Life Sciences Commons^™

Ecosystem-Scale Biogeochemical Fluxes From Three Bioenergy Crop Candidates: How Energy Sorghum Compares To Maize And Miscanthus, Caitlin E. Moore, Adam C. Von Haden, Mark B. Burnham, Ilsa B. Kantola, Christy D. Gibson, Bethany J. Blakely, Evan C. Dracup, Michael D. Masters, Wendy H. Yang, Evan H. Delucia, Carl J. Bernacchi

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

Perennial crops have been the focus of bioenergy research and development for their sustainability benefits associated with high soil carbon (C) and reduced nitrogen (N) requirements. However, perennial crops mature over several years and their sustainability benefits can be negated through land reversion. A photoperiod-sensitive energy sorghum (Sorghum bicolor) may provide an annual crop alternative more ecologically sustainable than maize (Zea mays) that can more easily integrate into crop rotations than perennials, such as miscanthus (Miscanthus × giganteus). This study presents an ecosystem-scale comparison of C, N, water and energy fluxes from energy sorghum, maize and miscanthus during a typical …

Combined Effects Of Phosphorus Nutrition And Elevated Carbon Dioxide Concentration On Chlorophyll Fluorescence, Photosynthesis, And Nutrient Efficiency Of Cotton, Shardendu K. Singh, Vangimalla R. Reddy

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

To examine the combined effects of phosphorus (P) nutrition and CO2 on photosynthesis, chlorophyll fluorescence (CF), and nutrient utilization and uptake, two controlled-environment experiments were conducted using 0.01, 0.05 and 0.20 mM external phosphate each at ambient and elevated CO2 (aCO2: 400 and eCO2: 800 mmol mol–1, respectively). The CF parameters were affected more by P nutrition than by CO2 treatment. Photoinhibition of photosystem II (PSII) was due to increased minimal CF (Fo') and decreased maximal CF (Fm'), and efficiency of energy harvesting (Fv'/Fm'). In addition, reduced electron transport rate (ETR), the quantum yield of PSII (FPSII) and CO2 assimilation …

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) …

Effect Of Nitrogen Application Timing On Corn Production Using Subsurface Drip Irrigation, David D. Tarkalson, Simon J. Van Donk, James L. Petersen

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

The use of subsurface drip irrigation (SDI) in row-crop agriculture is increasing because of potential increases in water and nutrient use efficiency. Research-based information is needed to manage N applications through SDI systems in field corn (Zea-mays L.) production. This study was conducted to assess the effect of different in-season SDI system N application timings on corn production and residual soil N0₃-N at the University of Nebraska-Lincoln West Central Research and Extension Center in North Platte, Neb, on a Cozad silt loam (fine-silty, mixed, mesic Fluventic Haplustoll). We evaluated the effect of three N application timing methods …

Container And Installation Time Effects On Soil Moisture, Temperature, And Inorganic Nitrogen Retention For An In Situ Nitrogen Mineralization Method, Brian J. Wienhold, Gary E. Varvel, Wallace W. Wilhelm

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

Mineralization contributes significantly to agronomic nitrogen (N) budgets and is difficult to accurately predict. Models for predicting Nmineralization contributions are needed, and development of these models will require field-based data. In situ mineralization methods are intended to quantify N mineralization under ambient environmental conditions. This study was conducted to compare soil moisture and temperature in intact soil cores contained in cylinders to those in adjacent bulk soil, compare the effect of two resin-bag techniques on water content of soil within cylinders, and assess the effect of installation duration on inorganic N retention by resins. The study was conducted at a …

Nationally Coordinated Evaluation Of Soil Nitrogen Mineralization Rate Using A Standardized Aerobic Incubation Protocol, T. S. Griffin, C. W. Honeycutt, S. L. Albrecht, K. R. Sistani, H. A. Torbert, B. J. Wienhold, B. L. Woodbury, R. K. Hubbard, J. M. Powell

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

Aerobic incubation methods have been widely used to assess soil nitrogen (N) mineralization, but standardized protocols are lacking. A single silt loam soil (Catlin silt loam; fine-silty, mixed, superactive, mesic, Oxyaquic Arguidoll) was subjected to aerobic incubation at six USDA-ARS locations using a standardized protocol. Incubations were conducted at multiple temperatures, which were combined based on degree days (DD). Soil water was maintained at 60% waterfilled pore space (WFPS; constant) or allowed to fluctuate between 60 and 30% WFPS (cycle). Soil subsamples were removed periodically and extracted in 2 M potassium chloride (KCl); nitrate (NO₃) and ammonium (NH …

Epic Evaluation Of The Impact Of Poultry Litter Application Timing On Nutrient Losses, H. Allen Torbert, Thomas J. Gerik, Wyatte L. Harman, Jimmy R. Williams, Melanie Magre

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

Recently, changes in the utilization practices of animal manures for fertilization have been encouraged to reduce the potential of nonpoint pollution of lakes and streams from agricultural land. However, the potential impact of changing some of these practices has not been fully studied. The objective of this study was to examine the potential impact of limiting poultry litter application times on nutrient movement important to water quality. The WinEPIC model was used to simulate poultry litter applications during the winter months and chemical fertilizer application, with both cool season and warm season grass pastures on the major soil regions of …

Comparison Of Laboratory Methods And An In Situ Method For Estimating Nitrogen Mineralization In An Irrigated Silt-Loam Soil, Brian J. Wienhold

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

Nitrogen (N) mineralization makes a considerable contribution to crop-available N and is difficult to estimate. Reliable methods for measuring N mineralization are needed to produce data sets for developing N-mineralization models, as a component in fertilizer recommendation algorithms, and to assess the effect of management practices on N mineralization. Numerous methods are available for estimating N mineralization. Laboratory methods are relatively easy but may not reflect conditions in the field, and field methods are usually labor-intensive. A study was conducted to compare N-mineralization estimates using anaerobic and aerobic laboratory methods and an in situ field method for the 0- to …

Mineralization Of Nitrogen In Soils Amended With Dairy Manure As Affected By Wetting/Drying Cycles, D. B. Watts, H. A. Torbert, S. A. Prior

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

Interest in manure management and its effects on nitrogen (N) mineralization has increased in recent years. The focus of this research was to investigate the N-mineralization rates of different soil types in Coastal Plain soils and compare them to a soil from Illinois. Soils with and without dairy composted manure addition were subjected to different wetting/drying cycles [constant moisture at 60% waterfilled pore space (WFPS) and cycling moisture from 60 to 30% WFPS] under laboratory conditions at three different temperatures (11 °C, 18 °C, and 25 °C). Samples were collected from three different soil types: Catlin (Mollisols), Bama (Ultisols), and …

Non-Composted Municipal Solid Waste Processing Byproduct Effect On Soil Reclamation, H. Allen Torbert, Dick L. Gebhart, Ryan R. Busby, Kenneth N. Potter, Deborah R. Curtain

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

A new garbage processing technology has been developed that sterilizes and separates inorganic and organic components of municipal solid waste. The non-composted byproduct of this process, Fluff ®, has the potential to be utilized as a soil amendment to improve soil conditions in highly degraded soils. A study was initiated to evaluate Fluff as a soil amendment for establishing native grasses on disturbed US Army training lands. The Fluff was incorporated into a sandy loam soil at Fort Benning Military Reservation, GA on two sites: a moderately degraded and a highly degraded soil. The Fluff was incorporated at rates of …

Comparison Of Ground-Based Remote Sensors For Evaluation Of Corn Biomass Affected By Nitrogen Stress, Soon-Dal Hong, James Schepers, Dennis D. Francis, Michael R. Schlemmer

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

The nondestructive determination of plant biomass is not possible; however, crop-canopy sensors that determine the normalized difference vegetation index have the potential to estimate living biomass, which is indicative of plant vigor and stress. Pot experiments using sand culture were conducted in 2002 and 2003 under greenhouse conditions to evaluate the effect of nitrogen (N) deficiency on corn biomass and reflectance. Stress was imposed by implementing six to eight levels of N in Hoagland’s nutrient solution. Canopy reflectance measurements made at three growth stages with a variety of handheld spectral sensors (active and passive) were closely correlated with dry weight …

Maintenance Of A Narrow Host Range By Oxyops Vitiosa; A Biological Control Agent Of Melaleuca Quinquenervia, G. S. Wheeler

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

Host range expansion in insect herbivores is often thought to be mediated by several factors, principal among them are secondary plant metabolites. In weed biological control, the host range of a prospective agent is one of the most important considerations in its implementation. Extensive host testing tests seek to determine the behavioral acceptance and nutritional value of different test plant species to the potential agent. A list of test plants is compiled that comprises species that are close taxonomic relatives of the target weed plus other species of economic or ecologic importance. The host testing of the Melaleuca quinquenervia biological …

Tallgrass Prairie Vegetation Response To Spring Burning Dates, Fertilizer, And Atrazine, Robert B. Mitchell, Robert A. Masters, Steven S. Waller, Kenneth Moore, Linda J. Young

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

Tallgrass prairies provide an important source of hay and summer forage in eastern Nebraska. A study was conducted in 1989 and 1990 on 2 late seral tallgrass prairies near Lincoln and Virginia, Nebraska to determine if production of selected components of tallgrass prairie communities could be altered by burning (not burned, or burned in either early, mid-, or late spring) and applying fertilizer (0 and 67-23 kg N-P ha^-1) and atrazine [6- chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine] (0 and 2.2 kg a.i. ha^-1). Vegetation was harvested the year treatments were applied at about 30-day intervals starting in June and ending …