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Effect Of Nitrogen Fertilization On Central Tendency And Spatial Heterogeneity Of Soil Moisture, Ph And Dissolved Organic Carbon And Nitrogen In Two Bioenergy Croplands, Xuehan Wang, Siyang Jian, Lahiru Gamage, Jianwei Li

Agricultural and Environmental Sciences Faculty Research

Background

Soil moisture, pH, dissolved organic carbon and nitrogen (DOC, DON) are important soil biogeochemical properties in switchgrass (SG) and gamagrass (GG) croplands. Yet their spatiotemporal patterns under nitrogen (N) fertilization have not been studied.

Aims

The objective of this study is to investigate the main and interactive effects of N fertilization and bioenergy crop type on central tendencies and spatial heterogeneity of soil moisture, pH, DOC and DON.

Methods

Based on a 3-year long fertilization experiment in Middle Tennessee, USA, 288 samples of top horizon soils (0–15 cm) under three fertilization treatments in SG and GG croplands were collected. …

Understanding Common Perceptions Of The Drylands, C. Bedelian, D. Pertaub, F. Ngarachu, C. Hesse, S. Krätli, J. Obando, C. Shisanya, J. Maraigua

IGC Proceedings (1977-2023)

Drylands occupy over 40% of the earth’s surface and are home to more than 2 billion people. Drylands are key to the food and nutritional security of the planet and vital to the economies and livelihoods of dryland inhabitants. Yet, drylands are commonly perceived as unproductive, economically inefficient and marginal lands where small-scale farmers and pastoralists practice environmentally degrading activities. Driven by inadequate understanding and misconceptions of the drylands, policy-makers devise inappropriate policies and interventions. The BRECcIA project developed an online Drylands Perceptions Survey to understand the perceptions of researchers, practitioners and policy makers working in the drylands of Kenya, …

Relationships Between Biodiversity And Production In Grasslands At Local And Regional Scales, A. Hector, M. Loreau

IGC Proceedings (1977-2023)

Key points

1. Experimental manipulations of plant species diversity in unfertilised prairies and meadows has revealed that increasing diversity often leads to increased productivity (range of observed relationships varies from flat to log-linearly positive); driven by a combination of facilitation, niche-partitioning and sampling/selection effects.

2. The longer-term effects of diversity on ecosystem stability are not as clear and in need of further work.

3. Recent applied work, and a new review of the grassland literature, both show the potential for biodiversity to increase productivity under realistic field conditions.

4. The longer-term feedback of grazers on biodiversity gradients is unknown, and …

Methane And Nitrous Oxide Emissions From Grazed Grasslands, Harry Clark, C. Pinares-Patiño, C. De Klein

IGC Proceedings (1977-2023)

Key points

1. Emissions of methane (CH₄) and nitrous oxide (N₂O) from grasslands make a substantial contribution to total agricultural emissions of these two gases.

2. At present practical mitigation options that relate to grazing ruminants and grazed pastures are limited.

3. Research into agricultural greenhouse gas emissions is of low priority in most developed countries.

4. Direct manipulation of the rumen ecosystem provides the best opportunity for large reductions in CH₄ in the long term.

5. Reducing the amount of nitrogen (N) excreted by grazing animals is a priority in N₂O research, …

Phenotypic Evaluation Of Energycane Varieties For Bioenergy, Wyatt Eason, D. M. Hollowell, Anna Hale, Jesse Ira Morrison, Brian Baldwin

IGC Proceedings (1977-2023)

The need for renewable and carbon-neutral energy is growing as fossil fuel supplies decrease and concerns of climate change increase. C₄ grasses are among the most efficient carbon accumulators. Sugarcane (Saccharum officinarum) is a renewable bioenergy crop with low inputs and high yields, but it is limited to tropical and sub-tropical climates. A close relative, Saccharum spontaneum, readily hybridizes with S. officinarum. S. spontaneum lends cold tolerance and higher yields to the hybrid progeny, called energycane. The Sugarcane Breeding Unit (USDA, Houma, Louisiana, USA) selected twenty-six genotypes for testing at Mississippi State University to determine production …

Fast-Decaying Plant Litter Enhances Soil Carbon In Temperate Forests But Not Through Microbial Physiological Traits, Matthew E. Craig, Kevin M. Geyer, Katilyn V. Beidler, Edward R. Brzostek, Serita D. Frey, A. Stuart Grandy, Chao Liang, Richard P. Phillips

Faculty Publications

Conceptual and empirical advances in soil biogeochemistry have challenged long-held assumptions about the role of soil micro-organisms in soil organic carbon (SOC) dynamics; yet, rigorous tests of emerging concepts remain sparse. Recent hypotheses suggest that microbial necromass production links plant inputs to SOC accumulation, with high-quality (i.e., rapidly decomposing) plant litter promoting microbial carbon use efficiency, growth, and turnover leading to more mineral stabilization of necromass. We test this hypothesis experimentally and with observations across six eastern US forests, using stable isotopes to measure microbial traits and SOC dynamics. Here we show, in both studies, that microbial growth, efficiency, and …

Grazing Land Contributions To Carbon Sequestration, Ronald F. Follett, G. E. Schuman

IGC Proceedings (1977-2023)

Key points

1. Grazing management can be used to increase soil organic carbon sequestration.

2. Grazing land soils contain large amounts of carbon with depth, and can store it for centuries.

3. Policies to encourage terrestrial carbon sequestration through conservation and good management of grazing lands are critical for many countries and the world.

Global Atmospheric Change And Its Effect On Managed Grassland Systems, Andreas Lüscher, J. Fuhrer, P. C. D. Newton

IGC Proceedings (1977-2023)

Key points

1. Increasing atmospheric CO2 concentration and a trend to warmer mean temperatures are the most reliable aspects of global atmospheric change. Projections of the extent of climate change and the frequency of extreme weather conditions remain uncertain.

2. Research has considerably reduced the uncertainty about effects of global atmospheric change on physiology of plants, productivity and species composition of plant communities.

3. Other factors (e.g. nutrient availability, soil type) and long-term adaptation of the ecosystem (e.g. nutrient cycling and sequestration) influence the response of plant communities to global atmospheric change. Generalisation is not possible with respect to the …

Grassland Productivity And Water Quality: A 21St Century Issue, David M. Nash, P. M. Haygarth

IGC Proceedings (1977-2023)

Key points

1. Irrigation and other changes to the hydrological cycle can increase soil and water salinity.

2. Primary salinisation is a natural process that affects much of Europe, Asia, Africa, the Americas and Australia. Secondary salinisation is caused by human activities such as irrigation and land clearing that mobilise salt stored in the soil.

3. The critical water contaminants exported from grasslands are nitrogen, phosphorus, potential pathogens and sediment.

4. The mechanisms responsible for diffuse pollution from grasslands and mitigation strategies are most effectively investigated using a ‘source-mobilisation-transport’ framework.

5. There is a lack of coherent interaction across discipline …

Soil Quality Assessment And Management, M. G. Kibblewhite

IGC Proceedings (1977-2023)

Key points

1. Soil quality is related to the capacity of soil to deliver ecosystem services on a sustainable basis.

2. Effective management of soil within grasslands can deliver many benefits to mankind but poor management may cause loss of soil quality from erosion, loss of organic matter, physical deterioration etc.

3. Services are delivered from soil by biological processes. Soil quality depends on the form and condition of the soil habitat. Fixed factors (e.g. texture) are useful for assigning soil to types. Variable factors (e.g. organic carbon) can then be used to assess quality within soil types, by reference …

Water Resources, Agriculture And Pasture: Implications Of Growing Demand And Increasing Scarcity, M. W. Rosegrant, R. A. Valmonte-Santos, S. A. Cline, C. Ringler, W. Li

IGC Proceedings (1977-2023)

Key points

1. Water availability for irrigation is threatened in many regions by rapidly increasing demand for nonagricultural water uses in industry, households, and the environment. The scarcity of irrigation water will not only impact crop production, but also meat production, as much of the pasture used to feed livestock is irrigated.

2. Grassland is caught between two countervailing forces: a requirement for increasing meat demand that boosts the need for additional pasture to support livestock production, and rapidly increasing water scarcity that makes pasture irrigation uneconomical.

3. The most effective means of dealing with water scarcity is likely to …

Soil Microbial Community: Understanding The Belowground Network For Sustainable Grassland Management, Y. G. Zhu, W. D. Kong, B. D. Chen, Z. B. Nan, P. Christie

IGC Proceedings (1977-2023)

Key points

1. In addition to the use of conventional methodologies in soil microbial research, molecular techniques are now being applied to gain insights into the soil microbial community;

2. Plant diversity can exert impacts on soil microbial diversity (through root activities and plant litter etc.), but may in itself be significantly altered by soil properties;

3. Soil microbial diversity largely determines the stability of soil ecosystems under biotic and abiotic perturbations.

4. Management of soil microbial diversity can only be achieved through better understanding their structures and functions.

The Potential Of Grassland And Associated Forages To Produce Fibre, Biomass, Energy Or Other Feedstocks For Non-Food And Other Sectors: New Uses For A Global Resource, M. F. Askew

IGC Proceedings (1977-2023)

Key points

1. In developed countries increased areas of land will become available for non-food production. Recent reforms of the Common Agricultural Policy will further intensify this trend in Europe.

2. There is potential for grassland and associated species to contribute to large tonnage markets of energy and bulk fibres, to the supply of fermentation products and to speciality markets, but processes and approaches to the market are not as yet developed.

3. There is potential for the establishment of Graminaceous species - specifically for nonfood use. For European conditions particular attention is being given to Miscanthus sinensis (Miscanthus), Arundo …

Adoption Of Tropical Legume Technology Around The World: Analysis Of Success, H. M. Shelton, S. Franzel, M. Peters

IGC Proceedings (1977-2023)

Key points

1. Examples of successful adoption of forage legumes are reported from all continents, where they delivered profitability and often provided multipurpose benefits to farmers.

2. Factors vital to successful adoption were: meeting the needs of farmers; building relevant partnerships; understanding the socio-economic context and skills of farmers; participatory involvement with rural communities; and long-term involvement of champions.

3. Organisation of seed supply, achieving scale-up and forming partnerships to implement adoption are key features.

4. Legumes remain an important but under-exploited resource for tropical farming systems. The alternative to legumes will be greater and more costly use of N-fertilisers …

Grasses As Biofactories: Scoping Out The Opportunities, Nick Roberts, K. Richardson, G. Bryan, C. Voisey, W. Mcnabb, T. Conner, M. Christey, R. Johnson

IGC Proceedings (1977-2023)

Key points

1. Plant biopharming is set to dominate commercial recombinant protein expression for specific proteins.

2. The choice of plant species depends on a multitude of factors and is determined on a caseby- case basis.

3. As a leaf based expression system grasses would have to compete predominantly with tobacco and alfalfa.

4. The grass-endophyte symbiosis offers a number of unique possibilities for biopharming.

Evolution Of Integrated Crop-Livestock Production Systems, Martin H. Entz, William D. Bellotti, J. M. Powell, S. V. Angadi, W. Chen, K. H. Ominski, B. Boelt

IGC Proceedings (1977-2023)

Key points

1. Many factors contribute to changes in the crop-livestock systems, but no logical end-point in the evolution process exists.

2. While benefits of integrated crop-livestock systems over specialised crop and livestock systems are well documented, there has been a move to specialised crop and livestock production.

3. Sustainability issues (manure nutrient concentration, soil quality maintenance, salinity, herbicide resistance, economic instability) have created a renewed interest in integrated crop-livestock systems.

4. Farmer adaptability is as an important link in the evolution between ‘states of integration’.

Overcoming Seasonality Of Production: Opportunities Offered By Forage Conservation Technologies, P. O'Kiely, A. G. Kaiser

IGC Proceedings (1977-2023)

Key points

1. Seasonality of forage supply is a key contributor to the seasonality of meat and milk production.

2. Conserving forages as silage or hay can help reduce the seasonality of feed supply.

3. Forage conservation technologies make this contribution mainly through increases in the yield or quality of suitable crops, through an improved efficiency of the conservation process or by allowing a reduction in costs.

4. Future research needs differ considerably among regions of the world.

Grasslands For Production And The Environment, David R. Kemp, David L. Michalk

IGC Proceedings (1977-2023)

Key points

1. To manage grasslands for production and enhanced environmental values requires a redefinition of the frameworks within which management decisions are made, and a tailoring of practices to suit the ways that farmers operate.

2. Improving the perenniality and permanence of grasslands usually leads to better environmental and production outcomes.

3. There is a case for a more conservative approach to utilising grasslands in order to sustain the functioning of local ecosystems and to improve water quality, nutrient and energy cycling and biodiversity.

4. A landscape rather than paddock focus is more appropriate for meeting current grassland management …

Strategies To Mitigate Seasonality Of Production In Grassland-Based Systems, Claudio Porqueddu, S. Maltoni, John G. Mcivor

IGC Proceedings (1977-2023)

Key points

1. Fertilisation use and manipulation can cost-effectively alter species composition, increase seasonal herbage production and improve herbage quality.

2. Choice of suitable grassland species, varieties and mixtures offers opportunity to mitigate limitations of seasonal grassland production.

3. Special purpose fodder crops, cereals, shrubs and trees offer alternative or supplementary feed sources.

4. Manipulation of stocking rates, grazing systems, transhumance and pasture management at various times of the season are significant advantageous options.

5. Integration of different strategies is essential to mitigate seasonality in systems of animal production that must be inherently more sustainable over a longer time frame.

Interactions Between Foraging Behaviour Of Herbivores And Grassland Resources In The Eastern Eurasian Steppes, Deli Wang, Guodong Han, Yuguang Bai

IGC Proceedings (1977-2023)

Key points

1. In rangeland areas such as the eastern Eurasian steppes (Mongolia and China), foraging behaviour is influenced by plant or vegetation properties with high heterogeneity.

2. Until recently foraging theory has not accounted for the foraging process or ingestive behaviour. Existing theories on foraging behaviour need to evolve and begin to coalesce, and combine with observations or manipulative experiments.

3. Plant and patch properties such as diversity and height influence animal foraging behaviour (related to foraging process or diet selection) in heterogeneous steppes.

4. Stocking rate is the most important management factor for grazing or vegetation management, and …

Foraging Behaviour And Herbage Intake In The Favourable Tropics/Subtropics, S. C. Da Silva, Paulo C. De F. Carvalho

IGC Proceedings (1977-2023)

Key points

1. Herbage intake by animals grazing tropical/sub-tropical pastures is directly related to bite mass, as it is for those grazing temperate pastures.

2. Where these swards have low proportions of stem and dead material (controlled swards), herbage intake follows a similar pattern to that of temperate pasture species, but leaf characteristics, such as lamina length play an important role and influence the short-term rate of intake.

3. Sward structural characteristics and behavioural factors are relatively more important than nutritional factors in terms of herbage intake regulation. The feeding value of the herbage produced is potentially adequate to sustain …

Grass And Forage Plant Improvement In The Tropics And Sub-Tropics, Liana Jank, Cacilda B. Do Valle, Rosangela M. S. Resende

IGC Proceedings (1977-2023)

Key points

1. The majority of tropical and subtropical forage grass genera and/or species have not yet been collected, or need further collection to be representative of their natural distribution.

2. New biotechnological techniques will only result in the release of superior forage cultivars if supported by strong breeding programs.

3. More funding and investment in the formation of strong public research teams in forage conservation and improvement are needed to guarantee the sustainability of tropical and subtropical pasture-based livestock systems in the future.

4. The creation of a permanent international working group on tropical and subtropical forages is essential …

Grass And Forage Improvement: Temperate Forages, Chris J. Pollock, M. T. Abberton, M. O. Humphreys

IGC Proceedings (1977-2023)

Key points

1. Plant breeding has contributed significantly to the development of effective grassland production systems.

2. New technologies offer enhanced precision in breeding and access to wider genetic variation.

3. The requirement for more sustainable production systems will require genetic improvements in complex traits where the use of new technology will be vital.

Improving The Quality Of Products From Grassland, Nigel D. Scollan, R. J. Dewhurst, A. P. Moloney, J. J. Murphy

IGC Proceedings (1977-2023)

Key points

1. Consumers are increasingly aware of the links between diet and health, and place increasing emphasis on nutritional quality as a component of product quality.

2. Meat and milk products are rich sources of nutrients such as omega-3 (n-3) fatty acids and conjugated linoleic acid, which offer health benefits to consumers.

3. Green plants are the primary source of n-3 fatty acids in the food chain.

4. Grassland production systems have the potential to enhance the content of beneficial fatty acids, improve stability (from higher antioxidant content) and alter sensory attributes of meat and milk.

5. Grassland offers …

Rising Demand For Meat And Milk In Developing Countries: Implications For Grasslands-Based Livestock Production, C. L. Delgado

IGC Proceedings (1977-2023)

Key points

1. Meat and milk consumption in developing countries has grown three times as fast as in developed countries over the past 30 years.

2. By 2020, developing countries will consume 72 million metric tons (mmt) more meat and 152 mmt more milk compared to 2002/3, dwarfing developed-country increases of 9 mmt for meat and 18 mmt for milk.

3. Ruminant livestock will account for 27% of the increase in global meat consumption between 2003 and 2020, up from 23% over the previous two decades.

4. The inflation-adjusted prices of livestock and feed grains are expected to fall only …

Grassland In Ireland And The Uk, Myles Rath, S. Peel

IGC Proceedings (1977-2023)

Key points

1. Grassland is the dominant land use option in Ireland and the UK, and is characterised by a long growing season.

2. Dynamic, interactive systems of grassland management have been developed which combine high grass dry matter intakes with good sward quality. In the better grassland areas milk yields in excess of 7000 kg/cow are attainable with low levels of concentrate supplementation.

3. In the times to come, measures to protect the environment will constrain stocking rates, and fertiliser and manure use on intensive grassland enterprises.

4. A high proportion of beef and sheep farms participate in voluntary, …

Comparative Evaluation Of Physicochemical And Fermentative Responses Of Three Sorghum Varieties From Dryland And Irrigated Land And The Properties Of Proteins From Distillers’ Grains, Jikai Zhao, Thomas Weiss, Zhenjiao Du, Shan Hong, Scott R. Bean, Yonghui Li, Donghai Wang

School of Earth, Environmental, & Marine Sciences Faculty Publications

Three sorghum varieties [waxy sorghum (WS), high protein sorghum (HPS), and normal sorghum (NS)] grown under dryland and irrigated conditions were evaluated with respect to the physicochemical and fermentative properties. The proteins were extracted from wet distillers' grains with solubles (WDGS) and characterized in terms of purity and in vitro digestibility. Starch, crude protein, crude fat, and fiber contents of the sorghums ranged from 64.16 to 68.05 g/100 g, 11.49–13.54 g/100 g, 2.45–2.98 g/100 g, and 1.62–1.80 g/100 g, respectively. For the same variety, the sorghums grown under dryland conditions had higher protein (0.33–0.91 g/100 g) and lower …

Comparative Assessment Of Pollutant Concentrations And Meteorological Parameters From Tceq Cams Sites At Houston And Rio Grande Valley Regions Of Texas, Usa In 2016, Esmeralda Mendez, Jonathan Rodriguez, August Luna, Amit U. Raysoni

School of Earth, Environmental, & Marine Sciences Faculty Publications

Spatial and temporal heterogeneity in pollutant concentrations exists at the intra-urban level. In this research work, the concentrations of various pollutants and meteorological parameters are characterized between various central ambient monitoring sites at Houston, TX, and the Rio Grande Valley Regions of South Texas. Meteorological (temperature, relative humidity, wind speed and direction) and pollutant (O3, SO2, CO, NO2, and various PM species) concentrations were downloaded from the appropriate Texas Commission on Environmental Quality (TCEQ) Central Ambient Monitoring Station (CAMS) sites for the year 2016. Correlation Analyses and Coefficient of Divergence (COD) analyses suggest that statistically significant differences occur between the …

An Analysis Of The Effects Of Large Wildfires On The Hydrology Of Three Small Catchments In Central Chile Using Tritium-Based Measurements And Hydrological Metrics, Francisco Balocchi, Diego Rivera, José Luis Arumi, Uwe Morgenstern, Donald A. White, Richard P. Silberstein, Pablo Ramírez De Arellano

Research outputs 2022 to 2026

Wildfires are an important disturbance affecting catchments’ soil and hydrological processes within. Wildfires are predicted to increase in both frequency and severity under climate change. Here, we present measurements of tritium (3H) in surface water of three streams before and after the ‘las Máquinas’ megafire of January 2017 in central Chile and streamflow metrics. Mean transit times (MTTs) of water were calculated in three coastal catchments with the Mediterranean climate type, covered by native forest, a mixture of native forest and Pinus radiata D. Don, and P. radiata. Lumped parameter models (LPMs) were used to obtain MTTs. Tritium activities from …

Now You See Me: “First” Records Of The Greater Amberjack Seriola Dumerili At Rapa Nui Range Extension Or Increased Scientific Effort?, Naiti Morales, Amy Rose Coghlan, Erin E. Easton, Alan M. Friedlander, James J. Herlan, Carlos F. Gaymer

School of Earth, Environmental, & Marine Sciences Faculty Publications

We report new records of the fisheries-harvested subtropical greater amberjack Seriola dumerili for the south-east Pacific Ocean. Previously, only one species of Seriola (the yellowtail amberjack Seriola lalandi) was scientifically recorded for Rapa Nui (also known as Easter Island) despite local fishers' asserting that three Seriola morphotypes are found in the region. Here we present the first 'scientific record' of what could be a pre-existing (albeit transient) species of the Rapa Nui ecoregion. Establishing the existing range limits of commercially and ecologically valuable species is key for observing climate-driven distribution shifts, and the inclusion of traditional ecological knowledge is likely …