Performance of para grass (Brachiaria mutica) and Ubon paspalum (Paspalum atratum) on seasonally wet soils in Thailand

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1 Tropical Grasslands (1999) Volume 33, Performance of para grass (Brachiaria mutica) and Ubon paspalum (Paspalum atratum) on seasonally wet soils in Thailand M.D. HARE, P. BOONCHARERN, P. TATSAPONG, K. WONGPICHET, C. KAEWKUNYA AND K. THUMMASAENG Faculty of Agriculture, Ubon Ratchathani University, Ubon Ratchathani, Thailand Abstract The production, quality and persistence of Brachiaria mutica and Paspalum atratum cv. Ubon, with and without legumes, were compared under cutting on infertile, low lying, seasonally wet-seasonally dry soils in north-east Thailand. Both species grew well in the first year, producing an average of 20 t/ha DM. There were no significant differences in production between the two species and no production differences between 45-day and 60-day cutting intervals in the first wet season. In the second wet season, P. atratum produced about 30 t/ha DM, which was approximately 10 t/ha more than B. mutica. Under both 30-day and 60-day cutting intervals in the second wet season, P. atratum produced significantly more dry matter than B. mutica. Cutting P. atratum every 30 days produced higher quality grass than cutting every 60 days and did not significantly reduce dry matter yield. B. mutica cut at 30-day intervals produced nearly 40% less dry matter than that cut every 60 days. B. mutica was 2 3 percentage units higher in crude protein than P. atratum throughout the study. None of the legumes tested (llanos macro, Calvalcade centurion and Lee jointvetch) persisted after the second wet season in association with these grasses on low lying, wet-dry sites. The importance of P. atratum in village pasture systems is discussed. Correspondence: M.D. Hare, Faculty of Agriculture, Ubon Ratchathani University, Warin Chamrab, Ubon Ratchathani 34190, Thailand. Michael@agri.ubu.ac.th Introduction Dairy farming in north-east Thailand is expanding on to former rice paddy land comprising grey podzolic (Khorat soils) and low humic gley soils (Roi-et soils), and covering >40% of the area (Hare et al. 1999a). These soils are largely structureless and have very low nutrient-holding capacity and high bulk densities (Mitsuchi et al. 1986). They are very low in organic matter and have a closely packed topsoil over a packed subsoil. As such, they can be waterlogged for long periods during the wet season (2 3 months) and then dry out quickly during the dry season forming a hard pan (Ragland and Boonpuckdee 1986). It is extremely difficult to get forages to grow and persist on these soils, especially under grazing. Currently, only 2 grass species are suited to these wet soils in Thailand. They are para grass (Brachiaria mutica) and plicatulum (Paspalum plicatulum). Para grass is one of the most widely used, good quality forages for low lying, seasonally waterlogged areas of the tropics (Schultze- Kraft and Teitzel 1992) and is now naturalised in many parts of Thailand (Stur et al. 1996). It has been in use for many years in central Thailand and is the most popular grass on low lying, seasonally flooded areas, where it is used as a cut-and-carry forage to supplement rice straw (Topark-Ngarm and Gutteridge 1986). It is planted vegetatively by stolons and stems cut from old pastures, ditches and along roadsides. Plicatulum is a very persistent grass which grows well on waterlogged, infertile soils (Mannetje and Kersten 1992). Even though seed is readily available, plicatulum is not a popular forage, being considered by farmers to have low palatability and nutritive value, even in south Thailand where it is most widely grown (Sophanodora 1997). It is not commonly grown by farmers in north-east Thailand where the seed is produced, as farmers there prefer to grow ruzi grass (Brachiaria ruziziensis).

2 76 M.D. Hare, P. Booncharern, P. Tatsapong, K. Wongpichet, C. Kaewkunya and K. Thummasaeng Ruzi grass is the most widely grown grass in Thailand (Hare and Phaikaew 1998; Hare et al. 1999a). It establishes readily from seed and grows very well during the wet season on well drained soils. However, it performs poorly on waterlogged sites and dries off very quickly in the dry season. On such sites, it rarely persists for more than 2 years. Recent research has shown that Paspalum atratum is well suited to waterlogged, acid soils which become seasonally dry in north-east Thailand (Hare et al. 1999a) and to similar soils in Florida (Kalmbacher et al. 1997a; 1997b; 1997c). P. atratum BRA was consistently found to be the best grass on seasonally wet soils and it was released for pasture use by Ubon Ratchathani University in 1997 as cultivar Ubon (Hare et al. 1999a) and seed is readily available from the University (Hare et al. 1999b). In the above trials (Hare et al. 1999a), Ubon paspalum was compared with other grass species sown by seed, but para grass was not included as seed was unavailable. However, when our research found that Ubon paspalum could be established from tillers from older plants, we decided to evaluate Ubon paspalum and para grass in a series of trials. The objective of the research was to examine the production, quality and persistence of para grass and Ubon paspalum, with and without forage legumes, under different cutting regimes. Materials and methods The research was conducted in Ubon Ratchathani province, Thailand (15 N) on the Ubon Ratchathani University farm. Rainfall was recorded 1 km from the trial site (Table 1). The soil at the trial site is classified as a very sandy, low humic gley soil (Roi-et soil series) with some mixture of grey podzolic soil (Khorat soil series) and usually is waterlogged from July to early October. A soil test taken in June 1995 showed that the soil was acid (ph 4.6), with low organic matter ( %), N ( %) and P (3 13 ppm; Bray II extraction method) concentrations and very low K (20 50ppm). The site was formerly rice paddy land but prior to cultivation had supported native grasses (mainly Eremochloa spp.) for 6 years. Trial 1. Para grass with and without legumes and Trial 2. Ubon paspalum with and without legumes These two trials were planted adjacent to each other on the University farm. Para grass stems were cut from an established 5-year-old para grass pasture and Ubon paspalum tillers from 1-year-old plants on the University farm. Both species were hand planted into well cultivated seed beds with cm grid spacings, with each plot measuring 5 5 m. Each trial was a randomised complete block design with 4 replications and 5 legume treatments as follows: T1 no legume T2 with llanos macro (Macroptilium gracile cv. Maldonado) T3 with Cavalcade centurion (Centrosema pascuorum cv. Cavalcade) T4 with Lee American jointvetch (Aeschynomene americana cv. Lee) T5 with llanos macro, Cavalcade centurion and Lee American jointvetch. The para grass stems and Ubon paspalum tillers were planted on May 13, 1996, and on the same day, inoculated legume seed was broadcast at 6 kg/ha and lightly surface raked into the soil. The plots were fertilised at sowing with K (50 kg/ha), P (10 kg/ha) and S (20 kg/ha). Dry matter cuts were taken from four 0.25 m 2 quadrats cut 5 cm from ground level in each plot. The samples were sorted into grass and legumes, and a 200 g subsample of each species from each plot was dried at 70 C for 48 hours and dry weight recorded. In the second wet season only, dried subsamples were bulked across replicates and then 3 samples per treatment were analysed for total N in order to calculate crude protein levels (%N 6.25). Sampling dates were as follows: First wet season Trial 1. August 7 and September 24, Trial 2. August 28 and October 28, First dry season Trial 1. December 6, 1996, March 18 and April 28, Trial 2. February 4 and April 28, Second wet season Both trials. June 12, July 25, September 10 and November 5, Second dry season Both trials. January 6 and April 30, 1998.

3 Performance of para grass and Ubon paspalum 77 After each sampling cut, all plots were cut to about 5 cm above ground level, the forage removed and the plots fertilised with N (40 kg/ha), K (50 kg/ha), P (10 kg/ha) and S (20 kg/ha). Trial 3. Effect of cutting frequency on Ubon paspalum and para grass This trial was sited about 50 metres from Trials 1 and 2. The trial was a randomised complete block design comprising 2 grass species (Ubon paspalum and para grass), 2 cutting frequencies (30- and 45-day intervals in the first year and 30- and 60-day intervals in the second year) and 6 replications. Ubon paspalum and para grass were planted by tillers and stems, respectively, at cm spacings into a well cultivated seed bed on May 15, On the same day, seed of llanos macro, Cavalcade centurion and Lee American jointvetch was broadcast at 6 kg/ha, together with N (40 kg/ha), K (50 kg/ha), P (20 kg/ha) and S (20 kg/ha). The seed and fertiliser were lightly hand raked into the soil. Each plot measured 6 5 m. On July 10, 1997, 8 weeks after planting, all plots were cut to 10 cm above ground level and dry weights and grass and legume proportions recorded. From then until January 8, 1998, plots were cut at 30-day (6 cuts) or 45-day (4 cuts) intervals. At each cut, four 0.25 m 2 quadrats were cut to 10 cm above ground level from each plot, sorted into grass and legumes, weighed fresh, and a 200 g subsample of each species from each plot was dried at 70 C for 48 hours and dry weight recorded. This dried subsample was bulked across replicates and then 3 samples per treatment were analysed for total N in order to calculate crude protein levels (%N 6.25). After each sampling cut, the remaining forage in the plots was cut and removed and fertiliser applied at the same rates as at sowing, to the cut plots only. On April 24, 1998, all plots were cut to 10 cm above ground level and dry weights and grass and legume proportions recorded. Between that date and October 22, 1998, plots were cut at 30- day (6 cuts) or 60-day (3 cuts) intervals and cutting and sampling were as for Year 1 but fertiliser, at the same rates as at sowing, was applied to all plots every 30 days. Data from all trials were analysed using the IRRISTAT programme from IRRI. Crude protein data were not statistically analysed because samples were bulked across replicates. Results Rainfall Rainfall during the studies was similar to or slightly above the long-term average of 1563 mm/year (Table 1). Trial sites were waterlogged in September 1996 and from July to September 1997 following heavy rain. Wet season (May October) rainfall in 1998 was slightly below average, evenly distributed and without heavy thunderstorms, so waterlogging did not occur. Table 1. Rainfall (mm) at Ubon Ratchathani University during the study and the long-term mean. Month 1 14-year average, Rainfall Average (mm) January February March April May June July August September October November December Total Trial 1. Para grass with and without legumes Both para grass and legumes established well. In the first wet season, legumes grew well and these plots produced less para grass than pure grass plots (non-significant) but total yields were higher on plots containing llanos macro and the 3-legume combination (Table 2) than in the pure grass plots. Llanos macro and the combination produced more dry matter than did Lee jointvetch. Llanos macro contributed 45% of sward dry matter in the llanos macro-para grass plots and 37% in the 3-legume combination-para grass plots. In the first dry season, grass yield increased while legume yield declined. Total sward dry matter production was 15 35% higher on legume

4 78 M.D. Hare, P. Booncharern, P. Tatsapong, K. Wongpichet, C. Kaewkunya and K. Thummasaeng Table 2. Dry matter production (t/ha) from para grass swards with and without legumes at Ubon Ratchathani University, (Trial 1). No legume Llanos macro Cavalcade Lee jointvetch Llanos + Lee + Cavalcade LSD (P<0.05) First wet season (2 cuts) Para grass ns Legume Total First dry season (3 cuts) Para grass ns Legume ns Total Second wet season (4 cuts) Para grass ns Legume ns Total ns Second dry season (2 cuts) Para grass ns Legume plots than on pure grass plots, the differences being significant (P<0.05) for plots containing Cavalcade or the 3-legume combination (Table 2). In the second wet season, grass growth continued to increase while legume growth declined. Para grass produced more than 22 t/ha DM with no differences between pure para grass plots and para grass-legume plots (Table 2). Legumes contributed very little to dry matter production and by the fourth cut on November 5, 1997, the legumes had virtually disappeared. At the first cut in the second wet season (June 1997), para grass in legume plots contained higher crude protein than that from pure grass stands (5.4 vs 4.2%; Table 3). By the end of the second wet season, para grass averaged 5.5% crude protein in all plots. In the second dry season, there were no legumes in any plots and there were no differences in dry matter production between para grass plots (P>0.05; Table 2). Table 3. Crude protein percentage of para grass (Trial 1) and Ubon paspalum (Trial 2) at Ubon Ratchathani University in the second wet season. No legume Llanos macro Cavalcade Lee jointvetch Llanos + Lee + Cavalcade Para grass Cut Cut Cut Cut Average Ubon paspalum Table 3. Crude protein percentage of para grass (Trial 1) and Ubon paspalum (Trial 2) at Ubon Ratchathani University in the second wet season. Cut Cut Cut Cut Average Trial 2. Ubon paspalum with and without legumes All legumes and the grass established well. In the first wet season, Ubon paspalum produced significantly (P<0.05) more dry matter in pure grass plots than when mixed with legumes (Table 4). Although all legumes grew well ( t/ha DM), total dry matter production was similar (P>0.05) for all treatments. In the first dry season, grass yields increased and legume growth decreased. However, Ubon paspalum produced less dry matter in combination with llanos macro or the mixed legumes than when grown alone or with Lee jointvetch (Table 4). Plots containing Cavalcade were the most productive, producing significantly more legume than other legume plots and more total dry matter than the llanos macro and the 3- legume combination plots. Grass growth was excellent (mean 32 t/ha DM) during the second wet season while legumes declined. Cavalcade outyielded other legumes in both the Cavalcade and the 3-legume plots (Table 4). Lee jointvetch had disappeared

5 Performance of para grass and Ubon paspalum 79 Table 4. Dry matter production (t/ha) from Ubon paspalum swards with and without legumes at Ubon Ratchathani University, (Trial 2). No legume Llanos macro Cavalcade Lee jointvetch Llanos + Lee + Cavalcade LSD (P<0.05) First wet season (2 cuts) Ubon Legume ns Total ns First dry season (3 cuts) Ubon Legume Total Second wet season (4 cuts) Ubon ns Legume Total ns Second dry season (2 cuts) Ubon ns Legume by the second cut and llanos macro made only a minor contribution to dry matter production in the second wet season. Crude protein concentration in Ubon paspalum averaged 4.1% crude protein at the first wet season cut and increased to average 4.7% for the next 3 cuts (Table 3). Ubon paspalum produced, on average, 7 t/ha DM in the second dry season with significant differences between plots. All legumes had disappeared (Table 4). Total grass dry matter production during the second year was nearly 40 t/ha. In pure grass plots it was almost 43 t/ha. Trial 3. Effect of cutting frequency on Ubon paspalum and para grass In the first season, there were no differences in dry matter production between Ubon paspalum and para grass and between 30- and 45-day cutting intervals (Table 5). However, crude protein concentration of para grass was higher than that of Ubon paspalum and cutting every 30 days produced higher crude protein in both grasses than 45-day cutting intervals (Table 6). Para grass averaged 7.8% crude protein and Ubon paspalum 6.5% when cut every 30 days but, when cut every 45 days, relative values were 5.4% and 4.8%. Table 5. Effect of cutting interval on dry matter production of Ubon paspalum and para grass (Trial 3). Cutting interval Grass dry matter Table 5. Effect of cutting interval on dry matter production of Ubon paspalum and para grass (Trial 3). (t/ha) Period Jul 97 Jan days (6 cuts) days (4 cuts) LSD (P<0.05) 3.37 Period Apr Oct days (6 cuts) days (3 cuts) LSD (P<0.05) 8.04 In the second year, Ubon paspalum produced significantly more dry matter than para grass at both 30- and 60-day cutting intervals (Table 5). Cutting interval did not affect (P>0.05) yield of Ubon paspalum while para grass cut every 30 days produced nearly 40% less dry matter than when cut every 60 days. Crude protein concentration was again higher in para grass than Ubon paspalum and cutting every 30 days produced higher crude protein concentrations in both grasses than cutting every 60 days (Table 6). Para grass averaged 10.9% crude protein and Ubon paspalum 7.1% when cut every 30 days; however, when cut every 60 days, levels decreased to 7.7% and 6.0% for para grass and Ubon paspalum, respectively. In Trial 3, legumes made only a minor contribution to dry matter yield in the first wet season and, after the final cut in the first year in January 1998, had disappeared from all plots. Ubon paspalum Para grass

6 80 M.D. Hare, P. Booncharern, P. Tatsapong, K. Wongpichet, C. Kaewkunya and K. Thummasaeng Table 6. Effect of cutting interval on crude protein percentage of Ubon paspalum and para grass (Trial 3). Cutting interval Crude protein (%) July 97 Jan day (6 cuts) 45 day (6 cuts) Ubon paspalum Para grass Apr Oct day (6 cuts) 60 day (3 cuts) Ubon paspalum Para grass Discussion This study has shown that both para grass and Ubon paspalum can be successfully established vegetatively on infertile, low lying, periodically waterlogged soils in north-east Thailand. Establishment of para grass vegetatively is a well established practice (Schultze-Kraft and Teitzel 1992), but this study represents the first documented case of establishment of Ubon paspalum by vegetative propagation. For vegetative propagation to be successful, the soil must be moist at the time of planting and must remain moist throughout the establishment period. Establishing Ubon paspalum vegetatively is an advantage for small farmers who may not have access to seed and for seed growers to produce seed in the first year of establishment (Hare et al. 1999b). Both species produced about 20 t/ha DM in the first year of establishment when fertilised. They also grew well under lenient cutting over the dry season. However, it was in the second wet season that Ubon paspalum showed a productive advantage over para grass, producing, on average, 10 t/ha DM more than para grass in the 6-month wet season. Previous studies have also shown that, in the second and subsequent years after establishment, Ubon paspalum was the highest producing grass on wet lowland sites (Hare et al. 1999a). Furthermore, Ubon paspalum was significantly more productive than para grass under both frequent cutting (every 30 days) and infrequent cutting (every 60 days) in the second wet season. Kalmbacher et al. (1997a) found that cutting cv. Suerte every 20 days reduced annual yield compared with a 40- or 60-day cutting interval, but maximised nutritive value. In our studies, cutting every 30 days produced higher quality grass than a 45- or 60-day interval, but did not significantly reduce yields. In grazing trials at Ubon Ratchathani University (M.D. Hare, unpublished data), Ubon paspalum under a 21-day grazing interval produced leafy pasture and enabled young dairy cattle grazing at a stocking rate of 6.25 head/ha from June to September to gain 500g/hd/d. In village pasture systems, frequent cutting and overgrazing often weaken grass species and they fail to persist after 2 years. This has been a common problem with para grass and, in many farms, it is treated as an annual with replanting at the beginning of each wet season. In Trial 3, the para grass plots cut every 30 days carried a sparse cover at the end of the study. Ubon paspalum, however, seems to become more productive with time, particularly under frequent cutting or hard grazing. In Florida, Paspalum atratum cv. Suerte was tolerant of repeated defoliation during the wet season (Kalmbacher et al. 1997a) and in Brazil, P. atratum BRA , though establishing poorly, recovered in subsequent years under close grazing and trampling in association with Arachis pintoi (Barcellos et al. 1997). Ubon paspalum, therefore, appears to be suited to village pasture systems on low lying wet soils in Thailand. Legumes to use in association with either para grass or Ubon paspalum on waterlogged soils in Thailand have not yet been identified. Our initial research (Hare et al. 1999a) has failed to reveal any legume which could be recommended for use on such sites. The legumes grow well in the first wet season, decline over the first dry season and gradually disappear during the second wet season when sown with grasses. The ecosystem of wet and then dry conditions adds to the difficulty of legume persistence, productivity and sustainability. This study has shown that, while both para grass and Ubon paspalum are suited to lowland seasonally wet areas, Ubon paspalum is more

7 Performance of para grass and Ubon paspalum 81 productive and persistent in the second year after establishment, and more tolerant of repeated defoliation. Acknowledgements We thank the Thailand Research Fund for providing financial support to this research program and the Faculty of Agriculture, Ubon Ratchathani University for research facilities. We also thank Mrs Chaisang Phaikaew for advice during the program and Mr Sukri Saipraset for technical assistance. References BARCELLOS, A.O., PIZARRO, E.A. and COSTA, N.L. (1997) Agronomic evaluation of novel germplasm under grazing: Arachis pintoi BRA and Paspalum atratum BRA Proceedings of the XVIII International Grassland Congress. Session 22, pp HARE, M.D. and PHAIKAEW, C. (1998) Forage seed production in Northeast Thailand: A case history. In: Loch, D.S. and Ferguson, J.E. (eds) Forage Seed Production Volume 2: Tropical and Subtropical Species. pp (CAB International: Oxon, UK). HARE, M.D., THUMMASAENG, K., SURIYAJANTRATONG, W., WONGPICHET, K., SAENGKHAM, M., TATSAPONG, P., KAEWKUNYA, C. and BOONCHARERN, P. (1999a) Pasture grass and legume evaluation on seasonally waterlogged and seasonally dry soils in north-east Thailand. Tropical Grasslands, 33, HARE, M.D., WONGPICHET, K., TATSAPONG, P., NARK- SOMBAT, S. and SAENGKHAM, M. (1999b) Method of seed harvest, closing date and height of closing cut affect seed yield and seed yield components in Paspalum atratum in Thailand. Tropical Grasslands, 33, KALMBACHER, R.S., MULLAHEY, J.J., MARTIN, F.G. and KRET- SCHMER, A.E. JR, (1997a) Effect of clipping on yield and nutritive value of Suerte Paspalum atratum. Agronomy Journal, 89, KALMBACHER, R.S., PATE, F.M., MARTIN, F.G. and KRET- SCHMER, A.E. JR, (1997b) Supplementation of diets of weaned steers grazing Suerte Paspalum atratum. Soil and Crop Science Society of Florida Proceedings, 56, KALMBACHER, R.S., BROWN, W.F., COLVIN, D.L., DUNAVIN, L.S., KRETSCHMER, A.E. JR, MARTIN, F.G., MULLAHEY, J.J. and RECHCIGL, J.E. (1997c) Suerte atra paspalum. Its management and utilization. University of Florida, Agricultural Experimental Station. Circular S-397. MANNETJE, L. t and KERSTEN, S.M.M. (1992) Paspalum plicatulum Michaux. In: Mannetje, L. t and Jones, R.M. (eds) Plant Resources of South-East Asia No. 4: Forages. pp (Pudoc-DOC: Wageningen, the Netherlands). MITSUCHI, M., WICHAIDIT, P. and JEUNGNIJNIRUND, S. (1986) Outline of soils of the Northeast Plateau, Thailand. Their characteristics and constraints. Technical Paper No. 1. Agricultural Development Center in Northeast, Khon Kaen, Thailand. RAGLAND, J. and BOONPUCKDEE, L. (1986) Fertilizer responses in Northeast Thailand: a four part review. (NERAD Northeast Regional Office of Agriculture: Khon Kaen, Thailand). SCHULTZE-KRAFT, R. and TEITZEL, J.K. (1992) Brachiaria mutica (Forssk.) Stapf. In: Mannetje, L. t and Jones, R.M. (eds) Plant Resources of South-East Asia No. 4: Forages. pp (Pudoc-DOC: Wageningen, the Netherlands). STUR, W.W., HOPKINSON, J.M. and CHEN, C.P. (1996) Regional experience with Brachiaria: Asia, the South Pacific, and Australia. In: Miles, J.W., Maass, B.L. and Valle, C.B. do (eds) Brachiaria: Biology, Agronomy, and Improvement. pp (International Centre for Tropical Agriculture: CIAT, Colombia). SOPHANODORA, P. (1997) Crop-livestock integration in Southern Thailand: Prospects and constraints. In: Stur, W.W. (ed.) Feed Resources for Smallholder Livestock Production in Southeast Asia. pp CIAT Working Document No. 156, Los Banos, Philippines. TOPARK-NGARM, A. and GUTTERIDGE, R.C. (1986) Forages in Thailand. In: Blair, G.J., Ivory, D.A. and Evans, T.R. (eds) Forages in Southeast Asian and South Pacific Agriculture. ACIAR Proceedings No. 12. pp (ACIAR: Canberra, Australia). (Received for publication February 11, 1999; accepted April 29, 1999)