Soil Organic Carbon Budget and Turnover Rates Under No-till Cropping Systems in a Heterogeneous Palouse Landscape.

Abstract

Soil is a potential carbon sink to mitigate climate change by counteracting rising levels of atmospheric CO₂. The capacity of soils to store and sequester carbon relies on the amount of carbon inputs from plant primary productivity and other organic amendments relative to carbon exports controlled by microbial decomposition and soil erosion processes. Conservation tillage and crop rotation, highly recommended management practices for heterogeneous landscapes, have the potential to improve carbon sequestration in agroecosystems. An investigation is being conducted to evaluate spatiotemporal variability of profile soil carbon stocks as deep as 1.5m across a 37-ha field after conversion from conventional tillage to no-till with crop rotation for 17 years. Important predictors of soil organic carbon (SOC) dynamics such as soil characteristics and terrain attributes will be identified through random forest regression analysis. SOC stocks estimated from CropSyst, and RothC versus measured SOC will aid corroboration and improvement of models for simulating SOC in heterogeneous landscapes. Furthermore, carbon pool fractions obtained from mineralization incubation studies and SOM functional groups identified from NMR spectra will be used to evaluate interactive effects of soil, landscape, tillage and cropping system on SOC quality and sequestration mechanisms. 

Keywords: Soil organic carbon. No-till, land management, modelling