Dan B. Jaynes

TL;DR: In this paper, the authors examine how changes in agricultural management practices during the past century have affected N in midwestern soils through biological fixation, the legumes generally and to identify the types of research and management practices needed increased the amount of residual N in the soil profile to reduce the potential for nonpoint NO3 leakage into water resources.

TL;DR: The economically optimum N fertilizer rate for corn was between 67 and 135 kg ha(-1) in 1996 and 114 and 172 kg ha−1 in 1998, but the net N mass balance indicated that N was being mined from the soil at these N fertilizer levels and that the system would not be sustainable.

TL;DR: Rye winter cover crops grown after corn and soybean have the potential to reduce the NO3 concentrations and loads delivered to surface waters by subsurface drainage systems.

TL;DR: In this article, the authors analyzed continuous in-field soil water measurements from 2008 to 2014 at a Central Iowa research site that has included a winter rye cover crop in a maize-soybean rotation for thirteen years.

TL;DR: In this article, the surface water quality of Walnut-creek watershed with about 86% of the land used for crop production was investigated. But, the authors did not report any quantitative information describing the impact of farming on water quality at the watershed scale.