Effects of long-term fertilization on soil respiration in spring maize field in the central part of northeast China

Objectives In order to provide scientific basis for the study of carbon sequestration and emission reduction in black soil area of northeast China, the effects of long-term different fertilization measures on soil respiration were explored.

Methods This study was based on the long-term fertilization experiment from the National Black Soil Fertility and Fertilizer Efficiency Monitoring Base. Five fertilization treatments were selected, including no fertilizer (CK), only chemical fertilizer application (NPK), combining chemical fertilizer with straw (NPKS), combining chemical fertilizer with low level of organic fertilizer (NPKM1), combining chemical fertilizer with high level of organic fertilizer (NPKM2). Field monitoring was conducted using Soil-box343 soil respiration measuring system, and environmental conditions were observed at the same time.

Results The soil respiration rate of the treatments was in range of 4.12 to 7.23 μmol/(m²·s), showing the trend of “increasing first and then decreasing” during the growth period of corn, and the highest value appeared at about 69 days after sowing. The peak respiration rate of NPKM2 treatment was significantly higher than those of other treatments (P < 0.05). There was a significant positive correlation between soil respiration rate and soil temperature during the monitoring period. Soil temperature can explain 41%–77% of the variation of the soil respiration rate, and the range of soil temperature sensitive coefficient Q₁₀ was from 2.35 to 3.49. The total soil respiration varied from 3473 to 5643 kg/hm². NPKM2 treatment was respectively 21.0%, 26.4% and 62.4% higher than those in NPKS, NPK and CK treatments, and NPKS was 34.2% higher than that in the CK (P < 0.05). The increasing trend of soil organic carbon content in long-term organic and inorganic treatments is more obvious than other treatments, and the soil organic carbon contents in NPKM1 and NPKM2 treatments were increased by 6.01 g/kg and 5.55 g/kg compared with the initial soil organic carbon content, respectively.

Conclusions Long-term application of organic fertilizer can increases soil respiration, and improve the content of soil organic carbon at the same time. Manure application plays a win-win effect for improving agricultural productivity and sustainable utilization.