scholarly journals Drainage N Loads Under Climate Change with Winter Rye Cover Crop in a Northern Mississippi River Basin Corn-Soybean Rotation

2020 ◽  
Vol 12 (18) ◽  
pp. 7630
Author(s):  
Robert Malone ◽  
Jurgen Garbrecht ◽  
Phillip Busteed ◽  
Jerry Hatfield ◽  
Dennis Todey ◽  
...  

To help reduce future N loads entering the Gulf of Mexico from the Mississippi River 45%, Iowa set the goal of reducing non-point source N loads 41%. Studies show that implementing winter rye cover crops into agricultural systems reduces N loads from subsurface drainage, but its effectiveness in the Mississippi River Basin under expected climate change is uncertain. We used the field-tested Root Zone Water Quality Model (RZWQM) to estimate drainage N loads, crop yield, and rye growth in central Iowa corn-soybean rotations. RZWQM scenarios included baseline (BL) observed weather (1991–2011) and ambient CO2 with cover crop and no cover crop treatments (BL_CC and BL_NCC). Scenarios also included projected future temperature and precipitation change (2065–2085) from six general circulation models (GCMs) and elevated CO2 with cover crop and no cover crop treatments (CC and NCC). Average annual drainage N loads under NCC, BL_NCC, CC and BL_CC were 63.6, 47.5, 17.0, and 18.9 kg N ha−1. Winter rye cover crop was more effective at reducing drainage N losses under climate change than under baseline conditions (73 and 60% for future and baseline climate), mostly because the projected temperatures and atmospheric CO2 resulted in greater rye growth and crop N uptake. Annual CC drainage N loads were reduced compared with BL_NCC more than the targeted 41% for 18 to 20 years of the 21-year simulation, depending on the GCM. Under projected climate change, average annual simulated crop yield differences between scenarios with and without winter rye were approximately 0.1 Mg ha−1. These results suggest that implementing winter rye cover crop in a corn-soybean rotation effectively addresses the goal of drainage N load reduction under climate change in a northern Mississippi River Basin agricultural system without affecting cash crop production.

2006 ◽  
Vol 71 (2) ◽  
pp. 195-231 ◽  
Author(s):  
Tristram R. Kidder

Archaeologists frequently assume the cultural transition from Archaic to Woodland (ca. 3000–2500 cal B.P.) in the Mississippi River basin is a gradual process. In the lower Mississippi Valley, however, there is an abrupt gap in the archaeological sequence at this time and pronounced differences between Late Archaic and Early Woodland archaeological remains. Elsewhere in the basin, this transition is marked by an occupation hiatus or decline and is accompanied by significant changes in settlement and material culture organization. In most parts of the floodplain of the Mississippi River and its tributaries there are few sites dating to this interval suggesting the river bottom was abandoned for several hundred years as a location for sustained habitation. High-resolution climate data demonstrates an episode of rapid global climate change involving significant alterations in temperature and precipitation in the period ca. 3000–2600 cal B.P. The proximate cause of this global climate occurrence is change in galactic cosmic ray intensity and solar irradiation possibly amplified by variations in the earth"s geomagnetic field. Global climate changes led to greatly increased flood frequencies and magnitudes in the Mississippi River watershed during the shift from Late Archaic to Early Woodland. In northeast Louisiana, increased flooding led to major fluvial reorganization that caused settlement abandonment and is associated with the demise of Poverty Point culture. Climate change and associated flooding is implicated as one cause of major cultural reorganization at the end of the Archaic throughout much of eastern North America.


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