Time and Rate of Fertilizer Application for Seeded Warm‐season and Bluegrass Pastures. I. Yield and Botanical Composition¹

Abstract

Field studies were initiated in 1971 and continued through 1974 to evaluate the influence of time and rate of fertilizer application for both seeded warm‐season and bluegrass (Poa pratensis L.) pastures. The warm‐season pastures consisted of a mixture of big bluestem (Andropogon gerardi Vitman), switchgrass (Panicum virgatum L.), indiangrass (Sorghastrum nutans L.) and sideoats grama (Bouteloua curtipendula L.). Prior studies had shown that fertilization would increase production of several forage species. Yet results were often conflicting and influence of time of fertilizer application had not been investigated. Rates of fertilization ranged from 0 to 180 kg N/ha and from 0 to 34 kg P/ha. Fertilizer was broadcast in both early and late spring on established stands on Crofton silt loam, a Typic Usthorthert. Applications were repeated each year. The relationship between yields of the bluegrass to rate of applied N and P was linear in each year of the study. Higher yields were recorded when fertilizer was applied in early (15 April) compared to late (30 May) spring. For the warm‐season grasses, the relationship of yields to rate of N application was linear in 1971 and 1972 but was curvilinear in 1973 and 1974. Yields were linearly related to rate of P applied in all years except 1972. Botanical composition of the warm‐season grass mixture was influenced by time of fertilization. Early spring application encouraged encroachment by cool‐season species, intermediate wheatgrass (Agropyron intermedium Host.), which dominated the stand after 2 years of fertilization. Application of N rates less than 90 kg/ha in late spring did not result in encroachment. At the lower N rates, higher yields of warm‐season grasses were observed when fertilizer was applied in late spring.

Biomass Yield and Nutrient Responses of Switchgrass to Phosphorus Application

“…Similar increases in switchgrass forage yield in response to P fertilization have been reported elsewhere [19][20][21] and also in greenhouse studies [23]. A 22% increase in forage yield in response to 90 kg Pha −1 was reported for four warm-season grasses: bermudagrass (C. dactylon L.), weeping lovegrass [Eragrostis curvula (Schreb.)…”

“…Despite presence of data showing P fertilizer response of switchgrass grown for forage in low P soils [19][20][21][22] and in greenhouse studies [23], there is a paucity of information on the effects of P on biomass yields of switchgrass harvested after frost for bioenergy. Therefore, experiments were conducted from 2008 to 2010 at two locations in southern Oklahoma to evaluate how P fertilizer rates affect switchgrass on P-deficient soils in the Great Plains.…”

Atrazine and Fertilizer Effects on Sandhills Subirrigated Meadow

“…The purpose of the fertilizer treatments was to stimulate the dominant vegetation so that yields of a cool-season system could be compared to yields of the warm-season system. The warm-season plots (atrazine-treated) and the cool-season plots (untreated) were each fertilized at the optimum time (Rehm et al 1976). The field plot design was a split plot.…”

Managing and enhancing switchgrass as a bioenergy feedstock

“…28 However, research in Nebraska suggested switchgrass may respond to applied P if P availability in the soil is low. 29,30 Th e response of switchgrass to other mineral elements is largely uninvestigated and remains a major research need in most areas where switchgrass potentially will be grown as a bioenergy crop.…”