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Published online 25 April 2006
Published in Crop Sci 46:1299-1304 (2006)
© 2006 Crop Science Society of America
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FORAGE & GRAZINGLANDS

Litter Mass, Deposition Rate, and Chemical Composition in Bahiagrass Pastures Managed at Different Intensities

J. C. B. Dubeux, Jr.a, L. E. Sollenbergerb,*, J. M. B. Vendraminic, R. L. Stewart, Jr.d and S. M. Interranteb

a Depto. de Zootecnia/UFRPE, Av. Dom Manoel de Medeiros, S/N, Dois Irmãos, 52171-900, Recife-PE, Brazil
b Agronomy Dep., University of Florida, Gainesville, FL, 32611-0300
c Soil and Crop Science Department, Texas A&M University, Overton, TX 75684
d Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0306

* Corresponding author (lesollenberger{at}ifas.ufl.edu)


   ABSTRACT
TOP
 NOTES
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS
 REFERENCES
 
Plant litter is an important pathway of nutrient return to the soil in grazed swards, but the effects of pasture management on litter mass and composition are not well understood. This research evaluated the effect of management intensity, defined in terms of N fertilization and stocking rate (SR), on litter mass, deposition rate, and chemical composition in continuously stocked ‘Pensacola’ bahiagrass (Paspalum notatum Flügge) pastures growing on Pomona and Smyrna sands. Treatments were three management intensities: Low (40 kg N ha–1 yr–1 and 1.3 animal units [AU, one AU = 500 kg live weight] ha–1 SR), Moderate (120 kg N ha–1 yr–1 and 2.7 AU ha–1 SR), and High (360 kg N ha–1 yr–1 and 4.0 AU ha–1 SR). Greater management intensity resulted in less litter mass on the pasture early in the growing season and more litter mass later in the season. Rate of litter deposition was generally greatest for High and ranged between 23 and 40 kg organic matter (OM) ha–1 d–1 compared with 13 to 30 kg OM ha–1 d–1 for Low and Moderate management intensities. Increasing management intensity from Low to High resulted in greater litter N (14.1 vs. 22.9 g kg–1) and P (0.8 vs. 1.3 g kg–1) concentrations and lesser C:N (~40 vs. 22), C:P (649 vs. 433), and lignin:N (5.8 vs. 4.4) ratios. More intensive pasture management was associated with greater litter deposition rate and litter quality than less intensive management, suggesting a larger nutrient contribution from litter in intensively managed swards.

Abbreviations: ADF, acid detergent fiber • AU, animal units • DM, dry matter • NDF, neutral detergent fiber • OM, organic matter • SE, standard error • SR, stocking rate


   INTRODUCTION
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS
 REFERENCES
 
PLANT LITTER is an important pathway of nutrient return to the soil in grassland ecosystems. In extensively managed and utilized pastures in many warm-climate areas, nutrient dynamics in the plant litter pool have a major influence on pasture productivity and persistence. When compared with nutrients from animal excreta, those from litter are more evenly distributed across the pasture (Rezende et al., 1999), but nutrients in litter are not as readily available to plants (Haynes and Williams, 1993).

Management intensity affects the pathway of nutrient return on pastures. Increasing SR at a given forage growth rate increases the proportion of nutrient returned via excreta compared with litter (Thomas, 1992). The rate of flow of nutrients among nutrient pools increases with greater SR because the nutrients in dung and urine are more readily available than in litter (Haynes and Williams, 1993; Cantarutti and Boddey, 1997). Nitrogen fertilization may also play a role by increasing litter deposition and quality (Beare et al., 2005). Greater litter quality, because of higher nutrient uptake and greater availability of soil nutrients in fertilized systems, may increase litter turnover, resulting in greater nutrient supply to the pasture via litter (Lupwayi and Haque, 1999).

Understanding seasonal patterns of litter mass, deposition, and chemical composition are critical components of effective nutrient management of pastures, but there is a lack of information regarding management intensity effects on litter dynamics, particular in subtropical and tropical environments. Thus, the objective of this study was to determine the effect of management intensity, defined in terms of N fertilization and SR, on litter mass, deposition, and chemical composition in continuously stocked Pensacola bahiagrass pastures.


   MATERIALS AND METHODS
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS AND DISCUSSION
 CONCLUSIONS
 REFERENCES
 
Experimental Site
A grazing experiment was conducted at the University of Florida Beef Research Unit, northeast of Gainesville, FL, at 29°43' N lat on Pensacola bahiagrass pastures that had been established at least 10 yr before initiation of the study. Treatments were imposed during 2001, 2002, and 2003, but litter responses were quantified only in 2002 and 2003. Soils are classified as Spodosols (sandy siliceous, hyperthermic Ultic Alaquods from the Pomona series or sandy siliceous, hyperthermic Aeric Alaquods from the Smyrna series) with average pH of 5.9. Average soil P, K, Ca, and Mg concentrations (Melich-I) at the beginning of the experiment were 5.3, 28, 553, and 98 mg kg–1, respectively.

Treatments and Design
Treatments included three management intensities of continuously stocked bahiagrass pastures. These intensities were defined in terms of combinations of SR and N fertilization and were Low (40 kg N ha–1 yr–1 and 1.2 AU ha–1 target SR), Moderate (120 kg N ha–1 yr–1 and 2.4 AU ha–1 target SR), and High (360 kg N ha–1 yr–1 and 3.6 AU ha–1 target SR). These management intensities were selected because Low approximates average bahiagrass management practice in Florida cow-calf systems, Moderate represents the upper range of current practice, and High is well above what is currently in use. Actual SR obtained was calculated on the basis of initial and final live weights during each grazing season. These SR were 1.4, 2.8, and 4.1 AU ha–1 in 2002, and 1.3, 2.6, and 4.0 AU ha–1 in 2003 for Low, Moderate, and High management intensities, respectively. These values deviated from target values because initial heifer liveweight was greater than anticipated. A randomized complete block design was used and each treatment was replicated twice.

Two crossbred (Angus x Brahman) yearling heifers were assigned to each experimental unit. Pasture area varied according to management intensity, decreasing from 1 to 0.5 to 0.33 ha as the intensity increased from Low to Moderate to High. Artificial shade (3.1 x 3.1 m) was provided on each of the experimental units and cattle had free-choice access to water and a salt-based mineral mixture.

Low management intensity pastures received 40 kg N ha–1 in one application in late April each year. Moderate intensity pastures received 40 kg N ha–1 at each of three dates (late April, mid-July, and mid-August), while High intensity pastures received 90 kg N ha–1 at each of four dates (mid-June in addition to those for Moderate). Phosphorus (17 kg ha–1 yr–1) and potassium (66 kg ha–1 yr–1) were applied to all management intensities with the initial N application each year. There was a second application of the same amount of P (17 kg P ha–1 yr–1) and K (66 kg K ha–1 yr–1) in mid-July 2002 for Moderate and High intensities only. Micronutrients were applied in April 2003 at a rate of 360 g B, 2.7 kg Fe, 3.6 kg Mn, and 1.4 kg Zn ha–1. Sulfur was also applied in April 2002 at a rate of 30 kg S ha–1.

Response Variables
Herbage Mass and Existing and Deposited Litter Mass
Herbage mass was estimated by a double-sampling procedure where disk plate settling height was the indirect measurement. Every 14 d, 30 disk plate readings (0.25-m2 aluminum disk) were taken per experimental unit. The disk plate was calibrated every 28 d by measuring the disk settling height and the actual herbage mass, by hand clipping to soil level, at 18, 0.25-m2 sites (three per pasture). These double sampling sites were chosen across the six experimental units to represent the range of herbage mass in those pastures. From these data, regression equations relating disk settling height to actual herbage mass were obtained and used to predict herbage mass from the average of the 30 disk heights. Coefficients of determination (r2) for these equations ranged from 0.75 to 0.94.

Existing and deposited litter mass were measured on the basis of the technique described by Bruce and Ebersohn (1982) and also used by Thomas and Asakawa (1993) and Rezende et al. (1999). Litter was defined as dead plant material on the surface of the soil, no longer attached to the plant. Existing litter in the pasture was determined at 28-d intervals by sampling six circular quadrats (0.55 m2) in areas that represented the average herbage mass in each pasture. The existing litter contained within each quadrat was raked and collected, dried (72 h at 60°C), and weighed. After clearing the sites of litter, exclusion cages were placed there, and 14 d later the deposited litter within the cleared area was similarly collected, dried, and weighed. To correct for sand contamination, final weights were expressed on an OM basis. While raking the sites to recover either existing or deposited litter, some green material was collected along with the litter. Correction for green herbage was performed by hand separating green material from litter. Every 28 d, six new 0.55-m2 areas were chosen in each pasture for measurement of existing and deposited litter, and this procedure was repeated five times each grazing season. Litter, within litter type (i.e., existing or deposited litter), from the six caged sites per pasture was composited for each evaluation date for subsequent laboratory analyses.

Litter Deposition Rate
Estimation of litter deposition rate used the approach described by Rezende et al. (1999) with some modifications in respect to the use of the rate of decomposition. According to Rezende et al. (1999), the litter on the ground at any time is a function of the litter deposition minus the litter decomposition that occurred within a given period. Therefore, in the case of litter deposited in an area that had been cleared of litter, the quantity of litter (dX) present after the increment of time dt is:

Formula

Formula 1[1]
Where L is the true daily rate of litter deposition in g m–2 d–1; X is the quantity of litter on the ground at any time (g m–2); k is the relative decomposition rate; dt is the period of time after clearing the site of existing litter.

The daily rate of litter deposition was calculated using deposited litter 14 d after an area was cleared as X. The relative decomposition rate used was obtained from the decomposition model for litter bag data (Dubeux et al., 2006) and with 14 d as the incubation period.

Litter Chemical Composition
Litter samples were oven-dried and milled to pass a 1-mm screen in preparation for analysis of dry matter (DM), OM, C, N, P, neutral detergent fiber (NDF), acid detergent fiber (ADF), and lignin. Dry matter and OM analyses were performed by the procedure described by Moore and Mott (1974). Carbon and N analyses were done after dry combustion with a Carlo Erba NA-1500 C/N/S analyzer (Haak-Buchler Instruments, Saddlebrook, NJ). Phosphorus was determined by micro-Kjeldahl digestion and read in the auto-analyzer using a colorimetric procedure. The NDF, ADF, and lignin analyses were run in an ANKOM fiber analyzer (ANKOM Technology, 2003a, 2003b, 2003c).

Statistical Analyses
Herbage mass, existing litter, litter deposition rate, and litter composition data were organized by evaluation period within each year and analyzed by a repeated measures procedure in PROC MIXED from SAS (SAS Inst. Inc., 1996). The LSMEANS procedure was used to compare treatment means within an evaluation period.


   RESULTS AND DISCUSSION
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
CONCLUSIONS
 REFERENCES
 
Herbage Mass
There was management intensity x evaluation date interaction for herbage mass (Fig. 1A ). Low and Moderate intensities followed a similar trend of increasing herbage mass through September, but herbage mass in the High intensity did not change (P > 0.10) throughout the grazing season.


Figure 1
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  		Fig. 1. Effect of management intensity and evaluation date on herbage mass (A), existing litter mass (B), and rate of litter deposition (C) of grazed Pensacola bahiagrass pastures during 2002–2003. Means followed by the same letter, within an evaluation date, are not different (P > 0.10) by the SAS LSMEANS test. SE = 490 kg DM ha–1 for herbage mass, 356 kg OM ha–1 for existing litter mass, and 6.8 kg OM ha–1 d–1 for rate of litter deposition.

 
Changes in herbage mass reflect the net result of the processes of herbage growth, herbage senescence, and animal intake. Bahiagrass growth rate reaches its peak by mid-summer (Beaty et al., 1963; Gates et al., 2001), and the growth rate slows as autumn approaches. Beginning in August, herbage mass was greater on Low than High pastures, but High and Moderate management intensities differed only in June (Fig. 1A). In High, the greater stocking rate increased forage intake per unit area and no changes in herbage mass occurred. Because of lower SR in the Low and Moderate intensities, however, herbage mass increased through September, at which time slowing herbage accumulation rates resulted in a decrease in herbage mass.

Existing Litter Mass
There was management intensity x evaluation date interaction for existing litter (Fig. 1B). The High management intensity had least existing litter in June and July, and greatest existing litter, along with the Low, by September and October. Existing litter is the net result of the deposited litter and the litter decomposed within a given period of time. Less existing litter in High at the beginning of the season was likely due to greater litter decomposition rates during the cool season and the spring before initiation of grazing. Greater N fertilization and better quality of the deposited litter from the previous grazing season (same intensities were imposed on these pastures in 2001, the year preceding the start of this study in 2002) may explain greater decomposition rates for the High management intensity. There was greater existing litter for the Low management intensity during the majority of the grazing season, and the lesser SR for Low compared with other intensities may partially explain this result. Lesser SR and greater herbage mass often cause more litter to be deposited because of a lesser forage utilization rate and an increase in senescent herbage (Reardon and Merril, 1976; Thomas, 1992). Rezende et al. (1999) found a significant increase in litter deposition when SR was halved from 4 to 2 animals ha–1. In the current experiment, the range in herbage mass across management intensities was relatively small because as SR increased so did N fertilization rate. Thus, there likely were other factors influencing the response. One possible contributor was the greater litter C to N ratio (Fig. 2A ) in Low that would likely result in slower rates of decomposition.


Figure 2
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  		Fig. 2. Effect of management intensity and evaluation date on C to N ratio (A), neutral detergent fiber (NDF; B), and acid detergent fiber (ADF; C) of existing litter on grazed Pensacola bahiagrass pastures during 2002–2003. Means followed by the same letter, within each evaluation date, are not different (P > 0.10) by the SAS LSMEANS test. SE = 2.3 for C:N, 224 g kg–1 for NDF, and 119 g kg–1 for ADF.

 
Accumulation of existing litter (Fig. 1B) started in September (P < 0.10) for Low and Moderate compared with July (P < 0.10) for the High management intensity. This occurred because the rate of litter deposition was greater at the beginning of the season for High than for Low and Moderate (Fig. 1C). Despite the variation within the season, existing litter did not differ between years (P > 0.54) and averaged 1570 kg ha–1 across management intensities. Rezende et al. (1999) reported values of existing litter ranging from 800 to 1500 kg DM ha–1 in creeping signalgrass [Brachiaria humidicola (Rendle) Schweick.] pastures in pure stand or mixed with desmodium [Desmodium heterocarpon (L.) DC. subsp. ovalifolium (Prain) Ohashi] or tropical kudzu [Pueraria phaseoloides (Roxb.) Benth]. The same authors also found seasonal effects on amount of existing litter.

Litter Deposition Rate
There was management intensity x evaluation date interaction for litter deposition rate (Fig. 1C). Interaction occurred because there were no differences among intensities in September, but at all other evaluation dates, management intensity differences did occur (Fig. 1C). High had greater litter deposition rates than Moderate at all dates except September. Low had a lesser litter deposition rate than High only in July. The consistently high rates of litter deposition throughout the season in the High management intensity were reflected in a gradual increase in existing litter for High (starting from July, Fig. 1B). The average (across intensities and dates) litter deposition rate for the grazing season was 27 kg OM ha–1 d–1, which multiplied by the grazing season length (168 d) results in approximately 4540 kg OM ha–1 deposited during this period. Thomas and Asakawa (1993) reported values ranging from 2830 to 11 800 kg DM ha–1 of litter deposited from May to December in creeping signalgrass and gambagrass (Andropogon gayanus Kunth) pastures, respectively.

Litter Chemical Composition
Nitrogen Concentration
There was no management intensity x evaluation date interaction (P ≥ 0.22) for litter N concentration. Existing and deposited litter N concentrations were approximately 50% greater for the High management intensity than for the other intensities (Table 1). These greater concentrations reflect the impact of greater N fertilization and SR and indicate the importance of litter as a nutrient buffering pool that may reduce N losses to the environment (Wedin, 1996, 2004) and gradually release N to plants and microbes.


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  		Table 1. Effect of management intensity on N and P concentrations (OM basis) and lignin:N and C:P ratios of existing and deposited litter during 2002 and 2003.

 
The potential litter mineralization may be estimated on the basis of litter C and N concentration. Considering the average rate of litter deposition and the deposited litter N concentration for the Low management intensity, the amount of N cycled through the above-ground deposited litter was approximately 58 kg N ha–1. Carbon concentration in deposited litter was relatively constant averaging 506 g kg–1 on an OM basis (or 436 g kg–1 on a DM basis). With this N amount (58 kg N ha–1), 2750 kg of above-ground litter (OM basis) would be decomposed by soil microorganisms, assuming microbial C to N ratio of 8:1 and that one third of the metabolized C is actually incorporated into microbial biomass (Brady and Weil, 2002). The remaining two thirds would be utilized during the respiratory process (Brady and Weil, 2002). Using the value for total-season litter deposition and subtracting the litter decomposed by soil microbes, the undegraded remaining biomass is 1790 kg ha–1. This biomass tends to accumulate and act as a sink for the N from pasture pools (e.g., soil OM, excreta) or other nutrient inputs like fertilizers. This amount of litter (i.e., 1790 kg ha–1) is close to the average existing litter of 1570 kg ha–1 for 2002 and 2003.

C:N and Lignin:N Ratio
Management intensity interacted with evaluation date to affect litter C to N ratio for both existing litter and deposited litter. The responses were similar for both litter types, so only data for existing litter are presented (Fig. 2A). The C to N ratio was least for the High management intensity in all evaluations of existing and deposited litter, and there were no differences among dates within years for High (P > 0.10). Interaction occurred because during mid-season the C to N ratio for the Low and Moderate intensities started to increase, and the change was greatest for Low for both existing and deposited litter. Therefore, at the beginning of the season the C to N ratio of Low and Moderate was similar, but at the end of the season Low presented a greater C to N ratio. Carbon concentration did not differ among management intensities, but N concentration did differ, both for existing and deposited litter (Table 1). Thus, the greater N concentration in the litter resulted in lesser C to N ratio for the High management intensity (Fig. 2A).

Ratios of C:N and lignin:N are considered important components of decomposition models (Palm and Rowland, 1997), with lower values associated with more rapid decomposition. The C to N ratio in plant residues ranges from between 10:1 to 30:1 in legumes and young green leaves to as high as 600:1 in some kinds of sawdust (Brady and Weil, 2002). It is generally accepted that C to N ratio less than 20:1 favors mineralization, whereas C to N ratio greater than 30:1 favors immobilization (Wagner and Wolf, 1999), but fungi and bacteria can decompose residues with far higher ratios (Heal et al., 1997). Data from the current study showed that at lesser management intensity (Low and Moderate) the litter C to N ratio was greater than 30:1, presenting potential for N immobilization, while at the High intensity the C to N ratios were less than 30:1 (22:1 for existing litter).

The lignin:N ratio differed among management intensities with lesser values observed for High in both existing and deposited litter (Table 1). Lignin concentration did not differ (P > 0.10) among management intensities, averaging 92 g kg–1 for existing litter and 84 g kg–1 for deposited litter. Therefore, the lesser lignin:N ratio observed in the litter from the High management intensity is related to its greater N concentration. The lignin:N ratio of residues with low polyphenol concentration is a useful indicator of net N mineralization rates, and it also regulates the synchrony between soil N supply and plant uptake, reducing N losses (Thomas and Asakawa, 1993; Becker and Ladha, 1997; Whitmore and Handayanto, 1997). Lignin concentration varies widely, increasing with senescence of plant materials and as litter decomposition proceeds. Concentrations in fresh, nonsenescent leaves of a broad range of plants ranged from 50 to 200 g kg–1, while those of senesced litter range from 100 to 400 g kg–1 (Palm and Rowland, 1997). Thomas and Asakawa (1993) reported lignin:N ratios ranging from 13.8 to 31.5 in litter collected from pastures of four different tropical grass species. These ratios are greater than the range of 4.4 to 5.8 in the current experiment (Table 1), with the main difference being litter N concentration that was in the range of 2.7 to 6.9 g N kg–1 in their grass litter compared with 12.7 to 22.9 g N kg–1 in the current study. This is likely attributable to lower N fertilizer inputs and lesser levels of forage utilization in their experiment. It is interesting to note in the current study that the lignin:N ratio of existing and deposited litter were very similar within a management intensity despite decomposition processes occurring for a longer time in existing litter. This suggests that both lignin and N are relatively recalcitrant components of bahiagrass litter.

P Concentration and C:P Ratio
Existing and deposited litter P concentrations were greater and C:P ratios less for High than for Moderate and Low management intensities (Table 1). Considering that P fertilization was the same among Moderate and High intensities, and those pastures only received 17 kg P ha–1 more than Low over the 2 yr, the primary reason why P was greater in the High management intensity is likely the greater SR and N fertilization. Increasing SR increases the proportion of nutrients returned via excreta relative to litter (Thomas, 1992), and nutrients in excreta are more readily available than those in plant litter (Haynes and Williams, 1993), particularly below-ground litter. Nitrogen fertilization may increase the rates of soil OM mineralization, increasing P availability. As a result of these processes, soil P availability increased leading to greater plant P uptake.

The C:P ratio in deposited litter ranged from 394 (High) to 662 (Low). When C:P ratio is below 200:1, mineralization predominates, whereas above 300:1 immobilization is greatest (Dalal, 1979; McLaughlin and Alston, 1986). Therefore, P immobilization by the litter pool was expected to occur even for the High management intensity.

NDF and ADF Concentrations
Management intensity interacted with evaluation date affecting NDF and ADF concentration in the existing litter (Fig. 2B and 2C). The High management intensity had less seasonal variability in existing litter NDF and ADF concentrations, while those of Low and Moderate decreased significantly during July and August. Litter NDF and ADF concentration is a function of the deposited litter quality and also the rate of litter decomposition. Greater decomposition rates, associated with the High management intensity, increase NDF and ADF because fiber compounds are recalcitrant, particularly ADF (Heal et al., 1997).

There were no management intensity effects, but there was an evaluation-date effect for NDF and ADF concentration in the deposited litter (data not shown). Deposited litter NDF increased from 620 to 710 g kg–1 and ADF from 310 to 360 g kg–1 from the beginning to the end of the grazing season. Because this litter was all deposited within 14 d of the sampling date, the response was most likely due to decreasing nutritive value of standing herbage that occurred as the grazing season progressed.


   CONCLUSIONS
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS
REFERENCES
 
Management intensity affected existing litter mass, deposition rate, and chemical composition in continuously stocked Pensacola bahiagrass pastures. Existing litter mass was greatest for the Low intensity early in the grazing season and for High late in the grazing season. After declining following the onset of grazing in Spring in all management intensities, litter mass began to reaccumulate earlier for the High management intensity because of greater litter deposition rate. Lesser existing litter mass at the beginning of the grazing season for High was likely due to greater rates of litter decomposition between seasons associated with the lower litter C:N and lignin:N ratios and the greater N and P concentrations of litter in the High management intensity. This combination of greater litter deposition rate and litter quality suggests a larger nutrient contribution from litter in intensively managed swards. However, litter quality was generally low across management intensities, indicating potential for N and P immobilization, particularly at the beginning and at the end of the grazing season. This characteristic suggests that bahiagrass litter may serve as an important buffering pool, immobilizing nutrients and mineralizing them later, potentially reducing nutrient losses, particularly in nutrient-rich environments.


   NOTES
TOP
 NOTES
ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS
 REFERENCES
 
This research was sponsored in part by USDA CSREES Tropical and Subtropical Agricultural Research Program Grant 34135-12348.

Received for publication August 19, 2005.


   REFERENCES
TOP
 NOTES
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS
 REFERENCES
 




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J. C. B. Dubeux Jr., L. E. Sollenberger, B. W. Mathews, J. M. Scholberg, and H. Q. Santos
Nutrient Cycling in Warm-Climate Grasslands
Crop Sci., May 31, 2007; 47(3): 915 - 928.
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