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Featured researches published by Andrew H. Heggenstaller.


Weed Science | 2005

Are many little hammers effective? Velvetleaf (Abutilon theophrasti) population dynamics in two- and four-year crop rotation systems

Paula R. Westerman; Matt Liebman; Fabian D. Menalled; Andrew H. Heggenstaller; Robert G. Hartzler; Philip M. Dixon

Abstract To improve understanding of relationships between crop diversity, weed management practices, and weed population dynamics, we used data from a field experiment and matrix models to examine how contrasting crop rotations affect velvetleaf. We compared a 2-yr rotation system (corn–soybean) managed with conventional rates of herbicides with a 4-yr rotation (corn–soybean–triticale + alfalfa–alfalfa) that received 82% less herbicide. In November 2002, a pulse of velvetleaf seeds (500 seeds m−2) was added to 7- by 7-m areas within replicate plots of each crop phase–rotation system combination. Velvetleaf seed, seedling, and reproductive adult population densities, seed production, and seed losses to predators were measured during the next year. Velvetleaf seed production was greater in the 4-yr rotation than in the 2-yr rotation (460 vs. 16 seeds m−2). Averaged over 12 sampling periods from late May to mid-November 2003, loss of velvetleaf seeds to predators also was greater in the 4-yr rotation than in the 2-yr rotation (32 vs. 17% per 2 d). Modeling analyses indicated that velvetleaf density in the 4-yr rotation should decline if cumulative losses of seeds produced in the soybean phase exceeded 40%. Achieving such a level of predation appears possible, given the observed rates of velvetleaf seed predation. In addition, no tillage occurs in the 4-yr rotation for 26 mo after soybean harvest, thus favoring seed exposure on the soil surface to predators. Models that included estimates of seed predation indicated that to prevent increases in velvetleaf density, weed control efficacy in soybean must be ≥ 93% in the 2-yr rotation, but could drop to 86% in the 4-yr rotation. These results support the hypothesis that diverse rotations that exploit multiple stress and mortality factors, including weed seed predation, can contribute to effective weed suppression with less reliance on herbicides. Nomenclature: Velvetleaf, Abutilon theophrasti Medicus ABUTH; alfalfa, Medicago sativa L.; corn, Zea mays L.; soybean, Glycine max (L.) Merr.; triticale, Triticosecale spp.


Weed Science | 2006

Symposium Integrating measurements of seed availability and removal to estimate weed seed losses due to predation

Paula R. Westerman; Matt Liebman; Andrew H. Heggenstaller; Frank Forcella

Abstract To better understand seed predation and enhance weed seed losses in arable fields, we developed a conceptual model that integrates seed dispersal, seed burial, and seed demand, the three processes that determine the dynamics of summer annual weed seeds on the soil surface in late summer and autumn. Published and unpublished experimental data were used to parameterize a simulation model for a number of crop–weed combinations. Sensitivity analyses of models for giant foxtail in corn and soybean indicated that factors related to seed availability were more important in determining overall seed losses due to predation than those related to seed demand. Delaying harvest date and destroying unshed weed seeds collected at harvest emerged as promising strategies to reduce seed input into the seed bank. The role of plant debris in hiding weed seeds from predators was ambiguous and requires further investigation. Estimates of overall seed losses due to predation based on model simulations in various crops and cropping systems indicated that weed seed predation could serve as an important tool in ecological weed management. Nomenclature: Giant foxtail, Setaria faberi Herrm. SETFA; corn, Zea mays L.; soybean, Glycine max (L.) Merr.


Journal of Applied Ecology | 2006

Seasonal patterns in post-dispersal seed predation of Abutilon theophrasti and Setaria faberi in three cropping systems

Andrew H. Heggenstaller; Fabian D. Menalled; Matt Liebman; Paula R. Westerman


Agriculture, Ecosystems & Environment | 2006

Post-dispersal weed seed predation by invertebrates in conventional and low-external-input crop rotation systems

Megan E. O’Rourke; Andrew H. Heggenstaller; Matt Liebman; Marlin E. Rice


Agronomy Journal | 2008

Productivity and nutrient dynamics in bioenergy double-cropping systems.

Andrew H. Heggenstaller; Robert P. Anex; Matt Liebman; David N. Sundberg; Lance R. Gibson


Agronomy Journal | 2008

Agronomic and Economic Performance Characteristics of Conventional and Low-External-Input Cropping Systems in the Central Corn Belt

Matt Liebman; Lance R. Gibson; David N. Sundberg; Andrew H. Heggenstaller; Paula R. Westerman; Craig Chase; Robert G. Hartzler; Fabian D. Menalled; Adam S. Davis; Philip M. Dixon


Crop Science | 2007

Potential for enhanced nutrient cycling through coupling of agricultural and bioenergy systems.

Robert P. Anex; Lee R. Lynd; Mark Laser; Andrew H. Heggenstaller; Matt Liebman


Archive | 2009

Switchgrass as a Bioenergy Crop: Biomass Production and Soil Carbon Sequestration in Response to Nitrogen Fertilization [abstract]

Andrew H. Heggenstaller; Kenneth J. Moore; Matt Liebman


Archive | 2008

Productivity and nutrient cycling in bioenergy cropping systems

Andrew H. Heggenstaller


Archive | 2007

Agronomic and Economic Performance Characteristics of Conventional and Low-External-Input Cropping Systems

Matt Liebman; David N. Sundberg; Jaclyn K. Borza; Andrew H. Heggenstaller; Craig Chase

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Robert P. Anex

University of Wisconsin-Madison

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Adam S. Davis

Agricultural Research Service

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