Comparative Yields of Seven Native Grasses Growing in An Ungrazed Mixed Prairie
Authors:   , Franks James 
Published: February 2023

A study was made to determine the average monthly and seasonally yields of seven native grasses as they grew in pure stands in an ungrazed mixed prairie near Hays, Kansas. The study was conducted for two growing seasons (1952-1953) on the upland, gentle hillside, steep hillside, and lowland. The study area consisted of 320 acres with gently rolling hills and steep hillsides broadening at their based to form ravines and a broad lowland. Grasses which were studied on the upland were blue grama (Boutelous gracilis (H.B.K.) Lab.), buffalo grass (Buchloe dactyloides (Nutt.) Englem.), side-oats grama (Bouteloua curtipendula (Michx.) Torr.), big bluestem (Andropogon gerardi, Vitaman), and western wheatgrass (Agropyron smithii, Rydb.). On the gentle hillside, yields were ascertained for buffalo grass, blue grama, side-oats grama, big bluestem, and little bluestem (Andropogon scoparius, Michx.). Grasses on the steep hillsides form which yields were taken were side-oats gram, big bluestem, and little bluestem. On the lowland yields were obtained from big bluestem, switchgrass (Panicum virgatum L.), and western wheatgrass. Randomly located square-foot quadrats were used to determine basal cover and yields. Fifteen or more square-foot quadrats were clipped each month (June to September) at the top of underlying mulch to determine yields of each species of grass on each site. The clipped forage was air dried, weighed and computed to pounds per acre. Average basal cover was determined for each species by many individual measurements. Height of growth was determined at each clipping period. Measurements were made of new growth prior to clipping the quadrats and also of unclipped growth outside the quadrats. Soul moisture was determined every 2 weeks to a depth of 4 feet on the upland and lowland. Samples were taken in duplicate and an average percent moisture for the two samples was recorded for each depth. Climate for the two seasons was characterized by low, uneven distribution of rainfall, deficiency of soil moisture and accompanying high temperatures and wind velocities. The two growing season were abnormally dry, each received about 11 inches of rainfall. Climate for the two seasons was characterized by low, uneven distribution of rainfall, deficiency of soil moisture and accompanying high temperatures and wind velocities. The two growing season were abnormally dry, each receiving about 11 inches of rainfall. Production of grasses usually reached a peak in late spring or early summer and then declined during the latter part of the growing season. Generally more forage was produced by June 15 than thereafter. Height of growth and yield were greatest when soil moisture became deficient. During the latter part of both seasons, except for sporadic greening, most grasses were in semi-dormancy with their leaves either rolled or folded. Generally the amount of forage produced was greatest from species which occupied the mesic areas and lowest form those of more xeric ones. The tall-grasses, while occupying less surface area than the short grasses, produced larger amount of forage due to their greater height and coarser growth. On the upland habitat about 1,000 pounds of forage was produced by the short grasses each season, while the yield of side-oats grama was somewhat higher. Big bluestem which occurred only in isolated bunches produced slightly more than 3,500 pounds per acre. The yield of western wheatgrass was slightly more than 1,500 pounds the first season and somewhat less the second season. On the gentle hillside habitat the two short grasses were again low producers. However, buffalo grass produced slightly more forage than blue grama and side-oats grama each season. The yield of little bluestem and big bluestem was somewhat comparable each season, each producing more than 2,000 pounds. Big bluestem produced the greatest yield followed by little bluestem and side-oats grama in that order on the steep hillside habitat. Big bluestem produced less forage on this habitat than on other sites while the yields of side-oats grama and little bluestem were somewhat higher. On the lowland habitat big bluestem produced about 6,013 pounds in 1952 followed by switchgrass (5,872 pounds) and western wheatgrass (4,940 pounds). 1953 yields were considerably less for each species. The amount of forage produced by each species generally increased with an increase with an increase in basal area.