Simon Fordyce, a member of the CREWS JRW Working Group, will give his Master's defense on Friday, January 7 at 10 a.m.
Title: How important is soil depth in explaining spatiotemporal patterns of N mineralization in dryland wheat systems?
Abstract: Shallow soils (< 50 cm) under dryland wheat production are known to lose a disproportionate amount of inorganic nitrogen to leaching. However, due to lower fertilizer recovery and suppressed mineralization, crops grown in these environments may be more responsive to nitrogen fertilizer. Therefore, recommended fertilizer rates can be higher than in deeper, more productive soils. To assess the potential for suppressed nitrogen mineralization in shallow soils of Central Montana, we used remote sensing to spatially characterize soil depth on three fields and compared surficial (0-20 cm) carbon and nitrogen cycling indices between deep (40 ± 3 cm) and shallow (32 ± 2 cm) depth classes. Carbon dynamics were stable across depth classes while nitrogen mineralization was lower in the shallow depth class. Results confirm multispectral imagery as an invaluable tool for non-destructively characterizing fine-scale spatial patterns in soil depth and corroborate previous findings of lower nitrogen mineralization in shallow soil environments. Decision support systems for site-specific fertility management (e.g., variable rate fertilizer application) should assess the environmental consequences of leaching alongside the economic benefits of applied fertilizer rates which maximize responses of yield and same-year net revenue.
This seminar is offered virtually at the following Webex address: