||Millions of hectares of pasture in the Northeast have low available soil P levels. Introducing forage species that produce well on these soils could increase forage production with minimum economic input.
The objective of this study was to compare the performance of warm and cool-season grasses under low or high available P. Several warm and cool-season forage grasses were grown on a Berks shaly silt loam
soil (Typic Dystrochrept; fine, loamy, skeletal, mesic), low in native available P (5 ppm Bray and Kurtz #I extractable P), with and without added P. The warm-season grasses included two Old World
bluestems, ‘Caucasian’ Bothriochloa caucasica (Trin.), C. E. Hubh. and “B”-strain, B. intermedia (R. Br.) A. Camus; three big bluestem cultivars, Andropogon gerardi Vitman; three little bluestern cultivars,
Schizachyrium scoparium, Michx.; six switchgrass cultivars, Panicum virgatum L.; and two indiangrass cultivars, Sorghastrurn nutans (L.) Nash. The cool-season grasses were Ky 31 tall fescue, Festuca arundinacea
Schreb., ‘Pennlate’ orchardgrass, Dactylis glomerata L., and ‘Tioga’ deertongue grass, Dichanthelium clandestinum (L.) Gould. Yields of most warm-season grasses nearly doubled from 1977 to
1978, whereas yields of the cool-season grasses decreased. Forage yields and P concentrations of all cultivars generally were greater with applied P both years. At the low P level, warm-season grass
yields in the second year were up to three times higher than yields of cool-season grasses, whereas P concentrations in forage of cool season grasses were twice those of warm-season grasses: The warm season
grasses, Ky 729 and ‘Blackwell’ switchgrass, Ky 2 Caucasian and B-strain Old World bluestems, and NJ 1617-72 indiangrass absorbed more total P than all other cultivars. Warm-season grasses
had relatively low crude protein and IVDMD levels, ranging from 4.7 to 8.5% and 34.0 to 52.3%, respectively. Of the warm-season grasses, Old World bluestems, Caucasian and B-strain, had the highest
IVDMD values, 52.2 and 51.2%. The cool-season grasses had an average crude protein level of 14.6% and IVDMD value of 59.4%, respectively. The two Old World bluestems, Ky 729 and Blackwell
switchgrasses, and NJ 1617-72 indiangrass appear to have the highest potential to produce forage on soils with low levels of available P.