Nitrogen Management for Forage Production from Endophyte‐Free Tall Fescue Grown on Claypan Soil

Abstract

Core Ideas Better N management may be required for endophyte‐free fescue forage production. Knifed N may result in greater fescue yield and N uptake, especially when fall applied. Tall fescue yield increases were diminished as N rate approached 150 lb/acre. Average N uptake by fescue was linear to N rate, with ∼25% apparent recovery. Nitrogen fertilizer management affects forage production of tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.], but data are limited regarding yield and N uptake of endophyte‐free tall fescue on claypan soil of the eastern Great Plains. A 3‐yr study was conducted to determine the effects of N fertilizer timing (late fall or late winter), N placement (surface broadcast, spoke [point injection at 3‐inch depth], and knife [subsurface band at 4‐inch depth]), and N rate (0, 50, 100, 150, and 200 lb/acre) on endophyte‐free tall fescue yield and N uptake. Each harvest (E2, R4, and stubble hay) was taken from individual, nonoverlapping subareas in each plot. In Year 1, subsurface placement (knife or spoke) increased yield by up to 34% above N broadcast. In Year 2, applying N in late winter instead of late fall resulted in greater E2 and R4 yields. In Year 3, broadcasting N in late winter or knifing N in late fall improved R4 hay yield, whereas stubble hay yield was >10% greater with knifing because average agronomic N use efficiency was >30% greater. Forage yield increased with low N rates, but the response diminished or plateaued as rates approached 150 lb N/acre. Nitrogen uptake in the R4 and stubble hay harvests, however, increased linearly with N rate, averaging 26 and 23% apparent N recovery, respectively. Nitrogen management for endophyte‐free tall fescue may be complex and variable by year, but yield and N uptake may be increased with knife applications, especially when fall applied.

Nitrogen fertilization for hay and seed from endophyte‐free and endophyte‐infected tall fescue

“…Sweeney et al. (2017) found that timing only affected R4 yield in 1 yr of 3. In this study, the average N concentration of the R4 hay harvest was approximately 6% greater when 100% of N was applied in late winter (14.0 g kg −1 ) than when N was 100% applied in late fall (13.1 g kg −1 ) or split between late fall and late winter (13.2 g kg −1 ) (data not shown).…”

“…Estimates of grazing potential of established tall fescue were improved with N fertilization in the fall, but normal May harvest was greater with late winter fertilization (Sweeney & Moyer, 2014). Endophyte‐free tall fescue May harvests were generally increased by late winter N applications, especially when broadcast (Sweeney, Moyer, & Farney, 2017). Even though fescue seed production in Canada did not appear to be affected by time of application (Fairey & Lefkovitch, 1998; Fairey & Lefkovitch, 2000), in Kansas seed production was greatest with late fall application, especially at greater N rates (Sweeney & Moyer, 2017; Sweeney & Moyer, 2018).…”

Nitrogen Management to Improve Nutritive Value of Endophyte‐Free Tall Fescue Grown on Claypan Soil

“…Percent crude protein increases with N rate were maximized with late winter and knife application whereas, late‐fall N fertilization increased the amounts of fiber in both R4 and stubble hays. Thus, knife application of N or fertilizing in late winter may not only improve yields (Sweeney et al, 2017), but also forage nutritive value of endophyte‐free tall fescue cut for hay at R4. However, fertilizing in late fall for maximum seed production (Sweeney and Moyer, 2017) may result in poor forage nutritive value in stubble hay that remains after seed harvest.…”

“…Crude protein was calculated by multiplying the percent N by 6.25, and relative feed value (RFV) was calculated from NDF and ADF values (Jeranyama and Garcia, 2004). Measured nutritive value variables were statistically analyzed using the MIXED, REG, and NLIN procedures of SAS as described for yield responses in Sweeney et al (2017). Table 1 presents regression equations for individual graphs presented in Fig.…”

“…The experiment was conducted from 1999 through 2001 at the Southeast Agricultural Research Center in Parsons, KS on established, verified endophyte‐free ‘Kentucky 31’ tall fescue (Sweeney and Moyer, 2017; Sweeney et al, 2017) grown on a claypan soil. Treatment descriptions are summarized here for the reader's benefit; more experimental details are available in Sweeney and Moyer (2017) and Sweeney et al (2017).…”