In 2018, the Manitoba Agricultural Museum wrote on the backsetting method of breaking virgin sod.
A reader, Mr. Bollman, contacted us to inform the museum that there is more information on backsetting in the book Profitable Grain Growing, written in 1919 by Seager Wheeler, a noted agronomist and grain grower of the time, known as the ‘Wheat Wizard of Rosthern’ and the ‘Wheat King of the Prairies.’
Seager Wheeler immigrated to Canada from England in 1885 and in 1890 took up a homestead near Rosthern, Saskatchewan. He became knowledgeable about dryland farming and continued to expand this knowledge through observation and experimentation throughout his long career farming. His book Profitable Grain Growing became a bestselling study of dryland farming and remains a comprehensive discussion of 1919 western Canadian agricultural practices.
The museum’s interpretation committee searched for and found a copy of the book in a Winnipeg used bookstore.
The book lays out the backsetting process as first plowing the virgin sod shallow, about an inch and a half to two inches deep with the plowing being carried out as thoroughly as possible with no misses or skips. If a skip occurred, then the plowman should immediately turn around and replow the missed area.
Wheeler recognized that it is difficult to plow shallow and suggested that in uneven ground where the plow is likely to skip over depressions or go deep on knolls, it may be advisable to go a little deeper.
Wheeler suggested that it was important to turn the sod over so that it laid flat. This would result in the sod maintaining contact with the soil below to maintain capillary action and continue the movement of moisture from further below in the soil.
Packing of the breaking should then be carried out soon after plowing in order to rot the turned-under sod. As soon as the sod is sufficiently rotted, the field should be replowed to a depth of six inches. The field then should be disced, plank dragged and then harrowed or cultivated as soon as possible.
The replowing and discing needed to be carried out in the same direction as the original plowing. While some people carried out the discing diagonally across the plowing, Wheeler did not advise this as the disc may cut the sod into squares or turn the sods over which resulted in the vegetation drying out and not rotting. The aim of these operations was to produce two inches of mellow soil on the surface. If the field was properly plank dragged the surface was fairly level as well.
Wheeler also discussed breaking virgin prairie sod by a single pass of the plow to a depth of approximately six inches deep. Even in a single-pass operation, further field operations such as discing, plank dragging and harrowing were necessary to produce an adequate seedbed.
Wheeler recognized that a single plow breaking operation was more economical than backsetting, however, a single plowing could result in problems later on in that the turned-under vegetation may not sufficiently rot and so decompose, particularly if the field was immediately sown and the resulting crop took up most of the soil moisture. In this case, when the field was plowed the following spring to prepare it for a crop, the plow turned up the buried vegetation which would then pose problems to seeding the crop. As well, the vegetation may result in a loose soil surface which may result in the soil drying out which would be a detriment to a developing crop.
Wheeler appears to be of the opinion that backsetting in the long run was a better way to break virgin sod particularly if the first plowing took place in the spring or early summer when there was generous soil moisture. If one examined the turned-down vegetation in July, one would find that the vegetation would be well rotted as a result of the soil moisture.
Agronomists now know that decomposing vegetation results in the organisms involved in the decomposing process taking up the available nitrogen in the soil. As the decomposition process continues on, these organisms release the taken-up nitrogen plus nitrogen found in the vegetative material being decomposed, back into the soil making the nitrogen available to any plants growing in the soil.
Single plowing of virgin sod may have resulted in slow decomposition of the vegetative material with the resulting effect that available nitrogen in such a field being lower than a comparative field that was backset. Backsetting then may have resulted in better soil nitrogen levels in the years immediately after the field was broken.
In addition, a backset field posed fewer problems when the field was plowed the following spring. The vegetative material should have been quite decomposed by then and even so, it was buried in the soil at approximately the two-inch depth. So if the field was plowed to a depth of five to six inches then the decomposed material was not brought to the surface but rather reburied.
Wheeler does point out that if virgin sod was plowed in late summer, drier conditions usually prevailed by then. These dry conditions would delay the decomposition of the vegetation turned under.
Wheeler suggested that another reason to consider backsetting as the preferred method of breaking was if the field being broken was in an area where native grasses were liable to give trouble.
However, Wheeler did not discuss this any further so it is not known whether he was referring to districts of Western Canada where there was greater rainfall which would result in grasses being better able to re-establish themselves or districts which contained certain species of native grasses that were more persistent.
The interpretation committee would like to thank Mr. Bollman for informing us of the book, Profitable Grain Growing.
The Manitoba Agricultural Museum is open year round and operates a website which can provide visitors with information on the museum and the Threshermen’s Reunion including location and hours of operation.