Carbon dioxide flush as a soil health indicator related to soil properties and crop yields

Carbon dioxide flush after rewetting of dried soils has been recommended as a promising soil health indicator, but it has not been related to most soil properties and crop yields. We evaluated the effect of cropping systems and N fertilization on CO2 flushes at 1‐ (1dC) and 4‐d incubations (4dC) after rewetting of dried soils and related to 54 soil physical, chemical, and biological properties and annualized crop yields in two long‐term experimental sites in eastern Montana (USA). Treatments included till and no‐till spring wheat (Triticum aestiveum L.), pea (Pisum sativum L.), and fallow rotations with and without N fertilization. Carbon dioxide flushes were lower in till crop–fallow than in no‐till continuous cropping systems at both sites. The 1dC was correlated to 5 soil physical, 7 chemical, and 12 biological properties, and 4dC was correlated to 9 physical, 8 chemical, and 11 biological properties in Froid. In Sidney, 1dC was correlated to 10 physical, 13 chemical, and 9 biological properties, and 4dC was correlated to 7 physical, 11 chemical, and 2 biological properties (1–8 moderately, 18–21 strongly, and 1–3 very strongly related). Carbon dioxide flushes were also related to mean annualized crop yields in both sites, except for the relationship between 4dC and crop yield in Sidney. Because of its stronger relationship with soil properties and crop yields, 1dC after rewetting of dried soils determined by using the infrared gas analyzer can be used as a simple, rapid, reliable, and inexpensive indicator of measuring soil health in dryland cropping systems. Core Ideas A rapid and inexpensive soil health indicator that relates to soil properties and crop yield is needed. Relationships between CO2 flushes, soil properties, and crop yields were examined in long‐term experiments. CO2 flushes were related to 11 soil physical, 26 chemical, and 11 biological properties and mean crop yield. CO2 flush at 1‐d incubation was related to five more soil properties and two more crop yields than at 4‐d incubation. CO2 flush at 1‐d incubation can be used as a rapid and inexpensive indicator of soil health in dryland farming.