Earth Sciences Commons^™

Potential Yield Of Cocksfoot (Dactylis Glomerata) Monocultures In Response To Irrigation And Nitrogen, A. Mills, D. J. Moot, R. L. Lucas, P. D. Jamieson, B. A. Mckenzie

IGC Proceedings (1977-2023)

Cocksfoot is a widely sown grass in temperate pastures. However, while potential yield of cocksfoot can exceed 28 t DM/ha per year, it is often restricted by water, temperature and nitrogen (N). Of these, Peri et al. (2002) showed that N was severely limiting in all seasons. The aim of this study was to confirm the potential yield of cocksfoot and quantify the extent of yield reductions due to environmental constraints.

Blood Meal As A Source Of Histidine For Cattle Fed Grass Silage And Barley, R. Berthiaume, C. Lafrenière

IGC Proceedings (1977-2023)

Previous research has shown that cattle fed grass silage are responsive to protected amino acids (Veira et al., 1991). Methionine and lysine were suggested as the most limiting amino acids for grass silage diets. Recently, Korhonen et al. (2000) have shown that histidine is the first limiting amino acids for dairy cows fed grass silage and barley-based concentrates. However, histidine is not available in a rumen protected form and needs to be provided through dietary ingredients. Blood meal is rich in histidine. This trial was designed to determine the effect of increasing histidine supply through blood meal on …

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

IGC Proceedings (1977-2023)

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 boundaries that links pollutant sources to impact. …

Nitrogen Behavior In A No-Tillage Agroecosystem Located In The Inner Bluegrass Of Kentucky, Alec William Besinger Mr.

Theses and Dissertations--Plant and Soil Sciences

Nitrogen (N) is a crucial element, often limiting productivity in ecosystems. This limitation is relieved N fertilizer additions. No-tillage (NT) agroecosystems are prone to lower N availability translating to lower crop yields. The default explanation for lower N availability in NT is microbial immobilization of added N fertilizer. Historically, N availability is often assessed using chemical extractions such as KCl to evaluate levels of inorganic N in the soil. The possibility of this abiotic clay mineral fixation as mechanism in well-drained NT soils has been overlooked. The objectives of this study are to quantify N availability using KCl, NaCl, and …

Nitrite Cycling In The Primary Nitrite Maxima Of The Eastern Tropical North Pacific, Nicole M. Travis, Colette L. Kelly, Margaret R. Mulholland, Karen L. Casciotti

OES Faculty Publications

The primary nitrite maximum (PNM) is a ubiquitous feature of the upper ocean, where nitrite accumulates in a sharp peak at the base of the euphotic zone. This feature is situated where many chemical and hydrographic properties have strong gradients and the activities of several microbial processes overlap. Near the PNM, four major microbial processes are active in nitrite cycling: ammonia oxidation, nitrite oxidation, nitrate reduction and nitrite uptake. The first two processes are mediated by the nitrifying archaeal/bacterial community, while the second two processes are primarily conducted by phytoplankton. The overlapping spatial habitats and substrate requirements for these microbes …

Dynamic Soil Properties In The Lower Rio Grande Valley: Carbon And Nitrogen Responses To Different Tillage Practices, Luzyannet Ballesteros Gonzalez

Theses and Dissertations

There has been increased attention in utilizing agriculture for carbon sequestration. Soil carbon and nitrogen are two dynamic soil properties (DSPs) that are indicators of soil health and function and have overlapping cycles. These soil properties change frequently as a result of environmental conditions and agricultural management practices. This study focuses on the impact of tillage practices in unirrigated agricultural fields in Hidalgo and Willacy counties located in South Texas on Hidalgo Sandy Clay Loam; With a particular focus on Soil Total Carbon (TC), Soil Inorganic Carbon (SIC), Permanganate Oxidizable Carbon (POXC), Carbon and Nitrogen ratio (C:N), Soil Organic Matter …

Diagnosing Excess Nitrogen In Rice Using Post-Season Tissue Samples, Kyle Hoegenauer

Graduate Theses and Dissertations

Proper nitrogen (N) management in rice production can be difficult to achieve without the aid of tools such as soil and tissue tests. There are no tests currently available to rice producers that determine whether N has been managed properly throughout the season or that detect instances of over fertilization. Rice stalk samples were collected from N response trials within 3 days of harvest from the primary Arkansas rice growing region in 2016-2018. Stalk samples were analyzed for N concentration through a KCl extraction and spectrofluorometric quantification. Samples analyzed with leaf material intact contained statistically different N concentrations than samples …

Mechanical Aeration And Liquid Dairy Manure: Application Impacts On Grassland Runoff Water Quality And Yield, T. J. Basden, S. B. Shah, J. L. Miller

IGC Proceedings (1977-2023)

Wet weather on heavy soils reduces oxygen availability in the root zone and reduces forage yields. Mechanical aeration can improve forage yield in these soil conditions. Research has shown that under certain conditions, mechanical aeration can increase yield by improving drainage and aeration (Davies et al., 1989); aeration can also increase depression, storage and infiltration thus reducing surface runoff and improving nutrient distribution in the root zone. Aeration on sloping, fertilised grassland can provide environmental (Douglas et al., 1995) and agronomic benefits. The objectives of this study were to evaluate the runoff water quality and agronomic impacts of …

Assessment Of Nitrogen Nutrition Status Of Grasses Under Water Deficit And Recovery, V. G. Dugo, Jean-Louis Durand, F. Gastal

IGC Proceedings (1977-2023)

Grasslands are rarely irrigated. They are therefore systematically submitted to more or less severe water deficits: as well as mineral deficiencies, water scarcity often also results in a reduction of nitrogen (N) status. Although identified some time ago, qualitatively, the interaction with N still remains difficult to take into account in quantitative analyses of crop physiology under water deficits. This paper illustrates how the nitrogen (N) status of the crop changes under water deficits. A N nutrition index (INN) was defined as the ratio of the actual N concentration of forage with the theoretical N concentration under optimal conditions, the …

Nitrogen Mineralisation In Situ And In Controlled Environment, F. Pálmason

IGC Proceedings (1977-2023)

Net mineralisation may be underestimated by in situ soil core methods for at least two reasons: (1) absence of plant N uptake in the soil cores, causing higher immobilisation than in intact soil. Schimel & Bennet (2004) thus concluded that plants compete effectively with microbes, as strongly indicated by cases, where net mineralisation was lower than plant uptake. (2) Gaseous losses of N₂O in closed cylinders can lead to underestimation especially during long incubation periods, Abril et al. (2001) and Vor & Brumme (2002).

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 …

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.

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 …

Assessment Of Nitrogen-Based Fertilizer Transport And Microbial Activities In Sandy Soil Profiles In South Texas, Gladys De La Rosa

Theses and Dissertations

Conventional farming is a common practice in Lower Rio Grande Valley (LRGV) and the application of nitrogen fertilizer is essential for plant growth and support. However, managing the rate of nitrogen that is applied can benefit farmers financially and reduce nitrate leaching that can have an adverse effect on the local environment and aquatic systems, e.g., rivers and estuaries. Sandy soils are more vulnerable to water infiltration due to the large proportion of macropores. This study aims to (i) assess how nitrate from a variety of fertilizers (i.e., synthetic and organic) distributes on the top 60 cm layer of a …

Sedimentary Characteristics And Associated Carbon And Nutrients Of Overbank Sediments Deposited During The 2018, 2019, And 2020 Floods In Embanked Floodplains Along The Lower Mississippi River Near Natchez, Mississippi, Rachel Kelk

Master's Theses

The Lower Mississippi River (LMR) experienced major floods in 2018, 2019, and 2020. Sediment deposition in the embanked floodplains during floods represent important storage and sequestration opportunities for carbon and nutrients from ~40% of the continental USA. This research aims to compare depositional thicknesses, organic matter (OM), carbon (C), nitrogen (N), phosphorous (P) concentrations, and grain sizes in floodplain sediments deposited by the combined 2018-19 floods to the 2020 flood along the LMR near Natchez, Mississippi. Greater depositional thicknesses in 2018-19 are best explained by their combined flood durations; the 2019 flood was the longest in recorded history. Slightly higher …

Stable Carbon And Nitrogen Isotopes Of Shell Bound Organic Matter, Implications For Modern And Ancient Food Web Dynamics, Shibajyoti Das

Dissertations - ALL

Stable isotopes are an important tool for solving biogeochemical problems and have been increasingly applied in ecosystem studies because of their utility as source-to-sink tracers and for ecological information. Elements like C and N have more than one stable isotope, and their isotopic compositions (δ15N and δ13C) vary in a foreseeable way and are specifically useful in studying global elemental cycles and energy flow through ecosystems. δ15N and δ13C of organic matter (OM) are diagnostic of an organism's diet and have been used as a proxy for trophic level reconstructions. However, because of several analytical constraints, the use of stable …

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 …

Elevated Co2 And Extreme Climatic Events Modify Nitrogen Content And Ruminal Protein Digestion Of Temperate Grassland, V. Niderkorn, C. Picon-Cochard

IGC Proceedings (1977-2023)

This study was aimed at analyzing changes in nitrogen (N) content and in vitro protein rumen digestion of an upland grassland exposed to climate changes in controlled conditions. Monoliths of grassland were inserted in 12 macrocosms in which climatic conditions for the 2050s were simulated (i.e., +2.3°C and 33 mm less precipitation compared to the current climatic conditions). Six of them were subjected to ambient CO₂ (390 ppm) while the other six were subjected to elevated CO₂ (520 ppm). After four months, an extreme climatic event (ECE) consisting of four weeks of reducted precipitation (-50%) followed by two …

Effect Of Native Grassland Intensification Over Cattle Performance, N. Caram, F. Casalás, M. Cadenazzi, R. Zanoniani, P. Boggiano

IGC Proceedings (1977-2023)

The objective was to evaluate the effect of different levels of intensification in native grassland over cattle live weight gain (LWG), stocking rate (SR) and average daily gain (ADG) in Uruguay. The study was carried out in 7.8 ha in Paysandú, between winter 2015 and autumn 2019. Experiment was a randomized complete block design, with 4 replicates. The four treatments applied were native grassland (NG), NG overseeded with Trifolium pratense (6 kg.ha^-1) and Lotus tenuis (6 kg.ha^-1) + 40 kg.ha^-1 of P₂O₅ (NGO), NG fertilized with 60 kg.ha^-1 of N + …

Mapping Nitrogen Fixing Shrubs In Dry Unimproved Tussock Grassland, C. C. Boswell, W. L. Lowther, P. D. Espie

IGC Proceedings (1977-2023)

Global Positioning System (GPS) was used to both map the positions of individual nitrogen-fixing shrub plants and record individual plant height and breadth dimensions, within a small catchment of dry sub-humid unimproved short tussock grassland. The distributions of different species of shrubs varied with different landscape units within the catchment. The information will provide the base data for a first approximation of the role of the shrubs in the nitrogen balance of the ecosystem, which is pivotal to the sustainability of pastoral farming in the tussock grasslands.

Importance Of Haresfoot Clover (Trifolium Arvense) As A Nitrogen Fixer In Semi-Arid Grasslands Of New Zealand, C. C. Boswell, W. L. Lowther, P. R. Espie

IGC Proceedings (1977-2023)

The aim of the study was to determine the distribution of annual haresfoot clover (Trifolium arvense) in a depleted indigenous short tussock grassland catchment in the dry subhumid MacKenzie Basin, South Island, New Zealand. Haresfoot clover was present on all landscapes, and widely distributed on lower sunny aspects, suggesting that it is an important component of the nitrogen cycle in these environments even in the absence of fertiliser application. The study was conducted during an atypically moist summer when a bloom of the annual clover occurred. Nitrogen inputs will vary with landscape and spring/summer rainfall and it is …

Vegetation Changes In Southeast Australian Temperate Grasslands, D. L. Garden, T. P. Bolger

IGC Proceedings (1977-2023)

In temperate areas of southeast Australia, the combined effects of tree clearing, grazing, application of fertilizer and the introduction of exotic species have modified the original grasslands. This paper describes these changes and attempts to explain them in terms of ecological principles derived from North American grasslands. Stability of the original grasslands appears to have been due to the lack of disturbance and the slow rates of nitrogen (N) cycling within them. Increased N cycling after disturbance has allowed invasion of species better adapted to higher N status, particularly exotic annual grasses and weeds. The present composition of grasslands, in …

Effects Of Nitrogen Fertilization On The Production Of Panicum Maximum Cv. Ipr 86 Under Grazing, S. M. B. Lugão, L. R. De A. Rodrigues, E. B. Malheiros, J. J. Dos S. Abrahão, A. De Morais

IGC Proceedings (1977-2023)

The experiment was conducted at the Experimental Station of Paranavaí/IAPAR-PR-Brazil, from October 1998 to May 1999, to evaluate the effects of N fertilization on Panicum maximum cv. IPR 86 pastures. Four doses of N (0; 150; 300; and 450 kg.ha^-1.year^-1) were applied to pastures under rotational grazing with grazing cycles (GCs) of 40 days (5 days-grazing and 35 days-rest). It was used a randomized complete block design, with split-plots, and two replications per treatment, being the N-doses studied in the main plots and the GCs in the sub-plots. In all GCs the variables dry matter of …

Animal Performance In Pastures Of Panicum Maximum Cv. Ipr 86 Fertilized With Nitrogen, S. M. B. Lugão, L. R. De A. Rodrigues, E. B. Malheiros, J. J. Dos S. Abrahão, A. De Morais

IGC Proceedings (1977-2023)

The experiment was carried out at the Experimental Station of the IAPAR in Paranavaí– PR, Brazil, from October 1998 to May 1999 to evaluate the response of crossbred steers grazing pastures of Panicum maximum cv. IPR 86 fertilized with four doses of N (0; 150; 300 and 450 kg.ha^-1.year). The grass was grazed according to a rotational grazing system with grazing cycles (GCs) of 40 days (grazing period of 5 days and rest period of 35 days). It was used a randomized complete block design, with split-plots, and two replications per treatment, being the N-doses studied in the …

Nitrogen Mineralization From Root Residues Of Subterranean Clover And Lucerne, T. P. Bolger, J. F. Angus, M. B. Peoples

IGC Proceedings (1977-2023)

To understand why crops grown in the first or second year after lucerne (Medicago sativa L.) yielded less than crops grown after subterranean clover (Trifolium subterraneum L.) despite greater nitrogen (N) fixation by the lucerne, we studied the N mineralization patterns of their root residues in soil incubation assays. Fine roots of both species produced more mineral N than the control soil with no root residues. In contrast, coarse roots mineralized less N than the control soil. These differences in N mineralization were not explained by the physical size and therefore surface area differences between fine and coarse …

Agronomic Evaluation Of Forage Grasses Under Mature Rubber Plantation, N. L. Costa, Valdinei T. Paulino, A. C. M. Igreja, C. R. Townsend, J. A. Magalhães, R. G. De A Pereira, T. S. Paulino

IGC Proceedings (1977-2023)

The agronomic performance of seven forage grasses, under a mature rubber plantation, was assessed in a cutting trial carried out at Porto Velho, Rondônia. During the rainy season, the higher dry matter yields were obtained with B. brizantha, P. atratum BRA-9610 and B. humidicola. During the dry season, the grasses more productive were B. brizantha and P. atratum BRA-9610. In both seasons, magnesium and potassium contents did not vary among grasses. During the rainy season, the higher nitrogen and phosphorus contents were obtained with P. regnelli BRA-0159 and, P. guenoarum BRA-3824 and B. humidicola, respectively, while P. atratum …

Optimizing Yield And Quality Of Orchardgrass Pasture In Temperate Silvipastoral Systems, P. L. Peri, R. J. Lucas, D. J. Moot, A. C. Varella, D. L. Mcneil

IGC Proceedings (1977-2023)

The objective of this study was to provide grazing management recommendations for a silvipastoral system by determining the effects of shade and nitrogen (N) on the pattern of dry matter accumulation and nutritive value of orchardgrass (Dactylis glomerata) in a subhumid temperate environment. Orchardgrass in open pasture (100% transmittance) and under 10 year old Pinus radiata tree shade (60% transmittance) at 200 stems/ha was used as the main plot and nitrogen (0 and 300 kg N/ha as synthetic urine) was the subplot factor. Dry matter (DM) production of orchardgrass in the first 60-day spring rotation was similar in …

Variability For Nitrogen And Phosphorus Uptake Among Timothy Genotypes, Réal Michaud, Gilles Bélanger, A. Brégard

IGC Proceedings (1977-2023)

Cultivars of timothy (Phleum pratense L.) with high N and P use efficiencies are required to reduce costs of production and risks of N and P pollution, and to meet the nutrition requirements of high producing animals. This field study aimed at comparing, (under three N rates) the relationship between DM yield, N uptake, and P uptake of 27 timothy half-sib families, plus the cultivar Champ as a control (Dry matter yield), N and P uptake increased with increasing N rates. Genotypes also differed for DM yield, N and P uptake. For a given DM yield, the genotypes had …

The Effect Of Perennial Ryegrass Cultivar Lock Up Length And Nitrogen On Forage Quality For Silage, Joseph L. Jacobs, Frank R. Mckenzie, G. N. Ward

IGC Proceedings (1977-2023)

A study was undertaken to determine the effects of three perennial ryegrass (Lolium perenne L.) cultivars (Vedette, Impact and Nevis) with differing maturities, lock up length and nitrogen (N) application upon the dry matter (DM) yield and nutritive characteristics of pasture for silage. The addition of N at 50 kgN/ha significantly (P< 0.05) increased DM yield for all cultivars. Metabolisable energy (ME) (MJ/kgDM) of the ryegrass declined with time for all treatments, although by week 8 of lock up the ME content of Vedette was significantly (P< 0.05) lower than for other cultivars. When the DM yield and ME content of ryegrass at early ear emergence for each cultivar was compared, the harvestable metabolisable energy (MJ/ha) was highest for Nevis followed by Impact and Vedette. In conclusion, there is potential to use later maturing cultivars of ryegrass in south east Australia to allow for later harvesting of forage for silage, whilst maintaining ME and maximising DM yields. Furthermore the use of N fertiliser can also increase DM yields without impinging on pasture quality.