Net N2O production from soil particle size fractions and its response to changing temperature.

Abstract Previous studies demonstrated that finer soil particles have smaller rates of CO 2 emission but larger Q 10 values (the proportionate increase in the rate for a warming of 10 °C) than coarser particles. However, it has not been tested whether there is a regular pattern for rates and Q 10 for N 2 O emission (net production) across soil particle size fractions, considering the known positive correlation between soil CO 2 and N 2 O emissions. A short-term incubation study with different soil particle fractions was conducted for soils from a grassland, a forest, an upland (including organic manure (OM) and chemical nitrogen, phosphorus, and potassium fertilizers (NPK) treatments), and a paddy (including manure plus chemical fertilizer (MNPK) and NPK treatments) under a series of increasing and decreasing temperatures between 5 °C and 30 °C with 5 °C intervals. For all the soils, net N 2 O production per unit mass of soil N was smaller from the silt (2–50 μm) fraction than from the sand (>50 μm) and clay (<2 μm) fractions. In paddy soils, Q 10 for net N 2 O production was highest from the clay fraction. In contrast, Q 10 was highest in the sand fraction for the grassland soil. In the upland and paddy soils, the rates of net N 2 O production were higher in OM or MNPK treatment than in their corresponding NPK treatment, but Q 10 values were similar between the manure and NPK treatments. The net N 2 O production rates positively correlated with CO 2 emission across all soil samples, and this was also the case for their Q 10 values. Q 10 values for net N 2 O production averaged 8% lower than those for CO 2 emissions. In conclusion, the net N 2 O production rates appear to be the smallest from the silt fraction. Graphical abstract Unlabelled Image Highlights • Net N 2 O production is the minimum from the intermediate-size (silt) particle. • Q10 of N 2 O emission is not always the maximum from the clay (finest) fraction. • Fertilizer type does not affect temperature sensitivity of net N 2 O production. • Q10 for N 2 O emission averaged 8% lower than that for CO 2. [ABSTRACT FROM AUTHOR]