Grants and Contracts Details
Description
Nitrogen (N) is an essential element, often limiting plant productivity in many
ecosystems. As a result, N fertilizers are added to enhance crop yields which has also
introduced reactive N into the environment. Despite recognition of the importance of N
as a nutrient and potential contaminant, uncertainty remains regarding the fate of added
ammonium inputs to soil. One possible abiotic immobilization pathway of fertilizer
ammonium is clay mineral fixation yet the mechanism of this process, how it competes
with biological assimilation, and the reactivity of the bound ammonium are poorly
understood. Accordingly, the overall goal of this proposed project is to investigate the
contribution of abiotic and biological immobilization processes and nitrification
processes in natural clay mineral assemblages and bulk soils from undisturbed sod and
long term no-tillage soil samples from four locations spanning a climate gradient (MAP
400-1300 mm). This goal will be achieved through two specific objectives: 1) Perform
reactivity (kinetic) studies of 15,14 NH 4
+ removal with bulk soil and clay fractions from
these sites using wet chemical and cutting-edge spectroscopic techniques (NanoSIMS,
ATR-FTIR, XRD, and SEM-EDS); 2) Investigate the transformations of bound (clay
mineral- and microbial-bound NH 4
+ ) from the four sites to nitrify to NO 2
- and NO 3
- in soil
using wet chemical and in situ spectroscopic techniques (ATR-FTIR). Historically,
following the clay mineral fixation of added fertilizer ammonium relied heavily on wet
chemical extractions using mineral acids to dissolve the silicate structure. This proposed
work is both creative and original because it combines spectroscopic tools (NanoSIMS
and ATR-FTIR) for following reactivity of ammonium with clay minerals with stable
isotope measurements and wet chemical experiments to unravel the complexities of N
transformations in undisturbed grassland and no-tillage agroecosystems. A n expected
outcome is fundamental rate data of abiotic versus biological immobilization processes
and how this is related to closely linked nitrification pathways, information that can be
incorporated in transport models. This proposed study corresponds to USDA-AFRI’s
program area priority to study nutrient cycles and management, including
interrelationships between soil chemical, biological, and physical characteristics and
processes controlling nutrient fate in soils. This research is a timely pursuit given the
desire to minimize adverse environmental consequences of reactive N additions into
ecosystems.
Status | Active |
---|---|
Effective start/end date | 6/1/20 → 5/31/25 |
Funding
- National Institute of Food and Agriculture: $439,757.00
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