Life Sciences Commons^™

Long-Term Effects Of Rice Rotation, Tillage, And Fertility On Near-Surface Soil Carbon And Nitrogen Cycling, Jill Marie Motschenbacher

Graduate Theses and Dissertations

Rice (Oryza sativa L.)-based cropping systems are different from other row crops due to the flood-irrigation scheme used from about one month after planting to a few weeks prior to harvest. The frequent cycling between anaerobic (i.e., flooding during the growing season) and aerobic (i.e., generally, the remainder of the year) conditions can influence the rate of soil organic matter (SOM) decomposition, which can greatly influence carbon (C) and nitrogen (N) storage and sequestration in the soil over time. Therefore, a study was conducted on a silt-loam soil (fine, smectitic, thermic, Typic Albaqualf) at the Rice Research and Extension Center …

A Review Of Cover Crops For Eastern Nebraska, Tyler Williams

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

The focus of this project is two fold, first to provide a short literature review of cover crops (CC) and then discuss the results from a field experiment that was designed to evaluate the nitrogen contribution from cover crop mixes to the subsequent corn crop. The literature review will focus on the aspects of CC that are related to the field of study. Cover crops, as defined by the United States Department of Agriculture (USDA) are crops that are agronomically sound and grown for the purpose of erosion control or other objectives related to conservation or soil improvement. Cover crops …

The Impact Of Selected Forage Legumes On Cattle Performance, Forage Production, And Soil Quality, And Evaluation Of Legume Persistence Under Grazing, Bradley Edward Briggs

Graduate Theses and Dissertations

Interest in substituting legumes for N fertilizer in beef cattle grazing systems has recently increased with rising fertilizer prices. Legumes are well known for their ability to fix atmospheric N and decrease dependence on input of N fertilizer. However, there are still difficulties associated with legume utilization including establishment and persistence. Two experiments were conducted to evaluate legume performance under herbivory. The objective of Experiment 1 was to compare forage production and beef cattle gains from annual ryegrass [Lolium multiflorum (L.)] and bermudagrass [Cynodon dactylon (L.) Pers.] pastures fertilized with N or overseeded with legumes. Gelbvieh × Angus …

Trait Convergence And Plasticity Among Native And Invasive Species In Resource-Poor Environments, Rebecca E. Drenovsky, Albina Khasanova, Jeremy J. James

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Premise of study: Functional trait comparisons provide a framework with which to assess invasion and invasion resistance. However, recent studies have found evidence for both trait convergence and divergence among coexisting dominant native and invasive species. Few studies have assessed how multiple stresses constrain trait values and plasticity, and no study has included direct measurements of nutrient conservation traits, which are critical to plants growing in low-resource environments.

Methods: We evaluated how nutrient and water stresses affect growth and allocation, water potential and gas exchange, and nitrogen (N) allocation and use traits among a suite of six codominant species from …

Water Use And Yields Of No-Till Managed Dryland Grasspea And Yellow Pea Under Different Planting Configurations, F.J. Calderón, M.F. Vigil, D.C. Nielsen, J.G. Benjamin, D.J. Poss

United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications

Grasspea (GP) (Lathyrus sativus) is a drought-tolerant legume that can be grown for forage and grain. It has potential value to be used as a nitrogen-fixing crop in dryland rotations with non-legume grain crops. However, the agronomy of GP for the Central Great Plains region have not been investigated. The objective of this research was to compare the grain and biomass yield, as well as N accumulation of GP relative to field pea (FP) in two planting configurations. We carried out a 3-year field experiment to compare dryland GP with Admiral yellow field pea (Pisum sativum) …

Influence Of The Neotyphodium--Tall Fescue Symbiosis On Belowground Processes, D. H. Mcnear Jr., Rebecca L. Mcculley

Plant and Soil Sciences Faculty Publications

Much of the work to date on the relationships between cool season grasses and Neotyphodium fungal endophytes has focused on the physiological, biochemical, and genetic ramifications of the host-fungus relationship and the subsequent influence these effects have on ruminant nutrition, plant adaptation to environmental stresses, and aboveground ecological processes. Relatively little attention has been paid to effects on belowground parameters. In this paper, we review the research evaluating the impact of one endophyte-grass association, the Neotyphodium – tall fescue symbiosis, on underground ecological and biogeochemical processes. We also present some preliminary data showing that the quantity and nature of tall …

Biomass Yield And Nutrient Responses Of Switchgrass To Phosphorus Application, M. K. Kering, J. T. Biermacher, T. J. Butler, J. Mosali, John A. Guretzky

Department of Agronomy and Horticulture: Faculty Publications

Increasing desire for renewable energy sources has increased research on biomass energy crops in marginal areas with low potential for food and fiber crop production. In this study, experiments were established on low phosphorus (P) soils in southern Oklahoma, USA to determine switchgrass biomass yield, nutrient concentrations, and nutrient removal responses to P and nitrogen (N) fertilizer application. Four P rates (0, 15, 30, and 45 kg Pha⁻¹) and two N fertilizer rates (0 and 135 kg Nha⁻¹) were evaluated at two locations (Ardmore and Waurika) for 3 years.While P fertilization had no effect on yield …