Source: Saskatchewan Agriculture and Food
Grazing forages may well be the most sustainable agricultural practice, and certainly the most economical method of value-added processing of forages, in Saskatchewan.
However, in order to achieve peak efficiency on an acre-by-acre and day-by-day basis, graziers must give forage plants enough time to regrow and recover their vigour after grazing, according to Dr. Jim Romo of the Department of Plant Sciences at the University of Saskatchewan.
“The importance of providing adequate rest after forage removal is well understood and applied by managers of forages that are used for hay. A conscious decision is made to allow plants adequate rest—or the opportunity to complete their growth—between haying operations. This ensures that the maximum quality and quantity is produced and harvested on each acre and in time,” says Romo.
“This principle of allowing plants to complete their growth would be equally advantageous to apply in grazing systems, and few pasture managers have so far capitalized on this opportunity because of the scarcity of information for forages other than those used for hay.”
To address this issue, Dr. Romo and his colleagues conducted studies in the Northern Mixed Prairie range on the Missouri Coteau in central Saskatchewan. Research was done over a three-year period on a Loamy Range Site in excellent ecological condition in the Dark Brown Soil Zone, with a view to determine the amount of time needed by northern wheatgrass (Agropyron dasystachyum), western wheatgrass (A. smithii), plains rough fescue (Festuca hallii) and western porcupine grass (Stipa curtiseta), among others, to recover their forage production potential following mowing.
“In June, July and August, regrowth for the six species or plant groups and soil water at the 0 to 30 cm depth was determined following a single mowing of the sward to a 7.5 cm stubble height in April, May, June, July, August, September, October or November on concave and convex landforms on north slopes and south slopes, as well as level uplands,” explains Romo.
“Mowing did not enhance current year standing crop and above ground net primary production (ANPP). Instead, mowing generally reduced current year standing crop and ANPP. Depending on the month of mowing, species or species groups and landforms, one to 25 months elapsed from the time of mowing until current year standing crop was similar to that in the ummowed control.
The documented recovery of forage production after mowing suggests that a deferred rotation grazing system should be used to maintain forage production by northern wheatgrass, western wheatgrass, western porcupine grass, forbs and shrubs, and "other" graminoids.
“However, it would appear that rest rotation grazing systems that incorporate one full year of rest after grazing are needed to maintain potential forage production of plains rough fescue and total forage production over the entire landscape. These documented responses of plant recovery after herbage removal can be used to develop grazing systems that sustain forage production,” concludes Romo.
“These recommendations should serve as guiding principles. However, the exact amounts of rest needed by plants after grazing may require modification for site-specific conditions and management objectives.”
For a copy of the complete Final Report, titled Landscape Level Variation in Recovery of Production in Native Rangeland After Grazing (#20000272), please call Saskatchewan Agriculture and Food at (306)787-5929.
For more information, contact:
Dr. Jim Romo
Department of Plant Sciences
University of Saskatchewan
(306) 966-5015
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