Poor sandy soils, reduced crop yields, low prices and high fuel costs have led to Sandhills cropland abandonment in Nebraska (north-central USA). To counter soil erosion and restore native prairie grassland species, this study evaluated various warm-season grass mixtures, seeding rates, tillage to control weeds, planting depths and irrigation, on grass establishment at a site on a terrace of the Middle Loup River (Custer County).
An abandoned center-pivot cropland sitewas divided into two blocks based on soil type. Each block (38 ha) was divided, and tillage (single disking on 6 May 1982) or no-till randomly assigned.
Within each block, tillage and irrigation level (water applied 14 July, 19 July and 5 August 1982, total application 0, 2 and 4 cm) combinations were established in plots (8 x 18 m) to evaluate establishment of three seed mixtures (6, 4 or 2 species) at two drill seeding rates (‘normal’ - 23.2 PLS/m²; or ‘reduced’ - 14.0 PLS/m²) on 23 May 1982 (row spacing 25 cm; planting depth 2.5 cm).
Grasses sown (and mix in which present) were: little bluestem Schizachyrium scoparium (6,4),prairie sandreed Calomovilfa longifolia (6,4), sand bluestem Andropogon gerardii var. paucipilus [Syn: A.hallii] (6,4), sand lovegrass Eragrostis trichodes (6,4,2), indiangrass Sorghastrum nutans (6)and switchgrass Panicum virgatum (6,2).
A second trial was undertaken to evaluate effect of soil depth bands (with and without) during seeding using the 6-species mix (at 21 PLS/0.l m²) seeded in late May 1982.
Seedling density was recorded in September 1982 and August 1983 in sample quadrats.
Above-average precipitation undoubtedly reduced the importance of irrigation within the first few weeks of seeding, and although irrigation generally increased initial seedling density but this was not apparent the following year.
The 6- and 4-species mixes established better than the 2-species mix (primarily due to the large proportion of switchgrass which had poor establishment).
In the first trial in tillage plots, the reduced seeding rate resulted in better establishment (1.1 seedlings/0.1m²) than the recommended normal rate (0.7). Neither rate provided the acceptable standard of establishment (i.e. >0.5 seedlings/0.1 m²) in the no-till plots.
In the second trial, tillage plots also had higher seedling density (1.3/0.1 m²) than no-till (0.5). Density was doubled with depth bands (1.2 vs. 0.6 seedlings/0.1m²).
The results suggest that a tilled seedbed with adequate moisture achieves successful warm-season grass establishment when using a 4+ species grass mix (at a reduced seeding rate) seeding with machinery with depth bands.
If using or referring to this published study, please read and quote the original paper, this can be viewed at: https://www.uair.arizona.edu/holdings/journal/issue?r=http://jrm.library.arizona.edu/Volume42/Number3/