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Richard J Thomas - One of the best experts on this subject based on the ideXlab platform.
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use of deep rooted Tropical Pastures to build up an arable layer through improved soil properties of an oxisol in the eastern plains llanos orientales of colombia
Agriculture Ecosystems & Environment, 2004Co-Authors: Edgar Amezquita, Richard J Thomas, D Molina, P HoyosAbstract:Abstract It is widely believed that Tropical soils (mainly Oxisols) have excellent physical characteristics such as high infiltration rates, high permeability of water, good and stable soil structure and that consequently, they can support mechanized agriculture. However in the Eastern Plains (Llanos Orientales) of Colombia, when Oxisols are subjected to tillage using disc harrow, soil physical conditions deteriorate rapidly. We report here that change in land use with deep-rooted Tropical Pastures can enhance soil quality by improving the size and stability of soil aggregates when compared with soils under monocropping. In addition, rates of water infiltration improved by 5–10-fold while rainfall acceptance capacity improved by 3–5-fold. We suggest that intensive and sustainable use of these Oxisols, could only be possible if an “arable” or “productive layer” (i.e. a layer with improved soil physical, chemical and biological properties) is constructed and maintained. One option to achieve this arable layer is through the use of introduced Tropical Pastures with deep-rooting abilities that can result in increased soil organic matter and associated improvements in soil physical, chemical and biological properties. One land use option that can achieve these soil improvements is agropastoralism whereby Pastures and crops are grown in short-term rotations.
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assessing the organic phosphorus status of an oxisol under Tropical Pastures following native savanna using 31p nmr spectroscopy
Biology and Fertility of Soils, 1996Co-Authors: Georg Guggenberger, Ludwig Haumaier, Richard J Thomas, Wolfgang ZechAbstract:31P nuclear magnetic resonance (NMR) spectroscopy, P fractionation, and a P sorption experiment were used to follow the changes in P in the A horizons (0–10 cm) of acid savanna soils, Colombia, after little P fertilization and 15 years' continuous growth of a grass (Brachiaria decumbens) and a grass/legume (B. decumbens+Pueraria phaseoloides) pasture. Ready P supply as analyzed by Bray P was low under native savanna (1.3 mg kg-1 soil) and responded moderately on pasture establishment. Concurrently, the affinity of the soil for inorganic P declined slightly after pasture establishment. 31P NMR spectroscopy revealed that P associated with humic acids was dominated by monoester P followed by diester P. Smaller proportions were observed for phosphonates, teichoic acid P, orthophosphate, and pyrophosphate. P associated with fulvic acids had lower proportions of diester P and higher contents of orthophosphate. Under native savanna the reserves of labile organic P species (phosphonates and diester P including teichoic acid P) associated with humic and fulvic acids were 12.4 and 1.1 kg ha-1, respectively, and increased to 18.1 and 1.8 kg ha-1 under grass pasture, and to 19.5 and 2.3 kg ha-1 under grass/legume pasture. These data emphasize the importance of labile organic P species in the P supply for plants in improved Tropical Pastures, and further indicate that humic acid P in particular responds to land-use changes within a relatively short time-scale. Earthworm casts were highly abundant in the B. decumbens+P. phaseoloides plot and were enriched in labile organic P species. We conclude that earthworm activity improves the P supply in soil under Tropical Pastures by creating an easily available organic P pool.
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lignin and carbohydrate alteration in particle size separates of an oxisol under Tropical Pastures following native savanna
Soil Biology & Biochemistry, 1995Co-Authors: Georg Guggenberger, Wolfgang Zech, Richard J ThomasAbstract:Abstract Establishment of improved Tropical Pastures on acid savanna soils of low fertility can increase the soil organic matter (SOM) content and soil fertility. Our objective was to follow the quantitative and qualitative changes of SOM associated with sand-, silt-and clay-sized separates after establishment of a grass-alone (Brachiaria decumbens) and a grass-legume (Brachiaria decumbens + Pueraria phaseoloides) pasture on isohyperthermic savanna soils of Colombia. Additionally, earthworm casts of anecic and endo-anecic species derived from the grass-legume pasture were investigated. Whole soil and size separates were analyzed for C, N, lignin-derived phenols (alkaline CuO-oxidation) and carbohydrates (4 m trifluoroacetic acid hydrolysis). For native savanna, grass-alone and grass-legume pasture the C content increased in the order sand (1.6–3.3 g C kg−1)
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Role of legumes in providing N for sustainable Tropical pasture systems
Plant and Soil, 1995Co-Authors: Richard J ThomasAbstract:Forage legumes have long been lauded for their ability to fix atmospheric nitrogen and contribute to the sustainability of agricultural production systems. However despite the benefits they bring in terms of increased herbage and animal production they are not widely used in temperate or Tropical regions. In this review the amounts of biological nitrogen fixation (BNF) needed to sustain the soil-plant-animal system are discussed and related to the amounts fixed in Tropical Pastures. The data suggest that Tropical forage legumes have the capacity to meet the requirements to balance the N cycle of grazed Pastures. The actual amounts required will depend on the rate of pasture utilization and the efficiency of recycling via litter, excreta and internal remobilization. The efficiency of nitrogen fixation (% of legume N derived from fixation) is usually high in Tropical Pastures (> 80%) and is unlikely to be affected by inorganic soil N in the absence of N fertilizer. Thus an estimate of the amounts of N fixed could be obtained from simple estimates of legume biomass provided tissue levels of other nutrients such as phosphorus and potassium are adequate. Key factors for the achievement of sustainable grass/legume Pastures include the selection of appropriate germplasm adapted to the particular environment and the judicious use of fertilizers such as phosphorus, potassium, calcium, magnesium and sulphur on acid infertile soils typical of the sub-humid and humid tropics. The main constraints to the widespread adoption of forage legumes include a lack of legume persistence, the presence of anti-quality factors such as tannins, variable Bradyrhizobium requirements and lack of acceptability by farmers. Strategies for the alleviation of these constraints are discussed. Forage legumes can be used to recuperate degraded soils via their ability to improve the physical, chemical and biological properties of soils and these benefits could be of particular use for small-scale resource-poor farmers. The incorporation of forage legumes into agropastoral systems is discussed as an environmentally and economically attractive means to encourage the widespread adoption of legumes in the humid tropics.
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the use of carbon isotope ratios to evaluate legume contribution to soil enhancement in Tropical Pastures
Plant and Soil, 1994Co-Authors: Miguel Angel Ayarza, Richard J ThomasAbstract:Soil carbon distribution with depth, stable carbon isotope ratios in soil organic matter and their changes as a consequence of the presence of legume were studied in three 12-year-old Tropical Pastures (grass alone —Brachiaria decumbens (C4), legume alone —Pueraria phaseoloides (C3) and grass + legume) on an Oxisol in Colombia. The objective of this study was to determine the changes that occurred in the13C isotope composition of soil from a grass + legume pasture that was established by cultivation of a native savanna dominated by C4 vegetation. The13C natural abundance technique was used to estimate the amount of soil organic carbon originating from the legume. Up to 29% of the organic carbon in soil of the grass + legume pasture was estimated to be derived from legume residues in the top 0–2-cm soil depth, which decreased to 7% at 8–10 cm depth. Improvements in soil fertility resulting from the soil organic carbon originated from legume residues were measured as increased potential rates of nitrogen mineralization and increased yields of rice in a subsequent crop after the grass + legume pasture compared with the grass-only pasture. We conclude that the13C natural abundance technique may help to predict the improvements in soil quality in terms of fertility resulting from the presence of a forage legume (C3) in a predominantly C4 grass pasture.
Erika Marinspiotta - One of the best experts on this subject based on the ideXlab platform.
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soil organic matter dynamics during 80 years of reforestation of Tropical Pastures
Global Change Biology, 2009Co-Authors: Erika Marinspiotta, Whendee L Silver, Christopher W Swanston, Rebecca OstertagAbstract:Our research takes advantage of a historical trend in natural reforestation of abandoned Tropical Pastures to examine changes in soil carbon (C) during 80 years of secondary forest regrowth. We combined a chronosequence approach with differences in the natural abundance of 13 C between C3 (forest) and C4 (pasture) plants to estimate turnover times of C in the bulk soil and in density fractions. Overall, gains in secondary forest C were compensated for by the loss of residual pasture-derived soil C, resulting in no net change in bulk soil C stocks down to 1m depth over the chronosequence. The free light fraction (LF), representing physically unprotected particulate organic matter, was most sensitive to land-use change. Reforestation replenished C in the free LF that had been depleted during conversion to Pastures. Turnover times varied with model choice, but in general, soil C cycling rates were rapid for the 0–10cm depth, with even the heavy fraction (HF) containing C cycling in decadal time scales. Turnover times of C in the free LF from the 0–10cm depth were shorter than for the occluded and HFs, highlighting the importance of physical location in the soil matrix for residence time in the soil. The majority of the soil C pool (82 � 21%) was recovered in the mineral-associated density fraction. Carbon-to-nitrogen ratios and differences in natural abundance 15 N of soil organic matter (SOM) showed an increasing degree of decomposition across density fractions with increasing mineral association. Our data show that the physical distribution of C in the soil has a large impact on soil C turnover and the ability of soils to maintain SOM stocks during land-use and land-cover change.
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chemical and mineral control of soil carbon turnover in abandoned Tropical Pastures
Geoderma, 2008Co-Authors: Erika Marinspiotta, Whendee L Silver, Christopher W Swanston, M S Torn, Sarah D BurtonAbstract:Abstract We investigated changes in soil carbon (C) cycling with reforestation across a long-term, replicated chronosequence of Tropical secondary forests regrowing on abandoned Pastures. We applied CP MAS 13C NMR spectroscopy and radiocarbon modeling to soil density fractions from the top 10 cm to track changes in C chemistry and turnover during secondary forest establishment on former Pastures. Our results showed that inter-aggregate, unattached, particulate organic C (free light fraction) and particulate C located inside soil aggregates (occluded light fraction) represent distinct soil C pools with different chemical composition and turnover rates. The signal intensity of the O-alkyl region, primarily representing carbohydrates, decreased, and alkyl C, attributed to recalcitrant waxy compounds and microbially resynthesized lipids, increased from plant litter to soil organic matter and with incorporation into soil aggregates. The alkyl/O-alkyl ratio, a common index of humification, was higher in the occluded than in the free light fraction. Greater variability in the chemical makeup of the occluded light fraction suggests that it represents material in varied stages of decomposition. Mean residence times (14C-based) of the free light fraction were significantly shorter (4 ± 1 years) than for the heavy fraction. We report two scenarios for the occluded light fraction, one fast-cycling in which the occluded and free light fractions have similar turnover rates, and one slow-cycling, in which the occluded light fraction resembles the heavy fraction. Mean residence times of the occluded light fraction and heavy fraction in active Pastures and 10-year old secondary forests in the earliest stage of succession were longer than in older secondary forests and primary forests. This is likely due to a preferential loss of physically unprotected C of more labile composition in the Pastures and in the youngest successional forests, resulting in an increase in the dominance of slow-cycling C pools. Soil carbon turnover rates of the mineral-associated C in secondary forests recovering from abandoned pasture resembled those of primary forests in as little as 20 years of succession.
D P Poppi - One of the best experts on this subject based on the ideXlab platform.
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Changes in the rumen bacterial community in steers fed with supplemented Tropical pasture
2020Co-Authors: Karen Harper, D P Poppi, Athol V. Klieve, Tanda Panjaitan, Diane OuwerkerkAbstract:A major factor determining live weight gain (LWG) in beef cattle consuming Tropical Pastures in Northern Australia, is the microbial crude protein (MCP) supply and the efficiency of MCP production (eMCP). Native Tropical Pastures are typically of low nutritive value and the eMCP of cattle grazed on these Pastures rarely exceeds 130gMCP/kgDOM, which is marginal for productive growth (NRC 1996). However, Panjaitan (2008) demonstrated that supplementation with spirulina (Spirulina platensis) increased eMCP to 166gMCP/kgDOM.
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challenges of beef cattle production from Tropical Pastures
Revista Brasileira De Zootecnia, 2018Co-Authors: D P Poppi, S P Quigley, Tiago Alves Correa Carvalho Da Silva, S R MclennanAbstract:ABSTRACT The live weight gain of cattle on Tropical Pastures is reviewed and found to be low and dependent on the length of the growing season. Supplements may be added to address the primary limiting nutrient, which, in the dry season, is crude protein. The response relationships of live weight gain to level of supplement (protein or energy) that have been developed for animals on pasture in Brazil and Australia have been compared and found to be very similar. This [...]
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efficiency of rumen microbial protein synthesis in cattle grazing Tropical Pastures as estimated by a novel technique
Animal Production Science, 2017Co-Authors: M K Bowen, D P Poppi, S R MclennanAbstract:The efficiency of microbial protein synthesis (EMPS) in cattle grazing a range of Tropical pasture types was examined using a new method of intra-jugular infusion of chromium–EDTA to estimate urinary excretion of purine derivatives. Seven pasture types were studied in south-eastern Queensland, Australia, over a 13-month period. These included native Tropical grass (C4) pasture (major species Heteropogon contortus and Bothriochloa bladhii) studied in the early wet, the wet–dry transition and the dry season; introduced Tropical grass (C4) pasture (Bothriochloa insculpta) in the mid-wet season; two introduced Tropical legume species (C3; Lablab purpureus and Clitoria ternatea); and the temperate-grass (C3) pasture, ryegrass (Lolium multiflorum). There was a large range in EMPS across pasture types, with a range of 26–209 g microbial crude protein per kilogram digestible organic matter intake (DOMI). Estimated rumen-degradable protein (RDP) supply (42–525 g/kg DOMI) was the major factor associated with EMPS across the range of pasture types studied. EMPS in steers grazing all Tropical grass Pastures was low (<130 g/kg DOMI) and limited by RDP supply. Negative linear relationships (P < 0.05) between EMPS and concentrations of both neutral detergent fibre and acid detergent fibre in extrusa were evident. However, non-fibre carbohydrate in extrusa, total non-structural carbohydrate concentration in plucked pasture leaf, rumen fluid and particle dilution rate, protozoal concentration in rumen fluid and rumen fluid pH were not correlated with EMPS. It was concluded that EMPS was well below 130 g microbial crude protein per kilogram DOMI when cattle grazed unfertilised, Tropical grass Pastures in south-eastern Queensland and that RDP was the primary limiting nutrient. High EMPS was associated with a very high RDP, vastly in excess of RDP requirements by microbes.
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defoliation patterns and their implications for the management of vegetative Tropical Pastures to control intake and diet quality by cattle
Grass and Forage Science, 2016Co-Authors: M A Benvenutti, D P Poppi, Daniel R Pavetti, I J Gordon, C A CangianoAbstract:This study assessed the use of pasture attributes to control daily intake and diet quality during progressive defoliation on Pastures of Axonopus catarinensis. Three consecutive 12-day grazing treatments of progressive defoliation were conducted with Brahman cross-steers. Daily forage intake and defoliation dynamics were assessed using a pasture-based method. The treatments differed in initial sward height (33, 44 and 61 cm) and herbage mass (1030, 1740 and 2240 kg ha−1). The post-grazing residual sward height, at which forage intake decreased, appeared to increase with the initial sward height (12·3, 14·6 and 15·5 cm). Steers grazed up to four distinctive grazing strata in all treatments. The depth and herbage mass content of the top grazing stratum were at least five times higher than the lower grazing strata in all treatments. This explains why forage intake decreased when the top grazing stratum was removed in approximately 93% of the pasture area in all treatments, equivalent to approximately 7% of the pasture area remaining ungrazed. We conclude that the residual ungrazed area of the pasture, rather than residual sward height, can be used to develop grazing management strategies to control forage intake and diet quality in a wide range of pasture conditions.
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ruminal protein degradability of a range of Tropical Pastures
Animal Production Science, 2008Co-Authors: M K Bowen, D P Poppi, S R MclennanAbstract:The rumen degradability parameters of the diet selected by two to four oesophageal-fistulated Brahman steers grazing a range of Tropical Pastures were determined by incubation of extrusa in nylon bags suspended in the rumen of rumen-fistulated (RF) Brahman steers. The effective protein degradability (Edg) was determined by measuring the rate of disappearance of neutral detergent insoluble nitrogen (NDIN) less acid detergent insoluble nitrogen (ADIN) in the incubated extrusa. Six to eight RF steers also grazed each of the Pastures along with the oesophageal-fistulated steers, to allow determination of key rumen parameters and rumen particulate matter fractional outflow rates (FOR). The seven Pastures studied included: native Tropical grass (C4) pasture (major species Heteropogon contortus and Bothriochloa bladhii), studied in the early wet (NPEW), the wet/dry transition (NPT) and the dry (NPD) seasons; introduced Tropical grass (C4) pasture (Bothriochloa insculpta), studied in the mid wet season (BB); the introduced Tropical legumes (C3), Lablab purpureus (LL) and Clitoria ternatea (BP); and the temperate grass (C3) pasture, ryegrass (Lolium multiflorum, RG). Using the measured particle FOR values in calculations, the Edg estimates were very high for both C4 and C3 species: 0.82–0.91 and 0.95–0.98 g/g crude protein (CP), respectively. Substitution of an assumed FOR (kp = 0.02/h) for the measured values for each pasture type did not markedly affect estimates of Edg. However, C4 Tropical grasses had much lower effective rumen degradable protein (ERDP) fractions (23–66 g/kg DM) than the C3 pasture species RG and LL (356 and 243 g/kg DM, respectively). This was associated with a lower potential degradability and degradation rate of organic matter (OM) in sacco, lower in vitro organic matter digestibility (IVOMD) and CP concentrations in the extrusa, and lower ammonia-N and branched-chain fatty acid concentrations in rumen fluid for the Tropical grasses. As Tropical grass Pastures senesced, there was a decline in Edg, the ERDP and rumen undegradable protein (UDP) fractions, the potential degradability and degradation rate of OM and the IVOMD. These results provide useful data for estimating protein supply to cattle grazing Tropical Pastures.
Wolfgang Zech - One of the best experts on this subject based on the ideXlab platform.
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assessing the organic phosphorus status of an oxisol under Tropical Pastures following native savanna using 31p nmr spectroscopy
Biology and Fertility of Soils, 1996Co-Authors: Georg Guggenberger, Ludwig Haumaier, Richard J Thomas, Wolfgang ZechAbstract:31P nuclear magnetic resonance (NMR) spectroscopy, P fractionation, and a P sorption experiment were used to follow the changes in P in the A horizons (0–10 cm) of acid savanna soils, Colombia, after little P fertilization and 15 years' continuous growth of a grass (Brachiaria decumbens) and a grass/legume (B. decumbens+Pueraria phaseoloides) pasture. Ready P supply as analyzed by Bray P was low under native savanna (1.3 mg kg-1 soil) and responded moderately on pasture establishment. Concurrently, the affinity of the soil for inorganic P declined slightly after pasture establishment. 31P NMR spectroscopy revealed that P associated with humic acids was dominated by monoester P followed by diester P. Smaller proportions were observed for phosphonates, teichoic acid P, orthophosphate, and pyrophosphate. P associated with fulvic acids had lower proportions of diester P and higher contents of orthophosphate. Under native savanna the reserves of labile organic P species (phosphonates and diester P including teichoic acid P) associated with humic and fulvic acids were 12.4 and 1.1 kg ha-1, respectively, and increased to 18.1 and 1.8 kg ha-1 under grass pasture, and to 19.5 and 2.3 kg ha-1 under grass/legume pasture. These data emphasize the importance of labile organic P species in the P supply for plants in improved Tropical Pastures, and further indicate that humic acid P in particular responds to land-use changes within a relatively short time-scale. Earthworm casts were highly abundant in the B. decumbens+P. phaseoloides plot and were enriched in labile organic P species. We conclude that earthworm activity improves the P supply in soil under Tropical Pastures by creating an easily available organic P pool.
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lignin and carbohydrate alteration in particle size separates of an oxisol under Tropical Pastures following native savanna
Soil Biology & Biochemistry, 1995Co-Authors: Georg Guggenberger, Wolfgang Zech, Richard J ThomasAbstract:Abstract Establishment of improved Tropical Pastures on acid savanna soils of low fertility can increase the soil organic matter (SOM) content and soil fertility. Our objective was to follow the quantitative and qualitative changes of SOM associated with sand-, silt-and clay-sized separates after establishment of a grass-alone (Brachiaria decumbens) and a grass-legume (Brachiaria decumbens + Pueraria phaseoloides) pasture on isohyperthermic savanna soils of Colombia. Additionally, earthworm casts of anecic and endo-anecic species derived from the grass-legume pasture were investigated. Whole soil and size separates were analyzed for C, N, lignin-derived phenols (alkaline CuO-oxidation) and carbohydrates (4 m trifluoroacetic acid hydrolysis). For native savanna, grass-alone and grass-legume pasture the C content increased in the order sand (1.6–3.3 g C kg−1)
Klaus Butterbachbahl - One of the best experts on this subject based on the ideXlab platform.
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influence of soil properties on n2o and co2 emissions from excreta deposited on Tropical Pastures in kenya
Soil Biology & Biochemistry, 2020Co-Authors: Lutz Merbold, Sonja Leitner, David E. Pelster, Eugenio Diazpines, Sheila Abwanda, Paul Mutuo, Klaus ButterbachbahlAbstract:Abstract Urine and dung patches deposited by grazing cattle on grassland are an important source of nitrous oxide (N2O). While a number of studies have investigated the effects of excreta on soil N2O fluxes in developed economies and in China, observations in sub-Saharan Africa (SSA) are scarce. Moreover, the effects of soil properties (e.g. pH or texture) on N2O emissions from excreta patches have hardly been studied. In this study we investigated the importance of soil properties on N2O and carbon dioxide (CO2) emissions from cattle excreta (dung, urine, and manure [dung + urine]) for five typical Tropical soils in Kenya. For this, intact soil cores were translocated from Western Kenya (Nandi county) to Nairobi, where N2O and CO2 fluxes were measured over four individual periods (two during dry seasons and two during wet seasons). Fluxes were measured for between 25 and 73 days following surface application of excreta, depending on how quickly emissions returned to baseline. Both dung and manure applications led to increased CO2 and N2O fluxes during both dry and wet seasons. On average, the N2O emission factor (EF) for manure was higher than for dung. The EFs during the wet season were higher for both the dung (0.12%) and urine (0.50%) compared to the dry season EFs (0.01% and 0.07% for dung and urine respectively). Soil type had no measurable effect on N2O and CO2 emissions for either dung or manure application. In contrast, soil clay content was negatively (P
