Nitrogen and Harvest Frequency Effect on Yield and Cost for Four Perennial Grasses

Abstract

A USDOE and USDA study concluded that more than 20 million U.S. hectares of cropland, idle cropland, and cropland pasture could be converted from current uses to the production of perennial grasses from which biomass could be harvested for use as biorefi nery feedstock. Th is study was conducted to determine the most effi cient species, level of N, and harvest frequency from among four perennial grass species {'Midland 99' bermudagrass [Cynodon dactylon (L.) Pers.], 'Carostan' fl accidgrass (Pennisetum fl accidum Griseb.), 'SL 93-3' (a selection from 'Alamo') switchgrass (Panicum virgatum L.), and weeping lovegrass [Eragrostis curvula (Schrad.) Nees]}. Each species was established in 2002 on a Kirkland silt loam soil near Stillwater, OK. Treatments in postestablishment years consisted of four N fertilization levels (34, 67, 134, and 269 kg ha −1 yr −1 ) and two harvest systems (once year −1 in October, and twice year −1 in July and October). Plots were harvested in 2003, 2004, and 2005. For bermudagrass, fl accidgrass, and lovegrass, the greatest biomass yield year −1 was produced from plots harvested twice year −1 . Switchgrass produced signifi cantly more biomass than the other three species. Biomass yield to N response functions were estimated for switchgrass. For most biomass price and N price combinations, the optimal strategy is to establish switchgrass, and in postestablishment years, to fertilize with 65 kg N ha −1 yr −1 and harvest once year −1 aft er senescence.

Biomass Yield of Warm‐Season Grasses Affected by Nitrogen and Harvest Management

“…Furthermore, at all the N responsive sites application of N at 67 or 101 kg ha -1 produced superior yields (5.8-11.1 Mg ha -1 ) compared to 34 kg N ha -1 and non-fertilized plots (3.5-8.6 Mg ha -1 ). Except for the two sites in De Witt in 2015, this observation is in accordance with an indication of a yield plateau of switchgrass biomass yield with an application of N at 67 kg ha -1 as reported by Haque et al (2009).…”

Yield, Yield Distribution, and Forage Quality of Warm-Season Perennial Grasses Grown for Pasture or Biofuel in the Southern Great Plains

“…"Alamo" switchgrass exhibited higher yields at the May harvest in both years of the study compared to other grasses (Tables 2 and 3). "Alamo" switchgrass has also been found to be among the highest yielding grasses in other studies in Oklahoma and Kansas [17,18]. "Alamo" has performed well in both one-and two-cut systems across multiple locations in the Southeast and out yielding upland types as well as the lowland type, "Kanlow" [19].…”

Economic Feasibility of Using Switchgrass Pasture to Produce Beef Cattle Gain and Bioenergy Feedstock

“…Cost of harvest activities (mowing, raking, baling into large (561 kg) round bales and hauling and stacking) were included in the annual budget for the no-graze feedstock only (NG/F) and for three graze plus feedstock systems (GL/F, GM/F, and GH/F). Cost of mowing and raking does not vary between systems as it is estimated on a per hectare basis; however, the cost of baling, hauling, and stacking varies between systems as it is a function of yield [11,26]. A custom rate of $34.86 ha −1 was used for the cost associated with mowing post-grazing forage regrowth in the budgets for the three graze-only systems.…”