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Title: SPATIAL VARIABILITY AND RELATIONSHIPS AMONG SOIL AND FORAGE TRAITS IN A PERENNIAL COOL-SEASON GRASS PASTURE

Author
item RADFORD, AMY - RCC, EL RENO, OK
item Mackown, Charles
item SLAGELL-GOSSEN, REONNA - RCC, EL RENO, OK
item Northup, Brian

Submitted to: Oklahoma Academy of Science Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 12/10/2004
Publication Date: 12/25/2004
Citation: Radford, A.R., Mackown, C.T., Slagell-Gossen, R., Northup, B.K. 2004. Spatial variability and relationships among soil and forage traits in a perennial cool-season grass pasture. Proceedings of the Oklahoma Academy of Science. 84:88.

Interpretive Summary: Abstract Only.

Technical Abstract: Manska intermediate wheatgrass [Thinopyrum intermedium (Host) Barkw. and Dewey], a perennial cool-season grass, is a promising alternative to annual winter wheat (Triticum aestivum L.) pasture for stockers in the southern Great Plains. Selected soil traits measured before the onset of grazing may be useful to assure sustained productivity of high quality forage from Manska pastures. To assess relationships between soil and forage traits, samples in a 2-ha paddock were collected from 208 points distributed in a modified grid pattern with most spaced 5-m apart in eight rows spaced 10- to 15-m apart. Although most soil traits were poorly correlated with those of plants, soil-to-soil trait relationships could be established. Mehlich III extractable P (27-140 mg/kg) and pH (4.9-7.2) at the 0- to 10-cm depth were moderately correlated and both were correlated to elevation. Also, amounts of total soil N (7-26 kg/ha) and soil C (27-140 kg/ha) at the 0- to 10-cm depth were strongly correlated (r=0.90; P<0.001) and relatively more uniform (CV=14 and 15%, respectively) among traits. Biomass was normally distributed and ranged from 470-6800 kg/ha (avg.=2700 kg/ha; CV=42%), but nitrate-N had a log normal distribution and varied from 8 to 3200 kg/ha (avg.=550 kg/ha; CV=91%). Biomass and N uptake were strongly associated (r=0.95; P<0.001) with total available N ranging from 32 to 297 kg/ha (avg.=103 kg/ha; CV=39%). Similarities in spatial distribution patterns among soil and forage traits reveal opportunities to modify management practices to improve forage biomass and composition.