Agronomy Journal Grow Your Career With ASA
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Published in Agron J 91:796-801 (1999)
© 1999 American Society of Agronomy
677 S. Segoe Rd., Madison, WI 53711 USA
This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF) Free
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Web of Science (4)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Pedreira, C. G.S.
Right arrow Articles by Mislevy, P.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Pedreira, C. G.S.
Right arrow Articles by Mislevy, P.
Agricola
Right arrow Articles by Pedreira, C. G.S.
Right arrow Articles by Mislevy, P.
Related Collections
Right arrow Forage Management
Right arrow Other Forage Crops
Right arrow Plant Nutrition
Agronomy Journal 91:796-801 (1999)
© 1999 American Society of Agronomy

FORAGE & GRAZING MANAGEMENT

Productivity and Nutritive Value of `Florakirk' Bermudagrass as Affected by Grazing Management

Carlos G.S. Pedreiraa, Lynn E. Sollenbergerb and Paul Mislevyc

a Dep. Zootecnia Ruminantes, Escola Superior de Agricultura "Luiz de Queiroz", Univ. de São Paulo (ESALQ-USP), Caixa Postal 9, Piracicaba, SP 13418-900, Brazil
b Dep. of Agronomy, P.O. Box 110300, Univ. of Florida, Gainesville, FL 32611-0300 USA
c Range Cattle Res. & Educ. Ctr., Univ. of Florida, Ona, FL, 33865 USA

les{at}gnv.ifas.ufl.edu


   ABSTRACT
TOP
 NOTES
 ABSTRACT
INTRODUCTION
 Materials and methods
 Results and discussion
 Conclusion
 REFERENCES
 
`Florakirk' bermudagrass [Cynodon dactylon (L.) Pers.] is a recently released cultivar for the lower southeastern USA, but its evaluation under grazing has been limited to southern Florida. Herbage accumulation, crude protein (CP), and in vitro digestible organic matter (IVDOM) responses of Florakirk to grazing management were studied in 1993 and 1994 on a sandy, siliceous, hyperthermic Ultic Haplaquod in northern Florida. Treatments were replicated twice in a randomized block design and consisted of all combinations of three lengths of grazing cycle (GC) (7, 21, and 35 d) and three postgraze stubble heights (SH) (8, 16, and 24 cm). Actual grazing periods were from 1 to 12 h. Herbage accumulation ranged from 6.9 to 17 Mg ha-1 and was maximized when pastures were grazed to a 24-cm SH every 7 d in 1993, and to 24 cm every 35 d in 1994. Lowest herbage accumulation occurred when pastures were grazed to an 8-cm SH every 21 d. Treatment combinations involving GC 7 were associated with high herbage accumulation in both years of the study. Nutritive value varied relatively little across the range of treatments imposed. Crude protein concentration ranged from 96 to 113 g kg-1 in 1993 and from 121 to 134 g kg-1 in 1994. Lower CP was associated with longer GCs in both years. In vitro digestible organic matter concentration was greatest at short SHs for all but the shortest GCs in 1993 and was greatest at intermediate GCs in 1994. Florakirk herbage accumulation was affected primarily by SH, and nutritive value was affected primarily by GC. Grazing to a SH of approximately 20 cm every 14 d is predicted by regression models to result in near maximum levels of both herbage accumulation and nutritive value.

Abbreviations: CP, crude protein • GC, grazing cycle • IVDOM, in vitro digestible organic matter • LAI, leaf area index • SH, stubble height


   INTRODUCTION
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
Materials and methods
 Results and discussion
 Conclusion
 REFERENCES
 
WARM-SEASON PERENNIAL GRASS PASTURES are key to cattle (Bos spp.) operations in the lower southeastern USA. Evaluation of new cultivars under a range of grazing strategies allows development of optimal management for their use in the region.

Florakirk (F1 hybrid between `Callie' and `Tifton 44' bermudagrasses) was developed by G.W. Burton at the Coastal Plain Experiment Station in Tifton, GA. It has been evaluated under clipping and grazing in southern Florida as experimental line 35-3 (sometimes called Tifton 35-3 or Callie hybrid 35-3) since 1979 and was released by the Florida Agricultural Experiment Station in 1994 (Mislevy et al., 1995). Another hybrid from the same cross was evaluated as line 35-4 and released as `Tifton 78' because it appeared to have greater rust resistance and lower HCN concentration than 35-3 at the Tifton location (Burton and Monson, 1988).

Tifton 78 is not well adapted to the Florida environment. Adjei et al. (1989) reported poor performance of Tifton 78 and concluded that it was slow to establish and not competitive against weeds during the establishment phase. In the same study, herbage accumulation of Florakirk was superior to Tifton 78, averaging 11.9 Mg ha-1 across grazing frequencies of 2 to 8 wk. Concentration of CP in Florakirk herbage was 152 (2 wk), 100 (4 wk), 91 (6 wk), and 69 g kg-1 (8 wk). Within a grazing frequency, CP was similar to or greater than that of the other warm-season perennial grasses evaluated. In vitro digestible organic matter concentration of Florakirk was similar to that of Tifton 78 at all grazing frequencies, but Florakirk showed the steepest decline of all grasses tested as intervals between grazing events increased from 2 to 8 wk (630 to 440 g kg-1). This was similar to a trend observed by Mislevy et al. (1988).

In several locations in north and north central Florida, Florakirk has been compared under clipping management with commercial bermudagrass cultivars including `Coastal', `Coastcross-1', `Alicia', and Tifton 44 (Mislevy et al., 1995). Productivity and nutritive value responses were equal to or better than those of the other cultivars in most cases. Data are lacking, however, on the responses of Florakirk to grazing management in environments like northern Florida, where frosts and freezes can occur frequently during winter.

Our objective was to evaluate the performance of Florakirk bermudagrass pastures under a range of grazing management treatments in northern Florida. Specific objectives were to measure herbage accumulation and forage nutritive value of Florakirk pastures grazed at different intervals and to different postgraze stubble heights.


   Materials and methods
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
 Materials and methods
Results and discussion
 Conclusion
 REFERENCES
 
The study was conducted in 1993 and 1994 at the University of Florida Beef Research Unit, 18 km northeast of Gainesville (29°43' N, 82°16' W). Florakirk bermudagrass pastures had been established in July 1992 and were not grazed or cut in 1992. The soil at the site is a Pomona sand (sandy, siliceous, hyperthermic Ultic Haplaquod), typically low in fertility and with moderate to poor drainage. It has an impermeable layer (hardpan) about 50 to 80 cm below the soil surface; standing water may occur during the summer rainy season. Average (1993 and 1994) soil pH was 5.5, and Mehlich I extractable P, K, Mg, and Ca concentrations were 4, 6, 36, and 372 mg kg-1, respectively. Monthly rainfall totals for the two years of experimentation are shown in Table 1 .


View this table:
[in this window]
[in a new window]
  		Table 1 Monthly rainfall totals at the research site near Gainesville, FL, and monthly average daily temperatures at Gainesville

 
Responses of plants to grazing were measured using a mob-grazing technique (Mislevy et al., 1983). Treatments included all possible combinations of three grazing cycles (GC of 7, 21, and 35 d) and three postgraze stubble heights (SH of 8, 16, and 24 cm) and were arranged in a randomized complete block design with two replications. Pasture size was 10 by 20 m. A grazing cycle consisted of a grazing period (1–12 h) plus a rest period between grazings. Each year, grazing commenced on a given pasture when average sward height was approximately 16 cm above the assigned stubble height. Grazing seasons were from 14 June to 11 Oct. 1993 (126 d) and from 16 May to 17 Oct. 1994 (161 d). Grazing was initiated later in 1993, due to late spring drought. Crossbred (B. taurus x B. indicus) 350-kg yearling beef heifers were assigned to a pasture; grazing was monitored until the stubble height was reached (based on mean of 15 height measurements per pasture), when the animals were removed.

Residue from 1992 growth was burned in March 1993, and in April all pastures were fertilized with 45, 20, and 74 kg ha-1 of N, P, and K, respectively. Rates of P and K used were based on soil test recommendations for improved perennial grass pasture. Pastures received 56 kg N ha-1 as NH4NO3 on 2 June, 21 July, and 1 Sept. 1993. Fifty millimeters of irrigation water was applied on 11 August and 25 mm on 18 August in 1993, because rainfall had been poorly distributed and below average during spring and summer (Table 1). Before grazing started in 1994, pastures were clipped to 10 cm, to remove frosted residue from the previous winter. Fertilization with 45, 20, and 74 kg ha-1 of N, P, and K, respectively, was done on 6 April. Nitrogen was applied at 56 kg ha-1 as NH4NO3 on 11 May, 13 July, and 23 August.

Pastures were sampled to determine herbage mass before and after each grazing, except for GC 7 treatments, which were sampled every 3 wk. Herbage mass was measured using double sampling. At each sampling date, four 0.25-m2 sites per pasture, representing the range of herbage mass, were selected and measured with a disk meter (Santillan et al., 1979). The herbage at the four sites was then clipped at soil level and dried at 60°C in a forced-air dryer to constant weight. The disk meter was also dropped at 30 additional sites within the pasture in a systematic fashion. The same procedure was repeated after grazing. At the end of each grazing season, a calibration equation was developed by regressing herbage mass on disk height using data from all pastures on all dates. The average of the 30 disk heights per pasture was calculated and herbage mass was estimated using the calibration equation. A single equation was used in 1993 and two were used in 1994 (one for GC 7, another for GC 21 and GC 35). Prediction equations had r2 values of 0.745 in 1993, and 0.746 (for GC 7) and 0.591 (for GC 21 and GC 35) in 1994.

Herbage accumulation during a rest period was calculated by subtracting postgraze herbage mass of the previous grazing cycle from pregraze herbage mass of the current cycle. Seasonal herbage accumulation was calculated by adding Cycle 1 pregraze herbage mass and the herbage accumulation values over the remainder of the grazing season for each pasture. For GC 7 pastures, sampling for herbage mass was done every 21 d, although they were grazed weekly to their assigned stubble height. Four caged exclosures in each of these pastures were used to measure herbage accumulation. In these pastures, there was no pregraze herbage mass sampling. After grazing, herbage mass on the pasture as a whole was determined using double sampling, and the herbage inside the four cages (0.25 m2 per cage) was clipped to soil level, dried at 60°C, and weighed. Four new sites for cages were then chosen where stubble height represented that of the pasture. Three weeks later, the same sampling procedure was repeated. Herbage accumulation over the 3-wk period was calculated as the difference between herbage mass inside the cages and herbage mass on the pasture 3 wk earlier.

In order to assess the effects of treatments on forage nutritive value, hand-plucked samples were clipped pregraze to the height of the target stubble height on each sampling date. Within a pasture, 20 samples were cut to make a 200-g fresh weight composite sample. These samples were dried at 60°C in a forced-air dryer to constant weight and ground in a Wiley mill to pass a 1-mm stainless steel screen. Nitrogen concentration was measured using a modification of the aluminum block digestion technique (Gallaher et al., 1975); NH3 in the digestate was determined by semiautomated colorimetry (Hambleton, 1977). Concentration of CP in herbage dry matter was calculated as N x 6.25. In vitro digestible organic matter concentration was determined by the two-stage procedure of Tilley and Terry (1963) modified by Moore and Mott (1974); neutral-detergent fiber determination followed the procedure described by Golding et al. (1985).

To determine the effects of grazing cycle and stubble height across years, data were analyzed using the General Linear Models procedure (PROC GLM) of the Statistical Analysis System software package (SAS Inst., 1989). In this analysis, the grazing treatment combination (GC–SH) was the main plot and year was the subplot in a split-plot arrangement. Interactions with year were numerous, so data are reported by year. Within years, data were analyzed using the Response Surface Regression procedure (PROC RSREG) of SAS (SAS Inst., 1989). This procedure tests for fitness of a second-order polynomial regression model of the form , where y is the response variable, ß0 is the intercept, ß1 is the linear coefficient for GC, ß2 is the linear coefficient for SH, ß3 is the quadratic coefficient for GC, ß4 is the quadratic coefficient for SH, ß5 is the interaction or cross-product coefficient for GC and SH, and {epsilon} is the experimental error term.

The second-order polynomial model was also tested for lack of fit. Reduced models were fitted with the coefficient estimates that showed a significant effect in the full model (P <= 0.10), and PROC GLM was used to test for significance (P <= 0.10) of the coefficient estimates in the reduced models. Terms that were not significant in the full model were included in the reduced model when higher-order terms were significant. For example, when there was a GC x SH interaction, the linear effects of both GC and SH were included in the model, regardless of their level of probability. Likewise, the linear effect of a factor was included when the quadratic effect of that factor was significant. The response surfaces generated are shown as two-dimensional projections on a plane surface (contour plots). When only one factor affected the response, line graphs are used. Coefficient estimates, probability levels for effects of experimental variables and their interactions, and coefficients of determination associated with each fitted model are listed in Table 2 . The P(|t| > t{alpha}) = {alpha} values are for effects in the reduced model.


View this table:
[in this window]
[in a new window]
  		Table 2 Coefficient estimates for the fitted regression models. Estimated response = b0 + b1 (GC) + b2 (SH) + b3 (GC)2 + b4 (SH)2 + b5 (GC x SH), or a reduced form of the model for responses reported.{dagger}

 

   Results and discussion
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
 Materials and methods
 Results and discussion
Conclusion
 REFERENCES
 
Herbage Accumulation
Lower herbage accumulation for 1993 than for 1994 (Fig. 1) was primarily related to drier than normal weather in May through July 1993 (Table 1), which resulted in drought stress and a shorter grazing season that year. In both years, herbage accumulation increased with increasing stubble height, while the intermediate grazing cycles tended to give lowest seasonal herbage accumulation. In 1993, all terms of the second-order polynomial were included in the reduced model except the quadratic effect of stubble height. Highest herbage accumulation (13.1 Mg ha-1) was observed for the GC 7-SH 24 combination, while lowest herbage accumulation (6.9 Mg ha-1) was measured for the GC 21–SH 8 treatment. In 1993, interaction occurred because increasing postgraze stubble height increased herbage accumulation more rapidly when the grazing cycle was 7 d than when it was longer. There was no GC x SH interaction in 1994 (Fig. 1). Herbage accumulation predicted by the regression model in 1994 exceeded 16 Mg ha-1 for GC 7–SH 24 and GC 35–SH 24 treatments; it was at a maximum for the GC 35–SH 24 treatment (17 Mg ha-1). Lowest herbage accumulation for a given stubble height in 1994 was observed around GC 21. For SH 16, for example, herbage accumulation was 14.4 Mg ha-1 for GC 7, decreased to 13 Mg ha-1 for GC 21, and increased to 15.2 Mg ha-1 for GC 35. All treatments maintained greater than 96% Florakirk in pregraze herbage mass throughout the experiment.



View larger version (26K):
[in this window]
[in a new window]
  		Fig. 1 Florakirk bermudagrass herbage accumulation (Mg ha-1) in 1993 and 1994 as affected by length of grazing cycle (GC) and postgraze stubble height (SH). Surface contours were generated using Models HA-1993 and HA-1994 (see Table 2)

 
In the current study, lowest seasonal herbage accumulation occurred in both years when stubble height was 8 cm and the grazing cycle was approximately 21 d. Morgan and Brown (1983a, 1983b) measured Coastal bermudagrass herbage accumulation of 2.0 and 0.83 kg m2 for plots mowed monthly and weekly over a 96-d period, respectively. The canopy of the treatment mowed monthly developed a high LAI during a longer regrowth period, which allowed for greater interception of incident solar radiation, a higher proportion of young, photosynthetically active tissue, and higher canopy photosynthesis rates. In contrast, the LAI of swards mowed weekly never reached optimum, because defoliation generally occurred at LAI {approx} 3 and reduced it to an average of 1.4. In addition, accumulation of dead material occurred below mowing height in weekly-mowed swards.

Unlike the responses observed for Coastal by Morgan and Brown (1983a, 1983b), Florakirk herbage accumulation was consistently greater when the grazing cycle was 7 d than when it was 21 d for a given level of stubble height. For frequently and closely grazed swards, it is likely that the Florakirk canopy had a higher tiller density (not measured) and thus was more efficient in intercepting incoming radiation than when grazing cycle was intermediate (e.g., 21 d). Stimulation of tillering by increased grazing intensity has been documented by several authors (e.g., Langer, 1963; Jewiss, 1972; Kays and Harper, 1974). Matthew et al. (1995) and Sackville Hamilton et al. (1995) have described this response as the "-3/2 self-thinning rule." According to those authors, in response to increasing defoliation intensity, reduced tiller weight is compensated by increased tiller population density. Binnie and Chestnutt (1991) found evidence of an increase in tiller number when they reduced the regrowth interval of perennial ryegrass (Lolium perenne L. cv. Talbot) from 4 to 3 wk. In the mob-grazing trial reported here, pastures grazed every 7 d to 8 cm appeared on visual examination to have greater ground coverage, with plants growing more prostrate, almost turf-like, and probably with more tillers per unit area. In this situation, the continuous emergence of new tillers may have contributed substantially to interception of a high proportion of light by young, photosynthetically active tissue and thus increased C assimilation via photosynthesis. Hodgson (1990) explained that the decline in the rate of net C assimilation with defoliation is not as great on continuously stocked or very frequently cut swards as it is on less frequently swards cut or grazed swards. He attributes this response to high tiller populations and large numbers of young leaves which, because they have developed in bright light, have a high photosynthetic potential.

As the grazing cycle increased from 7 to 21 d in the current study, there was probably less stimulus to tillering. Carbon uptake per unit land area may therefore have been reduced, resulting in lower herbage accumulation when the grazing cycle was 21 d. Increased herbage accumulation when the grazing cycle was increased to 35 d is probably related to optimization of LAI. In other words, tiller density was probably lower than in GC 7 treatments, but the longer regrowth interval afforded the plants time to increase LAI and grow for an extended period at optimal LAI. The proportion of leaf tissue removed by grazing may have been greatest for GC 21 treatments, because stimulation of basal tillering and the development of leaf area close to soil surface was not as great as in GC 7 plots and, at the same time, there was not as much time for leaf development as in GC 35 treatments.

In addition to the physiological mechanisms already described, the cage technique used to quantify herbage accumulation in this study may have contributed in part to higher herbage accumulation for GC 7. On these pastures, herbage accumulation was measured in caged areas and the cages were rotated every 21 d. This length of time was necessary to avoid clipping a large proportion of the pasture area over the course of the season, something that would have occurred with weekly sampling. Inflated herbage accumulation within cages was reported by Cowlishaw (1951) and Heady (1957), and explained on the basis of a modified environment within the cage, including increased humidity, decreased wind velocity, and lower transpiration losses. In addition, plants inside cages probably benefited from greater leaf area than those outside during the 3-wk exclusion period (Heady, 1957) and there was no damage by animal treading or fouling within the caged exclosure (Cowlishaw, 1951).

The increase in herbage accumulation associated with increasing stubble height has been addressed by Parsons (1988). He explained that, in swards maintained at high LAI (i.e., taller swards), high rates of respiration result from the greater gross photosynthesis and the greater weight of live tissue to be maintained. Although the absolute amount of dry matter lost in respiration is greater in swards of high rather than low LAI, in both cases the proportion of gross photosynthesis consumed by this route is the same (about 45%) (Parsons et al., 1983). This means that, in effect, shaded leaves respire less than illuminated leaves and, as a result, the gross rate of shoot production is greater in a sward maintained at a high LAI than in a sward maintained at a low LAI (Parsons, 1988).

Herbage Nutritive Value of Hand-Plucked Samples
Range in herbage CP and IVDOM was relatively small, but both were affected by grazing treatment. Crude protein concentration was not affected by stubble height in either year (P > 0.20 in 1993; P > 0.57 in 1994), but there were linear and quadratic effects of grazing cycle in both years (Fig. 2) . From short (7 d) to intermediate (21 d) levels of grazing cycle, there was a slight increase in CP. This was followed by a decline in CP concentration reaching a minimum at GC 35. Even so, the range in herbage CP concentration was less than 18 g kg-1 in both years (96 to 113 g kg-1 in 1993 and 124 to 133 g kg-1 in 1994). Figure 2 shows that the maximum CP concentration is predicted to occur when the grazing cycle is less than 21 d, regardless of the height of the stubble left after grazing.



View larger version (16K):
[in this window]
[in a new window]
  		Fig. 2 Crude protein concentration (g kg-1) in Florakirk bermudagrass herbage in 1993 and 1994 as affected by length of grazing cycle (GC) and postgraze stubble height (SH). Curves were generated using Models CP-1993 and CP-1994 (see Table 2)

 
In 1993, there was a GC x SH interaction affecting IVDOM concentration (Fig. 3) . There was little effect on IVDOM from varying stubble height at GC 7. Increasing stubble height at GC 35, however, caused a decline in IVDOM concentration from a maximum of 650 g kg-1 in the GC 35–SH 8 treatment, to a minimum of 598 g kg-1 in the GC 35–SH 24 treatment. A different response was observed in 1994, when stubble height did not (P > 0.62) affect IVDOM concentration. Similar to CP concentration, there were both linear and quadratic effects of grazing cycle on IVDOM. Intermediate levels of grazing cycle tended to maximize IVDOM, with declines at both ends of the grazing cycle scale. Whereas IVDOM concentration peaked at 592 g kg-1 for GC 21, it was 565 and 569 g kg-1 for GC 7 and GC 35, respectively. Concentration of neutral-detergent fiber in the herbage did not respond to grazing treatments in 1993 or .



View larger version (15K):
[in this window]
[in a new window]
  		Fig. 3 In vitro digestible organic matter (IVDOM) concentration (g kg-1) in Florakirk bermudagrass herbage in 1993 as affected by length of grazing cycle (GC) and postgraze stubble height (SH). Surface contour was generated using Model IVD-1993 (see Table 2)

 
In the current study, lower concentrations of CP and IVDOM were generally associated with longer grazing cycles and, consequently, with older regrowth. Mislevy et al. (1988) and Adjei et al. (1989) reported decreasing CP concentration as the interval between grazings increased for bahiagrass (Paspalum notatum Flügge), limpograss [Hemarthria altissima (Poir.) Stapf. & C.E. Hubb.], stargrass (C. nlemfuënsis Vanderyst var. nlemfuënsis and C. aethiopicus Clayton & Harlan), and bermudagrass. Linear and quadratic effects of plant maturity (represented by GC) were observed in both years of the current study. For Florakirk pastures fertilized with 150 kg N ha-1 yr-1 and grazed to 7.5 cm every 4 wk, Adjei et al. (1989) measured a CP concentration of 100 g kg-1, whereas results of this research predict 108 and 129 g kg-1 for a similar grazing management in 1993 and 1994, respectively (Fig. 2). Also in the study of Adjei et al. (1989), Florakirk bermudagrass IVDOM concentration was 560 g kg-1 when grazed to a 7.5-cm stubble height every 4 wk. Predicted response in the current study for a GC–SH combination of 28 d and 8 cm is about 644 g kg-1 in 1993 and about 587 g kg-1 in 1994 (Fig. 3).

In 1993, there was a GC x SH interaction effect on IVDOM. When the grazing cycle was long, taller stubble heights were detrimental to digestibility, perhaps because a greater proportion of the regrowth was made up of stem, which reduces digestibility. Reduced digestibility of Coastal bermudagrass stem was attributed by Akin et al. (1990) to increased presence of lignified ring tissues when plants are 6 wk old. This effect of stubble height was not observed in the short-GC treatments. This is consistent with the notion that young regrowth present at short grazing cycles, regardless of stubble height, consists mainly of high nutritive value leaf and young stem tissue.


   Conclusion
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
 Materials and methods
 Results and discussion
 Conclusion
REFERENCES
 
Based on the results of this study, we conclude that Florakirk is productive and relatively high in nutritive value under a wide range of grazing treatments. Relatively high herbage accumulation at short grazing cycles, together with a tall stubble height (20–25 cm), suggests that this type of management will allow for high stocking rates and liveweight gains per hectare, although use of cages for measuring herbage accumulation GC 7 may have inflated herbage accumulation values for those treatments. In an animal performance grazing trial, Pedreira and coworkers (unpublished data) have observed occurrence of leaf spot (caused by Helminthosporium spp.) and significant stand loss on continuously stocked pastures of Florakirk grazed to 20 to 25 cm. The relative role of the grazing method and the pathogen in stand loss have not been determined, and this merits further study. Data from the current trial suggest that, if forage nutritive value is to be maximized so as to favor individual animal performance, a rotational stocking system with shorter stubble heights (10–15 cm) and intermediate rest periods (3–5 wk) will provide grazed forage of good digestibility (600 g kg-1 or even higher) and CP concentrations of 100 to 130 g kg-1 (assuming N fertilizer applications of >150 kg N ha-1 yr-1).SAS Institute 1989


   NOTES
TOP
 NOTES
ABSTRACT
 INTRODUCTION
 Materials and methods
 Results and discussion
 Conclusion
 REFERENCES
 
Florida Agric. Exp. Stn. Journal Series no. R-06519.

Received for publication September 11, 1998.
   REFERENCES
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
 Materials and methods
 Results and discussion
 Conclusion
 REFERENCES
 




This article has been cited by other articles:


Home page
 Agron. J.Home page
J. R. Kiniry, B. L. Burson, G. W. Evers, J. R. Williams, H. Sanchez, C. Wade, J. W. Featherston, and J. Greenwade
Coastal Bermudagrass, Bahiagrass, and Native Range Simulation at Diverse Sites in Texas
Agron. J., February 6, 2007; 99(2): 450 - 461.
[Abstract] [Full Text] [PDF]

Home page
 Agron. J.Home page
C. G.S. Pedreira, L. E. Sollenberger, and P. Mislevy
Botanical Composition, Light Interception, and Carbohydrate Reserve Status of Grazed `Florakirk' Bermudagrass
Agron. J., March 1, 2000; 92(2): 194 - 199.
[Abstract] [Full Text]

This Article
Right arrow Abstract Freely available
Right arrow Figures Only
Right arrow Full Text (PDF) Free
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Web of Science (4)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Pedreira, C. G.S.
Right arrow Articles by Mislevy, P.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Pedreira, C. G.S.
Right arrow Articles by Mislevy, P.
Agricola
Right arrow Articles by Pedreira, C. G.S.
Right arrow Articles by Mislevy, P.
Related Collections
Right arrow Forage Management
Right arrow Other Forage Crops
Right arrow Plant Nutrition

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
The SCI Journals Crop Science Vadose Zone Journal
Journal of Natural Resources
and Life Sciences Education		 Soil Science Society of America Journal
Journal of Plant Registrations Journal of
Environmental Quality		 The Plant Genome