Soil Moisture and Temperature Effects on Nitrogen Mineralization in a High Tunnel Farming System LeiLili McDonaldLouis M. 2019 <p>Effects of temperature and moisture on nitrogen (N) mineralization from organic amendments in high tunnel farming systems are rarely studied to assist N fertilizer management for high N-demand crops with short cycles. In this study, soils from a new high tunnel site were incubated at four temperatures (2, 10, 20, & 30°C) and five gravimetric water contents (15, 20, 25, 30, & 35%) with and without a dried and ground alfalfa amendment. Net N mineralization was determined by measuring NH<sub>4</sub><sup>+</sup>-N and NO<sub>3</sub><sup>–</sup>-N contents periodically over 84 days. Significant main effects of temperature and moisture were found (<i>p</i> < .0001) and tendencies of a significance of alfalfa amendment (<i>p</i> = .0855) and interaction between amendment and temperature (<i>p</i> = .0842) were observed. Only a significant increase of the net mineralized N at 30ºC in amended soil was observed compared to unamended soil (<i>p</i> = .0043). Estimated from the first-order exponential model, maximum potential mineralized N was 1.2 times greater while mineralization rate was up to 2.1 times greater in amended soil compare to un-amended soil. Q<sub>10</sub> estimated from the Arrhenius model ranged from 1.62 to 2.04 in the amended soil and 1.66 to1.85 in the un-amended soil. The average optimal soil water content for maximum N mineralization estimated from the Gaussian function model was 33.8% in amended soil and 35.9% in un-amended soil. The results from this study can be used to suggest soil moisture and temperature management strategies to control N availability in high tunnel systems.</p>