Relationship between soil carbon and nitrogen, soil properties, and dryland crop yields

Soil organic carbon (SOC) is an important indicator of soil health, but its analysis requires a two-step process of measuring soil total carbon (STC) and inorganic carbon (SIC) in arid and semiarid regions. Determination of STC or soil total nitrogen (STN) for SOC can shorten the analytical process, which may be used for measuring soil health. We related STC, STN, SOC, and SIC to 62 soil properties and mean crop yields across years in two long-term (14- and 36-yr-old) experiments in the northern Great Plains. Treatments were rotations of till- and no-till spring wheat (Triticum aestivum L.)/barley (Hordeum vulgare L.), pea (Pisum sativum L.), and fallow with and without N fertilization. No-till continuous cropping (every year cropping) increased STC, STN, and SOC compared to till and no-till crop-fallow, with limited effect of N fertilization. Treatments had little effect on SIC. The STC correlated to 6, 7, and 28 more soil physical, chemical, biological, and biochemical properties than SOC, STN, and SIC, respectively. A combination of data from both experiments enhanced the relationships among STC, STN, SOC, and selected soil properties. The STC also more strongly related to mean crop yield across years than SOC, STN, and SIC. Because of rapid determination and sensitivity to management practices, STC can be used as a potential soil health indicator to relate to more soil properties and crop yields in dryland cropping systems in the semiarid northern Great Plains.