Digital Commons Network^™

Long-Term Manure Application Improves Soil Health And Stabilizes Carbon In Continuous Maize Production System, Saurav Das, Daniel Liptzin, Bijesh Maharjan

Department of Agronomy and Horticulture: Faculty Publications

Soil health lies at the core of a sustainable food production system. A comprehensive evaluation of different agronomic practices and their effect on soil health is essential to determine the best practices that support soil ecosystem services. However, it may take years or decades to observe measurable changes in soil health under varying management practices. The objective of this experiment was to evaluate the effects of long-term (>77 years) manure and inorganic nitrogen (N) fertilizer on soil health and determine the interrelationship among the measured soil bio-physicochemical indicators. The study also aims to understand the sustainability of the monocropping …

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

Department of Agronomy and Horticulture: Faculty Publications

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) …

Using A Vnir Spectral Library To Model Soil Carbon And Total Nitrogen Content, Nuwan K. Wijewardane

Department of Biological Systems Engineering: Dissertations and Theses

n-situ soil sensor systems based on visible and near infrared spectroscopy is not yet been effectively used due to inadequate studies to utilize legacy spectral libraries under the field conditions. The performance of such systems is significantly affected by spectral discrepancies created by sample intactness and library differences. In this study, four objectives were devised to obtain directives to address these issues. The first objective was to calibrate and evaluate VNIR models statistically and computationally (i.e. computing resource requirement), using four modeling techniques namely: Partial least squares regression (PLS), Artificial neural networks (ANN), Random forests (RF) and Support vector regression …

Root Biomass And Soil Carbon Response To Growing Perennial Grasses For Bioenergy, Leonard C. Kibet, Humberto Blanco-Canqui, Robert B. Mitchell, Walter H. Schacht

Department of Agronomy and Horticulture: Faculty Publications

Background: Dedicated bioenergy crops such as switchgrass (Panicum virgatum L.), miscanthus [Miscanthus x giganteus (Mxg)], indiangrass [Sorghastrum nutans (L.) Nash], and big bluestem (Andropogon gerardii Vitman) can provide cellulosic feedstock for biofuel production while maintaining or improving soil and environmental quality. To better understand bioenergy crop effects on soils, we studied changes in soil properties of a Tomek silt loam under inorganic fertilization of switchgrass after 4 years and warm-season grass monocultures and mixtures after 6 years in eastern Nebraska.

Methods: The first experiment had two study factors: two switchgrass harvest dates (August and …

Field-Scale Soil Property Changes Under Switchgrass Managed For Bioenergy, Marty R. Schmer, M. A. Liebig, K. P. Vogel, Robert B. Mitchell

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

The capacity of perennial grasses to affect change in soil properties is well documented but information on switchgrass (Panicum virgatum L.) managed for bioenergy is limited. An on-farm study (10 fields) in North Dakota, South Dakota, and Nebraska was sampled before switchgrass establishment and after 5 years to determine changes in soil bulk density (SBD), pH, soil phosphorus (P), and equivalent mass soil organic carbon (SOC). Changes in SBD were largely constrained to near-surface depths (0–0.05 m). SBD increased (0–0.05 m) at the Nebraska locations (mean=0.16 Mgm^-3), while most South Dakota and North Dakota locations showed declines …

Soil Carbon Dynamics During A Long-Term Incubation Study Involving 13C And 14C Measurements, Ronald F. Follett, Eldor A. Paul, Elizabeth G. Pruessner

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

Soil organic matter is the earth's largest terrestrial reservoir of carbon (C). Thus, it serves as a major control on atmospheric carbon dioxide (CO₂) levels. To better understand these controls, decreases in soil organic C (SOC), soil microbial biomass (SMB) C, and the role of SMB as a source of mineralizable C were measured during a long-term incubation (853 days) without added substrate. The 2 soils used were a Weld loam (fine montmorillonitic, mesic, Aridic Paleustoll) from near Akron, Colorado, and a Duroc loam (fine silty, mixed mesic Pachic Haplustoll) from near Sidney, Nebraska. The Akron soil was …