Herbage Yield and Chemical Composition of Switchgrass as Affected by N, S, and K Fertilization 1

The nutrient requirements of filegrass (Anthephora ampulacea, Stapf and Hubb), a potential pasture species, is hardly known. A greenhouse experiment was conducted to study the effects of applied N, P, and K fertilizers on its herbage yield and quality. Four rates of N (0, 100, 200 and 300 kg N/ha−1as ammonium sulfate); three rates of P (0, 33, and 66 kg P ha−1as single superphosphate); and three rates of K (0, 62, and 124 kg K ha−1as muriate of potash) were applied in solution in all possible treatment combinations (36 treatments). Plants were first harvested when 50% of the primary tillers were at early anthesis, A second harvest was made after 4 weeks of regrowth. Fertilizer application at 100 kg N/ha−1rate at least doubled filegrass yield (7.4 vs. 14.8 g pot−1for 0 vs. 100 kg N ha−1rates). Higher rates of N application gave further significant yield increases (19.4 and 19.9 g pot−1for 200 and 300 kg N ha−1, respectively). For the regrowth harvest, yields differed significantly such that 0 < 100 < 200 < 300 kg N ha−1. Filegrass response to applied N is represented by the following regression equations Y = 9.2 + 0.05 × (for first harvest) and Y = 1.39 + 0.018 × (for second harvest). Applied P and K fertilizers did not significantly affect the dry matter yields and concentration of other nutrients in both the leaf and stem fractions. Applied N at 100 kg ha−1rate increased N concentration of the leaf fraction but decreased P, Ca, and Mg of the leaf. Higher N rates, however, increased these nutrients in the leaf blade. Nitrogen application, at all rates, increased the stem concentrations of N from 0.49 to 1.20; P from 0.16 to 0.26; K from 0.87 to 1.12; Ca from 0.11 to 0.56 and Mg from 0.06 to 0.19% on dry matter basis. The dry matter digestibility (DMD) values for both leaf and stem fractions were relatively close (62.8 and 53.4%, respectively). The DMD of each fraction was increased by N application from 45.6 to 65.7 in the leaf and stem when the rate was increased from 0 to 300 kg N ha−1. These results were discussed in terms of herbage production and livestock requirements.

Section: Resultssupporting

confidence: 90%

Herbage Yield and Quality of Filegrass as Influenced by N, P, and K Fertilizer Applications¹

Omaliko

1984

“…Reports by several workers suggest that warm-season grasses n:spond to P, K, or S fertilization (6,9,11). In the pn~sent study, no DM yield response was observed for P and K (including S and Mg) fertilization in 1976 even though soil P and K levels were relatively low in the unfertilized plots.…”

Section: Phosphorus and K Fertilizationmentioning

confidence: 61%

Herbage Dry Matter Yields of Switchgrass, Big Bluestem, and Indiangrass with N Fertilization¹

Hall¹,

George²,

Riedl

1982

Herbage dry matter (DM) yield potential and N requirement of native perennial, warm‐season grasses must be known before these species can be effectively used in forage‐livestock systems. This study was initiated to determine the herbage yield response of ‘Blackwell’ switchgrass (Panicum virgatum L.), ‘Kaw’ big bluestem (Andropogon gerardi Vitman), and ‘Nebraska 54’ indiangrass (Sorghastrum nutans L. Nash) to N fertilization. Four replications of a randomized complete block field experiment were established on a Clarion loam (Typic Hapludoll) soil in 1971. A four‐cut management system was used in 1974; a two‐cut system was used during 1975–1976. Applications of ammonium nitrate (34‐0‐0) were made on 21 May 1974 and 13 May 1975 at 0, 75, and 150 kg N/ha levels. Levels of 0, 75, and 150 kg were applied in 1976 as urea (45‐0‐0) on 22 May and again on 3 July after the first harvest. Two of the four replications received 50 kg P/ha as triple superphosphate (0‐46‐0) and 100 kg K/ha as K2SO4 . MgSO4 (0‐0‐22) on 7 May 1976. The K source included 60 kg Mg/ha and 118 kg S/ha. Switchgrass, big bluestem, and indiangrass produced herbage dry matter (DM) yields of 6.14, 6.29, and 5.59 metric tons/ha, respectively, when averaged over N levels and years. In 1974, big bluestem out‐yielded the rest, and in 2 out of 3 years indiangrass yielded significantly less than one or both of the other species. All species generally responded positively to N through 75, and often through 150 kg N/ha. No herbage yield response was observed in 1976 to applied P and K fertilizers, the latter containing both S and Mg. Herbage DM yields generally increased with each of three successive harvests in 1974, whereas second harvest yields decreased with a two‐cut management system used in 1975 and 1976. Relatively unfavorable July–August precipitation seemed primarily responsible for lower second harvest DM yields. A 5 Oct. 1974 harvest of aftermath herbage cut at a 5‐cm height suggests that 2.2 to 2.4 metric tons/ha of herbage would be available for use by nonlactating beef cows. No species difference in DM yield was observed, suggesting equal carrying capacity/ha, for the aftermath.

“…Switchgrass (SG) has received more attention agronomically (8,11,15) than FG, but animal acceptability and animal growth data from SG is limited. In shortterm trials, steers (Bos taurus) grazing SG have averaged about 1 kg day-1 (13) and in vitro estimates have demonstrated acceptable quality provided SG was not overmature (1, 9,10,17).…”

mentioning

confidence: 99%

Intake and Digestibility of Dry Matter and Fiber of Flaccidgrass and Switchgrass¹

Burns¹,

Mochrie²,

Timothy

1985

Subtropical grasses are generally considered of lower nutritive value than temperate grasses. Flaccidgrass (Pennisetum jloccidum Griseb.) and switchgrass (Panicum virgatum L.) are subtropical species with high quality potentials. The objective of this study was to compare dry matter intake and the digestive coefficients for dry matter and several fiber constituents from hays of flaccidgrass (FG) and switchgrass (SG) with 'Coastal' bermudagrass (Cynodon dactylon (L.) Pers.) at similar neutral detergent fiber (NDF) concentrations. Initial growths were harvested as hay at appropriate development stages to obtain forages having similar NDF. Tall fescue (Festuca arundinacea Schreb.) was included to provide comparisons with a temperate species. Hay intakes by eight Holstein heifers were measured in two squares of a 4 by 4 Latin square design. Digestion coefficients were calculated from data obtained during the fourth intake period of each square and were analyzed as a completely random design. The subtropical hays had similar NDF concentrations (0.710 to 0.753 g kg-1 ), but intakes differed. Coastal bermudagrass (CB) intakes of 2.70 kg 100 kg-1 of body weight were followed by FG (2.29) and SG (2.09). Tall fescue (TF) intakes were similar to those for FG (2.25 vs. 2.29 kg 100 kg-1 body weight). Dry matter digestibility of CB averaged only 0.496 compared with the greater but similar coefficients for the other three hays (0.624 g kg-1 ). The digestive coefficients for NDF and constituent acid detergent fiber (ADF) and cellulose were similar for FG, SG, and TF, averaging 0.649, 0.587, and 0.675, respectively, compared with lesser coefficients of 0.486, 0.435, and 0.517 from CB. Hemicellulose digestion was similar for FG and SG (avg 0.741) and appreciably greater than for CB (0.537); whereas, that for TF was intermediate (0.683). The greater digestibility of dry matter and fiber of FG and SG, compared with CB, partially explains the reported greater than expected animal daily performance from these two subtropical species and supports their use in ruminant feeding systems.