Cultural and Management Practices o n Sudangrass Performance TEXAS A&M UNIVERSITY TEXAS AGRICULTURAL EXPERIMENT STATION R. E. Patterson, Director, College Station, Texas DECEMBER 196s, Contents Summary ...................................................... --2 ' Introduction ................................................. ..3 Establishment Practices .............................. ..3 Seeding Rate and Row Spacing .............. --3 Single Versus Double Rows .................. ..4 Seeding Rate and Harvest Frequency .... --5 Harvest Practice .......................................... -.5 Height and Frequency .............................. -.5 Method of Harvest .................................. ._6 Frequency of Harvest .............................. --7 Acknowledgments ........................................ _-8 Summary Sudangrass is widely adapted in Texas and is . extensively for grazing, hay and silage. Sudangrass- hybrids, generally crosses between a male sterile grain and a sudangrass variety, have been used widely in rece p‘ The hybrids generally grow faster, produce more to matter and recover more rapidly following harvest ' sudan varieties. General culture and management pra ' similar for the varieties and hybrids. Seeding rates and row spacings generally have little; on total dry-matter yield of the various sudan types. of the first cutting may increase with seeding rate. If f cutting is made at a late stage of maturity, total yield _ increased to some extent by heavier seeding rate. Ti tends to compensate for stand differences, especially af primary growing point is removed at the first cutting. ' The first-cutting yield is likely to be higher for brf or close-drilled planting than for row plantings. Thus, practices are favored for hay production. Total yields, if __ cuttings are made, are not significantly different with if and row plantings. Generally, better distribution of duction during the growing season results from plan cultivated rows. 1 Frequent harvest reduces total forage production; though more total cuttings are made. The percentage tion from frequent harvest is greater with the hybrids th the varieties; however, the hybrids produce more total ‘y at any cutting frequency. Protein content decreases with ad a stages of maturity. Thus, both maximum yield and m protein content cannot be obtained with the same t‘; practice. ’ ~ Leaf development of the sudangrass hybrids is at a5; mum at an early stage of growth. After the plants are?‘ inches high, additional growth consists mainly of stalk d ment and elongation. While frequent harvest reduces?- plant yield, leaf yield is not reduced and may be greate frequent harvest. Effect! of Cultural and iManagement Practice; ort Sudangrass Performance Ethan C. Holt Professor, Department 0f Soil and Crop Sciences Sudangrass, Sorghum radanense (Piper) Stapf., has been grown in Texas for more than 5O years. It is used for grazing, hay, silage, green-chop, bundle feed and as a green manure crop. Its area of adaptation extends from the arid sections of the Rolling and High Plains to the high rainfall, humid sections of East Texas and the Gulf Coast. It is broadcast, drilled and planted in cultivated rows at widely varying seeding rates. In recent years, sudangrass-sorghum hybrids have been developed and introduced into the market. These are largely hybrids between male sterile grain sorghum lines and sudangrass varieties. These hybrids have demonstrated increased vigor over open-pollinated sudan- grass varieties and have come into widespread use. Seed of the hybrids generally are round, but a wide range in seed size is found among the hybrids. Thus, the number of seed per pound also varies widely. The use, distribution and culture of the hybrids are similar to the varieties. Research has shown that harvesting and planting practices in- fluence the type and amount of growth produced by many forage plants. Numerous studies of seeding rates, row spacings and harvest practices have been conducted in Texas with the sudan varieties and to some extent with the hybrids. Results of these studies are reported in this publication. Results from these types of studies should provide valuable information in developing management practices for hay, silage, green-chop and other types of harvested feed operations. It should be pointed out that mechanical harvesting, especially of a tall growing plant, is not comparable to grazing, and the results cannot be inter- preted specifically in terms of grazing responses. Even then, certain principles such as growth behavior patterns and potential yield differ- ences between types developed in clipping studies may have general application. ESTABLISHMENT PRACTICES Seeding Rate and Row Spacing Sweet sudangrass was planted in 40, 2O and 10-inch rows at McGregor at rates ranging from 4 to 32 pounds of seed per acre. Two harvests were made: the first in the flowering stage and the second at the end of the season. Average production for a 3-year period is given in Table 1. In general, these results indicate very little effect of seeding rate on total forage production. The only major difference in yield was with the 32-pound seeding rate in 10-inch rows which produced considerably more forage than any other treatment. This difference was primarily in increased yield at the first cutting, which in this study was made rather late. The first cutting contributed approximately 75 percent of the total yield, regard- less of the method or rate of seeding. Sudangrass has the capacity to adjust or compensate for stand, especially within the row, through tillering. Thin stands will develop more tillers than thick stands. Since most of the tillering occurs after the primary growing point is removed, the late initial harvest 3 TABLE 1. THE EFFECT OF ROW SPACING AND SEED- ING RATE ON SWEET SUDANGRASS FORAGE PRODUC- TION, McGREGOR, 1960-62 (3-YEAR AVERAGE) Row spacing Seeding rate Pounds of dry forage per acre (inches) (pounds per acre) First cutting Total yield 40 4 3,780 5,550 8 4,040 5,610 Average 3,910 5,480 20 4 4,130 5,750 8 , 4,160 5,560 16 4,430 5,720 32 4,740 6,160 Average 4,560 5,790 10 4 4,930 6,680 8 4,980 6,660 16 4,750 6,120 32 5,920 7,510 Average 5,140 6,740 in this study allowed less opportunity for tillers to exert an influence on yield. This probably accounts for the increased yield of the heavy seeding rate in 10-inch rows. These data indicate that sudan may be established with light seeding rates, even in narrow rows, and yet produce a satisfactory yield. There was some yield advantage to narrow rows at McGregor, both in 1962 which was a dry year and in 1961 which was a very favorable year. The effect is expressed almost completely in the first cutting, at which time tillering had not developed to any extent. First- cutting yield was much higher in 10-inch rows with 4 and 8 pounds of seed per acre than in wider rows at the same seeding rates. This indicates that either less competition occurred within the narrow row because of -~ greater spacing between plants, or more tillering occurred because of the greater spacing, or a combination of the two factors helps to produce the higher yields. Earlier work at College Station (Table 2) had indicated better yield in row plantings. In the College Station study, four harvests were made in the boot stage. When the tops (growing points) are removed, tillering is enhanced. Cultivation improves aeration and water penetration. These factors favor row plantings, whereas yields are generally better with close-drill or broadcast plantings at the initial harvest or with a single harvest at a later stage of maturity. Increased seeding rates also may increase yields at the initial harvest. In 1956 at College Station, there was almost a straight line increase in first-cutting yield with increased seeding rates from 7 to 50 pounds of seed per acre (Figure 1). However, when several cuttings are made in the boot stage or earlier, seeding rates have relatively little effect (Table 2). The response to seed- ing rate was somewhat erratic in this study. Differences 4 ing are dictated to some extent by the intend TABLE 2. FORAGE YIELD OF IRRIGATED SWEET i?‘ GRASS, ON LUFKIN FINE SANDY LOAM SOI COLLEGE STATION, 1955-56 i» pounds of Pounds of air-dry forage V; Seeding Seed . method per acre 1955‘ 1956’ ' 40-inch row 7 4,790} 6,390 14 7,160" 6,580 21 6,220 6,930 28 6,090 5,950 Average 6,050 6,460 Broadcast 20 4,990 5,010 a; 50 5,420 4,480 ’ 40 5,790 5,250 50 6,330 5,220 Average 5,630 4,990 ‘The difference in yield between any two seeding equal or exceed 845 pounds to be significant (.05 l) “Difference in average yield of the two seeding m significant statistically (.05 level). but differences due“ ing rates were not significant. w in yield due to seeding rates were significant st if in 1955 but not in 1956. These results suggest that method and rate Heavier seeding rates and closer row spacings fav’ cutting yields which would be desirable in a hay» tion. Wider row spacings with cultivation "__ better regrowth and possibly better total yields and-i be favored for grazing where sustained pro desired. " Single Versus Double Rows Two methods of planting in basic 40-in‘ were studied at Temple in 1964. A sudangrass- hybrid was planted in single 40-inch rows and rows 12 inches apart with the main rows on U 1500" H U m H El U D- CU %° ,8 1000- A "" A B 5 >4 H ‘U I Pi u‘: 500,. A A 40-inch rows O C] Broadcast V) ‘U t: :1 O m I I I I '10 2O 3O 40 Pounds of seed per acre Figure 1. The relationship of seeding rate to first-cutti of sweet sudangrass. , THE EFFECT OF METHOD AND RATE OF {COMMON SUDANGRASS ON FORAGE PRODUC- PLE, 1964 Seeding fate Pounds of dry forage per acre (pounds Per acre) July 6 October 2O Total 10 4,880 3,000 7,880 10 5,510 3,250 8,760 15 5,640 2,180 7,820 '5 . were on 40-inch centers. V; In addition, two seeding rates were employed ble rows. The seeding was made May 11, harvests were on July 6 and October 20. The i} Table 3 indicate that seeding in a double row F increase yield, even though the same amount as used as in a single row. In fact, there was tage to increasing the seeding rate in double T} e the 10 pounds per acre used in single rows. l‘ Rate and Harvest Frequency azer, a sudangrass-sorghum hybrid, was planted Station on May 13, 1964 in 12-inch rows. ‘I was fertilized with 42-42-42 at planting and “d with 40 pounds of nitrogen per acre in early ests were made in the early boot stage, early fstage and ‘hard dough stage. It is apparent _ re stage that heavy seeding rates are not neces- with harvesting in the mature stage did *5 rate have any effect. This is similar to the Yat McGregor in 10-inch rows where the harvest a" made in a mature stage of growth. stage yields actually were higher in this case wet stage, possibly because of timing of the Q-stage harvest which did not permit enough re- ffollowing the second harvest for a third harvest. in- yields were produced with all treatments. E STATION, 1964 J4) that when harvest is initiated in the young. TABLE S. THE INFLUENCE OF STAGE OF MATURITY AT HARVEST AND HEIGHT OF CUTTING ON FORAGE YIELD OF TWO SUDANGRASS TYPES, NEAR COLLEGE STATION, 1961-62 _ Pounds of dry forage per acre Stage of matumy at different cutting heights when harvested 6 inches 12 inches Average‘ Sweet sudan 24 to 36 inches high 5,540 5,620 5,530 Booting 5,760 7,550 6,540 Flowering 7,590 7,700 7,640 Average (Sweet sudan)‘ 6,300 6,880 6,590 Sudax 11 24 to 36 inches high 7,650 7,190 7,420 Booting 9,340 9,100 9,220 Flowering 10,280 11,500 10,890 Average (Sudax 11)‘ 9,090 9,260 9,130 ‘The differences in average yield between varieties and among stages of maturity were significant statistically. HARVEST PRACTICE Height and Frequency Sweet sudangrass and Sudax 11, a sudan-sorghum hybrid, were planted in 40-inch rows at the rate of 10 pounds of seed per acre on Brazos river bottom soil (Miller clay) in early April in 1961 and 1962. The plot area received 40 pounds per acre of nitrogen prior to planting and 4O pounds in early July. Harvests were made at three stages of maturity and with two stubble heights. The stages of maturity and stubble heights are given in Table 5. The stage of maturity was based on 50 percent or more of the plants having reached the stage indicated. A 9-inch stubble height was included in 1961 and an 18-inch stubble ‘height in 1962, but only the two heights common to both years are reported. Yields re- sulting from the treatment combinations are given in Table 5. ,4. THE EFFECT OF SEEDING RATE AND FREQUENCY OF HARVEST ON HAYGRAZER FORAGE YIELD NEAR 50 f Pounds of Pounds of dry forage per acre i seed x per acre‘ June 24 July 9 July 15 July 17 August 7 September 9 October 7 Total 2O 4,830 2,710 930 _ 3,600 12,070 p 50 4,250 5,030 650 3,290 11,220 ‘stage 2o 5,070 5,590 10,460 50 i 5,990 5,700 9,690 gh stage 20 7,890 7,480 15,570 i 10,570 6,740 17,510 _ er, a sudangrass-sorghum hybrid, established in 12-inch rows. t statistically, but the two seeding rates did not differ significantly. Differences in total yield due to stage of maturity were TABLE 6. THE EFFECT OF HARVEST PRACTICE ON SUDAX 11 FORAGE YIELD, COLLEGE STATION, 1964 stage of Method Pounds of dry forage per acre gmwth at of June June July July August September October T is harvest hafVCSt 24 29 8 17 12 8 8 ' 30 inches Plants cut 2,300 1,310 840 1,230 , high Leaves removed‘ 1,160 720 260 4,500‘ 6,, Boot Plants cut 3,940 3,300 1 _; 1,730 8,9, Leaves removed‘ 1,350 650 5,5602 7,5 Flower Plants cut 5,730 4,500‘ 10,2 Leaves removed‘ 1,130 540 4,5002 6,1. ‘All leaves were removed from the plants, but the stems were left standing. Harvests were made at the time plants were cut. g?» "'5 ‘The whole plant was cut at the last harvest. Yields were significantly reduced by harvesting sudan in immature stages. Each later stage represents approxi- mately 2 weeks in time on the average. Sweet sudan increased in total yield about 1,000 pounds per acre with each 2-week delay of harvest. Sudax 11, which has a higher potential yielding ability, increased over 1,600 pounds with each 2-week delay of harvest. At the most frequent harvest, Sudax 11 yielded ap- proximately 1,800 pounds of dry matter per acre more than Sweet sudan. When harvested in the flowering stage, the yield of Sudax 11 was over 3,200 pounds more than Sweet sudan. These data indicate that prac- tices which restrict or limit yield have a greater effect on types with greater potential. Height of cutting had less effect on yield than either the frequency of cutting or variety. Sweet sudan appeared to be favored by the 12-inch stubble height. The 12-inch stubble height produced more with each frequency than the 6-inch height. On the other hand, Sudax 11 showed no consistent response to height of cutting, and the average of the two heights differed less than 200 pounds per acre. In the second year of this study, an 18-inch stubble height was included which is not shown in the 2-year summary table. Average yields for the 6, 12 and 18- inch heights were 7,740, 8,290 and 7,080 pounds of dry matter per acre, respectively. Thus, it is apparent that TABLE 7. THE EFFECT OF HARVEST PRACTICE ON LEAF YIELD OF SUDAX 11, COLLEGE STATION, 1964 “i heights above 12 inches result in a reduction of r; dry matter. » Method of Harvest Sudax 11 was seeded May 13, 1964 in 40-inch r0 at the rate of 10 pounds per acre on Brazos bottom Mil l, clay soil. The test was fertilized with 42-42-42 » planting and topdressed with 40 pounds of nitrogen -. acre in early July. Two methods of harvesting for _i_ were utilized, each at three stages of maturity. A (1) 30-inch growth —— When initial growth was inches high, one set of plots was cut 'and another i " was stripped of leaves. When regrowth on the w‘ plots again reached 30 inches, both the “cut” and “strippep plots were again harvested in a similar fashion. on stripped plots were cut at the final harvest and separat into leaves and stems. - (2) Boot stage — The procedure was the same I for the "30-inch” plots except that harvesting was u; when regrowth on “cut" plots reached the boot f.‘ (3) Flower stage ——- The same procedure was u ' as for the "30-inch” plots, except that harvesting w‘ done when regrowth on “cut" plots reached the w‘ stage. The effect of harvest practice on total forage yiel and distribution of yield during the season is present Stage of Method Pounds of dry leaves per acre growth at 0f June June July July August September October harvest harvest 24 29 8 17 12 8 8 30 inches Plants cut 1,160 580 380 530 high Leaves removed‘ 1,160 720 260 390 Boot Plants cut 1,350 1,170 610 Leaves removed‘ 1,350 650 330 Flower Plants cut 1,130 1,580 Leaves removed‘ 1,130 540 250 ‘All leaves were removed from the plants, but the stems were left standing. Harvests were made at the time plants were cut. 6 able 6. It is apparent that when the whole plant irernoved, yields increased with each advanced stage ' rity. On the other hand, if only the leaves were ‘ed during the growing season, the stage of maturity - “ch this was done initially had little influence on V‘, plant growth. ‘Leaf growth appears to have reached a near maximum . time the plants were 30 inches high (Table 7). yield increased only 190 pounds with a delay in harvest from june 24 to 29. A further delay ly 8 actually resulted in some loss of leaf weight, gbly through shedding. Since new leaf growth on t plants developed primarily with stem elongation vie the previous leaf level, leaf yield with each suc- _"ng harvest decreased. Actually the same pattern of ‘se in leaf yield also occurred on the plants cut in ,.-younger stages. y.‘ Total leaf yields were remarkably similar with all ,- ods and stages of harvesting. The poorest leaf yield with leaf stripping at the most advanced stage of rity, and the best yield was with total plant harvest the boot stage. These data indicate that harvesting sudangrass prior the flower stage reduces total yield primarily by re- “cting stalk development. Maximum leaf development _]reached considerably before this stage, and total leaf d is influenced relatively little by harvest practice. a» oval of the leaves only, as may occur under grazing i, more advanced stages of maturity, does not greatly i uence either leaf or total plant yield. However, new ~ves are formed primarily above the earlier leaves, ‘ I. ing them less accessible. As the stalk matures, it is A useful as forage. _ If the primary growing point is not removed, as in jiipping, tillering is inhibited; thus, yield may be less y. with cutting. This is especially true with harvesting at the more advanced stages of maturity. Frequent re- moval of the growing point, as in the 30-inch cut, restricts total yield more than leaf yield because a greater part of the total plant weight is in the stalk. Frequently, the leaves of sudangrasses are removed by grazing animals, leaving only the bare stern. The above results suggest occasional removal of these defoliated stems to encourage new tiller development and the de- velopment of more accessible leaves. For hay or har- vested forage, harvesting in the boot or later stage is indicated for best production even though maximum leaf development has already occurred. Frequency of Harvest Several sudan varieties, sudan-sorghum hybrids and short lived perennial types were grown at Temple on Houston clay in 1960 and 1961 and harvested at three stages of maturity. In addition to determining yield, the forage was analyzed for protein content. Yield results are recorded in Table 8. It is obvious that the two hybrids were considerably higher yielding than the varie- ties, and that the perennial types performed about the same as the annual varieties. Forage yields of the varieties harvested in an im- mature stage, prior to booting, resulted in approximately 50 percent as much forage as harvesting in the hard dough stage. The hybrids produced only 35 percent as much forage when harvested in the immature stage as with late maturity. Yet the yields of the hybrids were greater than the yields of the varieties, even with early harvesting. Thus, the potenial of the higher yield- ing hybrids is limited more by early frequent harvesting than is the potential of the varieties or perennial types. The variety yields averaged approximately 75 percent of the hybrid yields with frequent harvest but only 50 percent with harvest in the hard dough stage. ‘ABLE 8. THE EFFECT OF STAGE OF MATURITY AT THE TIME OF HARVEST ON YIELD OF FORAGE, TEMPLE, 1960-61 Tons of dry forage per acre if Variety or h b _d Preboot stage‘ Boot stage‘ Hard dough stage‘ y r1 1960 1961 Average 1960 1961 Average 1960 1961 Average i. ariiw Greenleaf 1.7 1.9 1.8 4.1 1.9 3.0 3.8 3.9 3.9 Piper 1.7 2.5 2.0 4.5 2.5 3.4 3.8 4.2 4.0 Sweet 1.4 1.7 1.6 4.0 1.6 2.8 3.4 2.8 3.1 V Common 1.9 1.9 1.9 3.9 2.2 3.1 3.0 3.3 3.2 f Hybrid 3' ‘i Sudax 11 2.2 2.8 2.5 5.9 5.0 4.5 5.8 7.8 6.8 , Grazer 2.3 2.7 6.3 . Weak perennial Perennial Sweet 1.1 1.6 1.4 3.4 1.5 2.5 3.6 3.8 3.7 Sorghum almum 1.7 2.0 1.9 4.1 2.0 3.1 3.9 4.6 4.3 ‘Stage of maturity each time the plants Were harvested. TABLE 9. THE EFFECT or STAGE OF MATURITY AT THE TIME OF HARVEST ON PERCENT PROTEIN IN ‘A F ORAGE, TEMPLE, 1961 _ Preboot stage‘ Boot stage‘ Hard dough stage‘, Variety or hybrid May June July p Aug. Nov. A June July Aug. Sept. A June Aug. Nov. a0 19 20 24 4 "g' s 6 , s 26 "g- 2s 21 1 Variety V_ 61661116115 14.2 11.6 7.8 7.0 8.4 9.8 9.1 9.8 6.9 7.4 8.3 ‘ ‘10.4 3.9 8.2 Piper 15.4 12.9 7.2 5.2 8.5 9.4 15.9 8.0 6.2 7.8 9.5 7.4 5.1 8.0 . Sweet 14.0 12.4 8.8 8.1 9.5 10.5 11.7 8.5 7.5 7.7 8.9 7.1 5.4 8.7 K ‘ Common 12.7 11.2 7.5 6.2 9.8 9.5 11.1 7.6 7.4 7.1 8.5 6.1 4.9 8.1 Hybrid Sudax 11 14.5 14.4 8.6 6.5 8.0 10.5 9.2 9.5 6.0 6.7 7.8 7.8 5.8 6.5 Grazer 12.2 12.5 7.8 5.7 8.9 9.4 7.9 9.9 6.1 7.1 7.8 5.6 5.0 6.5 Weak perennial Perennial Sweet 15.5 12.9 7.5 6.7 9.3 10.4 15.7 10.5 8.4 8.5 10.2 9.2 3.1 7.7 Sorghum almum 14.7 12.9 8.8 6.7 9.0 10.4 14-2 7-4 6-8 7-3 3-9 7-0 5-8 7-6 ‘Stage of maturity each time the plants were harvested. Protein content was determined in both 1960 and 1961 and followed a similar pattern in both years. The in the season. This might be expected as a result greater production of the hybrids, especially if the =1 1961 data are shown in Table 9. g Protein content de- creased with advancing maturity as expected. Differences either among or within the varieties, hybrids and peren- nial types were small for any harvest date or the average for the season. There was some indication that the higher yielding hybrids were lower in protein than the varieties at the later stages of maturity, especially late gen supply in the soil was limited. ACKNOWLEDGMENTS Data were collected and made available for publication by E. D. Cook, agronomist, Blackland iment Station, Temple; and by M. ]. Norris, agronl Livestock and Forage Research Center, McGregor. i