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Amazonian Dark Earths (ADE) are a unique type of soils developed through intense anthropogenic activities that transformed the original soils into Anthrosols throughout the Brazilian Amazon Basin. We conducted a comparative molecular-level investigation of soil organic C (SOC) speciation in ADE (ages between 600 and 8700 years B.P.) and adjacent soils using(More)
Effect of irrigation amounts applied with subsurface drip irrigation on corn evapotranspiration, yield, water use efficiency, and dry matter production in a semiarid climate" (2008). Publications from USDA-ARS / UNL Faculty. Paper 199. a g r i c u l t u r a l w a t e r m a n a g e m e n t x x x (2 0 0 8) x x x – x x x Corn Maize Deficit irrigation Water(More)
Competition for water is becoming more intense in many parts of the U.S., including west‐central Nebraska. It is believed that reduced tillage, with more crop residue on the soil surface, conserves water, but the magnitude of water conservation is not clear. A study was initiated on the effect of residue on soil water content and corn yield at North Platte,(More)
Knowledge of the cumulated effect of long-continued nitrogen (N) inputs is important for both agronomic and environmental reasons. However, only little attention has been paid to estimate the crop response to mineral fertilizer N residues. Before interpreting estimates for the crop response to previous N input rates, the experimental design for testing(More)
  • J Petersen
  • 1990
The frequencies for correct answers to individual Landolt-Cs were measured as a function of their size in 183 eyes ("psychometric function", 48 tests per acuity step, computer screen). An integrated Gauss function modified for assessing bias was fit (least squares) to the values of each subject. The mean value of the fitting function is a measure of visual(More)
Competition for water is becoming more intense in many parts of the USA, including west-central Nebraska. It is believed that reduced tillage with increased crop residue conserves water, but the magnitude of water savings is not clear. In 2007, a study was initiated on the effect of residue on soil water content and crop yield at North Platte, Nebraska. The(More)
A field study was conducted at North Platte, Nebraska in 2007–2009, imposing eight irrigation treatments, ranging from dryland to fully irrigated. Four of the eight treatments allowed for various degrees of water stress only after tasseling and silking. In 2007, corn yield ranged from 8.9 Mg ha−1 with a season total of 41 mm of irrigation water to 11.5 Mg(More)