Life Sciences Commons^™

Invasive Species In An Urban Flora: History And Current Status In Indianapolis, Indiana, Rebecca W. Dolan

Rebecca W. Dolan

Invasive plant species are widely appreciated to cause significant ecologic and economic damage in agricultural fields and in natural areas. The presence and impact of invasives in cities is less well documented. This paper characterizes invasive plants in Indianapolis, Indiana. Based on historical records and contemporary accounts, 69 of the 120 species on the official Indiana state list are reported for the city. Most of these plants are native to Asia or Eurasia, with escape from cultivation as the most common mode of introduction. Most have been in the flora of Indianapolis for some time. Eighty percent of Indianapolis’ invasive …

Developing And Using The Iowa P-Index, John E. Sawyer

John E. Sawyer

Movement of phosphorus (P) from farm fields to surface waters can elevate P above critical levels for aquatic plant growth and thus enhance nutrient enrichment and seasonal deficient oxygen, a process called eutrophication. Phosphorus commonly controls vegetative production in freshwater bodies, and hence the potential for eutrophication. The sourcing of P from production fields (including P from soil, manure, and fertilizer) is one area identified as being an important contributor of total P entering surface waters, and hence significantly contributing to water quality concerns. In recent years considerable effort has focused on developing methods to assess risk of P loss …

Modeling Long-Term Corn Yield Response To Nitrogen Rate And Crop Rotation, Laila A. Puntel, John E. Sawyer, Daniel Barker, Ranae N. Dietzel, Hanna Poffenbarger, Michael J. Castellano, Kenneth J. Moore, Peter Thorburn, Sotirios Archontoulis

John E. Sawyer

Improved prediction of optimal N fertilizer rates for corn (Zea mays L.) can reduce N losses and increase profits. We tested the ability of the Agricultural Production Systems sIMulator (APSIM) to simulate corn and soybean (Glycine max L.) yields, the economic optimum N rate (EONR) using a 16-year field-experiment dataset from central Iowa, USA that included two crop sequences (continuous corn and soybean-corn) and five N fertilizer rates (0, 67, 134, 201, and 268 kg N ha-1) applied to corn. Our objectives were to: (a) quantify model prediction accuracy before and after calibration, and report calibration steps; (b) compare crop …

Slow Spread Of The Aggressive Invader, Microstegium Vimineum (Japanese Stiltgrass), Emily S.J. Rauschert, David A. Mortensen, Ottar N. Bjørnstad, Andrea N. Nord, Nora Peskin

Emily Rauschert

Microstegium vimineum (Japanese stiltgrass) is a non-native weed whose rapid invasion threatens native diversity and regeneration in forests. Using data from a 4 year experiment tracking new invasions in different habitats, we developed a spatial model of patch growth, using maximum likelihood techniques to estimate dispersal and population growth parameters. The patches expanded surprisingly slowly: in the final year, the majority of new seedlings were still within 1 m of the original patch. The influence of habitat was not as strong as anticipated, although patches created in roadside and wet meadow habitats tended to expand more rapidly and had greater …

Plant Community Associations Of Two Invasive Thistles, Emily S.J. Rauschert, Katriona Shea, Sarah Goslee

Emily Rauschert

In order to combat the growing problems associated with biological invasions, many researchers have focused on identifying which communities are most vulnerable to invasion by exotic species. However, once established, invasive species can significantly change the composition of the communities that they invade. The first step to disentangling the direction of causality is to discern whether a relationship with other vegetation exists at all. Carduus nutans and C. acanthoides are similar invasive thistles, which have caused substantial economic damage worldwide. We assessed the associations between the thistles and the standing flora in four sites in central Pennsylvania in which they …

Japanese Stiltgrass: An Invasive Plant On The Move, Emily S.J. Rauschert, Andrea N. Nord

Emily Rauschert

No abstract provided.

Coexistence Patterns Of Two Invasive Thistle Species, Carduus Nutans And C. Acanthoides, At Three Spatial Scales, Emily S.J. Rauschert, Katriona Shea, Ottar N. Bjørnstad

Emily Rauschert

To better understand the competitive processes involved in invasion by congeners, we examine coexistence patterns of two invasive species, Carduus nutans and C. acanthoides, at three spatial scales. A roadside survey of 5 × 5 km blocks in a previously identified overlap zone provided information about the regional scale. At smaller scales, we surveyed four fields of natural co-occurrence, quantifying the spatial patterns at the field scale by randomly placed 1 × 1 m quadrats and at the smallest scale by detailing plant position within the quadrats. The patterns observed are strikingly different at the different scales. At the regional …

Influence Of Microsite Disturbance On The Establishment Of Two Congeneric Invasive Thistles, Emily S.J. Rauschert, Katriona Shea

Emily Rauschert

The successful establishment of invasive species has been shown to depend on aspects of the invaded community, such as gap characteristics. Biotic resistance may be particularly critical for stopping invaders at early life history stages, but new species can often invade following disturbances, which may create microsites with very different characteristics than are usually present. We examine the response of two invasive thistle species, Carduus nutans L. and C. acanthoides L., to three different microsite characteristics: disturbance type, size, and water availability. The two species initially responded differently to the type of disturbance: C. acanthoides had higher emergence and survival …

Invasional Interference Due To Similar Inter- And Intraspecific Competition Between Invaders May Affect Management, Emily S.J. Rauschert, Katriona Shea

Emily Rauschert

As the number of biological invasions increases, the potential for invader– invader interactions also rises. The effect of multiple invaders can be superadditive (invasional meltdown), additive, or subadditive (invasional interference); which of these situations occurs has critical implications for prioritization of management efforts. Carduus nutans and C. acanthoides, two congeneric invasive weeds, have a striking, segregated distribution in central Pennsylvania, USA. Possible hypotheses for this pattern include invasion history and chance, direct competition, or negative interactions mediated by other species, such as shared pollinators. To explore the role of resource competition in generating this pattern, we conducted three related experiments …

Mapping Temperate Vegetation Climate Adaptation Variability Using Normalized Land Surface Phenology, Liang Liang, Mark D. Schwartz, Xiaoyang Zhang

Xiaoyang Zhang

Climate influences geographic differences of vegetation phenology through both contemporary and historical variability. The latter effect is embodied in vegetation heterogeneity underlain by spatially varied genotype and species compositions tied to climatic adaptation. Such long-term climatic effects are difficult to map and therefore often neglected in evaluating spatially explicit phenological responses to climate change. In this study we demonstrate a way to indirectly infer the portion of land surface phenology variation that is potentially contributed by underlying genotypic differences across space. The method undertaken normalized remotely sensed vegetation start-of-season (or greenup onset) with a cloned plants-based phenological model. As the …

Developmental Functions Of Mir156-Regulated Squamosa Promoter Binding Protein-Like (Spl) Genes In Arabidopsis Thaliana, Mingli Xu, Tieqiang Hu, Jianfei Zhao, Mee-Yeon Park, Keith W. Earley, Gang Wu, Li Yang, Scott Poethig

Jianfei Zhao

The Vascular Flora And Community Structure Of Little Calumet Headwaters Nature Preserve, Laporte Country, Indiana, Julia L. Angstmann, Paul E. Rothrock, Thomas W. Post

Julia Angstmann

Little Calumet Headwaters Nature Preserve is a 108-acre tract of woodland and wetland areas that comprise the headwaters of the Little Calumet River in northwestern Indiana. The preserve, consisting of upland hardwood forests, groundwater seeps, and wetland complex, is an area of high diversity due to its topographical variation. A floristic inventory, plot sampling, and seed bank analysis were used to determine the structure and composition of the plant communities. The flora consists of 298 species (27 exotic) representing 188 genera and 84 families. Dominant vegetation of the forest includes Liriodendron tulipifera, Prunus serotina, Packera aurea and Podophyllum peltatum. Each …

Suppressor Of Phytochrome B4-#3 Represses Genes Associated With Auxin Signaling To Modulate Hypocotyl Growth, David Favero, Caitlin Jacques, Akira Iwase, Kimberly Le, Jianfei Zhao, Keiko Sugimoto, Michael Neff

Jianfei Zhao

The Illinois Soil Nitrogen Test: Should It Be Used In Iowa?, John E. Sawyer, Mohammod Ali Tabatabai

John E. Sawyer

The test was developed several years ago at the University of Illinois by researchers in the Department of Natural Resources and Environmental Sciences. It is a laboratory procedure designed to measure N liberated from soil heated for 5 hours with dilute alkali solution (sodium hydroxide). The test does not measure nitrate, but does measure exchangeable ammonium and a fraction of soil organic N.

Surface Waters: Ammonium Is Not Ammonia – Part 3, John E. Sawyer, Matthew J. Helmers

John E. Sawyer

Two previous ICM News articles outlined the difference between ammonium and ammonia, the relationship between the two nitrogen forms, and the implication of a combined (ammonium-N plus ammonia-N) analysis related to water quality criteria for aquatic life and chlorination treatment for drinking water.This article focuses on the potential sourcing of ammonium and ammonia in surface waters. Ammonium and ammonia in surface water systems can originate from many sources, and are naturally occurring forms of nitrogen. Predominant sources will vary on a watershed or sub-watershed basis. Also, sources and concentrations are greatly influenced by hydrology, including timing and volume of water …

Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker

John E. Sawyer

Historically sulfur (S) application has not been recommended on Iowa soils for corn and soybean production. The soil supply or combination from sources such as manure or precipitation has met crop S needs. However, soil S levels or supply will become depleted with prolonged crop removal, sulfate leaching, low precipitation deposition, and declining soil organic matter. The objective of this study was to determine the responsiveness of corn and soybean to S application (first year and residual second year) and S fertilizer material at multiple sites across Iowa soils and climatic conditions.

Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker

John E. Sawyer

Historically, sulfur (S) application has not been recommended on Iowa soils for corn and soybean production. Soil supply or combination from sources such as manure or precipitation has met crop S needs. However, soil S levels or supply may become depleted with prolonged crop removal, sulfate leaching, low precipitation deposition, and declining soil organic matter. The objective of this study was to determine if corn and soybean yields would respond to S fertilizer rate and material at multiple sites across Iowa soils and climatic conditions.

Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker

John E. Sawyer

Historically sulfur (S) application has not been recommended on Iowa soils for corn and soybean production. The soil supply or combination from sources such as manure or precipitation has met crop S needs. However, soil S levels or supply will become depleted with prolonged crop removal, sulfate leaching, low precipitation deposition, and declining soil organic matter. The objective of this study was to determine the responsiveness of corn and soybean to S application (first year and residual second year) and S fertilizer material at multiple sites across Iowa soils and climatic conditions.

Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker

John E. Sawyer

Historically sulfur (S) application has not been recommended on Iowa soils for corn and soybean production. The soil supply or combination from sources such as manure or precipitation has met crop S needs. However, soil S levels or supply will become depleted with prolonged crop removal, sulfate leaching, low precipitation deposition, and declining soil organic matter. The objective of this study was to determine the responsiveness of corn and soybean to S application (first year and residual second year) and S fertilizer material at multiple sites across Iowa soils and climatic conditions.

Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker

John E. Sawyer

Historically, sulfur (S) application has not been recommended on Iowa soils for corn and soybean production. Soil supply or combination from sources such as manure or precipitation has met crop S needs. However, soil S levels or supply may become depleted with prolonged crop removal, sulfate leaching, low precipitation deposition, and declining soil organic matter. The objective of this study was to determine if corn and soybean yields would respond to S fertilizer rate and material at multiple sites across Iowa soils and climatic conditions.

Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker

John E. Sawyer

Historically sulfur (S) application has not been recommended on Iowa soils for corn and soybean production. The soil supply or combination from sources such as manure or precipitation has met crop S needs. However, soil S levels or supply will become depleted with prolonged crop removal, sulfate leaching, low precipitation deposition, and declining soil organic matter. The objective of this study was to determine the responsiveness of corn and soybean to S application (first year and residual second year) and S fertilizer material at multiple sites across Iowa soils and climatic conditions.

Summary Of Sulfur Strip Trials Conducted In Central And Northeast Iowa Preliminary 2009 Results, John E. Sawyer, Daniel W. Barker, Brian J. Lang

John E. Sawyer

Sulfur (S) strip trials were conducted by ISU Extension field agronomists Brian Lang, George Cummins, and Mark Wuebker; Heartland Co-op; Innovative Ag; Five Star Co-op; Calcium Products, Inc; and cooperating growers.

Post-Plant Nitrogen Applications On Corn, John E. Sawyer

John E. Sawyer

Has the wet weather interrupted planned nitrogen (N) fertilizer applications? What are the options if corn has emerged? All is not lost. In fact, in wet springs sidedress N can be an advantage because delayed application avoids potential losses and increases use by the crop.

Potassium Deficiency Symptoms In Corn, John E. Sawyer

John E. Sawyer

The dry conditions this spring have resulted in corn plants expressing potassium (K) deficiency symptoms the past 2 weeks. This phenomenon has appeared in previous dry spring seasons and is back again this year, especially in southern Iowa. Areas of the state that received adequate rainfall are generally not showing K deficiency symptoms. Symptoms can appear even though soil K is adequate for crop production. How can this occur? Uptake of K by plants requires an active root system, especially in the soil zone where plant-available K is located.

Quantifying Corn N Deficiency And Application Rate With Active Canopy Sensors, Daniel W. Barker, John E. Sawyer

John E. Sawyer

Precision agriculture technologies are an integral part of many operations in Iowa corn production. Active canopy sensors have been developed as a tool to determine plant N stress deficiency and provide on-the-go decisions for implementing variable rate N application. The objectives of this study were to assess N deficiency stress levels at the mid-vegetative corn growth stages with active canopy sensors, calibrate active sensors and associated canopy indices, and develop N rate algorithms that can be used to determine variable rate N fertilization.

Surface Waters: Ammonium Is Not Ammonia – Part 1, John E. Sawyer

John E. Sawyer

A recent article in The Des Moines Register newspaper has caused considerable controversy regarding nitrogen in Iowa streams and rivers. The article (High ammonia levels threaten D.M.’s water, April 6, 2008) featured information about “ammonia” levels in certain Iowa surface water systems during the recent winter time period. The implications were that manure and fertilizer application to cropland, and subsequent snowmelt and runoff, had resulted in higher than normal “ammonia” levels in surface waters. In the article there was a comparison of the reported levels to an ammonia reading of 0.10 parts per million considered harmful to aquatic life.

Postemergence Application Of Herbicides In Corn, Micheal D. Owen, John E. Sawyer, Robert G. Hartzler

John E. Sawyer

The Iowa 2006 corn crop is mostly in the ground and much of it will be emerged by the end of the week. Planting progressed rapidly in late April prior to the current wet conditions, and this prolonged wet period will impact weed management plans for those fields planted prior to the rain but not treated with preemergence herbicides or nitrogen (N) fertilizer. This article is revised from a 2003 discussion and will describe two important issues.

Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker

John E. Sawyer

Historically, sulfur (S) application has not been recommended on Iowa soils for corn and soybean production. The soil supply or combination from sources such as manure or precipitation has met crop S needs. However, soil S levels or supply may become depleted with prolonged crop removal, sulfate leaching, low precipitation deposition, and reduced soil organic matter levels. The objectives of this study were to determine if corn and soybean yields would respond to S fertilizer application and rate at sites in central and northeast Iowa.

Post Applied Urea+Agrotain To V10 Corn Field Scale Strip Demonstrations, Daniel W. Barker, John E. Sawyer

John E. Sawyer

The objectives are to apply N fertilizer when corn rapidly accumulates N and dry matter during the mid-vegetative growth stages and utilize active sensors as a remote sensing method of applying VRT nitrogen.

Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker

John E. Sawyer

Historically, sulfur (S) application has not been recommended on Iowa soils for corn and soybean production. Soil supply or combination from sources such as manure or precipitation has met crop S needs. However, soil S levels or supply may become depleted with prolonged crop removal, sulfate leaching, low precipitation deposition, and declining soil organic matter. The objective of this study was to determine if corn and soybean yields would respond to S fertilizer rate and material at multiple sites across Iowa soils and climatic conditions.