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.
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]
Agriculture is strongly affected by changes in soil hydrology as well as changes in land use and management practices and the complex interactions between them. This book develops an understanding of these interactions on a watershed scale, using soil hydrology models and addresses the consequences of land use and management changes on agriculture from a research perspective. Case studies illustrate the impact of land use and management on various soil hydrological parameters under different climates and ecosystems.
Conventional tillage and burning crop residues has degraded the soil resource base and intensified soil degradation with concomitant decrease in crop production capacity. The emerging issue of global warming coupled with greenhouse gases emissions has further aggravated the scenario. Conservation agriculture helps in reducing many negative effects of conventional agriculture such as soil erosion, soil organic matter decline, water loss, soil physical degradation, and fuel use. Conservation Agriculture helps improve biodiversity in the natural and agro-ecosystems. Complemented by other good agricultural practices including the use of quality seeds, integrated pest, nutrient and water management, Conservation Agriculture provides a base for sustainable intensification of the agricultural production system. Moreover, the yield levels in Conservation Agriculture systems are higher than traditional intensive tillage systems with substantially less production costs. This book provides comprehensive understanding of the subject with topics related to climate change mitigation strategies, approaches and impact of conservation agriculture on natural resource management. Print and electronic editions not for sale in South Asia (India, Sri Lanka, Nepal, Bangladesh, Pakistan, Afghanistan and Bhutan)
Conservation tillage systems have been adopted by farmers in many countries to solve the problem of land degradation and declining water productivity. Direct application of such tillage systems has not been possible among resource-poor, smallholder farmers in semi-arid areas of Ethiopia. Problems such as the lack of rainfall, the costs of herbicide
Precision conservation is a reality, and we are moving towards improved effectiveness of conservation practices by accounting for temporal and spatial variability within and off field. This is the first book to cover the application of the principles of precision conservation to target conservation practices across fields and watersheds. It has clearly been established that the 21st century will present enormous challenges, from increased yield demands to climate change. Without improved conservation practices it will not be possible to ensure food security and conservation effectiveness. Readers will appreciate the application of the precision conservation concept to increase conservation effectiveness in a variety of contexts, with a focus on recent advances in technology, methods, and improved results. IN PRESS! This book is being published according to the “Just Published” model, with more chapters to be published online as they are completed.
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).
