Agronomy and Crop Sciences Commons^™

How Will Removal Of The Non-Organic Feed Derogation Affect Nutrient Budgets Of Organic Livestock Farms In Wales?, H. Mccalman, S. P. Cuttle

IGC Proceedings (1977-2023)

Agri-environment schemes encourage organic farming in Wales. The National Assembly Government second organic action plan has a target of 10-15% land in organic production by 2010. Although forage based, many organic livestock farmers buy in concentrate feeds, which are important sources of nutrients to the farm. The current derogation allowing organic producers up to 10% approved non-organic feed ends in 2005. Many organic farmers are beginning to make management changes to comply with this. The aims of this study were to construct simple nutrient budgets on different organic livestock farms, investigate any planned system changes, look at impacts on nutrient …

Diet Effects On Dairy Manure Nitrogen Excretion And Cycling, J. M. Powell, T. H. Misselbrook

IGC Proceedings (1977-2023)

The amount and forms of (nitrogen) N excreted by ruminant livestock and post excretion manure N cycling are highly influenced by what is fed. For example, the relative amount of urinary N, faecal endogenous N of microbial and gut origin, and faecal undigested feed N is affected by how much dietary fibre and secondary compounds (e.g., tannins, polyphneolics) are consumed. Each manure N component has a different propensity for loss; for example via ammonia (NH3) volatilisation (Misselbrook et al., 2004), leaching, and cycles differently in the soil-plant continuum (Powell, 2003). We evaluated dairy diet effects on amount and forms …

Effect Of A Grazing Intensity Gradient On Primary Production And Soil Nitrogen Mineralisation In A Humid Grassland Of Western France, N. Rossignol, A. Bonis, J-B. Bouzillé

IGC Proceedings (1977-2023)

Large herbivores have a major influence on the structure and the functions of humid grasslands and especially on primary production. Earlier work on the study site showed that grazing intensity was spatially varied and created a diversity of vegetation patches in the grassland (Loucougaray, 2003). The first objective of this study was to determine whether the variation in grazing intensity led to variation of primary production within the three plant communities located at three topographic levels in the grassland. The second objective was to determine whether a relationship linked primary production variation and net soil nitrogen (N) mineralisation.

The Role Of Grass Tussocks In Maintaining Soil Condition In North East Australia, B. K. Northup, J. R. Brown

IGC Proceedings (1977-2023)

Soils of the grazing lands of north eastern Australia are inherently nutrient-poor. Heterogeneously distributed plants are important to the conservation of the limited amounts of nutrients, through storage in plant tissues or in soil sinks close to plants (Ludwig et al., 1997). Loss of perennial vegetation through disturbance reduces conservation of these resources, to the detriment of feedback mechanisms, and ultimately causes loss of soil condition. Large areas of north east Australia have been degraded, or threatened by degradation, through combinations of variability in precipitation and heavy grazing (Gardener et al., 1990). This study examined the inter-related responses …

Within Resting Period Seasonal Soluble Carbohydrate Profiles Of Rotationally Grazed Elephant Grass, L. P. Passos, M. C. Vidigal, I. G. Perry, Fermino Deresz, F. B. De Sousa

IGC Proceedings (1977-2023)

Recent evidence indicates that carbohydrate-rich grazed herbage is effective for improving milk production (Trevaskis et al., 2004). However, the dynamics of water-soluble carbohydrate (WSC) seasonal accumulation as related to forage availability remains unknown, especially during the growth stage of tropical forage grazing systems. The objective of the work was to verify the seasonal WSC profiles of rotationally grazed elephantgrass (Pennisetum purpureum Schum.), by making measurements within each 30-day resting period.

Cool-Season Grass Response To Increasing Nitrogen Fertiliser Rates In Michigan, R. H. Leep, T. S. Dietz, D. H. Min

IGC Proceedings (1977-2023)

Nitrogen (N) fertility recommendations for cool-season grasses in the north central region of the USA have not been species specific. This broad recommendation assumes that all grasses have similar N demands, while seasonal growth patterns and dry matter yield of cool-season grass species vary. Nitrogen fertiliser costs have steadily increased, but recommendations are to be below optimal levels for economic return (Klausner et al., 1998). A more specific N fertiliser recommendation may increase the producers’ net income.

Effects Of Applied Quantity Of Phosphorus Fertiliser On Phosphorus Content In Plant Tissues Of Lucerne (Medicago Sativa) And Seed Yield In North-Western China, Y. W. Wang, J. G. Han, S. M. Fu, Y. Zhong

IGC Proceedings (1977-2023)

Phosphorus concentration in plant tissue can be a useful index of P deficiency in lucerne, P fertiliser recommendations and monitoring of effectiveness of current P fertiliser practices (Jacobsen & Surber, 1995). The objective of this study was to measure P concentration in different lucerne plant parts and seed yield in relation to P fertiliser application rates in order to improve recommendations for lucerne seed production.

Field Experiments To Help Optimise Nitrogen Fixation By Legumes On Organic Farms, A. Joynes, D. J. Hatch, A. Stone, S. Cuttle, G. Goodlass

IGC Proceedings (1977-2023)

During an organic rotation, the aim is to increase the nitrogen (N) content of the soil (and hence build up soil fertility) by recycling crop residues, applying manures/composts and from N fixed by legumes. IGER, with ADAS, Duchy College Cornwall and Abacus Organic Associates are developing improved guidance for organic farmers in the use of fertility-building crops. The main questions are: how to maximise N fixation and how to make the most efficient use of the fixed N? Available soil mineral N, which is generally thought to reduce N fixation, will be increased by manure applications, cutting/mulching and grazing. We …

The Effect Of Forage Legumes On Mineral Nitrogen Content In Soil, M. Isolahti, A. Huuskonen, M. Tuori, Oiva Nissinen, R. Nevalainen

IGC Proceedings (1977-2023)

The cultivation of forage legumes is often suggested as a possibility to improve nitrogen (N) utilisation in farming. However, previous studies have indicated examples in which the cultivation of legumes such as white clover has led to accumulation of large amounts of N in soil (Adams & Pattison, 1985). In this study the potential risks of N leaching were estimated by determining amount of mineral N in the soil.

Analysis Of The Soil Foodweb Structure On Organic- And Conventional Dairy Farms, N. Van Eekeren, F. Smeding, A. J. Schouten

IGC Proceedings (1977-2023)

The below ground biodiversity of soil organisms plays an important role in the functioning of the soil ecosystem, and consequently the efficiency of the above ground plant production on dairy farms. However, for farmers, soil biology remains a black box. It is difficult to interpret soil biology on dairy farms and to identify management measures to improve it. The objective of this study was to investigate if it is possible to classify the soil foodweb structure on a dairy farm in relation to management practices

Study Of Characteristics Of Soil Animals In Halophilous Plant Communities Of Leymus Chinensis Grasslands Of Northeast In China, Xiuqin Yin, Y. Zhang, W. Dong

IGC Proceedings (1977-2023)

We have researched soil animals in 8 types of halophilous plant communities of Leymus chinensis grasslands of Northeast China to characterise soil animal groups and explain the role and function of soil animals in grassland ecosystems (Richard & Roger, 1998) and provide a scientific basis for research to improve alkaline lands in these grasslands.

Impact Of Root Herbivory On Grassland Community Structure: From Landscape To Microscale, P. J. Murray, R. Cook, L. A. Dawson, A. C. Gange, S. J. Grayston, A. M. Treonis

IGC Proceedings (1977-2023)

Root herbivores are an important functional group in grassland ecosystems. Whilst there is a plethora of information on their impact as pests in productive grassland, few studies of their impact on biodiversity in upland grassland have been made. Root herbivores act in a number of ways, they reduce host plant biomass, alter root architecture, change root exudation patterns and increase water stress in the plant. Root herbivores may change above ground plant diversity, both through direct removal of plant species and through reduction in competitive ability of some species, through their feeding. In addition, we postulate that root herbivores affect …

How Soil Properties Affect Egg Development And Larval Longevity Of A Grassland Insect Pest - An Empirically Based Model, S. N. Johnson, X. Zhang, J. W. Crawford, P. J. Gregory, S. C. Jarvis, P. J. Murray, I. M. Young

IGC Proceedings (1977-2023)

The clover root weevil (Sitona lepidus Gyllenhal.) is a destructive pest of white clover in temperate grasslands. Adults lay thousands of eggs that give rise to soil-dwelling larvae that initially feed on the root nodules housing symbiotic N2-fixing Rhizobium spp. bacteria. The period between egg hatch and consumption of root nodules by larvae is probably the most vulnerable part in the lifecycle, and if larvae do not locate roots relatively quickly they will die of starvation. In particular, the shells of eggs and the cuticles of emergent larvae are in constant physical contact with the external soil environment, so …

Grassland Management Practices And The Diversity Of Soil Nematode Communities, R. Cook, P. J. Murray, K. A. Mizen

IGC Proceedings (1977-2023)

Nematodes are numerically abundant in northern temperate grassland soils where, through their feeding on plants, soil microbes and each other as well as being a food resource, they contribute to soil functioning and affect plant soil interrelationships. Permanent plant cover and the consequent abundance of root tissue supply a year-round food supply. There are only limited data on the effects of root-feeding by nematodes on the growth and development of pasture plants but under some circumstances above-ground biomass may be reduced. Herbivory by specific nematode parasites may not only directly affect the host plant but also promote soil microbial activity …

The Addition And Cessation Of Inorganic Fertiliser Amendments In Long-Term Managed Grasslands: Impacts On Above And Below-Ground Communities, C. D. Clegg, P. J. Murray, R. Cook, T. Tallec

IGC Proceedings (1977-2023)

In recent times, land use in the United Kingdom has undergone considerable changes because of social and economic pressures, leading to a fine balance between the demands of highly productive intensive systems and practices which are perceived to be more environmentally acceptable. Plant productivity is governed by the supply of nutrients from the soil, which in turn is dependent on the dynamics of organic matter decomposition driven by soil micro-, meso- and macro fauna. Considerable information is available concerning the impact of inorganic fertiliser additions on communities of macro-fauna and flora, but the effects on specific microbial communities in soils …

Benomyl Effects On Plant Productivity Through Arbuscular Mycorrhiza Restriction In A Greek Upland Grassland, M. Orfanoudakis, A. P. Mamolos, F. Karanika, D. S. Veresoglou

IGC Proceedings (1977-2023)

Interactions between plants and microbes are important for plant community structure. Many plants establish symbioses with arbuscular mycorrhizal (AM) fungi, which play a central role in soil fertility, plant nutrition and the maintenance of stability and biodiversity within plant communities by improving uptake of nutrients and water. AM fungi can improve growth/performance in a variety of plant species by influencing intra- and interspecific competition of neighbouring plants and thus regulate coexistence and diversity in mixed communities. The aim was to study AMF effects on plant productivity and diversity in Greek upland grasslands.

40 Years Of Studies On The Relationships Between Grass Species, N Turnover And Nutrient Cycling In The Lamto Reserve In The Ivory Coast (Côte D’Ivoire), L. Abbadie, J. C. Lata

IGC Proceedings (1977-2023)

The Lamto Station, dominated by grass savannas, was created in 1963. Among other problems, the relationships between savanna grasses (mainly Andropogoneae supertribe) and nutrient cycling, mainly nitrogen (N), have been intensively studied. Such grass systems are of major interest. Savannas represent 25% of terrestrial biomes and are second to tropical forests in the contribution to terrestrial primary production and are predominant in African social and economic environments. The Andropogoneae grasses are of particular interest for pastures. Second, savannas are generally extremely nutrient-poor, especially for N, which often limits productivity. Third, little is known about possible controls of grasses on N …

Cycling Of N And P In Grass-Alone (Brachiaria) And Mixed Grass/Legume (Brachiaria/ Desmodium Ovalifolium) Grazed Pastures In The Atlantic Forest Region Of Brazil, R. M. Boddey, R. Tarré, R. Macedo, C. De P. Rezende, J. M. Pereira, B. J. R. Alves, S. Urquiaga

IGC Proceedings (1977-2023)

There are estimated to be > 80 M ha of Brachiaria pastures in the tropical regions of Brazil. When continuously grazed with only modest fertiliser inputs (and no N) these pastures can maintain reasonable cattle weight gains (> 200 kg LWG/ha per year). However, without fertiliser and when overgrazed, LWGs fall rapidly to low levels. Recent studies have shown that N and P deficiency are the most important factors limiting productivity. The objective of this study was to study fluxes of N and P in the pasture system in order to understand resilience to poor management and minimum nutrient requirements to …

Estimating Nitrogen Fixation By Pastures On A Regional Or Continental Scale, Murray Unkovich

IGC Proceedings (1977-2023)

With fertiliser N inputs dramatically increasing in Australia in recent years (Angus, 2001), regional and continental scale estimates of biological nitrogen fixation (BNF) are now required for assessing the risks of terrestrial and surface water eutrophication, groundwater contamination, and gaseous N emissions.

Integrating Below-Ground Ecology Into Sustainable Grassland Management, R. D. Bardgett

IGC Proceedings (1977-2023)

Key points

1. Grasslands produce soils that sustain an abundant and diverse soil food web, providing tremendous opportunity for below-ground interactions to influence nutrient cycling processes and plant production.

2. Fast developing areas of ecological science offer scope to harness positive outcomes of below-ground ecology for enhancing efficient cycling of nutrients in sustainable grassland systems.