The capacity of mycorrhizal and non-mycorrhizal root systems to reduce nitrate (NO₃⁻) and ammonium (NH₄⁺) loss from soils via leaching was investigated in a microcosm-based study. A mycorrhiza defective tomato mutant and its mycorrhizal wildtype progenitor were used in this experiment in order to avoid the indirect effects of establishing non-mycorrhizal control treatments on soil nitrogen cycl...

Irrigation water is limiting for crop production in arid and semi-arid areas. Furthermore, excess nitrogen (N) application is a source of groundwater contamination. Partial root drying irrigation (PRD) can be used as water saving technique and a controlling measure of groundwater N contamination. The objectives of this investigation were to evaluate the effect of ordinary furrow irrigation (OFI...

Effective nitrogen (N) management in cotton production is essential in order to achieve proper growth and development. However, soil-incorporated N can undergo a series of chemical conversions along with numerous loss mechanisms (leaching, volatilization and denitrification) that can make N unavailable to the plant. In addition, soil-incorporated N has faced much scrutiny over the years for its...

Leaching losses of nitrogen (N) from soil and atmospheric N deposition have led to widespread changes in plant community and microbial community composition, but our knowledge of the factors that determine ecosystem N retention is limited. A common feature of extensively managed, species-rich grasslands is that they have fungal-dominated microbial communities, which might reduce soil N losses a...

High N fertilizer and irrigation amounts applied to potato (Solanum tuberosum L.) on coarse-textured soils often result in nitrate (NO3) leaching and low recovery of applied fertilizer N. This 3-yr study compared the effects of two rates (140 and 280 kg N ha(-1)) of a single polyolefin-coated urea (PCU) application versus split applications of urea on 'Russet Burbank' potato yield and on NO3 le...

Dissolved organic nitrogen (DON) is present in soils and streams around the world. We are only now beginning to explore the important roles this chemically heterogeneous mixture of compounds plays in terrestrial nitrogen (N) cycling. Over centuries, DON leaching may represent a significant "leak" of N, which occurs because plants and microbes cannot prevent DON losses, even in times of high N d...

Understanding forest carbon cycling responses to atmospheric N deposition is critical to evaluating ecosystem N dynamics. The natural abundance of N (dN) has been suggested as an efficient and non-invasive tool to monitor N pools and fluxes. In this study, three successional forests in southern China were treated with four levels of N addition. In each treatment, we measured rates of soil N min...

Improving nitrogen (N) use efficiency in crop production is important for obvious economic and environmental reasons. Nitrogen fertilization of corn usually provides the greatest return on investment of any crop input; therefore, farmers and their agricultural advisors must insure adequate N is available for the crop to maximize yields and economic returns. Soil contains N in organic (soil orga...

In Canterbury land-use intensification, particularly irrigated dairy expansion, is occurring on stony soils. Concerns exist about the ability of these soils to sustain intensified land-use, while maintaining nutrient leaching within discharge limits. Environmental models consistently predict stony soils as having a high vulnerability to leaching under intensive land use, but there is little exp...

Accounting for the fate of inorganic N fertilizer in agricultural systems is critical to sustainable production. Sebilo et al. (1) provide a unique long-term record of NO3 fertilizer fate that demonstrates N molecules from a discrete fertilizer application are transferred to soil organic matter (SOM) and subsequently mineralized over the course of approximately 100 y, during which they contribu...