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Articles 2221 - 2250 of 302419

Full-Text Articles in Physical Sciences and Mathematics

Mountain Meadow Response To Riparian Grazing Strategies In Western Usa, W P. Clary, J W. Kinney Jun 2024

Mountain Meadow Response To Riparian Grazing Strategies In Western Usa, W P. Clary, J W. Kinney

IGC Proceedings (1993-2023)

The purpose of this grazing study was to examine the response of a mountain meadow riparian system to different levels of livestock use in late June. Six pastures were used to evaluate three levels of grazing. Over an 8-year period there was a general trend of increased plant species and biomass. The largest increases in species number occurred in pastures receiving the most grazing use. The opposite was true for plant biomass. Total plant cover decreased on all dry meadows, but increased on grazed streamside locations. Shrub cover, including streamside willows, increased under all grazing treatments. Streambank stability increased and …

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Persistence Of Cheatgrass (Bromus Tectorum) Amid Bunchgrass/Shrub Steppe Communities, S B. Monsen, N L. Shaw Jun 2024

Persistence Of Cheatgrass (Bromus Tectorum) Amid Bunchgrass/Shrub Steppe Communities, S B. Monsen, N L. Shaw

IGC Proceedings (1993-2023)

Semiarid bunchgrass/shrub steppe communities throughout the Intermountain region were degraded by early livestock grazing and invasion of annual weeds. Patterns of secondary succession were investigated through establishment and maintenance of four exclosures on granitic soils in south-central Idaho. Species composition and plant cover were estimated periodically in grazed and protected areas at each site from 1930 to 1977. Cheatgrass (Bromus tectorum), an alien invader, occupied the sites initially, declining between 1933 and 1937 during a prolonged drought, and reappearing erratically after 1940. Perennial grasses recovered slowly in protected areas, requiring more than 45 years to increase in cover …

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Animal-Plant Interactions In An Atriplex Canescens Dominant Community Browsed By Cattle, A F. Cibils, D M. Swift, R H. Hart Jun 2024

Animal-Plant Interactions In An Atriplex Canescens Dominant Community Browsed By Cattle, A F. Cibils, D M. Swift, R H. Hart

IGC Proceedings (1993-2023)

Atriplex canescens is a relatively widespread shrub in rangelands of the western United States,with a longstanding reputation as a valuable browse resource for ruminants. The breeding system of tetraploid populations has been extensively studied both in common gardens and in natural populations. However, browser-driven alterations of shrub sex ratios, and the probable mechanisms involved in such processes, have received relatively little attention in these populations. We report results from a preliminary study conducted in a stand of A. canescens at a site on the shortgrass steppe. Numbers of young shrubs decreased with increasing shrub density. Sex ratios did not differ …

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An Examination Of Dry Weight Rank And Comparative Yield Techniques For Grasslands Production Estimation, H Arzani, G W. King Jun 2024

An Examination Of Dry Weight Rank And Comparative Yield Techniques For Grasslands Production Estimation, H Arzani, G W. King

IGC Proceedings (1993-2023)

Currently used method of dry matter yield estimation was tested compared with yield estimation from cover measurement using clipped data as an index. The dry weight rank (DWR) method was able to show variations within and between sites in different seasonal conditions. However it was less accurate than other techniques and possibly subject to personal bias.

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Application Of Remote Sensing (Landsat Tm Data) For Vegetation Parameters Measurement In Western Divisions Of Nsw, H Arzani, G W. King Jun 2024

Application Of Remote Sensing (Landsat Tm Data) For Vegetation Parameters Measurement In Western Divisions Of Nsw, H Arzani, G W. King

IGC Proceedings (1993-2023)

The capability of Landsat (TM) data for vegetation parameters estimation was examined. Suitable vegetation indices were selected for arid and semi-arid areas. The possibility of accurate estimation of cover and yield of group of species was found.

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Effect Of Nitrogen On The Reserve Nutrients Of Rhizomes And Their Relation To Shoot Regrowth In Miscanthus Floridulus, Y C. Wang, M L. Lee Jun 2024

Effect Of Nitrogen On The Reserve Nutrients Of Rhizomes And Their Relation To Shoot Regrowth In Miscanthus Floridulus, Y C. Wang, M L. Lee

IGC Proceedings (1993-2023)

A 3-week-treatment of nitrogen dressings and of shoot cuttings were conducted on Miscanthus floridulus before the harvest. The nitrogen dressing increased the fresh weight and dry matter of the plants, but did not increase the plant height and shoot number. The reserved nutrients, especially the sugars and starch in the rhizomes were decreased by the cut treatments. Crude protein in the rhizomes was increased with the nitrogen amounts applied, though the carbohydrates were decreased. The decrease in reserved nutrients caused the growth inhibition of new shoots, and the more the reserved nutrients decreased the more severely was the growth inhibited. …

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Grassland Mapping Units In The Flooding Pampa (Argentine), S P. Debelis, A A. Bozzo Jun 2024

Grassland Mapping Units In The Flooding Pampa (Argentine), S P. Debelis, A A. Bozzo

IGC Proceedings (1993-2023)

A thematic map of grassland has been drawn up using studies carried out at farm level as a starting point, correlating soils and specie group through significant parameters that condition their presence. The work method included the analysis of a geomorphologically homogeneous area through cartography and aerial photography. An elemental unit of the landscape was studied in detail with a pattern repeated all over the subregion, with soil samples at specie group level. Hidromorphism and variable alkalinity and saline patches are present in all profiles, gramineous, juncaceous, cyperaceous and forbs linked to the problems of soil already mentioned. A system …

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Improvement Of Subtropical Native Grasslands With The Introduction Of Forage Species And Phosphorous Fertilizers, M N. Baby, S.B C. Lustosa, A Moraes, A.C V. Motta, R L. Stanger Jun 2024

Improvement Of Subtropical Native Grasslands With The Introduction Of Forage Species And Phosphorous Fertilizers, M N. Baby, S.B C. Lustosa, A Moraes, A.C V. Motta, R L. Stanger

IGC Proceedings (1993-2023)

The experiment took place in Guarapuava-Brazil, from May 1994 to January, 1996 to evaluate the improvement of a subtropical native grassland by the introduction of species and phosphate fertilization. It was observed that for the higher dose applied there occurred an increase over the production of dry matter and crude protein production and absorption of P and K in the plant. A response was not found to the 180 kg P2O5/ha application probably because of the high capacity of soil adsorption, the method of fertilizer application, non favorable climatic conditions and liming interference. The single superphosphate-SS application was superior to …

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Manipulation Of Botanical Composition Of Native Pastures By Grazing In Temperate South-East Australia, D L. Garden, D A. Friend, P M. Dowling, G M. Lodge Jun 2024

Manipulation Of Botanical Composition Of Native Pastures By Grazing In Temperate South-East Australia, D L. Garden, D A. Friend, P M. Dowling, G M. Lodge

IGC Proceedings (1993-2023)

Historical evidence indicates that substantial changes have occurred in the botanical composition of native pastures in temperate southeast Australia as a result of grazing by sheep and cattle. However, the resulting pastures now appear to be relatively stable and there has been limited success in changing composition experimentally. This paper reports the results of experiments conducted at four locations in south-east Australia designed to increase the proportion of desirable species in native pastures by grazing management.

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Production, Stability And Biodiversity Of North Island New Zealand Kill Pastures, P K. Nicholass, P D. Kemp, D J. Barker, J L. Brock, D A. Grant Jun 2024

Production, Stability And Biodiversity Of North Island New Zealand Kill Pastures, P K. Nicholass, P D. Kemp, D J. Barker, J L. Brock, D A. Grant

IGC Proceedings (1993-2023)

The relationship between pasture biomass and pasture stability with species diversity was derived for two low fertility, hill land sites. At one site, pasture production increased with an increased number of species contributing to biomass. The coefficient of variation in biomass, however, decreased with higher numbers of species. At a second site, pasture biomass was also found to increase with increasing species diversity, but the relationship between yield stability and species diversity was not as strong as at the first site. This suggested there were other factors that influenced the stability of pastures, which could include the substitution effect between …

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Disturbance By Mechanical Phosphorous Fertilization On The Cover And Biomass Of Humid Alkaline Communities Of The Flooding Pampa (Argentina), O E. Ansin, E M. Oyhamburu, J L. Delgado Caffe Jun 2024

Disturbance By Mechanical Phosphorous Fertilization On The Cover And Biomass Of Humid Alkaline Communities Of The Flooding Pampa (Argentina), O E. Ansin, E M. Oyhamburu, J L. Delgado Caffe

IGC Proceedings (1993-2023)

Experiments were carried out in order to evaluate the impact of mechanical perturbations, phosphorous fertilization and grazing on the native grasslands. Six treatments were tested: three without grazing and three subjected to grazing. Both situations were plowed, plowed plus fertilization or kept untreated. During the study botanical composition, vegetative cover, species diversity and above ground biomass were measured. Plowed and plowed plus fertilization treatments drastically reduce all of these parameters related to community structure and forage production. These figures contrasted with the non-perturbated treatments, were values did not change significantly from the original state. Mechanical perturbations provoked reductions on grassland …

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Effect Of Cattle Grazing On The Aridity Level Of Humid Halomorphic Grass Communities Of The Flooding Pampa (Argentina), O E. Ansin, V A. Deregibus Jun 2024

Effect Of Cattle Grazing On The Aridity Level Of Humid Halomorphic Grass Communities Of The Flooding Pampa (Argentina), O E. Ansin, V A. Deregibus

IGC Proceedings (1993-2023)

The Argentine Flooding Pampa is a large humid rangeland, severely deteriorated by cattle grazing, to the point of causing the local extinction of many native grasses and important alterations in ecosystem function. Among grassland communities exist those that vegetate halomorphic soils, highly degraded due continuous grazing by domestic herbivores causing soil denudation and increased aridity. An alternate grazing method, that controls the periodicity and moment of important rest periods followed by disturbance events, should increase cover and favor water availability. This succession process will determine more vigorous and abundant foraging species in the degraded communities. After six years of controlled …

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Sustainability Of Management Practices Of Mountain Pastures In Reunion Island (Indian Ocean), V Blanfort, P Thomas, G Balent, A Michon Jun 2024

Sustainability Of Management Practices Of Mountain Pastures In Reunion Island (Indian Ocean), V Blanfort, P Thomas, G Balent, A Michon

IGC Proceedings (1993-2023)

The grazing systems are an essential component of these volcanic highlands (1000-2000m). Our investigations consist of building up diagnosis tools and decision rules for a sustainable control of these fragile grazed ecosystems composed of native and sown pastures. The use of a systemic approach allows us to analyse the interrelationship between the vegetation dynamic and the agricultural practices through three biological indicators which relate to one hundred paddocks in six cattle farms. Concerning the vegetation dynamics, it seems that some management practices lead to a nonreversable degradation stage. As regards the forage system, the measure of sward-height and estimation of …

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Restoration Of Degraded Coastal Grasslands In The Falkland Island, J A. Kerr Jun 2024

Restoration Of Degraded Coastal Grasslands In The Falkland Island, J A. Kerr

IGC Proceedings (1993-2023)

In the Falkland Islands the coastal grasslands are the most valuable for wool production and important habitats for wildlife. Tussac grass (Parodiochloa flabellata Lam.) and sandy areas which support an Ammophilia - Elymus association have been degraded by overgrazing, burning and invasion by alien flora and fauna. Traditional approaches to restoration, mainly by replanting, have had limited success. Research on

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Pathways For Losses Of Phosphorus For Rainfed Pastures In South Australia, J W. Cox, C A. Kirkby, D J. Chittleborough Jun 2024

Pathways For Losses Of Phosphorus For Rainfed Pastures In South Australia, J W. Cox, C A. Kirkby, D J. Chittleborough

IGC Proceedings (1993-2023)

This study showed that significant amounts of phosphorus (P) applied to grasslands in the Adelaide hills, South Australia move through kaolinitic clay subsoils. Large undisturbed soil cores were collected down a hillslope with soils and pasture typical of the Adelaide hills. Fertiliser was added to the surface of soil cores and catchment rainfall simulated. Leachate from the cores was measured daily and analysed for P. Results showed up to 34% of P applied to pastures on the upper-slopes, moves vertically through the subsoil clays mostly in the dissolved form. Elsewhere, < 1% of the applied P was lost. The subsoils where P movement was significant had high clay (44%) and iron oxide content (14%). These subsoils also had the greatest number of macropores (20% of pores > 5 mm). The results showed the importance of macropore flow …

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Proximity Of Water Affects Grazing Distribution And Soil Nutrient Cycling, J R. Gerrish, P R. Peterson, F A. Martz Jun 2024

Proximity Of Water Affects Grazing Distribution And Soil Nutrient Cycling, J R. Gerrish, P R. Peterson, F A. Martz

IGC Proceedings (1993-2023)

A three-year study was conducted to quantify the effects of travel distance to water on pasture utilization rate and soil nutrient gradients. A 64 ha unit was divided into 16 4 ha pastures having maximum travel distances ranging from 250 to 450 m. Temporal utilization rate (UR) and soil nutrient levels were determined at 30 m intervals beginning at the water source. Temporal UR significantly declined beyond 250 m in all pastures having travel distances exceeding 250 m while pastures with less than 250 m travel distance were uniformly grazed. Increased nutrient level gradients beginning within 60 m of water …

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Grassland N Fertilization In Humid Tropics: Production, Organic Matter Decomposition And Uptake, G Mandret, V Blanfort Jun 2024

Grassland N Fertilization In Humid Tropics: Production, Organic Matter Decomposition And Uptake, G Mandret, V Blanfort

IGC Proceedings (1993-2023)

Under tropical humid conditions at low altitudes in La Reunion island an experiment was conducted in 1995 to examine the effects of mineral and organic N fertilisation on regrowth of Chloris gayana . Mineral fertilisation stimulates the production of leaves for the first 20 days of regrowth. Dry matter production was increased of 181 % with the combination of manure plus ammonium nitrate and only 147 % with ammonium nitrate alone. The soil microbial biomass activity, measured after 50 days of regrowth, was increased of 31 % by application of manure, 41 % by ammonium nitrate and 50 % by …

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Grasslands As A Comparative For Farming Practices' Influence On Carbon/Nitrogen Dynamics, S A. Clancy, M E. Biondini, J C. Gardner Jun 2024

Grasslands As A Comparative For Farming Practices' Influence On Carbon/Nitrogen Dynamics, S A. Clancy, M E. Biondini, J C. Gardner

IGC Proceedings (1993-2023)

A remnant prairie was used for comparison of the soil as a natural resource among alternative and conventional farming systems. Beginning and ending biotic and abiotic characteristics were quantified directly. Carbon and N flow was calculated using CENTURY model. Carbon decay was not tied to the size of the soil organic matter pool (SOM), but to crop choice. Nitrogen decay was linked to the size of the SOM pool. Nitrogen fertilizer depressed the amount of N mineralized by soil biota. The alternative farming systems in North Dakota (no-till and green-manure fallow) more nearly mimic the ecosystem processes of the prairie …

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Effects Of Sodium And Cadmium Application To Pasture On Mineral Leaching, P C. Chiy, C.J C. Phillips, E Zachou Jun 2024

Effects Of Sodium And Cadmium Application To Pasture On Mineral Leaching, P C. Chiy, C.J C. Phillips, E Zachou

IGC Proceedings (1993-2023)

Leaching of essential elements from pasture constitutes a significant loss of valuable nutrients, and the release of nitrates and toxic elements such as cadmium to ground water poses a risk to wildlife and consumers. Results are presented from two experiements on the effects of applying Na and Cd to perennial ryegrass (Lolium perenne) swards on the leaching of essential and toxic elements. Socium application increased Na and decreased K concentration in leached waters, and cadmium contamination increased the leaching of Na, K, Mg, Ca and P. The application of cadmium did not increase the cadmium concentration in leached …

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Litter Decomposition And Nutrients Release During Decomposition In A Humid Grassland Of Northeastern India, P S. Yadava, N S. Thoudam Jun 2024

Litter Decomposition And Nutrients Release During Decomposition In A Humid Grassland Of Northeastern India, P S. Yadava, N S. Thoudam

IGC Proceedings (1993-2023)

The litter decomposition and nutrient release of two dominant grass species Sporobolus indicus (L) R. Br., Leersia Hexandra SW. and mixed grasses was studies by litter bag technique in the humid grassland ecosystem at Imphal, Northeastern India. On ermination of experiment after 12 months, the shoots decomposed from 97.2 to 100% and the roots from 82.9 to 91.8% of different species. The rate of litter decomposition of shoots were higher than roots. The decomposition constant (K) also varied from species to species. It is positively correlated with soil moisture content during the study period. The initial nitrogen, lignin and lignin …

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Nutrient Cycling For Pasture Fertilization Management Of Dairy Farms In The Basque Country (Northern Spain), M Oyanarte, M Rodriguez, G Besga, M Domingo Jun 2024

Nutrient Cycling For Pasture Fertilization Management Of Dairy Farms In The Basque Country (Northern Spain), M Oyanarte, M Rodriguez, G Besga, M Domingo

IGC Proceedings (1993-2023)

The implementation of the European Agricultural Policy implies a new orientation for the management of dairy farms and, as a result, of pasture fertilization. It is important to develop a new methodology for the calculation of fertilizer recommendations. In order to do this, a model based on P and K nutrient cycles has been used and a computer program has been developed to calculate these cycles and estimate the following parameters: potential pasture yield, yield at the different cuttings, efficiency of excreta recycling in the pasture and efficiency of grass utilization, all these parameters being necessary for the calculation of …

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Nutrient Leaching And Runoff In The Mediterranean Dairy Sheep Farming Systems, C Porqueddu, S Caredda, G Fara Jun 2024

Nutrient Leaching And Runoff In The Mediterranean Dairy Sheep Farming Systems, C Porqueddu, S Caredda, G Fara

IGC Proceedings (1993-2023)

Three years of research were carried out in Sardinia (Italy) to evaluate the environmental impact on the soil and water from intensification of the dairy sheep farming systems. An extensive rainfed system based on permanent pasture was compared with an intensive irrigated system based on a three year rotation (double cropping/lucerne). Runoff, soil erosion and nutrient losses were negligible. Nutrient losses by leaching had more important results with clear differences between forage crops. In terms of system losses, the differences were less marked.

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Nitrogen Cycling In A Ley-Dominated Production System, B Fagerberg Jun 2024

Nitrogen Cycling In A Ley-Dominated Production System, B Fagerberg

IGC Proceedings (1993-2023)

N balance in a full-scale experiment with conventional and ecological farming systems at Öjebyn in northern Sweden was calculated with a nutrient flow model. Due to increased milk production there was a yearly increase in both N-input and output. Nfixation was on average twice as large in the ecological system. The farm N balance was increasingly positive in the conventional system and negative in the ecological. The soil N balance was more negative in the ecological system and less positive in the conventional system. Conclusions are: (1) ecological farming is possible without immediate DM yield reductions, but with negative effects …

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The Relative Roles Of Livestock, Termites, Wild Animals And Human Beings In Nutrient Recycling In Nigeria, S M. Liya, A A. Agboola Jun 2024

The Relative Roles Of Livestock, Termites, Wild Animals And Human Beings In Nutrient Recycling In Nigeria, S M. Liya, A A. Agboola

IGC Proceedings (1993-2023)

Primary production of savanna woodland and cropland vegetation in semi-humid tropical Nigeria was 990t/km2 and contained 8.0 t of nitrogen (N) and 1.4 t of phosphorus (P). Of this biomass livestock, termites and humans consumed 4, 29 and 6% respectively; 18% was burnt. Of the N and P stocks, livestock, termites and humans consumed 9 and 5%, 17 and 22%, and 10 and 9% respectively. The liveweights per km2 of livestock, termites and humans were 3.5, 10.0 and 2.3t respectively. Annual grass burning consumed 25% of N and 16% of P. The role of wild animals was negligible. About 2/3 …

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Integrated Dairy Waste Management, Water Quality And Crop Utilization System, D R. Ivers, P D. Clayton, R H. Beck, G W. Randall, L J. Greub, M A. Schmitt, W F. Wedin Jun 2024

Integrated Dairy Waste Management, Water Quality And Crop Utilization System, D R. Ivers, P D. Clayton, R H. Beck, G W. Randall, L J. Greub, M A. Schmitt, W F. Wedin

IGC Proceedings (1993-2023)

Livestock-crop farmers have very limited opportunities to efficiently utilize manure in an environmentally safe manner during the cropgrowing season. In this study, dairy manure slurry was surfaceapplied over a two year period on reed canarygrass (Phalaris arundinacea L.), a perennial grass cover (living filter) at one location each in Iowa, Minnesota, and Wisconsin. Public and private (University and Cenex/Land O’Lakes) research and development capabilities were coupled to request and receive funding from a nationally-mandated program on water quality (United States Department of Agriculture). The primary objective was to study factors which impinge upon acceptable ground water quality using a …

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Nitrogen Cycling In Pasture Grazed By Lactating Dairy Cows, M P. Russelle, L D. Satter, T Dhiman, V R. Kanneganti Jun 2024

Nitrogen Cycling In Pasture Grazed By Lactating Dairy Cows, M P. Russelle, L D. Satter, T Dhiman, V R. Kanneganti

IGC Proceedings (1993-2023)

Increasing use of intensive rotational grazing for livestock production in the USA raises questions about the potential for nitrate-N (NO3- N) leaching losses. In grazing experiments with lactating dairy cows at two sites in the Upper Midwest, we monitored milk production, soil NO3-N concentration, and NO3-N leaching. Dietary supplementation increased milk yield, but there was no measurable impact on NO3-N leaching losses. Leaching volumes and NO3-N losses were small on these silt loam soils, even directly under urine patches. The results suggest that NO3-N leaching is not likely to be a problem on fine-textured soils in the Upper Midwest under …

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Groundwater Concentrations Of Non-Nitrogen Nutrients Under A Medium Fertility Pasture System, L B. Owens, R W. Van Keuren, W M. Edwards Jun 2024

Groundwater Concentrations Of Non-Nitrogen Nutrients Under A Medium Fertility Pasture System, L B. Owens, R W. Van Keuren, W M. Edwards

IGC Proceedings (1993-2023)

The purpose of this multi-year study was to determine concentrations and transport of non-nitrogen nutrients in groundwater under a medium fertility pasture system. Rotationally grazed grass pastures received 56 kg N/ha annually as NH4NO3 for a 5-yr period. A topsoil pH of 6.0 and available P and K levels of 28 and 168 kg/ha, respectively, were maintained. Concentrations of P, K, Na, Ca, Mg, and Cl were measured in water from springs draining each paddock. Nutrient concentrations did not vary greatly on a monthly basis but there some increases during the second 5-yr period when annual N fertilizer rates were …

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Monitoring The Movement Of N And S Through The Soil Plant Animal System Under Degraded And Perennial Pastures, Chen Wen, R.D B. Lefroy, G J. Blair, J M. Scott Jun 2024

Monitoring The Movement Of N And S Through The Soil Plant Animal System Under Degraded And Perennial Pastures, Chen Wen, R.D B. Lefroy, G J. Blair, J M. Scott

IGC Proceedings (1993-2023)

An experiment was carried at Armidale, NSW, Australia, to test the hypothesis that pastures dominated by the perennial grass phalaris (Phalaris aquatica) together with white clover (Trifolium repens) can optimize nutrient cycling and minimize nutrient leakage in comparison with one where the perennial grass has been lost through prior overgrazing (‘degraded’). The concentrations of mineral nitrogen present as ammonium and nitrate indicated limited opportunities for N leaching under either perennial or ‘degraded’ pastures in this environment. The high S content in the 40-60 cm soil layer indicates some movement of S under both ‘degraded’ and perennial …

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Can Forages Reduce Nitrate Leaching Losses From Mixed Cropping Rotations In New Zealand?, G S. Francis, K M. Bartley, F J. Tabley Jun 2024

Can Forages Reduce Nitrate Leaching Losses From Mixed Cropping Rotations In New Zealand?, G S. Francis, K M. Bartley, F J. Tabley

IGC Proceedings (1993-2023)

The objective of this two-year experiment was to determine the ability of forages grown as winter cover crops to reduce nitrate leaching losses after temporary leguminous pastures were ploughed. In both years, cover crops reduced cumulative leaching losses compared with bare fallow and were most effective when sown early in the autumn. When large amounts of residues with relatively low N concentrations were incorporated in the soil in the spring, there was extensive net N immobilisation that suppressed the yield of the following wheat test crop. When cover crops were grazed, the N consumed by sheep as herbage was returned …

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Use Of Novel Incubation Technique To Measure N2 On 0/N2 Following Surface Or Injected Application Of Slurry, D Scholefield, D Chadwick, J.M B. Hawkins Jun 2024

Use Of Novel Incubation Technique To Measure N2 On 0/N2 Following Surface Or Injected Application Of Slurry, D Scholefield, D Chadwick, J.M B. Hawkins

IGC Proceedings (1993-2023)

Measurements of N2O and N2 efflux were made following surface or injected application of slurry to a wet, fine-textured pasture soil. Intact blocks of the slurry applied soil were incubated in a laboratory system that permitted replacement of the original N2 in soil atmosphere with He, and thus the detection and estimation of N2 arising from denitrification. Following application at a rate equivalent to 112 kg N ha-1, 7.2 and 13.4 kg N ha-1 were lost from surface applied and injected slurry, respectively, during a 40 d period at 15 oC. Peak efflux of N2O occurred after about 20 d …

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