies and farmsteads with various poultry, hog and cattle operations. The farm fields outside the farmstead did not have excessive nitrate levels. The farmstead was still present in 1981 as recorded on the 1:50,000 scale topographic map.

LeClaire’s second site for his MSc thesis was NW34 Township 13 Range 12 W1, and that farmstead is still there. The domestic wells were slightly contaminated but test wells in parts of the farmstead were very high in nitrate. Test wells in farm fields were mostly unaffected.

It is one thing to read about a site on paper but to be able to fly on over and have a look and drive by on Highway No. 1 via Google Street View is a totally different perspective. With legal locations noted and detailed maps in the thesis, it would be possible for some keen young student to approach current owners to see if they would be interested in a second look 70 years later.

Alberta

Alberta has few shallow dug or bored wells and nitrate contamination of wells is not common. That is because Alberta has much thinner glacial deposits and mostly well-defined surface drainage.

Some further reading

In 1993, Bill Meneley (1933-2000, hydrogeologist) and I completed a book entitled, Fertilizers and Groundwater Nitrate. Phase 1 was a review of literature, with 191 references documented, including the original paper that described the chocolate colour of the blood associated with blue baby syndrome (methemoglobinemia is the $64 word).

It was published in 1868 — yes 18 is not a typo. It was published in the Philosophical Transactions of the Royal Society of London and authored by M.D. Gamgee. The University of Saskatchewan library got a Xerox copy for me via interlibrary loan, and it rests comfortably in a file cabinet in my garage.

The U of S library has been very helpful to me this week in accessing references dealing with this topic. The library is closed but computers are humming and helpful library staff come up with what I need. Thanks, folks!

Phase 2 was Nitrates in Western Canadian Groundwater. We assembled all available ground, and some surface, water nitrate and assembled 128 references on the tropic.

If CCA or PAg types want to have a look, that report is available at wsask.ca. Find it by pulling up wsask.ca, hover over the Water Info tab and then select the Science and Geology Reports heading. The reports are listed alphabetically by title of the report.

The risk map with that report gave a high-risk rating to the Assiniboine Delta Aquifer in Manitoba, the Outlook irrigated area in Saskatchewan and a few local valley aquifers in British Columbia. The note with the map stated, “Where surficial aquifers exist, even at a local scale, care must be exercised to ensure that fertilizer rates do not exceed crop requirements.”

The bottom line, groundwater nitrate and N fertilizers

The early work with nitrate dealt mainly with shallow dug or bored wells in farmsteads with outhouses, animals and manure piles. The yard wells were contaminated but local aquifers in adjacent fields were not. The small family farmstead was the problem. This was all before intensive livestock operations or widespread N fertilizer use. Current interest is with aquifers and domestic wells that may be completed in those aquifers.

If N fertilizers are used in significant excess to crop requirements on sandy soils over vulnerable surficial aquifers, nitrate accumulation will be the result. Normally, nitrate levels in aquifers are nowhere near the nitrate levels of shallow dug or bored wells studied in the 1950s.

To insure aquifers are not contaminated, the big R of the 4Rs is rate. For high value crops, it’s easy to pork on too much N just to be sure that maximum economic yield is obtained. Nitrate contamination of surficial aquifers can be prevented with three easy steps.

STEP 1: SOIL TEST
STEP 2: SOIL TEST
STEP 3: SOIL TEST

Soil test to a depth of at least two feet and deeper if required. If soil test is high, quit porking on so much N.

About the author

Columnist

Les Henry

J.L.(Les) Henry is a former professor and extension specialist at the University of Saskatchewan. He farms at Dundurn, Sask. He recently finished a second printing of “Henry’s Handbook of Soil and Water,” a book that mixes the basics and practical aspects of soil, fertilizer and farming. Les will cover the shipping and GST for “Grainews” readers. Simply send a cheque for $50 to Henry Perspectives, 143 Tucker Cres., Saskatoon, Sask., S7H 3H7, and he will dispatch a signed book.

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