Kentucky bluegrass growth curves

Published: 25 May 2023| Version 2 | DOI: 10.17632/khksjzsbjm.2


Dataset describes Kentucky bluegrass production and height throughout two growing seasons in a rangeland system in the northern Great Plains. One year of sampling was during a drought year and one year had average precipitation. 2017 was a drought year and 2018 was an average precipitation year. Dataset also includes the nutritive value of Kentucky bluegrass throughout the season. Dataset can be used for modeling or for grazing planning. 2017 was a drought year and 2018 was an average precipitation year. Some plots were mowed before the growing season to simulate early defoliation. Sampling occurred at the USDA Northern Great Plains Research Laboratory near Mandan, ND (46.7673 N, 100.9184 W) The 6-hectare pasture is at an altitude of 502 m above sea level and is within the temperate steppe ecoregion of the United States. This region is characterized by long, cold winters and short, hot summers. Predominant soil types include Temvik-Wilton silt loams (fine-silty, mixed, superactive, frigid Typic and Pachic Haplustolls). The pasture is on a loamy ecological site (site ID 054XY030ND) and is managed as a native grassland with no fertilization or irrigation. The average soil texture is a clay loam (31% clay, 49% silt, and 20% sand). Average soil chemical characteristics were: pH (H2O) = 6.4; OM = 7.4% LOI; Na (ppm) = 8.25; K (ppm) = 362.4; Ca (ppm) = 1925.4; Mg (mmolc/dm3) = 417.6; CEC (me/100 g) = 17.5; S (ppm) = 8.3; Cu (ppm) = 0.74; Fe (ppm) = 33.7; Mn (ppm) = 18.5; and Zn (ppm) = 9.7.


Steps to reproduce

Kentucky bluegrass samples were collected by clipping approximately every 3 weeks from May through September 2017 and June through September 2018. Samples were collected from two treatments that included plots that were or were not defoliated (mowed) before the start of the growing season. Plots were mowed in March to a 5-cm stubble height and all plots were covered with exclusion cages to prevent livestock from grazing. Sampling areas were selected based on the complete cover of Kentucky bluegrass and all measurements were done from inside the cages. Kentucky bluegrass samples were clipped from three 50 x 50 cm quadrats placed inside the 2 3.5 m exclosure cages. Samples were clipped at ground level, bagged, and dried at 60 C for at least 60 h. Dry samples were weighed to calculate herbage mass. These same samples were then ground to pass a 1-mm screen using a Wiley mill for nutritive value analyses. Samples were analyzed for crude protein using dry matter (AOAC, 1990; Method 967.03), organic matter (AOAC, 1990; Method 942.05), neutral detergent fiber (NDF) (Van Soest et al., 1991), acid detergent fiber (ADF; AOAC, 1990; Method 973.18), and total nitrogen concentrations (AOAC, 1990; Method 990.03). Nitrogen was converted to crude protein (CP) using 6.25 N to CP factor (Ward labs, Kearney, NE).


USDA-ARS Plains Area


Animal Science, Rangeland Management


Agricultural Research Service

Natural Resources Conservation Service