Abstract
Soil disturbance by tillage practices promotes soil respiration which is a main source of carbon dioxide emission into the atmosphere. The present study was conducted to investigate the effect of different tillage practices on soil respiration and the carbon source/sink characteristics of maize farmland ecosystems in the wheat–maize–soybean cropping system. Six tillage treatments, namely, traditional tillage (T), ridge tillage (R), traditional tillage + straw mulching (TS), ridge tillage + straw mulching (RS), traditional tillage + straw mulching + decomposing inoculants (TSD), and ridge tillage + straw mulching + decomposing inoculants (RSD), were used to measure the soil respiration and its hydrothermal factors. The results showed that the intensity of soil respiration increased initially and decreased afterwards throughout the growth period of maize ranging from 1.011 to 5.575 μmol (m2·s)−1. The soil respiration rate under different treatments varied remarkably presenting a trend of RSD > TSD > TS > RS > T > R. Ridge tillage reduced the soil respiration rate of maize farmland while straw mulching improved it. Meanwhile, ridge tillage and straw mulching increased the soil temperature sensitivity index of soil respiration, but the addition of decomposing inoculants reduced this trend. The soil moisture response threshold under ridge tillage was lower, while the straw mulching was found to increase it, compared with the control. Moreover, there was a positive correlation between trapped soil fauna and soil respiration. Compared with the control, ridge tillage and straw mulching were beneficial to the carbon sink of the farmland ecosystem as shown by the maize field for the entire growing season.
Highlights
Global climate change with the frequency and intensity of extreme weather events has had a devastating impact on human activities, especially in agricultural farmlands around the world
The soil respiration rate increased initially and decreased afterwards during the entire growth period of maize ranging from 1.011–5.575 μmol (m2·s)−1
The minimum soil respiration rate appeared during the maize jointing stage under the traditional tillage (T) and the maximum rate was recorded during the maize silking stage under TSD treatment (Figure 4)
Summary
Global climate change with the frequency and intensity of extreme weather events has had a devastating impact on human activities, especially in agricultural farmlands around the world. Farmland ecosystems are an important part of terrestrial ecosystems, accounting for 10.5% of the total land around the world. Among the greenhouse gases released by human activities, carbon dioxide emissions account for 21% to 25% [2]. In the entire terrestrial ecosystem, the farmland ecosystem is the most active carbon pool which can be adjusted by humans in the shortest time. A major source of carbon cycle in agricultural soils, contributes usually up to two-thirds of the total carbon exchange as both a source and sink of CO2 within the entire ecosystem [2]. It is essential to deeply study the mechanism of soil respiration in farmland ecosystems for global carbon reduction
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