Grasses

• In Western Canada most tame grass species are cool season species or C3 plants. Optimum growth occurs at temperatures between 18C to 24C.

• Warm season grasses or C4 plants perform best at temperatures between 28C and 32C. Introduced grass species such as millet or corn plus some native species are considered to be C4 plants.

• Grasses offer adaptability and flexibility to environmental conditions. Grass species vary in their tolerance to flooding, drought, heat, cold, salinity, acidity and alkalinity. These factors need to be considered when selecting forage species.

• Grasses can be categorized as being either annuals or perennials. Perennial grasses can be further divided into either long-lived or short-lived species. Well established long-lived species can form permanent forage stands.

• The root system of grasses is fibrous and is either rhizomatous or bunch in nature. Rhizomatous grasses spread and form a dense stand while bunch grasses remain as individual plants. Bunch grasses are less competitive in forage mixtures than rhizomatous grass species.

• Rooting depth also varies between species. Some species such as blue grass have shallow rooting depths while more drought tolerant species such as smooth brome have a higher proportion of their roots distributed deep within the soil profile.

• Perennial grasses normally replace 25 to 50 percent of their roots annually. New root growth is hampered if to much leaf area is removed during the growing season to frequently.

• Grasses grow differently. Some species tiller more actively and keep more leaf area near the soil surface with most of the seasonal growth as vegetative stems. This growth characteristic permits these species to tolerate more frequent grazing or clipping and still provide rapid re-growth. These species are referred to as short -jointed grasses.

• Other species produce mainly reproductive stems. These species are referred to as long-jointed grasses and are more sensitive to frequent clipping or grazing. As a result, these species are best suited to hay production or for use as seasonal pasture.

• Mixed stands of grasses or legumes are more stable as a sward than single specie stands. Where one specie suffers, another specie is better suited. This is particularly important in long term stands that need to produce well for many days in the growing season.

• Straight stands are best suited when the grower's expectations are specific and for short times. The most suitable specie is then able to perform under that particular management program for the specific goal.

• Fall management is critical in perennial grasses when plants are storing carbohydrates and developing new growing points. Without stored energy new spring growth is delayed and plants are less vigorous. Late summer grazing or cutting should be timed in order to provide a fall rest period.

• Some species initiate growth earlier in the spring. This aspect is especially important for early season grazing or for capturing maximum sunlight energy throughout the growing season as a whole.

• Growth curve differences exist amongst grass species. Grasses vary in the time required from first emergence to final seed set. Those grasses that have a long growth curve are easier to harvest especially when grazing. Long growth curves allow the grass to grow longer vegetatively compared to having quickly reached the objective of setting seed.

• Grass species differ in palatability. Because of taste and texture, some species are more palatable longer into their life cycle. This aspect is critical where graziers bank forage for eventual consumption later in the fall and winter.

• Some species utilize moisture better than others. Because of fundamental physiological differences, some species are better able to grow and reproduce under low levels of moisture compared to others. The nature of the roots and the leaf surface are two features that affect a species ability to thrive under heat, cold, drought or flooding.