Simulation modeling is widely used to assess water contamination risk associated with pesticide use and for evaluating effectiveness of agricultural conservation practices. Currently the Agricultural Policy/Environmental eXtender (APEX) model is being used for this purpose in the USDA Conservation Effects Assessment Project (CEAP) Cropland National Assessment. In support of the CEAP modeling ef...

Management of plant litter or crop residues in agricultural fields is an important consideration for reducing soil erosion and increasing soil organic C. Current methods of quantifying crop residue cover are inadequate for characterizing the spatial variability of residue cover within fields or across large regions. Our objectives were to evaluate several spectral indices for measuring crop res...

Relations between riverine export (load) of total nitrogen (N) and total phosphorus (P) from 133 large agricultural watersheds in the United States and factors affecting nutrient transport were evaluated using empirical regression models. After controlling for anthropogenic inputs and other landscape factors affecting nutrient transport-such as runoff, precipitation, slope, number of reservoirs...

Cotton (Gossypium hirsutum L.) yield and quality responses to irrigation have not been described for conservation management systems that growers are rapidly adopting. We conducted a field experiment from 2001–2003 in the Tennessee Valley near Belle Mina, AL on a Decatur silt loam (fine, kaolinitic, thermic Rhodic Paleudults) to examine how irrigation regimes and tillage systems affect ginning ...

Long-term tillage negatively affects soil aggregation, but little is known about the short-term effects of tillage. We investigated the effects of intensive tillage (moldboard plowing) and conservation tillage (chisel plowing) on aggregate breakage during tillage in a long-term study located in the semiarid Ebro river valley (NE Spain). The type of tillage resulted in different soil aggregate d...

A major challenge for agriculture is to enhance productivity with minimum impact on the environment. Several studies indicate that cover crops could replace anthropogenic inputs and enhance crop productivity. However, so far, it is unclear if cover crop effects vary between different cropping systems, and direct comparisons among major arable production systems are rare. Here we compared the sh...

Effect of haying (hayed or not hayed prior to tillage), tillage (notillage, minimum tillage, or conventional tillage), and N fertilization (0 or 67 kg ha ') on surface infiltration rates, Q(h), was evaluated for Conservation Research Program (CRP) site conversion. Soils included Amor loam (fine-loamy, mixed, superactive, frigid Typic Haplustoll) and Cabba silt loam (loamy, mixed, superactive, c...

There is a global concern about the increase in atmospheric concentrations of greenhouse gases. One method being discussed to encourage greenhouse gas mitigation efforts is based on a trading system whereby carbon emitters can buy effective mitigation efforts from farmers implementing conservation tillage practices. These practices sequester carbon from the atmosphere, and such a trading system...

BACKGROUND A three-year field experiment was conducted to examine the responses of corn yield and soil nitrous oxide (N2O) emission to various management practices in middle Tennessee. METHODOLOGY/PRINCIPAL FINDINGS The management practices include no-tillage + regular applications of urea ammonium nitrate (NT-URAN); no-tillage + regular applications of URAN + denitrification inhibitor (NT-in...

BACKGROUND Tillage practices greatly affect carbon (C) stocks in agricultural soils. Quantification of the impacts of tillage on C stocks at a regional scale has been challenging because of the spatial heterogeneity of soil, climate, and management conditions. We evaluated the effects of tillage management on the dynamics of soil organic carbon (SOC) in croplands of the Northwest Great Plains e...