" R I..: * A If ~ .i~* S pr ~ -. A fr' CIRCULAR 222 OCTOBER 1975 ,~-. A " THE MANAGEMENT OF SERALA SERICEA FOR FORAGE AND SEED AGRICULTURAL EXPERIMENT R. Dennis Rouse, Director STATION/AUBURN UNIVERSITY Auburn, Alabama CONTENTS Page EFFECT OF CLIPPING MANAGEMENT ON SERICEA, PRATTVILLE ----------- ---------------.----------- ----- 3 -- EFFECT OF CLIPPING MANAGEMENT ON SERICEA, PLANT BREEDING UNIT------------------------------------- Forage Production ---Stand -- ---------- -------------- Persistence ---------------------------------- F orage Seed Q uality----------------------------------------------------------- ---- 9 ---------- Production AND -------- .----- 11 SUMMARY CONCLUSIONS 11 ---- FIRST PRINTING 5M, OCTOBER 1975 Auburn University is an equal opportunity employer MANAGEMENT of SERALA SERICEA for FORAGE and SEED C. S. HOVELAND, R. F. McCORMICK, JR., W. B. ANTHONY and F. T. GLAZE* a fine-stemmed sericea (Lespedeza cuneata) variety, can be a highly productive legume for hay production.' It is also a satisfactory pasture for beef cows and calves but problems have been encountered with productivity and stand survival under grazing. 2 Increasing cost of nitrogen fertilizer has stimulated demand for seed of this sericea variety. Recent research in Alabama found that the short sericea variety, Interstate, should not be cut for hay if maximum seed yield is expected.3 A May hay cutting reduced combine-harvested Interstate seed yields from 645 pounds to 312 pounds per acre over a 2-year period. Since Interstate is grown mainly as a special ground cover plant, its use as a farm crop is mainly for seed production. Refraining from cutting hay may not be a problem with that short-stemmed variety, but farmers who grow Serala sericea may need to cut hay and still harvest some seed. This publication summarizes results of sericea management experiments at two locations in central Alabama. EFFECT OF CLIPPING MANAGEMENT ON SERICEA, PRATTVILLE In a 2-year experiment (1969-1970) at Prattville Experiment Field, Serala sericea planted the previous year in 5 x 20-foot plots replicated four times, was harvested two or four times per year with two stubble heights. * Professor and Research Associate, Department of Agronomy and Soils; Professor, Department of Animal and Dairy Sciences; and Superintendent, Prattville Experiment Field. Donnelly, E. D. 1963. Serala Sericea-A New Sericea Variety. Auburn Univ. (Ala.) Agr. Exp. Sta. Leaf. 70. 2Hoveland, C. S., W. B. Anthony, R. R. Harris, E. L. Mayton, and H. E. Burgess. 1969. Serala Sericea, Coastaled Bermuda, Goar Tall Fescue. Grazing for Beef Cows and Calves in Alabama's Piedmont. Auburn Univ. (Ala.) Agr. Exp. Sta. Bull. 388. SAdamson, H. C. and E. D. Donnelly. 1973. Seed Yields of Interstate Sericea as Affected by Cutting and Irrigation. Auburn Univ. (Ala.) Agr. Exp. Sta. Leaf. 87. SERALA, Forage yields were highest (4 to 5 tons per acre) when sericea was cut for hay twice each year, Figure 1. Cutting four times each year reduced the forage yield to half that produced by the two-cut treatment. First year yields with four cuts per year were highest where short stubble was left. How ever, the reverse was true the following year when plants cut to a 5-inch stubble height were most productive. At the end of the second harvest year, stands exceeded 85 percent when cut four times to a 5-inch stubble. In contrast, sericea cut four times each year to a 11/ 2 -inch stubble had stands of only 60 percent. Dry forage Ib. /A 10000 8,000 6,000 4 ,000 2,000 - Ist. yr. 2nd yr. Ist. yr.2nd yr. Ist yr.2nd yr. 2 Harvests/yr. 4 Harvests/yr. 4 Harvests/yr. I1/2in. stubble 112 in.stubble 5in. stubble FIG. 1. Forage yields as affected by stubble height and cutting frequency at Prattville Experiment Field. [41 Food reserves, or lack of them, in the roots probably account for the stand loss. Root carbohydrates were reduced by harvesting four limes a year as compared to twice a year, Figure 2. Leaving a 5-inch stubble resulted in more root carbohydrates than where a 11/2-inch stubble was left. Both varieties gave a similar response. These results suggest that where sericca is to be grazed, a high stubble should be maintained to permit the plants to accumulate root reserves. It is likely that where sericea is grazed closely for several years, stands will deteriorate. EFFECT OF CLIPPING MANAGEMENT ON SERICEA, PLANT BREEDING UNIT In a 3-year experiment (1970-1972) on an established stand of Serala sericea at the Plant,.Breeding Unit, Tallassee, forage was harvested from 5. x 20-foot plots replicated four times at 3, 6, or (Serala >.J SInterstate Carbohydrates in roots, % 15 10 5 0 I L 1 / 2-in. 5-in. 4 I Y -in. 2 2 Harvests B~:~:f:~:~:a~~li~~83~:8~1/ ////A Harvests FIG. 2. Carbohydrate storage in sericea roots in August of the second haonest year, Prattville Experiment Field. [5] 9-week intervals with stubble heights of 1 or 4 inches. Harvesting began in April and was terminated in early June, August, or October to determine the effect on forage yield, stand persistence and forage quality. Seed harvesting was done in mid-October using a sicklebar mower and a small stationary thresher. Forage Production Average sericea forage yields over 3 years were reduced about 44 percent by terminating harvesting in June as compared to S4-in. stubble 11/2 Dry forage Ib./A - in.stubble r r I I II I r/~ Cutting interval, wks. Cut until June Cut until Aug. Cut until Oct. FIG. 3 Three-year average forage yields for sericea at two stubble heights and three cutting intervals. [6] August, Figure 3. Additional harvesting from August until October increased yields only slightly. Forage yields were highest (over 4 tons per acre) when sericea was cut three times a year at 9-week intervals, Figure 3. Harvesting two hay cuts, one in early June and one in early August, resulted in hay yields nearly equal to that from three cuts a year. Stubble height had little effect on forage yield when sericea was cut at the hay stage. When sericea was cut every 3 weeks to simulate grazing, forage yields were one-half to two-thirds those obtained when cut at the hay stage, Figure 3. Sericea cut at 6-week intervals yielded somewhat better than at 3-week intervals but was much below the 9-week interval or hay stage. Leaving a 4-inch stubble on plants cut every 3 or 6 weeks resulted in higher forage yields than a 11/ 2 -inch stubble. This indicates that sericea is especially sensitive to close defoliation unless cutting intervals of about 9 weeks are used. The harmful effects of cutting at 3 or 6-week intervals were more noticeable by the third year, Figure 4. Although a severe late summer and autumn drought the third year reduced forage yields, sericea cut at 9-week intervals until August or October yielded two or three times more than that cut more frequently. FIG. 4. Serala sericea third-year forage yields as affected by cutting interval and stubble height. [7] height (left) than at 7 ! 2-inch height (right. Stubble height hvad no effect on forage production when seniea was cut at 9-week intervals. Howeve r, cultting( every 3 to 6 weeks at a short stulblle, height reduiced1 forage yields more the third v ear than in prev ious years even wvhen cutting was terminatedl in jine. Cutting evecry 3 weeks to a stubble from April until August or October resulted1 in forage yijelds only onethird that of scricea cut at 9-week intervals. Regrowth after cutting was much miore rapid on plants cut at .3-wvck intervals with a 4-inch stile( height than at 1I!.~inches, Figure 5. The slower recovery was a result of less growth buds on the short-stubble _?!)inch rV imm m ==A LGU UUM" u OWN OVIM am r wo w+r a cutat 2-nchstubble height (left), than at 4-inch height (right). 181 TABLE 1. SERICEA STANDS (GROUND COVER) DURING JUNE OF THIRD YEAR AS AFFECTED BY STUBBLE HEIGHT AND CUTTING FREQUENCY AT PLANT BREEDING UNIT Date of final harvest June-- Stubble height In. 4 11 Harvest frequency Wks. 9 6 3 9/221 Ground cover Pct. 34 45 42 14 19 52 6 3 August -4 9 6 3 11/2 9 61 55 45 October 4 1%/2 6 3 9 6 3 9 6 3 34 26 42 40 41 19 11 11 stubble plants also allowed more weeds to germinate and grow than with 4-inch stubble plants. Stand Persistence Leaving a 4-inch stubble on plants cut every 3 weeks resulted in better stand persistence than leaving a 1 -inch stubble, Table 1. Sericea cut at hay stage (9 weeks) generally maintained good stands although there was some reduction by the third year when a 11/2-inch stubble height was used. The loss of vigor and stand of sericea cut at 6-week intervals at a 1/-inch stubble height is illustrated in Figure 6. Forage Quality Digestible dry matter (DDM) of Serala sericea forage was constant for each cutting treatment throughout the season, Table TABLE 2. SERALA SERICEA DIGESTIBLE DRY MATTER (DDM) As AFFECTED BY MANAGEMENT, 3-YEAR AVERAGE AT PLANT BREEDING UNIT Stubble height In. 4 Harvest frequency May 12 June 1 46 June 23 Percent DDM July Aug. Aug. 14 3 25 - Sept. 15 .. 54 55 52 55 Oct. 6 49 45 46 Average 46 50 50 47 50 52 Wks. 9 6 3 9 11/2 6 3 49 49 49 50 51 45 47 48 48 .. 49 51 53 55 43 49 51 45 50 55 52 -50 55 [9] 2. Stubble height had no effect on DDM; however, more quently cut sericea had slightly higher DDM than sericea harvested at the hay stage of maturity. The DDM values reported here are similar to those for hay made from some warm season perennial grasses such as bermuda fre- Hulled cleoned seed/acre, 600 . 604 [ lb. LI 4-in, stubble 11/2/ 434432 40OF 350 300F -in. stubble 200r I9 17 205 174 104 119 32 1001 ~I f 45 -J -- 9 6 3 9 I 3 Cutting interval, weeks Cut until June and three intervals. Cut until Aug. FIG. 7. Three-year average seed yields of Serala sericea cut at two stubble heights [ 10] or bahia. Although the DDM of Serala sericea is not high, this forage can meet the feed needs of beef herds. Also, because growth interval was not of much importance for forage quality, sericea hay harvest .could be delayed as required to coincide with favorable weather for curing hay. Seed Production Seed yields were largely determined by cutting management, Figure 7. When forage harvesting continued to August, seed yields were only one-fourth to one-half of that made when cutting ended in June each year. Since only about 70 percent of the seed produced are recovered in combine harvesting, yields generally would be too low to justify harvesting sericea that had been cut for hay or grazed until August. Previous work has shown that highest sericea seed yields are obtained when no forage is harvested. In this experiment, about 600 pounds seed per acre were obtained by cutting sericea one time per year in early June to a height of 4 inches. More frequent cuttings reduced seed yields. This indicates that grazing sericea during the spring probably would reduce seed yields more than taking a single cutting for hay in May or early June. When forage harvesting was terminated in June, cutting frequently to a short stubble had more effect on seed production than on forage yields. Cutting forage to 11/2-inch stubble height reduced seed yields regardless of cutting frequency. This was probably a result of reduced root carbohydrate storage with the 11-inch as compared with the 4-inch stubble height. Results clearly establish that cutting Serala sericea for hay in May or June will reduce seed yields. However, 11/ to 2 tons of Serala hay can be harvested and still permit a good seed yield if the hay is cut to 4-inch stubble height. Harvesting seed after a May or June hay cut will reduce total annual forage yield by 50 percent. Frequent and close defoliation in spring can be expected to cut seed yields more than making a single hay cutting in May or early June. SUMMARY AND CONCLUSIONS Serala sericea was harvested under various management systems at Prattville Experiment Field for 2 years and at the Plant Breeding Unit, Tallassee, for 3 years to determine the effect on forage yield and quality, persistence, and seed yield. 1. Forage yields were highest (4 tons per acre) when sericea [11]1 was cut at 9-week intervals until August or October. Cutting at 6 and 3-week intervals reduced forage yields 41 percent and 53 percent respectively. 2. Harvesting sericea at a 11/ 2-inch stubble height reduced forage yields below that of a 4-inch stubble for the 3 or 6-week cutting intervals but had no effect at the 9-week interval. 3. Frequent cutting and a short stubble height reduced root carbohydrate reserves, slowed development of new shoots, and weakened stands of sericea. 4. Digestible dry matter (DDM) of forage was constant for given cutting treatment throughout the growing season. DDM a was slightly lower for forage when cut at 9-week intervals than at 3 or 6-week intervals but was unaffected by stubble height. 5. Maximum seed yields can be expected where no forage is harvested. Seed yields of about 600 pounds per acre were obtained when one hay harvest was removed to leave a 4-inch stubble than when cut more frequently. Cutting to a short stubble early in the season reduced seed yields. 6. To maintain a vigorous productive stand, sericea should probably not be cut for hay more than twice a year. If seed is to be harvested in October, a 4-inch stubble height should be left when making a May or early June hay cutting. 7. Grazing of Serala sericea will require that a high stubble be maintained. Continuous grazing can be expected to weaken sericea stands and reduce yields. Serala sericea requires more careful management when used for grazing than for hay. 8. Since sericea forage DDM is not affected appreciably by management, the major emphasis should be on maintaining stands and a high level of productivity.