The Agricultural Policy Environmental EXtender (APEX) Model
The Agricultural Policy Environmental EXtender (APEX) Model

Author:

Publisher:

Published: 2009

Total Pages: 109

ISBN-13:

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The Agricultural Policy Environmental eXtender (APEX) model was developed by the Blacklands Research and Extension Center in Temple, Texas. APEX is a flexible and dynamic tool that is capable of simulating a wide array of management practices, cropping systems, and other land use across a broad range of agricultural landscapes, including whole farms and small watersheds. The model can be configured for novel land management strategies, such as filter strip impacts on pollutant losses from upslope cropfields, intensive rotational grazing scenarios depicting movement of cows between paddocks, vegetated grassed waterways in combination with filter strip impacts, and land application of manure removal from livestock feedlots or waste storage ponds. A description of the APEX model is provided, including an overview of all the major components in the model. Applications of the model are then reviewed, starting with livestock manure and other management scenarios performed for Livestock and the Environment: A National Pilot Project (NPP), and then continuing with feedlot, pesticide, forestry, buffer strip, conservation practice, and other management or land use scenarios performed at the plot, field, watershed, or regional scale. The application descriptions include a summary of calibration and/or validation results obtained for the different NPP assessments as well as for other APEX simulation studies. Available APEX Geographic Information System-based or Windows-based interfaces are also described, as are forthcoming future improvements and additional research needs for the model.

Evaluation of the APEX Model for Organic and Conventional Management Under Conservation and Conventional Tillage Systems
Evaluation of the APEX Model for Organic and Conventional Management Under Conservation and Conventional Tillage Systems

Author: Kieu Ngoc Le

Publisher:

Published: 2011

Total Pages: 222

ISBN-13:

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Evaluates the performance of the agricultural policy environmental extender (APEX) in predicting crop yield and in simulating surface runoff under organic and conventional management in conservation and conventional tillage systems. Uses APEX to assess the long-term impact of organic and conventionally managed plots on crop yield and surface runoff under conventional and conservation tillage systems. Seeks to prove if APEX can capture the difference between organic management and conventional management (chemical use) under the two tillage systems.

Adaptation to Climate Change Impacts at Farm Level Using Swat and Apex Model
Adaptation to Climate Change Impacts at Farm Level Using Swat and Apex Model

Author: Ashvani Kumar Gosain

Publisher: Independently Published

Published: 2020-11-08

Total Pages: 256

ISBN-13:

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This study aimed to reveal that the computer simulation models play an important role in watershed management and decision making. The SWAT (Soil and Water Assessment Tool) model has been used for the hydrologic (watershed level) simulation and APEX (Agricultural Policy/Environmental eXtender) model has been used for crop growth and irrigation simulation (farm level). Both models have been used to simulate crop water requirement in field condition, but at different scales. To achieve this task the SWAT and the APEX models have been used in GIS (Geographical Information Systems) framework.

Evaluation of APEX for Simulating the Effects of Tillage Practices in Tropical Soils
Evaluation of APEX for Simulating the Effects of Tillage Practices in Tropical Soils

Author: Laura Wilson

Publisher:

Published: 2019

Total Pages: 89

ISBN-13:

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Tillage practices on agricultural fields have an impact on not only the amount of soil erosion from the fields, but also on the hydrologic and other environmental characteristics of the land. This erosion takes away soil that is necessary for sustainable agriculture, and the sediment and nutrient removal from the fields can pollute surrounding waterbodies. The Llanos Orientales of Colombia used to be a region of extended savannas and native fragile ecosystems dedicated to extended cattle ranch that has been transitioning to crop production. Agricultural expansion in this area, involving mechanization, could importantly accelerate the degradation of soils, limiting the development of sustainable agricultural systems. As a first step to understand long term effects of different tillage practices on new agricultural areas in the region, this study aims to evaluate the performance of the Agricultural Policy Environmental eXtender (APEX) model to simulate runoff, soil erosion and crop yield from fields under conventional tillage, reduced tillage, and no tillage in the Llanos Orientales of Colombia. Calibrated APEX model predictions were compared against measured runoff, soil loss and crop yield data from row crop plots established in the Experimental Station la Libertad in Colombia under conventional, reduced and no-tillage management. APEX satisfactorily predicted runoff (Nash Sutcliffe Efficiency NSE>0.53, Percent Bias - [PBIAS] 21%) and crop yield for all three tillage systems (NSE0.82, [PBIAS]

Watershed Models
Watershed Models

Author: Vijay P. Singh

Publisher: CRC Press

Published: 2010-09-28

Total Pages: 678

ISBN-13: 1420037439

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Watershed modeling is at the heart of modern hydrology, supplying rich information that is vital to addressing resource planning, environmental, and social problems. Even in light of this important role, many books relegate the subject to a single chapter while books devoted to modeling focus only on a specific area of application. Recognizing the

Evaluation of the APEX Model to Simulate Runoff, Sediment, and Phosphorus Loss from Agricultural Fields in Northeast Wisconsin
Evaluation of the APEX Model to Simulate Runoff, Sediment, and Phosphorus Loss from Agricultural Fields in Northeast Wisconsin

Author: Forrest Stephen Kalk

Publisher:

Published: 2018

Total Pages: 236

ISBN-13:

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Due to the negative consequences of elevated nutrients in surface water, research in the Lower Fox River Watershed in northeastern Wisconsin has focused on monitoring, quantifying, and defining techniques to reduce nutrient and sediment runoff. To support these efforts, the United States Geological Service and University of Wisconsin – Green Bay have been collecting data during runoff events at edge of field locations for several years. My research uses these critical data to parameterize an Agricultural Policy/Environmental eXtender (APEX) model to predict runoff, nutrient loads, and sediment loads from cropland. Data from three sites were used to both manually and automatically calibrate the model, and six additional sites were used in the validation of the model. I attempted to improve model predictions during snowmelt periods and for estimates of dissolved phosphorus (DP). Results show that the manually calibrated model out-performed the automatically calibrated model in nearly all comparisons. Runoff, sediment, total phosphorus (TP), and dissolved phosphorus (DP) were all successfully calibrated by the manual model. The automatic model only had reasonable estimates for runoff volumes. Validation of both models were poor overall, although several locations produced acceptable results both statistically and when visualized graphically. Generally, estimates of runoff were most successful during model validation, with slightly weaker estimates of sediment, TP, and DP. Simulation of snowmelt periods remained poor. The fraction of TP that's in the soluble form was simulated more realistically in comparison to previous research.

Modelling Soil Erosion by Water
Modelling Soil Erosion by Water

Author: John Boardman

Publisher: Springer Science & Business Media

Published: 2013-06-29

Total Pages: 552

ISBN-13: 3642589138

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TO THE MODEL EVALUATION 1. MODELLING SOIL EROSION BY WATER l 2 John Boardman and David Favis-Mortlock 1 School of Geography and Environmental Change Unit Mansfield Road University of Oxford Oxford OX1 3TB UK 2 Environmental Change Unit University of Oxford 5 South Parks Road Oxford OX1 3UB UK Introduction This volume is the Proceedings of the NATO Advanced Research Workshop 'Global Change: Modelling Soil Erosion by Water', which was held on II-14th September 1995, at the University of Oxford, UK. The meeting was also one of a series organised by the IGBP 1 GCTE Soil Erosion Network, which is a component of GCTE's Land Degradation Task (3.3.2) (Ingram et aI., 1996; Valentin, this volume). One aim of the GCTE Soil Erosion Network is to evaluate the suitability of existing soil erosion models for predicting the possible impacts of global change upon soil erosion. Due to the wide range of erosion models currently, in use or under development, it was decided to evaluate models in the following sequence Favis-Mortlock et al., 1996): • field-scale water erosion models • catchmenr-scale water erosion models • wind erosion models • models with a landscape-scale and larger focus. As part of this strategy, the first stage of the GCTE validation of field-scale erosion models was carried out at the Oxford NATO-ARW. I A list of Acronyms fonns Appendix A.

Methods of Introducing System Models into Agricultural Research
Methods of Introducing System Models into Agricultural Research

Author: Lajpat R. Ahuja

Publisher: John Wiley & Sons

Published: 2020-01-22

Total Pages: 480

ISBN-13: 0891181806

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Why model? Agricultural system models enhance and extend field research...to synthesize and examine experiment data and advance our knowledge faster, to extend current research in time to predict best management systems, and to prepare for climate-change effects on agriculture. The relevance of such models depends on their implementation. Methods of Introducing System Models into Agricultural Research is the ultimate handbook for field scientists and other model users in the proper methods of model use. Readers will learn parameter estimation, calibration, validation, and extension of experimental results to other weather conditions, soils, and climates. The proper methods are the key to realizing the great potential benefits of modeling an agricultural system. Experts cover the major models, with the synthesis of knowledge that is the hallmark of the Advances in Agricultural Systems Modeling series.

Agricultural Policy
Agricultural Policy

Author: Vítor João Pereira Domingues Martinho

Publisher: Springer Nature

Published: 2022-11-15

Total Pages: 156

ISBN-13: 3031201302

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This book gives insights into the agricultural policies in several countries located in different continents. It is of interest to students, researchers, and policy and decision makers. Given the particularities of agriculture, agricultural policies are indispensable for an adjusted development of farms according to the strategic objectives of each country, namely the socio-economic and environmental ones. The question that often arises is whether the practical effects of the various policy measures are in accordance with their design and what is the effect of these policy instruments among many other causes of structural and technological change. The aim of this book is to describe the main agricultural policies that have been implemented in countries such as the United States of America, Brazil, China, India, South Africa, Australia, as well as the European Union. It also aims to analyse the real impact of these policies on the structural and technological changes of farms in the European Union. As its methodology, the book considers bibliometric analysis, literature review and statistical approaches.

APEX Model Application to Assess the Impact of Best Management Practices on Runoff, Erosion, and Phosphorus Export in NE Wisconsin, USA
APEX Model Application to Assess the Impact of Best Management Practices on Runoff, Erosion, and Phosphorus Export in NE Wisconsin, USA

Author: Garek Holley

Publisher:

Published: 2016

Total Pages: 0

ISBN-13:

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Agroecosystems produce food and grain products for a growing global population. With new available land for farming finite, agriculture field management practices have become more intense. However, greater yield intensity requires increased fertilizer and pesticide inputs to cropping systems, potentially leading to unintentional, negative impacts to the environment. Additionally, tillage practices that decrease soil structure, and post-harvest management routines that leave the soil uncovered, collectively increase field susceptibility to erosional losses to adjacent surface waters. The influx of both free and sediment-bound nutrients into water bodies drives algal blooms, and ultimately, following algal death, oxygen depletion from the water column. The net result of these management choices on surface water bodies is a reduced aesthetic appeal for recreation and the reduction of aquatic biodiversity. The objective of my thesis was to evaluate best management practice (BMP) effectiveness at reducing surface runoff, sediment erosion, and phosphorus export from fields using a calibrated and validated Agricultural Policy/Environmental eXtender (APEX) model. Alternative management practices that I investigated included no-till, inclusion of a standard dairy rotation, planting of cover crops (rye), and implementation of grassed waterways. Each alternative practice was analyzed against common routines such as continuous corn, chisel plowing, and fallow soil post-harvest. The greatest percent reduction in erosion and nutrient exports occurred when fields were transitioned from continuous corn with conventional tillage to no-till. Alternatively, use of multiple BMPs together provided the greatest total reduction of runoff, sediment losses and phosphorus export. The modeled BMP that produced the greatest absolute reduction of phosphorus, sediment, and runoff losses was a standard dairy rotation with cover crops planted in the fall, and inclusion of a grassed waterway. This study is unique, in use of technically advanced edge-of-field monitoring stations to collect surface and subsurface runoff, sediment, and nutrient export from agricultural fields. Calibrated APEX models were found to be effective at demonstrating constituent losses from these fields, and capable of modeling various BMP scenarios. Specifically, this study showed that land managers and farmers would help reduce field losses by implementing BMPs which extend cover, living or non -living, to agricultural cropland soils (i.e. cover crops, and no-till).