Evaluation of management options for increasing the productivity of tropical savanna pastures. 3. Trees

1989 ◽  
Vol 29 (5) ◽  
pp. 631 ◽  
Author(s):  
WH Winter ◽  
JJ Mott ◽  
RW McLean
Keyword(s):  
Dry Season ◽  
Perennial Grasses ◽  
Fertility Level ◽  
Wet Season ◽  
Management Options ◽  
Themeda Triandra ◽  
Weight Losses ◽  
Nitrogen Concentrations ◽  
The Mean ◽  
Stocking Rates

The effect of killing trees upon the production and quality of native perennial grasses, Themeda triandra, Chrysopogon fallax, Sehima nervosum, and Sorghum plumosum, and oversown legumes from the genus Stylosanthes, was studied over 4 years at Katherine, in the semi-arid tropics of northwestern Australia. The pastures were either unfertilised or received low inputs of superphosphate, and for each fertility level were grazed at 3 stocking rates. At no time were legume yields affected by killing the trees but, in the first 3 years, the amount of grass was approximately twice as much when the trees were killed. During this period the mean grass yields declined 4-5 fold from about 2.2 t/ha. By the fourth year the advantage from tree killing upon grass yield was apparent only at the lowest stocking rates at each fertility level. Nitrogen concentrations of the grasses and legumes, with the exception of S. hamata, were increased 7 and 10% respectively above the mean annual values of 0.89 and 1.75% where the trees were killed, while the phosphorus and sulfur concentrations were not affected. Tree killing had no effect upon wet season liveweight gains during the last 2 years of the experiment. However, there were some benefits during the dry season when weight losses were lower for most treatments during the early dry season (June-September) and also lower for the lowest stocking rate treatment without fertiliser during the late dry season (October-November).

Evaluation of management options for increasing the productivity of tropical savanna pastures. 1. Fertiliser

1989 ◽  
Vol 29 (5) ◽  
pp. 613 ◽  
Author(s):  
WH Winter ◽  
JJ Mott ◽  
RW McLean ◽  
D Ratcliff
Keyword(s):  
Nitrogen Concentration ◽  
Grazing Pressure ◽  
Perennial Grasses ◽  
Low Fertility ◽  
Stocking Rate ◽  
Wet Season ◽  
Management Options ◽  
Themeda Triandra ◽  
Stylosanthes Humilis ◽  
Stocking Rates

Options for increasing pasture and animal production from native perennial pastures comprising predominantly Themeda triandra, Chrysopogon fallax, Sehima nervosum and Sorghum plumosum were studied over 5 years at Katherine in the semi-arid tropics of north-western Australia. The pastures were augmented with either Stylosanthes humilis, S. hamata or a mixture of S. scabra and S. viscosa, either without fertiliser or with low inputs of superphosphate (100 kg/ha at establishment and 25 kg/ha annually), and with the trees either killed or left undisturbed. At each fertiliser level there were 3 stocking rates. Five years after sowing, only half of the pastures persisted, due to the poor productivity of the legumes and the inability of the native perennial grasses to tolerate high grazing pressure which was about 10-fold that for non-augmented native pasture. This effect was greater in the unfertilised treatments, where the legume contributed less to pasture yield, so that the sustainable stocking rate was only half of that for pastures fertilised with small amounts of superphosphate. When fertilised, stable pastures of nearly pure legume were obtained after 3-4 years at the highest stocking rate of 1 steer/ha. Fertiliser also (i) increased the nitrogen and sulfur concentrations of S. humilis and the perennial stylos S. scabra and S. viscosa, but lowered their concentrations in S. hamata, particularly in the early wet season; (ii) decreased nitrogen concentration in Chrysopogon fallax; and (iii) increased phosphorus and sulfur concentrations of all the perennial grasses. In general, fertiliser promoted higher liveweight gains of cattle during the wet season and lower losses during the dry season. In the fertilised treatments growth tended to be poorer at the highest stocking rate, particularly during the late dry and early wet seasons. This effect was attributed to spoilage of dry legume by the early rainfall and lack of grass in these treatments. We conclude that S. hamata, S. scabra and S. viscosa grow reasonably well in soils of low fertility, but the productivity of the legumes and of the cattle can be improved by small inputs of superphosphate. The mediocre growth of the cattle in all the treatments may have been due to the low levels of some nutrients, particularly phosphorus and sulfur, in these pastures.

Supplementation of steers grazing Stylosanthes hamata pastures at Katherine, Northern Territory

1988 ◽  
Vol 28 (6) ◽  
pp. 669 ◽  
Author(s):  
WH Winter
Keyword(s):  
Rock Phosphate ◽  
Perennial Grass ◽  
Dry Season ◽  
Fertility Level ◽  
Wet Season ◽  
Active Growth ◽  
Weight Losses ◽  
Stylosanthes Hamata ◽  
Brahman Steers ◽  
Native Perennial Grass

Native perennial grass pastures were oversown with Stylosanthes hamata cv. Verano at 3 fertility levels, i.e, without fertiliser or with suboptimal levels of superphosphate or rock phosphate. Brahman steers, of varying ages, grazed the pastures and their responses to fertility level and direct supplementation with phosphorus and sulfur were determined over 4 years. Phosphorus supplementation doubled liveweight gains during the early and late wet season periods to about 0.9 and 0-7 kg/day, respectively. Pasture fertility level did not affect gains in the early wet season in most years but superphosphate increased the late wet season gains by about 0.1 kg/day. Small weight losses usually occurred in all treatments during the early dry season, with losses increasing with animal age. Weight losses were highest during the late dry season, particularly for the older, phosphorus supplemented, steers. This response was attributed to size rather than to age or supplementation per se. Sulfur supplementation had no effect upon liveweight gain or upon the pastures at any time. In unfertilised pastures, Verano increased to about 25% of the dry matter composition whilst pastures fertilised with superphosphate and rock phosphate became legume dominant after 2 and 3 years, respectively. Fertiliser also increased the nitrogen, phosphorus and sulfur concentrations in the forage, particularly the Verano, with superphosphate more effective than rock phosphate. In pastures where steers were supplemented with phosphorus there was a higher proportion of the naturalised legume Alysicarpus vaginalis and a lesser quantity of forage on offer. Blood inorganic phosphate and rib cortical thickness were reliable indicators of responsiveness of steers to phosphorus supplementation when measured during, or immediately after, the period of active growth.

Seasonal use of savanna landscapes by the Gouldian finch, Erythrura gouldiae, in the Yinberrie Hills area, Northern Territory

2001 ◽  
Vol 28 (4) ◽  
pp. 445 ◽  
Author(s):  
P. L. Dostine ◽  
G. C. Johnson ◽  
D. C. Franklin ◽  
Y. Zhang ◽  
C. Hempel
Keyword(s):  
Full Range ◽  
Northern Territory ◽  
Dry Season ◽  
Perennial Grasses ◽  
Grass Species ◽  
Wet Season ◽  
Themeda Triandra ◽  
Annual Grasses ◽  
Gouldian Finch ◽  
Hills Area

The diet, attributes of feeding sites and patterns of seasonal movements of a population of the Gouldian finch, Erythrura gouldiae, were studied in the Yinberrie Hills area north of Katherine in the Northern Territory. In the dry season (April–November) Gouldian finches foraged mostly on burnt ground and fed on exposed seed of annual grasses, especially seed of spear-grass, Sorghum spp. In the wet season (December–March) Gouldian finches fed on seed of a sequence of perennial grass species, including Themeda triandra, Alloteropsis semialata, Chrysopogon fallax and Heteropogon triticeus. Gouldian finches undertake regular seasonal shifts in habitat, from breeding areas in hill woodland in the dry season to adjacent lowlands throughout much of the wet season, in response to seasonal changes in food availability. There is an annual pulse in abundance of fallen seed in the early dry season that is depleted to near zero levels by germination of annual grasses early in the wet season. Thereafter, finches depend on seed from other sources, principally ripe and ripening seed of perennial grasses. Observations over three successive wet seasons suggest that Gouldian finches track seed resources provided by seeding perennial grasses over an extensive area of lowland grassy woodland adjacent to the breeding area, favouring small patches of grassy woodland for brief periods until seed fall. There were subtle differences between years in the types of resources used. Management of Gouldian finch populations will entail protection and management of the full range of grassland habitats used throughout the annual cycle, and will require predictive knowledge of the causes of patterning of seed resources and probably an ability to exert control over the timing and extent of fires in fire-prone seasonal savanna landscapes.

Evaluation of management options for increasing the productivity of tropical savanna pastures. 2. Legume species

1989 ◽  
Vol 29 (5) ◽  
pp. 623 ◽  
Author(s):  
WH Winter ◽  
JJ Mott ◽  
RW McLean
Keyword(s):  
Perennial Grasses ◽  
Legume Species ◽  
Forage Production ◽  
Wet Season ◽  
Management Options ◽  
Stylosanthes Humilis ◽  
Northwestern Australia ◽  
Animal Growth ◽  
Townsville Stylo ◽  
Stocking Rates

The effect of legume species, used for augmentation of native perennial grasses, upon forage production and quality and animal production was studied over 4 vears in the semi-arid troPics of northwestern Australia. The legumes were Stylosanthes humilis cv. Paterson (Townsville stylo), S. hamata cv. Verano (Caribbean stylo) and a mixture of perennial species S. scabra cvv. Fitzroy and Seca and S. viscosa (perennial stylo). They were compared at 2 levels of fertility, unfertilised (UF) and with small inputs of superphosphate (F); and at stocking rates of 0.45,0.6 and 0.75 steers/ha for UF and 0.6, 0.8 and 1.0 steers/ha for F. By 1980 only half of the 3 x 12 treatments persisted, 3 Townsville stylo, 9 Caribbean stylo and 6 perennial stylo. Without fertiliser the perennial stylos had the highest wet season yields of 1-2 t/ha which constituted 4040% of pasture yield, compared with 2-20% for the other legumes. Caribbean stylo yields were highest with fertiliser, yielding 2-4 t/ha and 50-90% of the pasture at the end of the wet season, compared with 60-70% for perennial stylo and 5-30% for Townsville stylo. Anthracnose devastated Townsville stylo, and also reduced the productivity of Fitzroy. The perennial stylos had the highest concentrations of nitrogen (N), phosphorus (P), and sulfur (S) during the dry season while Caribbean stylo and its associated grasses had the lowest P and S concentrations during the wet season. When annual liveweight gains for each legume were compared at the same stocking rate-fertiliser level, differences were less than 15 kg, but there were considerable differences in the patterns of growth within the year; these differences were related to the seasonal availability and relative palatability of grass and legume. The overall mediocre animal growth of 30-110 kg/steer.year was attributed to the inadequate supply of nutrients for most of the year, with the possible exception of N.

Effects of moisture supply in the dry season and subsequent defoliation on persistence of the savanna grasses Themeda triandra, Heteropogon contortus and Panicum maximum

1992 ◽  
Vol 43 (2) ◽  
pp. 241 ◽  
Author(s):  
JJ Mott ◽  
MM Ludlow ◽  
JH Richards ◽  
AD Parsons
Keyword(s):  
Growing Season ◽  
Close Correlation ◽  
Dry Season ◽  
Carbon Gain ◽  
Panicum Maximum ◽  
Wet Season ◽  
Themeda Triandra ◽  
Heteropogon Contortus ◽  
Moisture Conditions ◽  
Sheath Material

The close correlation between grazing-induced mortality and major climatic patterns in Australian savannas, led us to the hypothesis that moisture conditions during the dry, non-growing season could affect sensitivity to grazing in the subsequent growing season. Using three widespread savanna species (Themeda triandra, Heteropogon contortus and Panicum maximum), this hypothesis was tested experimentally and the mechanisms controlling this response examined and quantified. In T. triandra drought during the dry season led to major mortality in defoliated plants in the next growing season. This mortality was caused by a synchrony of tillering at the commencement of the wet season, leaving few buds for replacement once parent tillers were killed by defoliation. T. triandra was also the most sensitive species to defoliation. This sensitivity was due to the poor ability of the plant to maintain positive carbon gain after defoliation. Several factors contributed to this poor ability, including: low total photosynthetic rate, low specific leaf area, and a large proportion of sheath material with poor photosynthetic capacity remaining after cutting. Both H. contortus and P. maximum growing under irrigated and fertilized conditions did not display any effects of previous moisture treatments when defoliated during the next wet season and were much less sensitive to defoliation than T. triandra.

Beef production from native pastures sown to fine-stem stylo in the Burnett region of south-eastern Queensland

1979 ◽  
Vol 19 (97) ◽  
pp. 140 ◽  
Author(s):  
EJ Bowen ◽  
KG Rickert
Keyword(s):  
Stocking Rate ◽  
Management Options ◽  
North West ◽  
Heteropogon Contortus ◽  
South Eastern ◽  
Continuous Grazing ◽  
Weight Gains ◽  
The Mean ◽  
Native Pastures ◽  
Stocking Rates

At Gayndah, south-eastern Queensland, a native Heteropogon contortus pasture, sown to fine-stem stylo (Stylosanthes guianensis var. intermedia), and invaded by red natal grass (Rhynchelytrum repens), was grazed by weaner steers from June 1 in three treatments : heavy and light put-and-take grazing for five years from 1971, and set-stocked at 1.37 animals ha-1 for two years from 1974. Weight gains in the put-and-take treatments were not significantly different. The mean annual liveweight gain was 167 kg animal-1 at a mean equivalent stocking rate of 1.47 animals ha-1. Over the same period unsown native pasture, cleared of timber, gave a gain of 62 kg animal-1 at 0.62 animals ha-1. In all seasons except summer, weight gains declined linearly with stocking rate and in 1972-73, with a mean equivalent stocking rate of 2.66 animals ha-1, the annual gain was almost halved. When equivalent stocking rates were 0.9, 0.9, 1.8 and 1.2 animals ha-1 in winter, spring, summer and autumn, the respective gains were 4, 73, 65 and 45 kg animal-1. The set-stocked treatment had a mean annual gain of 147 kg animal-1. At another site 116 km north-west of Gayndah, two paddocks of Heteropogon contortus and fine-stem stylo were set-stocked with weaners over four years. One paddock had four applications of superphosphate of 250 kg ha-1. The mean annual liveweight gains were significantly different, being 154 and 143 kg animal-1 in the fertilized and unfertilized paddocks at mean stocking rates of 0.83 and 0.74 animals ha-1, respectively. In a grazing protection experiment the density of fine-stem stylo declined exponentially with an accumulation of pasture dry matter in spring and summer. Heavy continuous grazing, an annual hay cut and an accidental fire all increased the density of fine-stem stylo. Management options to maintain the density of fine-stem stylo and the relative importance of the legume and grass to animal production are discussed.

scholarly journals Investigation of Heavy Metals Level in selected Boreholes around the Vicinity of some Cemeteries in Benin City, Nigeria

2021 ◽  
Vol 25 (5) ◽  
pp. 841-845
Author(s):  
C.A.E. Ibhadode ◽  
I.R. Ilaboya
Keyword(s):  
Heavy Metals ◽  
Pollution Index ◽  
Mean Value ◽  
Dry Season ◽  
Wet Season ◽  
Monthly Basis ◽  
Benin City ◽  
Standard Procedures ◽  
The Mean ◽  
Mean Concentration

Groundwater pollution by heavy metals such as lead, copper, nickel and iron is one of the major environmental issues of concern which has developed into a widely studied area. In this study, attempt was made to investigate the level of heavy metals in selected boreholes around the vicinity of cemeteries in Benin City. Seventy-two (72) samples of groundwater were taken from boreholes in 9 stations around the three cemeteries in Benin City on monthly basis. The samples were analysed for 7 heavy metals, in accordance with standard procedures. The heavy metals include; Zinc, Lead Iron, Copper, Cadmium, Nickel and Mercury. From the results of the study, a variation in the mean concentration of zinc was observed. The mean concentration of zinc in site 1 was 0.450mg/l, for site 2, it was 0.140mg/l and for site 3, it was 1.0533mg/l. For iron, mean concentration was 0.072mg/l in site 1. For site 2, mean concentration of iron was 2.140mg/l and for site 3, mean concentration of iron was 0.560mg/l. It was further revealed based on the results that mean value of heavy metals in groundwater around cemeteries in Benin City were generally lower during dry season compared to wet season. In addition, result of computed pollution index (Pi) revealed that the heavy metal with the highest potential to pollute groundwater is Cadmium, with Pi of 0.5333 and 0.400 representing dry season and wet season respectively.

scholarly journals Aircraft observations of the chemical composition and aging of aerosol in the Manaus urban plume during GoAmazon 2014/5

2018 ◽  
Vol 18 (14) ◽  
pp. 10773-10797 ◽  
Author(s):  
John E. Shilling ◽  
Mikhail S. Pekour ◽  
Edward C. Fortner ◽  
Paulo Artaxo ◽  
Suzane de Sá ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Oxidation State ◽  
Biomass Burning ◽  
Urban Pollution ◽  
Organic Aerosol ◽  
Dry Season ◽  
Carbon Oxidation ◽  
Wet Season ◽  
The Mean ◽  
American Cities

Abstract. The Green Ocean Amazon (GoAmazon 2014/5) campaign, conducted from January 2014 to December 2015 in the vicinity of Manaus, Brazil, was designed to study the aerosol life cycle and aerosol–cloud interactions in both pristine and anthropogenically influenced conditions. As part of this campaign, the U.S. Department of Energy (DOE) Gulfstream 1 (G-1) research aircraft was deployed from 17 February to 25 March 2014 (wet season) and 6 September to 5 October 2014 (dry season) to investigate aerosol and cloud properties aloft. Here, we present results from the G-1 deployments focusing on measurements of the aerosol chemical composition and secondary organic aerosol (SOA) formation and aging. In the first portion of the paper, we provide an overview of the data and compare and contrast the data from the wet and dry season. Organic aerosol (OA) dominates the deployment-averaged chemical composition, comprising 80 % of the non-refractory PM1 aerosol mass, with sulfate comprising 14 %, nitrate 2 %, and ammonium 4 %. This product distribution was unchanged between seasons, despite the fact that total aerosol loading was significantly higher in the dry season and that regional and local biomass burning was a significant source of OA mass in the dry, but not wet, season. However, the OA was more oxidized in the dry season, with the median of the mean carbon oxidation state increasing from −0.45 in the wet season to −0.02 in the dry season. In the second portion of the paper, we discuss the evolution of the Manaus plume, focusing on 13 March 2014, one of the exemplary days in the wet season. On this flight, we observe a clear increase in OA concentrations in the Manaus plume relative to the background. As the plume is transported downwind and ages, we observe dynamic changes in the OA. The mean carbon oxidation state of the OA increases from −0.6 to −0.45 during the 4–5 h of photochemical aging. Hydrocarbon-like organic aerosol (HOA) mass is lost, with ΔHOA∕ΔCO values decreasing from 17.6 µg m−3 ppmv−1 over Manaus to 10.6 µg m−3 ppmv−1 95 km downwind. Loss of HOA is balanced out by formation of oxygenated organic aerosol (OOA), with ΔOOA∕ΔCO increasing from 9.2 to 23.1 µg m−3 ppmv−1. Because hydrocarbon-like organic aerosol (HOA) loss is balanced by OOA formation, we observe little change in the net Δorg∕ΔCO values; Δorg∕ΔCO averages 31 µg m−3 ppmv−1 and does not increase with aging. Analysis of the Manaus plume evolution using data from two additional flights in the wet season showed similar trends in Δorg∕ΔCO to the 13 March flight; Δorg∕ΔCO values averaged 34 µg m−3 ppmv−1 and showed little change over 4–6.5 h of aging. Our observation of constant Δorg∕ΔCO are in contrast to literature studies of the outflow of several North American cities, which report significant increases in Δorg∕ΔCO for the first day of plume aging. These observations suggest that SOA formation in the Manaus plume occurs, at least in part, by a different mechanism than observed in urban outflow plumes in most other literature studies. Constant Δorg∕ΔCO with plume aging has been observed in many biomass burning plumes, but we are unaware of reports of fresh urban emissions aging in this manner. These observations show that urban pollution emitted from Manaus in the wet season forms less particulate downwind as it ages than urban pollution emitted from North American cities.

scholarly journals Optical and Geometrical Properties of Cirrus Clouds in Amazonia Derived From 1-year of Ground-based Lidar Measurements

2016 ◽  
Author(s):  
Diego A. Gouveia ◽  
Boris Barja ◽  
Henrique M. J. Barbosa ◽  
Theotônio Pauliquevis ◽  
Paulo Artaxo
Keyword(s):  
Optical Depth ◽  
Diurnal Cycle ◽  
High Frequency ◽  
Dry Season ◽  
Cirrus Clouds ◽  
Cloud Base ◽  
Wet Season ◽  
Geometrical Properties ◽  
Lidar Ratio ◽  
The Mean

Abstract. For one year, from July 2011 to June 2012, a ground-based raman lidar provided atmospheric observations north of Manaus, Brazil, at an experimental site (2.89° S and 59.97° W) for long-term aerosol and cloud measurements. Upper tropospheric cirrus clouds were observed more frequently than previous reports in tropical regions. The frequency of occurrence was found to be as high as 82 % during the wet season and not lower than 55 % during the dry season. The diurnal cycle shows a minimum around local noon and maximum during late afternoon, associated with the diurnal cycle precipitation. Optical and geometrical characteristics of these cirrus clouds were derived. The mean values were 14.4 ± 2.0 km (top), 12.7 ± 2.3 km (base), 1.7 ± 1.5 km (thickness), and 0.36 ± 1.20 (cloud optical depth). Cirrus clouds were found at temperatures down to –90 °C and 7 % were above the tropopause base. The vertical distribution was not uniform and two cloud types were identified: (1) cloud base > 14 km and optical depth ~0.02, and (2) cloud base < 14 km and optical depth ~0.2. A third type, not previously reported, was identified during the wet season, between 16 and 18 km with optical depth ~0.005. The mean lidar ratio was 20.2 ± 7.0 sr, indicating a mixture of thick plates and long columns. However, the clouds above 14 km have a bimodal distribution during the dry season with a secondary peak at about 40 sr suggesting that thin plates are a major habit. A dependence of the lidar ratio with cloud temperature (altitude) was not found, thus indicating they are well mixed in the vertical. Cirrus clouds classified as subvisible (τ < 0.03) were 40 %, whilst 37.7 % were thin cirrus (0.03 < τ < 0.3) and 22.3 % opaque cirrus (τ > 0.3). Hence, not only does the central Amazon have a high frequency of cirrus clouds, but a large fraction of subvisible cirrus clouds as well. This high frequency of subvisible cirrus clouds may contaminate aerosol optical depth measured by sun-photometers and satellite sensors to an unknown extent.

The water intake of milking cows grazing Pangola grass (Digitaria decumbens Stent.) under wet- and dry-season conditions in Trinidad

1962 ◽  
Vol 58 (2) ◽  
pp. 257-264 ◽  
Author(s):  
P. N. Wilson ◽  
M. A. Barratt ◽  
M. H. Butterworth
Keyword(s):  
Water Intake ◽  
Free Water ◽  
Dry Season ◽  
Feed Water ◽  
Zebu Cattle ◽  
Wet Season ◽  
Drinking Habits ◽  
Digitaria Decumbens ◽  
Coefficients Of Variation ◽  
The Mean

1. The water intakes of ten Holstein × Zebu milking cows, yielding between one and two gallons of milk a day, were analysed on the basis of (a) freewater drunk, and (b) feed-water consumed with the herbage. Trials took place during a 10-day period in both the wet season, 1959 and the dry season, 1960. During both seasons the cows were rotationally grazed on Pangola grass pastures.2. The results showed a difference of only 24% in total water intake between seasons. However, the mean intake of free water increased from 18·5 lb. per cow in the wet season to 81·5 lb. per cow per day in the dry season, and the intake of feed water decreased from 94·9 to 59·2 lb. per cow per day, respectively. The between cow coefficients of variation were 9·7 and 8·7%, respectively.3. Results are presented for the drinking habits of Holstein × Zebu cattle grazing Pangola grass pastures. For 567 observed cow-days in the wet season, the cattle were found to drink water on average 0·8 times per day from troughs present in the pastures. For 332 observed cow-days in the dry season, the cattle increased their drinking habits to a mean figure of 1·4 times each day.

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