Location: Crops Pathology and Genetics Research
Project Number: 2032-22000-017-007-A
Project Type: Cooperative Agreement
Start Date: Nov 1, 2019
End Date: Jun 30, 2022
1) Characterize soil physicochemical properties in a N fertilization trial on a monthly basis and more frequently during the almond growing season. 2) Determine rates of microbial carbon and nitrogen usage in soils and relate this to nitrogen available for tree uptake. 3) Characterize microbial communities in soils via sequencing, PLFA profiling, and enzyme activity to better understand the stability of organic matter and nitrogen dynamics in the soil, and (4) assess tree responses (i.e., growth, leaf tissue nutrient content, etc.) to N fertilization treatments.
These objectives will be accomplished over the 2.5 year period, with 2 years of field and laboratory experiments and 6 months for data analysis and manuscript preparation. Overall, the proposed research would test the hypothesis that soil microbes immobilize more nitrogen from fertilization in wood chip plots compared to control. Soil physicochemistry will be assessed via standard methods that measure total and dissolved organic and inorganic carbon and nitrogen pools, pH, moisture, etc. Microbial carbon and nitrogen usage will be determined using methods involving isotope tracers into biomass in laboratory incubations of soil. Soil microbes will be characterized using sequencing of 16S rRNA and ITS genes, PLFA profiling to estimate relative ratio of bacteria and fungi, and fluorometric assays for extracellular enzyme activities (i.e., phosphatase, cellulases, chitinases, etc.). Trees will also be characterized by measuring trunk cross sectional area, leaf tissue nutrient and elemental composition, and stem water potential during the growing season.