Agronomic input and management practices have traditionally been applied uniformly on agricultural fields despite the presence of spatial variability of soil properties and landscape position. When spatial variability is ignored, uniform agronomic management can be both economically and environmentally inefficient. The objectives of this study were to: i) identify optimal N fertilizer rates usi...

Upon rewetting, lichens lose polyols through leaching. We quantified leaching losses for 21 species under simulated rainfall. Polyol concentrations in these lichens range from 1.0 to 8.8%, with a mean of 2.8%. Leaching losses range up to about 7.5 mg (polyol)/g (lichen dry weight) in a typical rain event. The rate of polyol leaching declines exponentially, becoming negligible within 1 hour of c...

Nitrogen (N) and phosphorus (P) are tightly cycled in most terrestrial ecosystems, with plant uptake more than 10 times higher than the rate of supply from deposition and weathering. This near-total dependence on recycled nutrients and the stoichiometric constraints on resource use by plants and microbes mean that the two cycles have to be synchronized such that the ratio of N:P in plant uptake...

Nitrogen (N) fertilization can greatly improve plant productivity but needs to be carefully managed to avoid harmful environmental impacts. Nutrient management guidelines aimed at reducing harmful forms of N loss such as nitrous oxide (N2O) emissions and nitrate (NO3(-)) leaching have been tailored for many cropping systems. The developing bioenergy industry is likely to make use of novel cropp...

Since 1995, neonicotinoid insecticides have been a critical component of arthropod management in potato, Solanum tuberosum L. Recent detections of neonicotinoids in groundwater have generated questions about the sources of these contaminants and the relative contribution from commodities in U.S. agriculture. Delivery of neonicotinoids to crops typically occurs as a seed or in-furrow treatment t...

Abstract Biochar amendment and substituting chemical fertilizers with organic manure (organic substitution) have been widely reported to increase crop production decrease reactive nitrogen (Nr) loss including nitrous oxide (N 2 O), nitric (NO), ammonia (NH 3 ) emissions, N runoff leaching. However, few comprehensive evaluations performed on the environmental economic aspects of biochar or subst...

The nitrogen isotopic composition (15N/14N) of forested ecosystems varies systematically worldwide. In tropical forests, which are elevated in 15N relative to temperate biomes, a decrease in ecosystem 15N/14N with increasing rainfall has been reported. This trend is seen in a set of well characterized Hawaiian rainforests, across which we have measured the 15N/14N of inputs and hydrologic losse...

Use of enhanced-efficiency N fertilizers (EENFs) in row crop agriculture has not been well studied despite increasing interest in these N sources to increase crop yield while decreasing N loss. A field study was conducted in Central Alabama from 2009 to 2011 to compare EENFs to standard N sources in a high-residue conservation cotton production system. Nitrogen fertilizers evaluated were: urea;...

The adoption rate of winter cover crops (WCCs) as an effective conservation management practice to help reduce agricultural nutrient loads in the Chesapeake Bay (CB) is increasing. However, the WCC potential for water quality improvement has not been fully realized at the watershed scale. This study was conducted to evaluate the long-term impact of WCCs on hydrology and NO3-N loads in two adjac...