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Productive and stable pasture systems for cattle fattening in the humid tropics. 2. Field testing on a naturally infertile site
Agricultural Systems 36 (1991) 267-277
Productive and Stable Pasture Systems for Cattle Fattening in the Humid Tropics. 2. Field Testing on a Naturally Infertile Site
J. K. Teitzel & R. J. Wilson Queensland Department of Primary Industries, South Johnstone, Queensland 4859, Australia (Received 13 November 1989; revised version accepted 28 November 1990)
ABSTRACT Selected pasture/cattle fattening systems were studied on a site representative of'forest grassland country', a land class once considered to be too infertile for improved pasture development. All Grass/Legume systems were compared with Integrated systems which integrated a grass/nitrogen pasture with grass~legume pastures. Various supplementary feeding systems were also evaluated. The objective was to mimic commercial cattle fattening enterprises, on a small scale, to determine safe carrying capacities and predictable beef production levels for the different systems. All Grass/Legume and lntegrated pasture systems were able to be stocked at an average of 2.5 and 3"6 steers ha- x and gave average liveweight increases of 512 and 578kg ha -1 yr -1, respectively. These were similar to levels of production attained with equivalent systems on a naturally fertile site. There was no evidence to suggest that the pastures were any less stable on the less favoured site. Thus, productivity and stability were a function of grazing management and fertilizer, regardless of initial soil fertility status.
INTRODUCTION Research leading to the development of an improved pasture technology, for the humid tropics o f Queensland, is described by Teitzel and Middleton 267 Agricultural Systems 0308-521X/91/$03"50 © 1991 Elsevier SciencePublishers Ltd, England. Printed in Great Britain
268
J. K. Teitzel, R. J. Wilson
(1980). Synthesis into a number of alternative pasture/cattle fattening systems is described in Part 1 of this series (Teitzel et al., 1991). This paper reports the field testing of similar systems on a site representative of the infertile 'forest grassland' or 'open schlerophyll forest' land class of the humid tropics of Queensland. Soil infertility was such that a Ministerial Committee of Enquiry reported (Sloan et aL, 1962) that 'No evidence was placed before the committee to show that forest grassland could be developed economically with improved pastures for intensive cattle fattening'. The objective was to determine maximum sustainable production from alternative pasture systems managed in a commercially realistic way on an infertile land class. The performance of the selected systems on a naturally fertile site is reported in Part 1 (Teitzel et al., 1991). Extrapolation of a wider range of management options over a range of commercial farming situations is reported in Part 3 (Teitzel, 1991).
MATERIALS AND METHODS
Description of the systems and experimental design The following six treatment systems were initially selected for comparison in a randomized block experiment with two replications: (1) (2) (3) (4) (5) (6)
All Grass/Legume: old varieties All Grass/Legume: new varieties All Grass/Legume: old varieties + supplement All Grass/Legume: new varieties + supplement Integrated: old varieties Integrated: new varieties
The old varieties were grass/legume associations of C o m m o n guinea grass
(Panicum maximum cv. Common), C o m m o n centro (Centrosema pubescens cv. Common) and Schofield stylo (Stylosanthes guianensis cv. Schofield). The new varieties were pastures of the above old varieties oversown with Makueni guinea (P. maximum cv. Makueni) and Cook stylo (S. guianensis cv. Cook). Belalto centro (C. pubescens cv. Belalto), a component of the new varieties on the fertile site (see Part 1: Teitzel et al., 1991), was not included here because seed was not available. In any case, when the experiment was initiated, the site was considered to be 'stylo country' (infertile) rather than 'centro country' (fertile). The All Grass/Legume: old varieties system, based on the most commonly used grass/legume pasture and receiving the recommended fertilizer
Cattle fattening in the humid tropics. 2
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programme, provided a 'control' treatment. Two systems with features designed to compensate for the poor cool season productivity of this grass/legume system were then formulated in the manner described in Part 1 (Teitzel et al., 1991). These were (a) the use of new varieties of grasses and legumes selected for their cool season productivity, and (b) the integration of the higher winter productivity and carrying capacity of a N-fertilized signal grass (Brachiaria decumbens) pasture with the economy of grass/legume pastures (Integrated system). Integrated systems had 75% of the area as grass/legume (various cultivars) and 25% grass/N (signal grass fertilized with 180kg N ha - l yr-l). In addition to pasture options, there was a general perception among local cattlemen that the land class under study would be incapable of fattening cattle without some form of supplementary feeding. Fattening systems involving supplementary feeding were therefore included in this study. As with the experiment on the fertile site, each treatment unit was designed to approximate a single whole farm production unit. In this experiment, the treatment units were 2-43ha instead of 1.62ha. It was expected that larger areas of the infertile land would be required to carry similar numbers of cattle. Two replicates of six treatment units resulted in a total experimental area of 29-16 ha. Because of difficulties with management supervision and costs of additional fencing and watering, it was decided not to employ a rotational grazing system on the All Grass/Legume units. Unit sub-division was of course essential on the Integrated systems where the management concept involved confining the cattle to the grass/N pasture to relieve pressure on the more delicate grass/legume pasture which would otherwise be preferentially grazed. The Integrated units therefore consisted of two paddocks: 1"82 ha of grass/legume and 0.61 ha of grass/N.
Pasture establishment When the experimental site was taken over, there was an existing commercial pasture mixture of about 80% C o m m o n guinea grass, about 10% Schofield stylo, < 2% C o m m o n centro, < 2% Calopo (Calopogonium mucunoides), with the remainder being weeds. Because of remoteness and private ownership of the land, the landowner's machinery had to be used and it was not possible to achieve the treatment purity or managerial control attained with the sister experiment on the fertile site which was located on a research station (see Part 1: Teitzel et al., 1991). The landowner agreed to discing the existing pasture land twice before fertilizer and seed of the desired treatment species were broadcast, harrowed and then rolled, in December 1972. Other farmers and extension officers
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advised that higher inputs for pasture replacement would not be commercially acceptable.
Experimental site and soil fertility A site representative of the 'layered schlerophyll forest: granitic soil' land class (Teitzel & Bruce, 1971) was provided on the Tully River Station (145 ° 45'E, 17° 57'S, 40 m ASL) by King Ranch Australia. The recommended establishment fertilizer application for this land class was 500kg superphosphate, 100 kg potassium chloride, 10 kg copper sulphate and l0 kg zinc sulphate ha-1 (Teitzel, 1979). Soil screening for the current study isolated an additional need for molybdenum. The above recommended fertilizers, together with 0.5kg sodium molybate, were applied at planting in 1972. Thereafter, 300 kg superphosphate was applied every two years and the above rates of trace elements every four years.
Supplementary feeding Supplementary feeding treatments varied from time to time. The first series consisted of feeding molasses (containing copper and cobalt sulphates) at the rate of 4 kg head - 1 d - 1 in treatment systems 3 and 4 during the winter and spring of 1974. Because of problems with feral animals and labour costs this was discontinued. Supplementation was again initiated on 6 October 1978. Proprietary mixes (meal and block forms of'Rumevite Green Feed Instant') provided by Rumevite Pty Ltd, Brisbane, were fed in treatment systems 3 and 4. These were designed as complete feed supplements for cattle on green pasture or crops and contain molasses dried solubles, crushed grain, vegetable protein meal, urea, biuret, tricalcium phosphate, copper sulphate, cobalt sulphate, potassium iodate and vegetable oil. Blocks were provided continuously whilst the meal was fed at the rate of 300 g head- 1 d - 1. Cobalt bullets and grinders were administered to half the cattle on a 'split plot' basis beginning on 27 April 1979. This cobalt supplementation continued with each successive new draft of cattle for the remainder of the experiment. During this period, treatment systems 3 and 4 were also used to determine any possible effect from supplementing with rock salt. Salt was fed a d lib in treatment 3, and 56 g head- 1 d - 1 in treatment 4. This was continued until the experiment was terminated on 25 January 1980.
Grazing management During the warm wet season (January-March), the two paddocks of the
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Integrated systems were grazed at a similar pressure on a four week rotation; i.e. three weeks in the 1.82 ha grass/legume paddock and one week on the 0.61 ha grass/2q paddocks. As the seasons became drier and cooler, the rotation was increased to eight weeks, with the cattle spending four of the eight weeks in the grassfN paddock. However, during occasional periods of unseasonal prolonged wet weather, the programme was changed back to the warm wet season cycle. Principles of stocking rate adjustment and general animal management were basically similar to those described for the fertile site (Teitzel et al., 1991). An exception was the use of yearling bulls instead of yearling steers in the December quarter of 1975 and the March quarter of 1976. This was done because the property owners were concerned about the growth rates of locally bred bulls. During 1973 there were various grazings and mechanical slashings to control the excess pasture growth. Stocking rates were initially set at 1 steer h a - 1 in all treatments. However, the pasture response to fertilizers was far greater than anticipated. Pastures grew above cattle and fence height, resulting in broken fence lines and some uncontrolled grazing. F r o m 1974 to 1977, stocking rates were varied (from 2.5 to 3"7 steers h a - 1) at the normal stock replacement periods (see Part 1: Teitzel et al., 1991). These were more than double the anticipated maximum stocking rates for the land class and exceeded stock watering capacity during the dry season. It was not possible to upgrade watering facilities and impose the desired management until the end of 1977. Pasture sampling then commenced and continued at quarterly intervals until November 1979. The 1978-79 period was one of 'regulated grazing' during which stocking rates were effectively regulated on the basis of feed supplies. Stocking rates therefore varied between treatments. The objective was to determine the maximum sustainable animal production levels from each treatment system. Procedures and decision rules were similar to those described in Part 1 (Teitzel et al., 1991) for the experiment on the fertile site. However, unlike that experiment, this 'regulated' period was not followed by a period of deliberate overgrazing. As the current experiment was on a private property it was unacceptable to induce the heavy weed infestations which were the result of deliberate crash grazing on the fertile site. Measurements
Procedures for cattle weighing, soil fertility monitoring and pasture assessment were similar to those described for the sister experiment on the fertile site (Teitzel et al., 1991).
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RESULTS Climatic data The dominant climatic features are the heavy falls of rain in the warm months of January, February and March and the cooler, drier periods in July, August and September. Rainfall, hours of bright sunshine, and maximum and minimum temperatures recorded at South Johnstone Research Station (46 km NE of this experiment) are presented in Part 1 (Teitzel et al., 1991). Average annual rainfall and daily temperature were 3528mm and 23.5°C, respectively. Notable deviations from average conditions included the exceptionally wet conditions in the January March quarters of 1977 and 1979. The heavy rainfall in January-March 1979 was accompanied by an average of only 4-6 h d - ~ of bright sunshine. Other deviations were the low temperatures in the July-September quarter of 1976 and the dry July-September quarters of 1976 and 1978. Pasture establishment Following germination, there were about six plants m-2 of Cook stylo and one plant m - 2 of Makueni guinea grass in the new varieties treatments. The dominant component of all grass/legume paddocks until mid 1973 was Schofield stylo. In contrast, there was strong establishment of signal grass in the grass/N paddocks of the Integrated systems. Makueni guinea and Cook stylo had virtually disappeared by 1975 and Common guinea and Common centro became the dominant species in all the grass/legume paddocks. Cultivar comparisons, therefore, were not achieved and subsequent data presentation is summarized accordingly. Grass/legume versus Integrated systems All Grass/Legume treatments 1 and 2 are contrasted with Integrated treatments 5 and 6 in Table 1 for the regulated grazing phase (1978 and 1979). During 1978, the Integrated system had higher yields of forage on offer despite the application of higher stocking rates. However, by the February 1979 pasture sampling, the situation had reversed. Readjustment of stocking rates resulted in roughly equivalent forage yields during mid 1979, but, by late 1979, pastures in the Integrated systems were again the highest yielding. Animal growth rates were lowest in the Integrated systems in all except one of the eight quarters of the study period. The averages were 0-44 and 0.52 kg head- 1day- 1 for the Integrated and All Grass/Legume systems, respectively.
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TABLE 1 Forage Yields, Stocking Rates and Cattle Liveweight Gains from the All Grass/Legume and Integrated Pasture Systems
Dale (year & quarter)
Grass/Legume
Integrated
Forage yield (kgha-1)
Stocking rate (steersha-1)
Steer L WG (kgd- 1)
Forage yield (kgha- l)
Stocking rate (steersha-1)
Steer L WG (kgd-1)
1978
1 2 3 4
3 645 3 518 2 368 2 937
3.4 2.5 2.5 2.5
0-66 0-48 0-23 0-65
6 153 5 043 3 843 3 977
3'7 3.7 3"7 3.7
0-53 0"62 0.15 0.46
1979
1 2 3 4
5 197 3 962 2 251 1 498
2.6 2'9 2'9 2.5
0"34 0"65 0-55 0-56
4868 3 335 2 524 2 053
3-7 3"7 3"7 3' 1
0"29 0"57 0-47 0"39
3 172
2.7
0.52
3 975
3.6
0.44
aAverage
"LWG ha -1 yr -1
512
578
Average of 2 years.
The corresponding average forage yields were 3975 and 3172kg ha -1 However, dividing these yields by the average stocking rates of 3-6 and 2.7 steers h a - 1 indicate similar grazing pressures of 1104 kg of forage head - 1 for the Integrated systems and 1175 kg for the All Grass/Legume systems. Total animal production per year was 578 and 512kg ha -1 for the Integrated and All Grass/Legume systems, respectively. Pasture yield and composition for these two systems are presented in Table 2. Grass was the dominant component of all pasture types. Legumes had disappeared from the grass/N pastures by 1979 but made up 6-18% of the grass/legume pastures of both systems. The average composition of the legume component during the 1978-79 period was 94.7% centro, 0"1% stylo and 5-2% calopo. Weed content in November 1977 was around 3% in the All Grass/Legume systems and 1% in both pasture types of the Integrated systems. Two years later it had increased to 10% in the all Grass/Legume systems and 8% in the grass/legume paddocks of the Integrated systems but remained at around 1% in the grass/N paddocks of the Integrated systems. Broadleaf weeds (mainly Ageratum spp., Solanum spp. and Sida spp.) were virtually non-existent in the grass/N paddocks but averaged 57% of the weed yield in the grass/legume paddocks at the November 1977 sampling. Over the next two years grass weeds (mainly Paspalum conjugatum, Imperata cylindrica and Sporobolus spp.) gradually increased relative to broadleaf
J. K. Teitzel, R. J. Wilson
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TABLE 2 Yield of Pasture Components (kg DM ha 1) in All Grass/Legume and Integrated Systems
Sampling All Grass~Legume system date Grass Legume Weeds
Integrated system Grass~Legume portion
Grass/N portion
Grass Legume Weeds
Grass Legume Weeds
Nov. 1977
2 876
191
95
4 844
302
64
5 287
3
41
Feb. 1978 May. 1978 Aug. 1978 Nov. 1978
3434 3 122 2136 2 602
211 396 232 335
110 135 96 181
5604 4 225 3997 3 741
438 491 375 466
42 53 36 79
6848 6019 2262 3 289
2 1 3 1
68 33 17 71
Feb. 1979 May. 1979 Aug. 1979 Nov. 1979
4 208 3 388 1 997 1308
903 574 254 192
224 286 236 165
4468 3 193 2 329 1716
878 413 193 121
301 208 177 151
2 976 2 528 2 527 2993
0 0 0 0
6 11 36 20
weeds. By the N o v e m b e r 1979 s a m p l i n g , grass weeds a v e r a g e d 98 % o f weed yield, with Paspalum conjugatum the d o m i n a n t grass.
Molasses supplementation D a i l y liveweight g a i n o f steers o n g r a s s / l e g u m e was o n a v e r a g e 0.14 k g d - t higher in the m o l a s s e s feeding t r e a t m e n t s . It w a s s u b s e q u e n t l y d i s c o v e r e d t h a t some, if n o t all, b a t c h e s o f m o l a s s e s delivered to the trial site c o n t a i n e d copper and cobalt supplements.
Proprietary mix supplementation T h e r e w a s n o r e s p o n s e to c o m p l e t e feed s u p p l e m e n t s as b l o c k s or meal.
Cobalt and salt supplementation A n i m a l liveweight gains were i n c r e a s e d by 0.12 kg h e a d - ~ d - ~ (P < 0.05) b y injecting c o b a l t bullets b u t t h e r e were n o effects f r o m feeding salt.
Bull growth rates G r o w t h rates o f y o u n g s t a t i o n b r e d S a n t a G e r t r u d i s bulls u s e d d u r i n g 1975 a n d 1976 a v e r a g e d a r o u n d 0.2 k g h e a d - 1 d - 1 with n o o b s e r v a b l e differences b e t w e e n the different t r e a t m e n t systems.
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Cattle fattening in the humid tropics. 2
TABLE 3 Average Annual (1978/79) Performance of Grass/Legume and Integrated Systems on Naturally Fertile and Infertile Sites System
Pasture yield (kg D M ha- x)
Stocking rate (steers ha- 1)
Liveweight d- 1 (kg steer d- 1)
Liveweight ha- 1 (kg/ha- 1)
All Grass/Legume Infertile site Fertile site
3 172 2 775
2-7 3-0
0-52 0"40
512 438
Integrated Infertile site Fertile site
3 975 3 623
3.6 3'55
0.44 0-43
578 551
Soil fertility When the area was taken over for the experiment in 1973 extractable P and K levels were 9 ppm and 0.29 meq.%, respectively. The following year (after routine fertilizer application) levels were 24 ppm and 0.27 meq.%, and at the end of the study period (1979) they were 39 ppm P and 0.36 meq.% K. Soil pH levels averaged 5.8 in the grass/legume paddocks and 5.6 in the grass/N paddocks at the end of the experiment. Comparison with similar systems on a fertile site The performance of the Integrated and All Grass/Legume systems on the infertile site are contrasted with that from corresponding systems on the fertile site in Table 3. T h e s e data represent the 1978/79 averages of treatments 1 and 2 (Grass/Legume), and 5 and 6 (Integrated), over two replicates on the infertile site and treatment 1 (All Grass/Legume: old varieties), and treatment 3 (Integrated: old varieties), over three replicates on the fertile site. Except for the higher stocking rate in the Grass/Legume system on the fertile site, marginally superior performance was recorded on the infertile site.
DISCUSSION Although the land class under study was once judged to be unsuitable for the development of a cattle fattening industry based on improved pastures (Sloan et al., 1962), this study showed that productive and stable management systems were possible. Following the correction of pasture
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J. K. Teitzel, R. J. Wilson
deficiencies of phosphorus, copper, zinc, molybdenum and potassium, and cattle deficiencies of cobalt, All Grass/Legume, and Integrated systems averaged stocking rates of 2.7 and 3"6 steers h a - 1 with liveweight increases of 512 and 578 kg h a - 1 yr- 1, respectively. These are close to the projections of safe carrying capacities and animal production levels for similar pasture systems on a naturally fertile site (see Part 1: Teitzel et al., 1991). Pasture yield and composition from equivalent systems also were similar on both soil types. There was no discernible disadvantage from continuous grazing. The continuously grazed All Grass/Legume system on the infertile site was, in fact, slightly more productive than the rotationally grazed All Grass/ Legume system on the fertile site. This experiment did not give clear indications of the value of feeding molasses, Rumevite or salt. However, contrary to early beliefs, similar pasture systems gave similar levels of production on the fertile and infertile sites without these supplements. On the other hand, cattle may require cobalt supplementation to give equivalent production levels. An unexpected result was the poor performance of locally bred bulls. The low weight gains were possibly due to the above cobalt deficiency which is likely to be more prevalent in locally bred animals than in animals from areas with a higher soil cobalt status. The poor performance of the new varieties of grass and legume was disappointing as they had been selected for the area. Makueni guinea failed to establish satisfactorily with the commercial land preparation given to the site. Poor seedling regeneration was also a characteristic on the fertile site where considerable effort had gone into ensuring that the new varieties were satisfactorily established in the designated treatment systems. Cook stylo was established reasonably satisfactorily but failed to persist, as did Schofield stylo, the recommended old variety of legume for the land class under study. This disappearance of the stylo varieties was offset by rapid spread of centro (the recommended old variety for fertile sites) following fertilizer application. It would appear that stylo is unable to compete with the vigorous grass which follows correction of mineral deficiencies. At a later stage in the experiment, the stylo population was depleted further by anthracnose. The main conclusion regarding the pasture/cattle fattening systems is that in this humid tropical environment, it is possible to compensate for initial differences in soil fertility status. Recommended regional fertilizer programmes resulted in similar production from equivalent systems on naturally fertile and infertile sites. Although the systems on the infertile site (a private property) were not deliberately overstressed, as were those on the fertile site (a research station), there is no evidence that they would be any less resilient.
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Thus productivity and stability were a function of stock management and fertilizer, regardless of initial soil fertility status.
A C K N O W L E D G E M ENTS The late M r R. A. Abbott, M r A. E. Holmes and M r W. A. Albrecht contributed skilled assistance on m a n y occasions throughout the experiment. The land, structures, machinery, stock, fertilizer and labour associated with pasture and stock management were provided by King Ranch Australia. The support and encouragement of King Ranch and its resident managers, first M r Neil Alderman and then Mr Richard Luck, was much appreciated. Specialist research finance was provided by the Australian Meat Research Committee. Soil chemical analyses were conducted by Agricultural Chemistry Branch o f the Queensland Department o f Primary Industries.
REFERENCES Sloan, W. J. S., Owens, A. J. & Johnston, M. A. (1962). Report of the North Queensland Land Classification Committee, 1960-61. Office of the Minister for Lands and Irrigation, Brisbane. Teitzel, J. K. (1979). Formulation of pasture fertilizer programs for the wet tropical coast of Australia. In Pasture Production in Acid Soils of the Tropics, ed. P. A. Sanchez & L. E. Tergas. CIAT Series 03EG-5, Centro Internacional de Agricultura Tropical, Colombia, pp. 95-108. Teitzel, J. K. (1991). Productive and stable pasture systems for cattle fattening in the humid tropics. 3. Development and use of a computer model to evaluate management options. Agric. Syst., 36, 279-96. Teitzel, J. K. & Bruce, R. C. (1971). Fertility studies of pasture soils in the wet tropical coast of Queensland. 1. Soil-vegetation classification units. Australian Journal of Experimental Agricultural and Animal Husbandry, 11(1), 71-6. Teitzel, J. K. & Middleton, C. H. (1980). Pasture research by the South Johnstone Research Station. Agriculture Branch Technical Report No. 22. Queensland Department of Primary Industries, Brisbane. Teitzel, J. K., Wilson, R. J. & Mellor, W. (1991). Productive and stable pasture systems for cattle fattening in the humid tropics. 1. Field testing on a naturally fertile site. Agric. Syst., 36, 251-265.
Productive and Stable Pasture Systems for Cattle Fattening in the Humid Tropics. 2. Field Testing on a Naturally Infertile Site
J. K. Teitzel & R. J. Wilson Queensland Department of Primary Industries, South Johnstone, Queensland 4859, Australia (Received 13 November 1989; revised version accepted 28 November 1990)
ABSTRACT Selected pasture/cattle fattening systems were studied on a site representative of'forest grassland country', a land class once considered to be too infertile for improved pasture development. All Grass/Legume systems were compared with Integrated systems which integrated a grass/nitrogen pasture with grass~legume pastures. Various supplementary feeding systems were also evaluated. The objective was to mimic commercial cattle fattening enterprises, on a small scale, to determine safe carrying capacities and predictable beef production levels for the different systems. All Grass/Legume and lntegrated pasture systems were able to be stocked at an average of 2.5 and 3"6 steers ha- x and gave average liveweight increases of 512 and 578kg ha -1 yr -1, respectively. These were similar to levels of production attained with equivalent systems on a naturally fertile site. There was no evidence to suggest that the pastures were any less stable on the less favoured site. Thus, productivity and stability were a function of grazing management and fertilizer, regardless of initial soil fertility status.
INTRODUCTION Research leading to the development of an improved pasture technology, for the humid tropics o f Queensland, is described by Teitzel and Middleton 267 Agricultural Systems 0308-521X/91/$03"50 © 1991 Elsevier SciencePublishers Ltd, England. Printed in Great Britain
268
J. K. Teitzel, R. J. Wilson
(1980). Synthesis into a number of alternative pasture/cattle fattening systems is described in Part 1 of this series (Teitzel et al., 1991). This paper reports the field testing of similar systems on a site representative of the infertile 'forest grassland' or 'open schlerophyll forest' land class of the humid tropics of Queensland. Soil infertility was such that a Ministerial Committee of Enquiry reported (Sloan et aL, 1962) that 'No evidence was placed before the committee to show that forest grassland could be developed economically with improved pastures for intensive cattle fattening'. The objective was to determine maximum sustainable production from alternative pasture systems managed in a commercially realistic way on an infertile land class. The performance of the selected systems on a naturally fertile site is reported in Part 1 (Teitzel et al., 1991). Extrapolation of a wider range of management options over a range of commercial farming situations is reported in Part 3 (Teitzel, 1991).
MATERIALS AND METHODS
Description of the systems and experimental design The following six treatment systems were initially selected for comparison in a randomized block experiment with two replications: (1) (2) (3) (4) (5) (6)
All Grass/Legume: old varieties All Grass/Legume: new varieties All Grass/Legume: old varieties + supplement All Grass/Legume: new varieties + supplement Integrated: old varieties Integrated: new varieties
The old varieties were grass/legume associations of C o m m o n guinea grass
(Panicum maximum cv. Common), C o m m o n centro (Centrosema pubescens cv. Common) and Schofield stylo (Stylosanthes guianensis cv. Schofield). The new varieties were pastures of the above old varieties oversown with Makueni guinea (P. maximum cv. Makueni) and Cook stylo (S. guianensis cv. Cook). Belalto centro (C. pubescens cv. Belalto), a component of the new varieties on the fertile site (see Part 1: Teitzel et al., 1991), was not included here because seed was not available. In any case, when the experiment was initiated, the site was considered to be 'stylo country' (infertile) rather than 'centro country' (fertile). The All Grass/Legume: old varieties system, based on the most commonly used grass/legume pasture and receiving the recommended fertilizer
Cattle fattening in the humid tropics. 2
269
programme, provided a 'control' treatment. Two systems with features designed to compensate for the poor cool season productivity of this grass/legume system were then formulated in the manner described in Part 1 (Teitzel et al., 1991). These were (a) the use of new varieties of grasses and legumes selected for their cool season productivity, and (b) the integration of the higher winter productivity and carrying capacity of a N-fertilized signal grass (Brachiaria decumbens) pasture with the economy of grass/legume pastures (Integrated system). Integrated systems had 75% of the area as grass/legume (various cultivars) and 25% grass/N (signal grass fertilized with 180kg N ha - l yr-l). In addition to pasture options, there was a general perception among local cattlemen that the land class under study would be incapable of fattening cattle without some form of supplementary feeding. Fattening systems involving supplementary feeding were therefore included in this study. As with the experiment on the fertile site, each treatment unit was designed to approximate a single whole farm production unit. In this experiment, the treatment units were 2-43ha instead of 1.62ha. It was expected that larger areas of the infertile land would be required to carry similar numbers of cattle. Two replicates of six treatment units resulted in a total experimental area of 29-16 ha. Because of difficulties with management supervision and costs of additional fencing and watering, it was decided not to employ a rotational grazing system on the All Grass/Legume units. Unit sub-division was of course essential on the Integrated systems where the management concept involved confining the cattle to the grass/N pasture to relieve pressure on the more delicate grass/legume pasture which would otherwise be preferentially grazed. The Integrated units therefore consisted of two paddocks: 1"82 ha of grass/legume and 0.61 ha of grass/N.
Pasture establishment When the experimental site was taken over, there was an existing commercial pasture mixture of about 80% C o m m o n guinea grass, about 10% Schofield stylo, < 2% C o m m o n centro, < 2% Calopo (Calopogonium mucunoides), with the remainder being weeds. Because of remoteness and private ownership of the land, the landowner's machinery had to be used and it was not possible to achieve the treatment purity or managerial control attained with the sister experiment on the fertile site which was located on a research station (see Part 1: Teitzel et al., 1991). The landowner agreed to discing the existing pasture land twice before fertilizer and seed of the desired treatment species were broadcast, harrowed and then rolled, in December 1972. Other farmers and extension officers
270
J. K. Teitzel, R. J. Wilson
advised that higher inputs for pasture replacement would not be commercially acceptable.
Experimental site and soil fertility A site representative of the 'layered schlerophyll forest: granitic soil' land class (Teitzel & Bruce, 1971) was provided on the Tully River Station (145 ° 45'E, 17° 57'S, 40 m ASL) by King Ranch Australia. The recommended establishment fertilizer application for this land class was 500kg superphosphate, 100 kg potassium chloride, 10 kg copper sulphate and l0 kg zinc sulphate ha-1 (Teitzel, 1979). Soil screening for the current study isolated an additional need for molybdenum. The above recommended fertilizers, together with 0.5kg sodium molybate, were applied at planting in 1972. Thereafter, 300 kg superphosphate was applied every two years and the above rates of trace elements every four years.
Supplementary feeding Supplementary feeding treatments varied from time to time. The first series consisted of feeding molasses (containing copper and cobalt sulphates) at the rate of 4 kg head - 1 d - 1 in treatment systems 3 and 4 during the winter and spring of 1974. Because of problems with feral animals and labour costs this was discontinued. Supplementation was again initiated on 6 October 1978. Proprietary mixes (meal and block forms of'Rumevite Green Feed Instant') provided by Rumevite Pty Ltd, Brisbane, were fed in treatment systems 3 and 4. These were designed as complete feed supplements for cattle on green pasture or crops and contain molasses dried solubles, crushed grain, vegetable protein meal, urea, biuret, tricalcium phosphate, copper sulphate, cobalt sulphate, potassium iodate and vegetable oil. Blocks were provided continuously whilst the meal was fed at the rate of 300 g head- 1 d - 1. Cobalt bullets and grinders were administered to half the cattle on a 'split plot' basis beginning on 27 April 1979. This cobalt supplementation continued with each successive new draft of cattle for the remainder of the experiment. During this period, treatment systems 3 and 4 were also used to determine any possible effect from supplementing with rock salt. Salt was fed a d lib in treatment 3, and 56 g head- 1 d - 1 in treatment 4. This was continued until the experiment was terminated on 25 January 1980.
Grazing management During the warm wet season (January-March), the two paddocks of the
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Integrated systems were grazed at a similar pressure on a four week rotation; i.e. three weeks in the 1.82 ha grass/legume paddock and one week on the 0.61 ha grass/2q paddocks. As the seasons became drier and cooler, the rotation was increased to eight weeks, with the cattle spending four of the eight weeks in the grassfN paddock. However, during occasional periods of unseasonal prolonged wet weather, the programme was changed back to the warm wet season cycle. Principles of stocking rate adjustment and general animal management were basically similar to those described for the fertile site (Teitzel et al., 1991). An exception was the use of yearling bulls instead of yearling steers in the December quarter of 1975 and the March quarter of 1976. This was done because the property owners were concerned about the growth rates of locally bred bulls. During 1973 there were various grazings and mechanical slashings to control the excess pasture growth. Stocking rates were initially set at 1 steer h a - 1 in all treatments. However, the pasture response to fertilizers was far greater than anticipated. Pastures grew above cattle and fence height, resulting in broken fence lines and some uncontrolled grazing. F r o m 1974 to 1977, stocking rates were varied (from 2.5 to 3"7 steers h a - 1) at the normal stock replacement periods (see Part 1: Teitzel et al., 1991). These were more than double the anticipated maximum stocking rates for the land class and exceeded stock watering capacity during the dry season. It was not possible to upgrade watering facilities and impose the desired management until the end of 1977. Pasture sampling then commenced and continued at quarterly intervals until November 1979. The 1978-79 period was one of 'regulated grazing' during which stocking rates were effectively regulated on the basis of feed supplies. Stocking rates therefore varied between treatments. The objective was to determine the maximum sustainable animal production levels from each treatment system. Procedures and decision rules were similar to those described in Part 1 (Teitzel et al., 1991) for the experiment on the fertile site. However, unlike that experiment, this 'regulated' period was not followed by a period of deliberate overgrazing. As the current experiment was on a private property it was unacceptable to induce the heavy weed infestations which were the result of deliberate crash grazing on the fertile site. Measurements
Procedures for cattle weighing, soil fertility monitoring and pasture assessment were similar to those described for the sister experiment on the fertile site (Teitzel et al., 1991).
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RESULTS Climatic data The dominant climatic features are the heavy falls of rain in the warm months of January, February and March and the cooler, drier periods in July, August and September. Rainfall, hours of bright sunshine, and maximum and minimum temperatures recorded at South Johnstone Research Station (46 km NE of this experiment) are presented in Part 1 (Teitzel et al., 1991). Average annual rainfall and daily temperature were 3528mm and 23.5°C, respectively. Notable deviations from average conditions included the exceptionally wet conditions in the January March quarters of 1977 and 1979. The heavy rainfall in January-March 1979 was accompanied by an average of only 4-6 h d - ~ of bright sunshine. Other deviations were the low temperatures in the July-September quarter of 1976 and the dry July-September quarters of 1976 and 1978. Pasture establishment Following germination, there were about six plants m-2 of Cook stylo and one plant m - 2 of Makueni guinea grass in the new varieties treatments. The dominant component of all grass/legume paddocks until mid 1973 was Schofield stylo. In contrast, there was strong establishment of signal grass in the grass/N paddocks of the Integrated systems. Makueni guinea and Cook stylo had virtually disappeared by 1975 and Common guinea and Common centro became the dominant species in all the grass/legume paddocks. Cultivar comparisons, therefore, were not achieved and subsequent data presentation is summarized accordingly. Grass/legume versus Integrated systems All Grass/Legume treatments 1 and 2 are contrasted with Integrated treatments 5 and 6 in Table 1 for the regulated grazing phase (1978 and 1979). During 1978, the Integrated system had higher yields of forage on offer despite the application of higher stocking rates. However, by the February 1979 pasture sampling, the situation had reversed. Readjustment of stocking rates resulted in roughly equivalent forage yields during mid 1979, but, by late 1979, pastures in the Integrated systems were again the highest yielding. Animal growth rates were lowest in the Integrated systems in all except one of the eight quarters of the study period. The averages were 0-44 and 0.52 kg head- 1day- 1 for the Integrated and All Grass/Legume systems, respectively.
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TABLE 1 Forage Yields, Stocking Rates and Cattle Liveweight Gains from the All Grass/Legume and Integrated Pasture Systems
Dale (year & quarter)
Grass/Legume
Integrated
Forage yield (kgha-1)
Stocking rate (steersha-1)
Steer L WG (kgd- 1)
Forage yield (kgha- l)
Stocking rate (steersha-1)
Steer L WG (kgd-1)
1978
1 2 3 4
3 645 3 518 2 368 2 937
3.4 2.5 2.5 2.5
0-66 0-48 0-23 0-65
6 153 5 043 3 843 3 977
3'7 3.7 3"7 3.7
0-53 0"62 0.15 0.46
1979
1 2 3 4
5 197 3 962 2 251 1 498
2.6 2'9 2'9 2.5
0"34 0"65 0-55 0-56
4868 3 335 2 524 2 053
3-7 3"7 3"7 3' 1
0"29 0"57 0-47 0"39
3 172
2.7
0.52
3 975
3.6
0.44
aAverage
"LWG ha -1 yr -1
512
578
Average of 2 years.
The corresponding average forage yields were 3975 and 3172kg ha -1 However, dividing these yields by the average stocking rates of 3-6 and 2.7 steers h a - 1 indicate similar grazing pressures of 1104 kg of forage head - 1 for the Integrated systems and 1175 kg for the All Grass/Legume systems. Total animal production per year was 578 and 512kg ha -1 for the Integrated and All Grass/Legume systems, respectively. Pasture yield and composition for these two systems are presented in Table 2. Grass was the dominant component of all pasture types. Legumes had disappeared from the grass/N pastures by 1979 but made up 6-18% of the grass/legume pastures of both systems. The average composition of the legume component during the 1978-79 period was 94.7% centro, 0"1% stylo and 5-2% calopo. Weed content in November 1977 was around 3% in the All Grass/Legume systems and 1% in both pasture types of the Integrated systems. Two years later it had increased to 10% in the all Grass/Legume systems and 8% in the grass/legume paddocks of the Integrated systems but remained at around 1% in the grass/N paddocks of the Integrated systems. Broadleaf weeds (mainly Ageratum spp., Solanum spp. and Sida spp.) were virtually non-existent in the grass/N paddocks but averaged 57% of the weed yield in the grass/legume paddocks at the November 1977 sampling. Over the next two years grass weeds (mainly Paspalum conjugatum, Imperata cylindrica and Sporobolus spp.) gradually increased relative to broadleaf
J. K. Teitzel, R. J. Wilson
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TABLE 2 Yield of Pasture Components (kg DM ha 1) in All Grass/Legume and Integrated Systems
Sampling All Grass~Legume system date Grass Legume Weeds
Integrated system Grass~Legume portion
Grass/N portion
Grass Legume Weeds
Grass Legume Weeds
Nov. 1977
2 876
191
95
4 844
302
64
5 287
3
41
Feb. 1978 May. 1978 Aug. 1978 Nov. 1978
3434 3 122 2136 2 602
211 396 232 335
110 135 96 181
5604 4 225 3997 3 741
438 491 375 466
42 53 36 79
6848 6019 2262 3 289
2 1 3 1
68 33 17 71
Feb. 1979 May. 1979 Aug. 1979 Nov. 1979
4 208 3 388 1 997 1308
903 574 254 192
224 286 236 165
4468 3 193 2 329 1716
878 413 193 121
301 208 177 151
2 976 2 528 2 527 2993
0 0 0 0
6 11 36 20
weeds. By the N o v e m b e r 1979 s a m p l i n g , grass weeds a v e r a g e d 98 % o f weed yield, with Paspalum conjugatum the d o m i n a n t grass.
Molasses supplementation D a i l y liveweight g a i n o f steers o n g r a s s / l e g u m e was o n a v e r a g e 0.14 k g d - t higher in the m o l a s s e s feeding t r e a t m e n t s . It w a s s u b s e q u e n t l y d i s c o v e r e d t h a t some, if n o t all, b a t c h e s o f m o l a s s e s delivered to the trial site c o n t a i n e d copper and cobalt supplements.
Proprietary mix supplementation T h e r e w a s n o r e s p o n s e to c o m p l e t e feed s u p p l e m e n t s as b l o c k s or meal.
Cobalt and salt supplementation A n i m a l liveweight gains were i n c r e a s e d by 0.12 kg h e a d - ~ d - ~ (P < 0.05) b y injecting c o b a l t bullets b u t t h e r e were n o effects f r o m feeding salt.
Bull growth rates G r o w t h rates o f y o u n g s t a t i o n b r e d S a n t a G e r t r u d i s bulls u s e d d u r i n g 1975 a n d 1976 a v e r a g e d a r o u n d 0.2 k g h e a d - 1 d - 1 with n o o b s e r v a b l e differences b e t w e e n the different t r e a t m e n t systems.
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Cattle fattening in the humid tropics. 2
TABLE 3 Average Annual (1978/79) Performance of Grass/Legume and Integrated Systems on Naturally Fertile and Infertile Sites System
Pasture yield (kg D M ha- x)
Stocking rate (steers ha- 1)
Liveweight d- 1 (kg steer d- 1)
Liveweight ha- 1 (kg/ha- 1)
All Grass/Legume Infertile site Fertile site
3 172 2 775
2-7 3-0
0-52 0"40
512 438
Integrated Infertile site Fertile site
3 975 3 623
3.6 3'55
0.44 0-43
578 551
Soil fertility When the area was taken over for the experiment in 1973 extractable P and K levels were 9 ppm and 0.29 meq.%, respectively. The following year (after routine fertilizer application) levels were 24 ppm and 0.27 meq.%, and at the end of the study period (1979) they were 39 ppm P and 0.36 meq.% K. Soil pH levels averaged 5.8 in the grass/legume paddocks and 5.6 in the grass/N paddocks at the end of the experiment. Comparison with similar systems on a fertile site The performance of the Integrated and All Grass/Legume systems on the infertile site are contrasted with that from corresponding systems on the fertile site in Table 3. T h e s e data represent the 1978/79 averages of treatments 1 and 2 (Grass/Legume), and 5 and 6 (Integrated), over two replicates on the infertile site and treatment 1 (All Grass/Legume: old varieties), and treatment 3 (Integrated: old varieties), over three replicates on the fertile site. Except for the higher stocking rate in the Grass/Legume system on the fertile site, marginally superior performance was recorded on the infertile site.
DISCUSSION Although the land class under study was once judged to be unsuitable for the development of a cattle fattening industry based on improved pastures (Sloan et al., 1962), this study showed that productive and stable management systems were possible. Following the correction of pasture
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J. K. Teitzel, R. J. Wilson
deficiencies of phosphorus, copper, zinc, molybdenum and potassium, and cattle deficiencies of cobalt, All Grass/Legume, and Integrated systems averaged stocking rates of 2.7 and 3"6 steers h a - 1 with liveweight increases of 512 and 578 kg h a - 1 yr- 1, respectively. These are close to the projections of safe carrying capacities and animal production levels for similar pasture systems on a naturally fertile site (see Part 1: Teitzel et al., 1991). Pasture yield and composition from equivalent systems also were similar on both soil types. There was no discernible disadvantage from continuous grazing. The continuously grazed All Grass/Legume system on the infertile site was, in fact, slightly more productive than the rotationally grazed All Grass/ Legume system on the fertile site. This experiment did not give clear indications of the value of feeding molasses, Rumevite or salt. However, contrary to early beliefs, similar pasture systems gave similar levels of production on the fertile and infertile sites without these supplements. On the other hand, cattle may require cobalt supplementation to give equivalent production levels. An unexpected result was the poor performance of locally bred bulls. The low weight gains were possibly due to the above cobalt deficiency which is likely to be more prevalent in locally bred animals than in animals from areas with a higher soil cobalt status. The poor performance of the new varieties of grass and legume was disappointing as they had been selected for the area. Makueni guinea failed to establish satisfactorily with the commercial land preparation given to the site. Poor seedling regeneration was also a characteristic on the fertile site where considerable effort had gone into ensuring that the new varieties were satisfactorily established in the designated treatment systems. Cook stylo was established reasonably satisfactorily but failed to persist, as did Schofield stylo, the recommended old variety of legume for the land class under study. This disappearance of the stylo varieties was offset by rapid spread of centro (the recommended old variety for fertile sites) following fertilizer application. It would appear that stylo is unable to compete with the vigorous grass which follows correction of mineral deficiencies. At a later stage in the experiment, the stylo population was depleted further by anthracnose. The main conclusion regarding the pasture/cattle fattening systems is that in this humid tropical environment, it is possible to compensate for initial differences in soil fertility status. Recommended regional fertilizer programmes resulted in similar production from equivalent systems on naturally fertile and infertile sites. Although the systems on the infertile site (a private property) were not deliberately overstressed, as were those on the fertile site (a research station), there is no evidence that they would be any less resilient.
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Thus productivity and stability were a function of stock management and fertilizer, regardless of initial soil fertility status.
A C K N O W L E D G E M ENTS The late M r R. A. Abbott, M r A. E. Holmes and M r W. A. Albrecht contributed skilled assistance on m a n y occasions throughout the experiment. The land, structures, machinery, stock, fertilizer and labour associated with pasture and stock management were provided by King Ranch Australia. The support and encouragement of King Ranch and its resident managers, first M r Neil Alderman and then Mr Richard Luck, was much appreciated. Specialist research finance was provided by the Australian Meat Research Committee. Soil chemical analyses were conducted by Agricultural Chemistry Branch o f the Queensland Department o f Primary Industries.
REFERENCES Sloan, W. J. S., Owens, A. J. & Johnston, M. A. (1962). Report of the North Queensland Land Classification Committee, 1960-61. Office of the Minister for Lands and Irrigation, Brisbane. Teitzel, J. K. (1979). Formulation of pasture fertilizer programs for the wet tropical coast of Australia. In Pasture Production in Acid Soils of the Tropics, ed. P. A. Sanchez & L. E. Tergas. CIAT Series 03EG-5, Centro Internacional de Agricultura Tropical, Colombia, pp. 95-108. Teitzel, J. K. (1991). Productive and stable pasture systems for cattle fattening in the humid tropics. 3. Development and use of a computer model to evaluate management options. Agric. Syst., 36, 279-96. Teitzel, J. K. & Bruce, R. C. (1971). Fertility studies of pasture soils in the wet tropical coast of Queensland. 1. Soil-vegetation classification units. Australian Journal of Experimental Agricultural and Animal Husbandry, 11(1), 71-6. Teitzel, J. K. & Middleton, C. H. (1980). Pasture research by the South Johnstone Research Station. Agriculture Branch Technical Report No. 22. Queensland Department of Primary Industries, Brisbane. Teitzel, J. K., Wilson, R. J. & Mellor, W. (1991). Productive and stable pasture systems for cattle fattening in the humid tropics. 1. Field testing on a naturally fertile site. Agric. Syst., 36, 251-265.