B- 1073 June 1968 Bermudagrass Production and Management in East T exas . TEX A&M UNIVERSITY . Texa gricultural Experiment Statnon H. O. Kunkel, Acting Director, College Station, Texas Summary Bermudagrass is an important forage plant in East Texas. It is best adapted to fertile loam and sandy loam soil, but will grow under a wide range of soil conditions. Several varieties of bermudagrass have been developed, and many of these have been tested for adaptation to East Texas. Coastal bermudagrass has shown the best performance in this area, produc- ing 20 to 50 percent more forage than Common ber- mudagrass. Other varieties have been tested and are satisfactory, but are not superior to Coastal. These include Midland, Suwannee and Selection No. 3. NK- 37, a seeded variety, was inferior to Coastal in a test conducted in 1960 and 1961. Coastcross-I, which was released from Georgia in 1967, has not been evaluated. Coastal bermuda responds favorably to nitrogen fertilization, interplanted winter legumes and a combination of these two practices. Coastal re- sponded favorably to applications of 200 or more pounds of nitrogen per acre per year. Both phos- phorus and potassium are needed for sustained pro- duction of berrnudagrass. Lime also is required, especially if 200 pounds or more of nitrogen are used annually. The practice of overseeding an adapted winter legume increased total forage production about as much as 60 pounds of nitrogen per acre without the legume. Coastal bermuda, overseeded in the fall with crimson clover and fertilized with 120 to 150 pounds of nitrogen per acre beginning approximately June l, has produced 5 to 6 tons of forage annually. This amount of nitrogen without the legume pro- duced 4 to 4.5 tons of forage. The use of the legume without nitrogen produced about 3.75 tons annually. The legume results in earlier forage production than Coastal without the legume. The best practice seems to be, therefore, a combination of a winter legume followed byv-nitrogen applications that begin approxi- mately at the time the legume matures. The peak of forage production is influenced to some extent by the time of nitrogen application. Production can be shifted by delaying the time of initial nitrogen application. However, late summer and early fall growth is poor, and response to late nitrogen applications is less than to spring applica- tions. Defoliation practices are known to affect both the yield and stand survival of forage plants. In a 5-year 2 study involving the effects of clipping prai fertility levels on Coastal bermudagrass, y’ greater with a short stubble height (2 in i’ quent harvest (14 to 16 inches of growth) an fertilization (240 pounds of nitrogen per a were almost as great with intermediate , quency (8-10 inches of growth or 3 to 4 w infrequent harvest. Yield and ground co increased with nitrogen fertilization and. succeeding year of the study. Root weig A influenced by nitrogen fertilization and i’? each succeeding year of the study. Groun crease and root weight decline were slighi: with close, frequent defoliation, but neither nor the root weight changes were related;- Differences in carbohydrate content of if and rhizomes were detectable immediately/f clipping, but no permanent or major sust ment effects were found. Height of cuttifi- to be less important in Coastal bermuda tion than either frequency of defoliation fertilization, but Coastal bermudagrass a wide range in both height and frequ foliation. i k. . Contents Summary ......................................................... .. A Introduction ..................................................... Bermudagrass Varieties .................................... '¢ Performance of Bermudagrass Varieties ...... Bermudagrass-Legume Combinations .......... Fertilization ...................................................... Nitrogen Rates ................................... .. Time of Nitrogen. Application ....... .. Fertilization and Legume Combinati Coastal Bermudagrass Management ......... __ " Forage Yields _______________________________________ __ Protein Content _________________________________ __ Root Weights and Stand Density.... Carbohydrate Content ______________________ Soil Temperature ............................... __ WV Literature Cited ............................................... .. dagrass ction and Management T exar i HOLT AND J. A. LANCASTERll‘ BERMUDAGRASS 1s THE MOST IMPORTANT pasture grass in East Texas. Bermudagrass will grow on most soils, but it does best 0n fertile loam and sandy loam soils. It can be grown satisfactorily 0n the light sandy soils of East Texas provided adeq1“te fertility is supplied. Bermudagrass is a long-lived perennial with a spreading growth habit and reproduces by runners, rootstocks and seed. The runners vary in length from a few inches to 3 or 4 feet, and the seed heads usually attain a height of 6 to 12 inches or more, depending on soil productivity. Figure 1 shows a typical im- proved pasture made by Common bermudagrass. Coastal bermudagrass, which is vegetatively more productive than Common bermudagrass and better adapted to hay making, has increased in acreage tre- mendously in recent years in this area. Coastal can produce 20 to 50 percent more forage than Common and perhaps even more under certain conditions. Improved management practices, including proper use of legumes and fertilizers, are necessary if the potential of Coastal is to be realized. This publication sum- marizes the results of several studies involving varieties and yield responses to various management practices. BERM UDAGRASS VARIETIES Several varieties and strains of bermudagrass have been developed in recent years. The first and most important of these, from a use standpoint, is Coastal. Coastal, which is a hybrid, was developed at the Georgia Coastal Plain Experiment Station by crossing Tift bermuda with a bermudagrass introduced from South Africa. Coastal has larger stems, stolons, rhizomes and longer internodes than Common ber- muda It is characteristically a lighter green than Common and produces few seedheads which rarely contain viable seed; therefore, it must be propagated vegetatively. The growth characteristics of Coastal are shown in Figure 2. Selection No. 3 bermudagrass also was produced at the Georgia Coastal Plain Experiment Station and resulted from the same cross that produced Coastal. Selection No. 3 has shorter internodes, a darker green color and denser growth than Coastal. Work in Georgia indicated that it was less palatable than Coastal and several other selections (2). Its forage production generally is equal to or greater than that of Coastal. Midland bermudagrass was developed in Georgia as a hybrid between Coastal and a cold-hardy variety from Indiana (3). Midland has somewhat less desir- able forage than Coastal, but is much more winter hardy. Midland is palatable, has good disease resist- ance and does not produce as many seedheads as most "“Respectively, professor, Department of Soil and Crop Sciences; and associate agronomist, East Texas Research and Extension _ Center, Overton, Texas. Figure 1. Typical improved pasture of Common bermudagrass in East Texas. common types of bermudagrass. Midland was released and named by the Oklahoma Agricultural Experiment Station for areas where Coastal is not winter hardy. The Oklahoma Station reports that Midland is two to four times as productive as unselected Common bermuda on fertile soils. It is reported also as being a better companion crop for legumes than Common because it has fewer rootstocks. Suwannee bermudagrass was released in I953 by the Georgia Coastal Plain Experiment Station for use on deep sands Suwannee is palatable and resists diseases, frost and drouth. It is a hybrid, pro duced from the same cross that resulted in Coastal, and grows tall enough to be cut for hayor silage. In some tests in Georgia, it has produced from l0 to 20 percent more forage than Coastal on drouthy, sandy soils with low levels of applied fertilizer. It has shown no superiority to Coastal, however, on sandy soils in East Texas. NK-37 bermudagrass was released by the Northup-King Company as an erect giant bermuda that can be reproduced by seed. Its erect growth makes it suitable for hay production. NK-37 makes rapid growth in the spring following establishment, Figure 2. A 4-week growth of well-fertilized Coastal bermuda- grass shown beside an 18-inch stake. 4 but generally produces less total growth than _ tive varieties. Also, NK-37 does not persist as Common bermudagrass. It is susceptible i diseases which reduce its vigor in years whe, disease attacks are severe. WS-300 bermuda; a Whitman Seed Company variety with desc‘ similar to NK-37. It has not been observed area. - Coastcross-I is a new hybrid released in 196 the Coastal Plain Experiment Station, Tifton, Coastcross-I resulted from a cross between bermudagrass and a plant introduction (25544 Kenya, South Africa. Coastcross-I is completely grows taller and has broader leaves than Coas has spreading stolons, but few, if any, rhizo 1 is highly resistant to foliage diseases and sting; tode. Its yield is slightly below Coastal, but’; consistently been ll to 12 percent higher in bility than Coastal, based on the nylon bag tec ' Coastcross-I spreads faster and becomes esta quicker than Coastal and makes more fall but it is less winter hardy than Coastal. Zimmerly Select was introduced from Ni Rhodesia, Africa, through the U. S. Depart_ Agriculture Plant Introduction Program in i. P.I. 224693. This plant introduction is some localities as “Zimmerly Select” bermuf P.I. 224693 is the same genus and species as and Coastal bermudagrass, but different fromif ' Stargrass. It spreads by both rhizomes and Trial plantings in Texas starting in 1966 that Zimmerly Select produces slightly lessi than Coastal, and its rate of spread is about t or slightly less than Coastal. It seems to ha f erect stems and leaves and to produce more sei under certain stress conditions than Coastal. Zi, Select has not been subjected to experimental and no animal response data are available. '.p in Louisiana showed the protein content patte spring to fall to be similar to that of Coastal. PERFORMANCE OF BERMUDAGRASS VARIETIES Most of the varieties described in the section have been evaluated in small-plot , studies in East Texas, but not all of them ha evaluated in any one study. The results of started in 1956 at Mt. Pleasant are summa Table l. The yield results by harvest pe 7 1959 and the annual total yields by years a The plots were fertilized with 0-60-60 each _' 30-0-0 following each clipping, giving an ann fertilization of I20-60-60 most years. Selectig produced more forage than Coastal most denser and shorter growth of Selection No. 3c? with Coastal makes it a less desirable hay plan combined with its lower palatability, proba any yield advantage of this strain over Coast Stage yield of bermudagrass varieties at Mt. Pleasant, rvest periods, 1959 and total annual yields, 1956-59 Tons of a1r-drywforage per acre " 1959 May ]une Aug. Sept. Sept. 28 29 3 1 29 Total 1.35 1.05 1.18 0.55 0.63 4.77 1.02 1.05 0.88 0.67 0.47 4.10 0.84 1.10 0.86 0.60 0.56 3.98 0.61 1.22 0.88 ' 0.45 0.53 3.69 1956-59 1956 1957 - 1958 1959 Average 1.85 5.55 7.83 4.77 5.03 2.07 5.11 7.21 4.10 4.63 2.64 3.75 7.13 3.98 4.25 1.07 4.18 6.83 3.69 3.94 0.69 0.87 0.64 0.48 l‘ nnee produced more forage than Coastal the of the test, which indicates that it became if» more rapidly. It did not produce as much ll after 1956. These results indicate no gained by growing Suwannee rather than was started in 1959 which included Mid- _ uda as well as Suwannee, and in 1960 added. Yield results for 3 years are sum- Table 2. The test area was sprigged May nd on July 24 more than 2 tons of hay per '~ harvested from Midland and more than "from Coastal and Suwannee. These results that these vegetatively propagated varieties ‘fly established. and produced about 0.6 tons more forage gstal in 1959, mainly because it became rapidly but it produced slightly less forage in ‘i 1961. Suwannee produced less forage than ;-stal or Common during the 3 years of this 1.437 was seeded on April 25, 1960. It became "d very rapidly, producing 2,600 pounds of i/Forage yield of bermudagrass varieties at Mt. Pleasant, 9-60 Tons of air-dry forage per acre 1959 1960 1961 Average 4.95 6.40 6.89 6.08 4.32 p 6.58 6.99 5.96 4.35 " 6.40 6.81 5.85 3.72 i 4.85 5.51 4.69 3.20 4.29 4.73 4.07 , 2.80 2.00 2.40 1.12 0.75 0.72 " ded in the spring of 1960. Table 3. Forage yield of bermudagrass varieties on very deep sand near Mt. Pleasant, Texas, 1958-60 Tons of air-dry forage per acre Variety 1958 1959 1960 Average Coastal 1 2.27 4.02 5.01 4.20 Suwannee 3.04 3.53 4.16 3.57 Common 2.78 2.94 2.55 2.76 LSD (.05) N.S. 1.02 1.06 1.22 forage per acre by July 1. The established grasses were harvested the second time when NK-37 was harvested the first time. However, the vegetative varieties produced significantly more than NK-37, omitting the first cutting. This may not be a fair comparison, since NK-37 was in its seedling year, but it became well established as indicated by the initial growth. Also, NK-37 produced less forage in 1961 than in 1960, whereas all other varieties increased in 1961. NK-37 and these varieties were planted in 1959 in a test near Kirbyville, and NK-37 produced significantly less forage than the other varieties. Suwannee was compared with Coastal and Com- mon on very deep sand near Mt. Pleasant during 1958-60. This study received a 60-60-60 fertilizer in 1958 and 150-60-60 in succeeding years. The results presented in Table 3 indicate that the performance of Suwannee relative to Coastal and Common was better than in the earlier test, but its actual yield was below Coastal. The results of these tests indicate that Coastal is well adapted to the East Texas area. The perform- ance of Midland was satisfactory, but it is not recom- mended as a replacement for Coastal. The perform- ances of Suwannee and NK-37 were inferior to Coastal and Midland. A test involving two varieties not previously evaluated was started near Mt. Pleasant in 1965. The test was re-established at the new research location near Overton in 1966. It is apparent from the 1965 and 1966 data in Table 4 that neither Zimmerly Select nor the San Antonio Selection became established more rapidly than Coastal. In the second year of the Overton study, Coastal was superior in yield to the other varieties. Table 4. Forage yields of bermudagrass varieties in East Texas Tons of air-dry forage per acre Variety 1965‘ 1966* 19672 Coastal 2.70 a 0.59 a 5.57 a Zimmerly Selection 2.25 ab 0.53 a 4.61 b San Antonio Selection 1.92 b 0.54a 5.14 ab Common 1.27 c 0.37 b 2.09 c lFirst-year planting near Mt. Pleasant. 2Planted April 20, 1966, near Overton. (Fl BERMUDAGRASS-LEGUME COMBINATIONS Various winter-annual legumes were evaluated in combination with Coastal bermudagrass on a light sandy soil near Mt. Pleasant. Legume establishment on Coastal is sometimes difficult and poor, especially in the Southern half of the Coastal growing area. A good grass-legume combination just before maturity of the legume is shown in Figure 3. Some of the legumes made good growth and resulted in earlier production than Coastal without a legume, since Coastal grows very little in this area before mid-April. Studies reported later in this publication show that a combination of legume on Coastal followed by nitrogen applications starting about June gives the best total production and also the longest production season. The best adapted legumes of those tested appear to be crimson clover, narrow leaf vetch and Singletary peas. Narrow-leaf vetch, Vicia angustifolia, is a native Figure 3. Grass and legume combination in East Texas. plant in East Texas which shows some prom used on permanent sod. Once established even under grazing, but commercial seed; available because mature seed are extremely‘; to harvest. Singletary peas have been used to so in sod, but the plant is not as well adapted f. as crimson clover. For thiszreason crimson c used in most of the later studies with Coastal grass reported in this publication. a FERTILIZATION Nitrogen Rates Coastal bermudagrass responds to high} fertilization with the response being limit by available light and moisture. A study ducted in East Texas near Mt. Pleasant to the response of Coastal to fertilization withoi mental irrigation. A plot area was estab, April 1960. The area was fertilized at pla l 30-60-60 followed by 30-0-0 in early June. clover was broadcast on all plots in early}. 1960 and each fall thereafter. Nitrogen, and potassium at the rates and combinatr in Table 5 were applied each year beginnini A The phosphorus and potassium were di two increments, the first half being applied i each year and the second half in early Mar gen application, in the form of ammoniuj began on June l with four split applications}; the first four Coastal clippings on these a dates: l/Q, (June 1); 1/3 (July l); 1/6 (Aug. 1);; 1). Clippings before May 15 contain}; amounts of crimson clover. The plots we g to seven times each year at approximately’ stubble height. ’ Total forage yields for each of the and the averages are given in Table 5. Cri l A i. "t 3i ‘$2 '._, . ' s, Table 5. Forage yield of Coastal bermudagrass as influenced by rates and ratios of nitrogen, phosphorus and pot Pounds per acre Tons of air-dry forage per acre N P205 K20 1961 1962 1963 A), 0 O 0 3.22 3.34 f 2.83 g 0 » 200 200 3.38 3.33 f 1.92 g 200 100 ' 100 7.46 6.27 cde 7.05 bcd 200 100 200 A 7.79 6.54 cde 5.82 de 200 200 100 7.91 6.86 bcde ' 7.75 ab 200 200 200 7.86 7.38 abc 6.95 bc 400 0 200 7.43 6.18 cde 5.21 ef 400 50 200 7 .65 7 .27 abc 7.60 ab 400 100 100 7.44 6.51 cde 6.76 bcd 400 100 200 7.91 6.95 bcd 6.94 bc 400 200 0 7.76 5.55 e 4.16 f 400 200 100 7 .89 7 .47 abc 7.56 ab 400 200 200 8.29 8.42 a 8.57 a 600 200 200 8.28 7.45 abc 8.51 a 800 200 200 8.23 7.36 abc 7.69 ab Values with a common letter designation do not differ significantly (.05) level. Duncan's Multiple Range. 6 I I I I 0 200 400 600 800 Pounds N per acre 400 pounds N 200 pounds N I I I 100 200 Pounds P205 per acre 400 pounds N 200 pounds N I I “ 0 100 200 Pounds K20 per acre g Coastal bermudagrass yields as influenced by varying levels of N, P or K in the presence 0f constant rates _. fertilizer elements (200 pounds of P205 and/or K20). (were poor and influenced total yield very little , with zero nitrogen rates. Approximately % of ld on zero nitrogen consisted of crimson clover. Yields decreased each year in the absence of nitrogen, phosphorus or potash, but remained relatively con- stant where all three fertilizer elements were applied. Approximately 7 tons of hay were produced with 200 pounds of N, whereas yields declined above 400 pounds of N, (Figure 4). Responses to phosphorus and potassium levels are shown graphically in Figure 4. In general, the response to applied phosphorus and potassium increased with higher rates of nitrogen. Soil samples were collected at the end of the second year from all nitrogen plots receiving 200 pounds each of P205 and K20. Results of the soil analysis are presented in Table 6. Organic matter, phosphorus and soluble salts remained fairly constant at all nitrogen rates while pH, potassium and calcium steadily decreased. Most of the potassium decrease occurred with the first 200 pounds of nitrogen and may be accounted for largely by uptake in the 4 tons of growth produced by the nitrogen. However, it is likely that potassium leaching also occurred. The decrease in calcium in the upper level of the soil profile is of concern mainly because of the change in pH and may dictate correction through the use of lime. The results of this study suggest the use of at least a 200-50-100 fertilizer. The use of a ton of lime every 3 years appears advisable. Additional phosphorus and potassium may be needed if condi- tions warrant the use of higher rates of nitrogen. Such conditions might include high production under irrigation and maintenance of high levels of crude protein. Periodic soil analysis might also indicate further alterations in the fertilizer regime. Time of Nitrogen Application A study of the effect of time and rate of nitrogen application on a crimson clover-Coastal bermudagrass combination was started in 1957. A well-established block of Coastal bermudagrass was fertilized with 0-60-60 in the fall of 1956 and overseeded with crimson clover. This practice was followed each fall. Nitrogen rates of 0, 60, 90 and 120 pounds per acre were applied in two, three or four applications beginning in May and also in June each year. The initial appli- cation was made approximately May l with one set of treatments and delayed until June l with a second set to permit legume maturity. jli- Soil analysis from plots receiving 0-200-200 fertilization in addition to nitrogen Soil analysis ‘i, N pH O.M. P205 K20 CaO Soluble salts 1i¢d »- (percent) (pounds (pounds (pounds (pounds 3m; per acre) per acre) per acre) per acre) 0 6.4 0.8 18 292 1,735 432 *1 4 5.7 1.0 24 106 743 120 ‘ ll 5.3 0.8 16 96 476 120 i n 5.2 0.8 24 96 392 240 0.9 32 88 308 120 II 5.3 Table 7. Influenceiof nitrogen amount and application time on Coastal bermudagrass, Mt. Pleasant, Texas, 1957-60 Treatment Total Time of application _ pounds N of each increment Total tons of air-dry forage per acre y per acre 1957 1958 1959 1960 l958__ 120 May, June 2.05 5.57 5.55 5.50 5. 13g léay, %une, guly, August 5.88 6.52 6.72 6.2? av, une, u Y . 5.18 6.08 5.58 5. 60 May, June 2.39 4.63 5.99 4.81 5. " " Average 3.13 5.31 6.28 5.53 5., 120 June, Ju1y 4.14 4.94 6.06 5.24 5. 120 June, July, August, September 3.94 6.11 6.45 5.38 5,‘ 90 June, ]uly, August 3.34 5.38 6.18 5,21 5 f: 60 June, July 3.09 4.67 5.55 5.18 5, Average 3.63 5.48 6,06 550 5_ No nitrogen 2.08 3.43 4.35 4.09 3 J LSD (.05) 0.59 0.50 0.51 0.51 0 _ The results of this study are summarized in Table 7. Good yields were obtained in 1958, 1959 and 1960 and fair yields in 1957, which was the first year of the test. Forage yields increased more than 1 ton with 60 pounds of nitrogen. With an additional 30 pounds of nitrogen, yields increased 0.45 tons or more; and with the final increment of 30 pounds, yields went up another 0.35 tons. The initial nitrogen application date did not significantly influence total yields, but it did influ- ence time of production. Initial applications earlier in the spring might give greater response in years when a moisture deficit is encountered in mid-summer. May production definitely was higher when nitrogen applications were started May 1. Plots receiving nitrogen about August 1 produced more forage in August than other plots even though moisture was limited during that month. September production was favored only slightly by a September nitrogen application. Good production on plots that received no nitro- gen is attributed to fall fertilization with O-60-6O and the winter legume. These results indicate that nitro- gen may be used economically in combination with a summer grass-winter legume combination. Maxi- mum production was not reached with 120 pounds of nitrogen. This was shown by the 0.35 ton increase in forage when nitrogen was raised from 90 to 120 pounds per, acre, thus indicating that higher rates might be used effectively. The fertilizer study re- ported in the previous section, but conducted later, verifies the suggestion of additional nitrogen. The potassium level in this study also was below that indicated by the fertilizer study, but the fertilizer study did not include rates between 0 and 100 pounds of K20 per acre. It is likely that 60 pounds of K20 is adequate at the levels of nitrogen used in this study. Fertilization and Legume Combinations A study was started in the fall of 1958 to de- termine both the total forage production and the 8 production period of a Coastal bermuda and?‘ combination as contrasted with Coastal fertilizv nitrogen. The Coastal was fertilized each f 0-60-60 and crimson clover seeded on certain‘ Nitrogen was applied in the spring and su u; rates of 9O and 120 pounds per acre. Yi obtained from the various treatments are Table 8. 4‘ ' I. The winter legume resulted in earlier production; no yields were obtained in lat ’ and early April without the legume. Production without nitrogen but with a _ was almost as successful as production with . 120 pounds of nitrogen on Coastal alone. Pr f,“ with nitrogen applied after the legume, or f; around June 1, increased 1.5 tons more thyi nitrogen used alone. September growth was-i fluenced by either nitrogen or the winter These results indicate that the best practice is; tion of a winter legume followed by nitrogen _ May 1 to June 1. Table 8. Forage yield of Coastal bermudagrass as by winter legume and nitrogen treatments, Mt. PleasaW 1958-60 Treatment Legume Nitrogen, Date of Tons of air'dl'l'\ . pounds nitrogen Per acre ‘i7 per acre application 1958 1959 1960i; a Legume - 3.78 . 3.71» Legume 60 June 1 00 July 1 5.71 . 5.7 Legume 30 June 1 1' s0 July 1 30 August 1 5.44 No legume 60 May 1 60 ]une 1 4.29 No legume 30 May 1 30 June 1 3O julY l 3.92 LSD (.05) 0.57 ‘EIAL BERMUDAGRASS MANAGEMENT ital bermudagrass is widely used as a pasture plant in East Texas. Numerous studies have _ucted on the response of Coastal to ferti- nd harvest frequency in terms of both forage f1- quality, but relatively little emphasis has jced onstand maintenance and sustained vigor studies. Neither has height of cutting re- ajor attention, likely because Coastal is a bus sod-forming plant which seldom presents roblcms in stand survival. However, ground y be important for other reasons, and plant {f following cutting could influence vigor as longevity. udy was conducted at Mt. Pleasant from 1961 Yto evaluate the effects of clipping management w: and nitrogen level on sustained vigor as 1v by yield, ground cover and root accumu- __lock of Coastal bermudagrass was established 4, 1961, on Sawyer fine sandy loam soil. A 3| study consisting of three clipping fre- two clipping heights and two nitrogen levels mbinations was initiated as soon as a ground .4 established. Clipping frequencies, based ' ount of growth, were 2-4 inches, 8-10 inches "l6 inches. These corresponded to approxi- 7.2, 4 and 6-week intervals; clipping (stubble) ‘were 2 and 5 inches; nitrogen rates were 120 l! pounds per acre. In addition, two zero y treatments were included and cut at 2 and ubble heights when 8-10 inches of growth e. _ ,'plots were fertilized with 0-60-60 at establish- ‘) ' in October of each year. In addition, all ire cut to a uniform 2-inch stubble height at I of the growing season and overseeded with clover. The initial harvest each spring, ‘g1 about May 1, consisted almost entirely of clover and was made at a uniform 2-inch i, Differential cutting heights were initiated " bermudagrass growth in May. Nitrogen was i, in split applications following harvest of the clover. The 2-4-inch and 8-10-inch clipping “i 1y received nitrogen after the first four clip- hile the 14-16-inch frequency received only ‘Lplications. Each application consisted of I or 60 pounds when four applications were a 40 or 80 when three applications were used, _ 120 and 240 pounds of N per acre annually. a g 4 years of the above treatments, all plots iated and harvested uniformly in the fifth year I ate cumulative treatment effects. i] nd cover density. was determined by making '1 nts in duplicate square foot samples located "E. in each plot at the time of the first ber- Yss clipping each spring and immediately "g the final clipping each fall. At the same em (stubble) samples and root samples taken to a depth of 18 inches using a 2-inch tube were obtained from each plot of selected treatments. Sample treatments consisted of combinations of 120 pounds of N per acre, 2 and 5-inch stubble height and 2-4 and 14-16-inch clipping frequency. Three samples per plot were taken and composited. Root samples were washed, dried and weighed with no attempt being made to separate live and dead tissue. Com- posites of the total root samples and stem samples of each treatment were analyzed for soluble carbohydrates and starch in 1964. In addition, root and stem samples were collected in July 1964 from the selected treatments at the time of clipping and 4, ll and 18 days later. A high percentage of the root sample was made up of rhizomes. Ethanol soluble reducing sugars were determined by the Wildman and Hanson method (5). The non-soluble residue remaining after Soxhlet extraction was submitted to initial hydrolysis by Takadiastase and subsequent hydrolysis by HCl. Reducing sugars were then determined with modi- fications on this residue by the method described above and all fractions totaled and reported as total soluble carbohydrates. Density counts and root sample weights determined in the spring are not reported because treatment differences were small and non- significant. All data except total carbohydrate percentages were subjected to various analyses. Chemical analyses were based on composite samples and could not be analyzed statistically. Treatments resulting in statis- tical significance are indicated in footnotes, but actual differences required for significance are not presented, since the number of values for comparison in each case is small. Total rainfall during the 4 months, June to September, was relatively uniform, ranging from approximately l3 to 15 inches. Total annual rain- fall varied from less than 32 to 48 inches. Forage Yields Average yields of Coastal bermudagrass during the 4-year period of the study are presented in Table 9. Table 9. Forage yield of Coastal bermudagrass with various treatments, 1961-64 Tons air-dry forage per acre (4-year averages) Inches of Clipping top growth height Pounds N per acre Aver- at harvest (inches) 0 120 240 age 2-4 2 4.6 5.9 5.2 5 4.5 5.4 4.9 Average 4.5 5.7 5.1 8-10 2 2.4 5.7 6.9 6.3 5 2 0 4.5 6 1 5.3 Average 5.1 6.5 5.8 14-16 2 6 1 7.5 6 8 5 5.2 6.1 5 6 Average 5.6 6.8 6.2 Nitrogen average 2.2 5,1 6,3 Height average: 2 inches—6.l tons, 5 inches—5.3 tons. 240 pounds N 129 pounds N 5 _ Tons of air-dry forage per acre 4- .3- ON 2- _,>. {l I 1 1 1961 1962 1963 1964 Figure 5. Forage yield of Coastal bermudagrass as influenced by nitrogen level. The first increment of nitrogen increased yields on the average 2.9 tons per acre per year, while the second increment increased yields 1.2 tons per acre. Other benefits, such as increased protein content and density, occurred with the second increment of N, leaving no doubt as to the value of the additional nitrogen. Average yields of Coastal increased with each delay in harvest or with more advanced stages of maturity. The greater increase, 0.7 tons, occurred between har- vesting 2-4 inches of growth and 8-10 inches of growth. Increasing the height of cut or stubble residue from 2 to 5 inches decreased yields 0.8 tons per acre. The effect of stubble height showed some interaction with both fertility level and clipping frequency. The differ- ence in yield between the two stubble heights was only 0.1 tons with 120 pounds of N and frequent harvest. This difference increased to 1.4 tons with 240 pounds of N and the least frequent harvest. Average yields with the three nitrogen levels for each year of the study are shown graphically in Figure 5. Response to the highest level of nitrogen was less the first year than in succeeding years, possibly be- cause of the shorter season in the establishment year. Although total rainfall varied considerably from year to year, both the total yields and response to nitrogen were fairly consistent after the first year. The yield" response to differential clipping treat- ments and years is shown in Figure 6. The infrequent harvest (14-16-inch regrowth) showed somewhat erratic behavior. However, following the initial year, yield with the two cutting heights and infrequent harvest- ing followed the same pattern. No major trends Tons per acre Z-inch stubble 4- inch regrowth ._x_x__5-in¢h stubble 3'2" ______2—inch stubble * * 5 1 h t bbl ]—1lo-16-inch regrowth _ _ - nc s u e I l L 1961 1962 1963 1964 Figure 6. Forage yield of Coastal bermudagrass, Mt. Pleasant. l0 Table 10. Average crude protein content of Coastal in grass, Mt. Pleasant, 1961-64 r Amount of growth at Weighted averages‘ (perl Ferti- harvest i lization (inches) 1961 1962 1963 1964 ‘ 120-60-60 2-4 13.6 10.8 12.4 14.1 8-10 12.5 _ 10.1 11.2 14-16 11.5 i ‘((5.6 7.0 7.5 Average 12.5 8.0 9.6 10.4 240-60-60 2-4 17.9 12.4 14.8 15.2 8-10 15.3 11.3 11.6 13.8 14-16 16.1 9.0 9.4 10.7 Average 16.3 10.6 11.8 12.9 ‘Individual harvests were analyzed, but yield per ha percent protein by harvest were used in calculating averages. suggesting changes in plant vigor are apparent.- reduced yield of the frequent harvest (2-4-ig growth) in 1964 could be assumed to be a trey had the test been terminated in 1963, the tr clusion could have applied to the infrequent Protein Content w Average crude protein content of the h’ forage is shown in Table 10. Protein cont’ creased 2.5 to 3 percent with the heavier rate and decreased 2 to 3 percent with each IQ, harvest or more advanced stage of maturity. height did not influence protein content of L’ vested forage, thus the stubble heights are not: Seasonal differences in crude protein conti shown in Figure 7. Obviously both nitr_ and stage of maturity at harvest are import protein content of 12 to 15 percent was mai‘ with 240 pounds of nitrogen per acre and ha 8-10 inches of growth. ’ Root Weights and Stand Density Root accumulation and stand density portant for two reasons. They reflect the A vigor and potential productivity of the st i; provide protection to the soil. Changes i i root accumulation or stand density may before yields are actually affected and thug‘. 1a _ /x/ ‘\\' X~ l‘ \x\ /* \ \ \ / , \ X\ "-7 12 \ \ \-\' a, r \ \ a T $ X / g 10 >- a i a E’ 5 ' 2: S-IO-lnch growth u é‘. 6 ,_ ..__1zo puundl I *_ ‘>240 pound! I _ 4 > lla-lb-lnch gnalth i110 pound: I 2 , .*_.l_21¢0 pound: I l I l l l l l l I l ' 1o 2o so 1o 2o an 1o 2o so 1o ; Jun: July Augult ' Figure 7. The effect of maturity and nitrogen level l protein content of Coastal bermudagrass, Mt. Pleasa‘ Weight of Coastal bermudagrass roots with various fertilizer and clipping management practices, Mt. Pleasant, Texas, jglrnary, 1962-64 of‘ . Clipping Tons of roots per acre th height 120-60-60 240-60-60 l est (inches) 1962 1963 1964 Average 1962 1963 1964 Average 2 5.92 4.00 2.62 4.18 6.70 4.29 2.06 4.35 g_ 5 6.97 5.09 6.46 5.16 6.22 6.01 6.17 6.16 6.45 4.55 3.02 4.67 6.46 5.15 2.61 4.74 10 2 5.00 3.10 3.03 3.71 5.33 4.05 2.24 3.87 5 5.92 6.30 2.12 4.78 5.59 4.39 2.68 4.22 5.46 4.70 2.57 4.24 5.46 4.22 2.46 4.05 x16 2 5.57 4.03 2.56 4.05 5.00 3.74 3.30 4.01 5 6.71 6.69 6.46 4.64 6.64 6.77 6.08 4.16 _, 5.64 3.96 2.99 4.20 5.32 3.75 3.19 4.09 y, year average 5.85 4.40 2.86 4.37 5.74 ' 4.38 2.76 4.29 ‘ modification of management practices before succeeding year of the test in contrast to root accumu- Uble changes develop. Accumulated root lation, which decreased, and yield, which was uniform A at the end of the second, third and fourth from year to year. the test are given in Table 11. Te most significant point in this table is the [-1 in root weight with each succeeding year. clipping frequency nor nitrogen level signifi- 2 5 2 5 2 5 ffected root weights. Average root accumu- ("th 5-inch stubble was 0.6 tons greater than 3 ch stubble, which was significant statistically. "ect of clipping height was greatest with fre- ‘rvest and decreased with less frequent harvest. Stubble height (inches) . ::--- i_ accumulative effect of 4 years of differential on root accumulation is shown in Figure 8. g fiesults, obtained in the fall of the fourth year, A}. ow a consistent height effect, and no definite i ' associated with stage of maturity. Harvesting ced stages of maturity apparently does not i enhance root accumulation. density is important both for forage produc- M’ inglleg 840 in-éxes T» soil protection. Density was favored by the jfertility rate and greater stubble height, but T‘ with infrequent harvesting (Table l2)‘ Figure 8. Coastal bermudagmss root accumulation following ground cover density generally increased each 4 years of differential clipping treatments. Tons per acre 14-16 inches Harvest frequency . Density of Coastal bermudagrass with various fertilizer and clipping management practices at Mt. Pleasant, Texas, 3-year , - 1962-64 i __ of Clipping Number of stems per square foot . wth height - 120-60-60 2410-50-50 rvest (inches) 1962 1963 1964 Average 1962 1963 1964 Average p; .4 2 183 256 331 257 222 248 268 246 5 243 306 376 308 245 359 375 326 ~,.- ;_ 213 281 354 283 234 304 322 236 __4: .10 i‘ 2 192 169 234 198 198 248 259 235 5 224 268 217 236 247 313 300 287 208 219 225 217 223 281 230 251 -16 2 177 178 174 176 218 204 178 200 A 5 233 220 268 240 273 255 303 277 g 205 199 221 208 246 230 241 239 ‘a —year average 209 233 267 236 234 272 281 262 11 2-inch stubble Fourth year Second year Stems per square foot P“ N) O O O O I I 2-4 inches 8- l0 inches 14-16 inches Harvest frequency Figure 9. Sod density of Coastal bermudagrass following 2 and 4 years of differential clipping treatments. The cumulative’ effect of differential cutting treatments on sod density at the end of the second and fourth years is shown in Figure 9. At the end of both the second and fourth years, density was consistently greater with the most frequent harvesting and with the greater height. Obviously, plants which were cut frequently tended to remain more prostrate and to produce a denser cover than less frequently cut plants. Also, more vegetative material would obviously be present with 5-inch stubble than with 2-inch stubble, which would give an increased ground cover. Density increased most between the second and fourth year with frequent harvest and actually de- creased slightly with close, infrequent harvesting. While there were some differences in both root weights and density associated with treatments, none of these differences were reflected in yields. The somewhat greater reduction in root weight with fre- quent close clipping could indicate some unfavorable cumulative effect of this management practice. How- ever, the amount of roots at the end of the fourth year apparently is more than adequate to support a vigorous and productive stand. Results of uniform harvests of all plots during the fifth year .of the experiment indicated no residual effect of previous fertility levels on yield. Differences in yield associated with previous height of cutting were significant and favored 5-inch stubble. How- ever, approximately 5O percent of the total yield in the fifth year consisted of crimson clover, and over 50 percent of the differences associated with previous height of cutting was in clover yields. Thus, differ- ences in actual Coastal yield were small. Ground cover density at the end of the year of uniform treat- ments showed significant differences (.05 level) due to previous height of cutting, fertility level and stage of growth at harvest. Differences in ground cover 12 Stubble Heights a2 inches .5 inchen SPRING FALL SPRING Stems r-I N r w O I Percent total carbohydrates s» a~ on I I I A 2-4 14- 16 2-4 14-16 2-4 110-16 Harvest frequency (inches of growth)‘, Figure 10. Carbohydrate content of Coastal berm l‘ and rhizomes following initiation of growth in t at the end of the growing season. were not related to yield except for the of height of cutting. Residual fertilize ground cover was a reversal of previous J}, Numerous studies of the effects of g quency on yield and stand productivityf reported in the literature, but relatively y’ of clipping heights are found. The res study agree with most of those reported ture and indicate that height of cutting important in bermudagrass production thi of defoliation. l Carbohydrate Content Total carbohydrate (soluble carbohi starch) content of bermudagrass stems in? spring growth in 1964 was not influenced‘; treatment (Figure l0). Carbohydrate c” cent) of stems at the end of the growing? higher from 2-inch than 5-inch stubble. upper part of tall stubble was not acti quite low in carbohydrates. Rhizomes '_ carbohydrates in early season, as might ._ since reserves would have been depleted 1i. tion of spring growth. Weimann (6) v bermudagrass rhizomes upon sprouting 90 percent of their total available carbohy fall carbohydrate content of roots in thi cates satisfactory recovery. Root wei’ harvest frequencies cut at the same stu also were essentially equal at the end of}, Thus, not only carbohydrate percentage total amount of carbohydrates were infl Q) tively little by harvest frequency. Stubble not appreciably influence carbohydrate,“ but did influence total root weight, t ' encing the total amount of available c“ Both stem and rhizome samples in July, starting on the day of cutting and} ‘<1 .1‘? yl-ff2-4-1nch growth ynltubble S-inch stubble 14- 16- inch growth Z-inch stubble S-inch stubble STFMS 041118 041118 RHIZOMES l'11V1B 0 4 1118 0 41118 0 4'11 l8 Days after cutting‘ iftCarbohydrate content of Coastal bermudagrass stems at intervals following cutting in mid-summer. ys thereafter (Figure ll). The sampling owed the third cutting of 24-inch frequency ‘_ 0nd cutting of l4-l6-inch frequency. Effects re frequent harvesting are shown in the hydrate content of both stems and rhizomes ‘treatment at the time sampling was started. a rates remained relatively low in 2-inch stems, ‘f- been harvested more frequently, but within days, the carbohydrate content of 5-inch I rhizomes from both heights was equivalent es from 2-inch clipping height and 14-16- , ency declined in carbohydrates through the ys. No other treatment combination showed V Close, infrequent harvesting would have f complete defoliation in contrast to close, ifiharvesting, which likely had greater leaf , us allowing continued photosynthesis. The i“ b'ble would retain greater leaf area and also greater total volume of storage to draw on; Could not likely show the degree of depletion jjtubble. ‘A less frequently harvested material. Stems a Table l3. Mean maximum soil temperatures under Coastal bermudagrass sod, Mt. Pleasant, 1962-64 Temperature — °F Stubble height (inches) Air Month temperature 2‘ 2” 5’ June 89 90 88 87 July 95 97 93 91 August 95 96 93 90 September 84 87 85 80 ‘N0 nitrogen. 2120 pounds N per acre. While clipping effects on the carbohydrate con- tent of both stems and rhizomes were detectable in early season and immediately following clipping, the reserve status at neither the end of a growth cycle nor the end of the growing season reflected any permanent or sustained major treatment effects. Soil Temperature No attempt was made to evaluate the effect of the added ground cover of the 5-inch stubble on the soil itself except for soil temperature records. Average soil temperatures recorded l inch below the surface are shown in Table l3. Average daily high soil temperatures were highest under 2-inch stubble and no nitrogen and lowest under 5-inch stubble with nitrogen fertilization. While plant density measure- ments are not shown for the no-nitrogen plots, soil temperature effects are no doubt related to ground cover. The 5-inch stubble would have provided more shading than 2-inch stubble, and this is reflected in a lower maximum temperature. Results of this study suggest that Coastal bermuda- grass is tolerant to a wide range of management prac- tices in terms of stand maintenance. Frequent cutting reduces yield, but apparently has little if any effect on stand maintenance. Height of cutting is much less important in Coastal bermudagrass production than either frequency of defoliation or level of ferti- lization. This study indicates that tall stubble is not necessary for the maintenance of Coastal bermudagrass and may actually result in slightly reduced yields, but the stubble may have other effects, either beneficial or detrimental, not evaluated in this study. 13 [Blank Page in Original Bulletin] LITERATURE CITED Burton, Glenn W. 1954. Coastal Bermuda for pasture, hay and silage. Georgia Agr. Exp. Sta. Bul. N.S. 2. Burton, Glenn W. 1947. Breeding Bermudagrass for the southeastern states. jour. Amer. Soc. Agron. 39:551-559. Harlan, ]. R., G. W. Burton and W. C. Elder. 1954. Mid- land Bermudagrass, a new variety for Oklahoma. Okla. Agri. Exp. Sta. Bul. 416. USDA News Release—Suwannee Bermudagrass thrives on deep sand. Nov. 23, 1954. Weinmann, H. 1961. Total available carbohydrates in grasses and legumes. Herb. Abstr. 31:255-261. Wildman, Sam G. and Elmer Hansen. 1940. A semi-micro method for the determination of reducing sugars. Plant Physiol. 15:719-729. 15 h‘ v" Texas Agricultural Experiment Station Texas A8=M University College Station, Texas 77843 H. 0. Kunkel, Acting Director-Publication