Effects of Maize-Soybean Intercropping on Nitrous Oxide Emissions from a Silt Loam Soil in the North China Plain

Abstract

Maize (Zea mays L.), a staple crop in the North China Plain, contributing substantially to agricultural nitrous oxide (N2O) emissions in this region. Many studies have focused on various agricultural management measures to reduce N2O emissions. However, few have investigated soil N2O emissions in intercropping systems. In the current study, we investigate whether maize-soybean intercropping treatments could reduce N2O emission rates. Two differently configured maize-soybean intercropping treatments, 2:2 intercropping (two rows of maize and two rows of soybean, 2M2S) and 2:1 intercropping (two rows of maize and one row of soybean, 2M1S), and monocultured maize (M) and soybean (S) treatments were performed using a static chamber method. The results showed no distinct yield advantage for the intercropping systems. The total N2O production from the various treatments was 0.15 ± 0.04–113.85 ± 12.75 µg m−2 min−1. The cumulative N2O emission from the M treatment was 16.9 ± 2.3 kg ha−1 over the entire growing season (three and a half months), which was significantly higher (P < 0.05) than that of the 2M2S and 2M1S treatments by 36.6% and 32.2%, respectively. Two applications of nitrogen (N) fertilizer (as urea) at 240 kg N ha−1 each induced considerable soil N2O fluxes. Short-term N2O emissions (within one week after each of the two N applications) accounted for 74.4%–83.3% of the total emissions. Soil moisture, temperature, and inorganic N were significantly correlated with soil N2O emissions (R2 = 0.246–0.365, n = 192, P < 0.001). Soil nitrate (NO−)3 and moisture decreased in the intercropping treatments during the growing season. These results indicate that maize-soybean intercropping can reduce soil N2O emissions relative to monocultured maize.