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Effect Of Nitrogen Fertilization On Central Tendency And Spatial Heterogeneity Of Soil Moisture, Ph And Dissolved Organic Carbon And Nitrogen In Two Bioenergy Croplands, Xuehan Wang, Siyang Jian, Lahiru Gamage, Jianwei Li

Agricultural and Environmental Sciences Faculty Research

Background

Soil moisture, pH, dissolved organic carbon and nitrogen (DOC, DON) are important soil biogeochemical properties in switchgrass (SG) and gamagrass (GG) croplands. Yet their spatiotemporal patterns under nitrogen (N) fertilization have not been studied.

Aims

The objective of this study is to investigate the main and interactive effects of N fertilization and bioenergy crop type on central tendencies and spatial heterogeneity of soil moisture, pH, DOC and DON.

Methods

Based on a 3-year long fertilization experiment in Middle Tennessee, USA, 288 samples of top horizon soils (0–15 cm) under three fertilization treatments in SG and GG croplands were collected. …

Soil Health Beneath Amended Switchgrass: Effects Of Biochar And Nitrogen On Active Carbon And Wet Aggregate Stability, Priya Saini, Jason P. De Koff, Richard Link, Chris Robbins

Agricultural and Environmental Sciences Faculty Research

Perennial crops, like switchgrass (Panicum virgatum L.), are important for bioenergy production and long-term carbon sequestration. Biochar, a byproduct of certain bioenergy production processes, is also identified as a potential tool for carbon sequestration and soil quality improvements, especially in marginal soils. Despite the focus on switchgrass, soil health characteristics under switchgrass production for biomass are unclear. This study focused on identifying the effects of four N rates (0, 17, 34, and 67 kg N ha−1) and biochar application (0 and 9 Mg ha−1) in a 3-year switchgrass field study on a silt loam soil. Soil active carbon (AC) and …

Differential Effects Of Warming And Nitrogen Fertilization On Soil Respiration And Microbial Dynamics In Switchgrass Croplands, Jianwei Li, Siyang Jian, Jason P. De Koff, Chad S. Lane, Gangsheng Wang, Melanie A. Mayes, Dafeng Hui

Agricultural and Environmental Sciences Faculty Research

The mechanistic understanding of warming and nitrogen (N) fertilization, alone or in combination, on microbially mediated decomposition is limited. In this study, soil samples were collected from previously harvested switchgrass (Panicum virgatum L.) plots that had been treated with high N fertilizer (HN: 67 kg N ha−1) and those that had received no N fertilizer (NN) over a 3-year period. The samples were incubated for 180 days at 15 °C and 20 °C, during which heterotrophic respiration, δ13C of CO2, microbial biomass (MB), specific soil respiration rate (Rs: respiration per unit of microbial biomass), and exoenzyme activities were …