Irrigated pastures offer many benefits to producers

Source: Saskatchewan Agriculture and Food

With the expansion of the livestock industry in Saskatchewan, many producers are searching for new ways to meet their forage and pasture needs. Depending upon the region of Saskatchewan in which they reside, irrigated pastures may be a good option for them.

Charlotte Ward, a Forage Development Specialist with Saskatchewan Agriculture and Food, states that a good irrigated pasture in Western Canada can produce more than 25 times the forage per acre that native grassland yields, and seven to 10 times more forage than cultivated dryland pasture.

“Irrigated pastures may still experience yearly and seasonal variations in forage yield and quality, but not to the same extent as dryland pastures,” Ward said. “The greatest potential for increased forage production is on good, well-drained soils where water supply is not restricted throughout the growing season.”

Grasses are quite often used as the basis of irrigated pastures because they are predictable and easy to manage. Legumes such as alfalfa have also been included, since they provide added nutritional value and decrease the need for nitrogen fertilizer. Using a legume such as cicer milkvetch eliminates the risk of bloat, which may be a concern if livestock are grazing young, vegetative alfalfa.

“Pastures need about 60 centimetres of water during the growth season,” Ward noted. “Very few areas in Saskatchewan can meet that requirement without the use of irrigation.”

On established pastures, the amount of water applied at once will depend upon the system’s capabilities. Ward says most producers have their systems set to administer between three-quarters and an inch of water in one application, usually applying 12 to 14 inches of irrigated water throughout the growing season.

“Because soil’s water-holding capacity varies with soil type, irrigation strategies will have to account for the fact that grasses get most of their water from the top 30 centimetres of the soil,” she said. “As a result, in sandy loam, the soil may only be able to hold a four-to-six-day supply of water to that depth at the peak demand of the season.”

It is also recommended that irrigation be timed to occur after grazing, haying or fertilizer treatment in order to ensure that moisture stress does not limit pasture regrowth. Watering can occur while cattle are grazing other paddocks to ensure that the soil-water capacity is being met.

On grass pastures, multiple nitrogen fertilizer applications will be required to maintain high yields. If legumes are included in the pasture, nitrogen fertilization will favour grass growth and decrease the quantity of legumes in the pasture. Pastures which contain at least 50 per cent legumes should not need nitrogen fertilization, but may require phosphorous and other nutrients if soil tests reveal deficiencies.

“Producers will want to carefully weigh the cost of fertilizer and application in relation to additional forage and animal production,” Ward noted.

Intensively grazed systems where livestock are moved frequently provide an opportunity for greater overall animal production per acre compared to extensively grazed, irrigated pastures. According to Ward, the timing of rotations is important to maximizing productivity.

“If cattle are allowed to graze forages too close to the ground, recovery after grazing will be delayed. If cattle are allowed to graze too lightly, forages will mature too quickly before the next grazing cycle,” she stated.

“A number of producers have had success limiting cattle to only two to four days worth of pasture at one time, which allows for longer plant recovery periods compared to pastures that are allowed to be grazed for durations of greater than a week.”

Some producers divide their pasture into multiple paddocks to allow for management of surplus forage in the spring. Another strategy to maintain the same herd size throughout the grazing season is to set aside one-third to one-half of the pasture area to be harvested once as silage or hay. This will allow usage of the forage before it is fully mature and allow timely regrowth for grazing later in the season.

Another suggestion is to avoid grazing while the ground is still wet from irrigation. “Grazing wet ground will result in greater trampling and soil compaction, and may lead to a loss of desirable species,” Ward said.

“Also, as with all grazing, herd health must be monitored continuously, as concentrating livestock on a small area may lead to an increase in the incidence of diseases such as pink eye or foot rot.”

For more information, contact:
Charlotte Ward, Forage Development Specialist
Saskatchewan Agriculture and Food
Phone: (306) 867-5559