Carbon dioxide flux and soil carbon stock as affected by crop residue management and soil texture in semi‐arid maize croplands in Tanzania

Abstract

Crop residue management strategies must be adapted for improving carbon (C) balance and soil C stock in agroecosystems in sub‐Saharan Africa with consideration of the crop residue availability and site‐specific soil characteristics. We conducted field experiments to determine the effects of crop residue application method (incorporation/mulching) and quality (maize/cowpea) and N fertilizer application on the soil respiration rate and soil C stock in the surface soil layer (0–15 cm) in maize croplands with contrasting soil textures (clay/sandy) over 2 years from 2012 to 2014 in Tanzania. At the clay site, the incorporation of maize residues showed a 38% increase in CO2 flux compared to mulching, whereas, at the sandy site, mulching showed a 16% increase compared to the incorporation. At the sandy site, mulching practice retained soil moisture content and apparently enhanced the decomposition of the original soil organic C in the surface layer. It is, therefore, suggested that mulching practice may accelerate a long‐term depletion of soil C stock at the sandy site. The cowpea residue incorporation led to rapid decomposition because of its high biodegradability at both sites. The N fertilizer application stimulated the decomposition of labile soil organic matter. The soil C stock in the surface layer did not significantly change after the 2‐year experiment, irrespective of crop residue treatment and soil type. In conclusion, adequate crop residue management in terms of suppressing CO2 flux during a cropping season depends on soil type, but the long‐term effect on soil C stock is unclear.

CO₂ emissions in a soil under different tillage practices

“…The use of crop residues as mulching materials or organic fertiliser can help to improve the soil organic carbon (SOC) and crop grain yield (Wang et al 2019). Nishigaki et al (2021) showed that the carbon storage after crop residue incorporation is not significant in a short time view but it increases with time. This is in accordance with Lu et al (2015) who found a significant increase in soil organic matter after 10 years of straw incorporation in the soil whereas the short-term effect was not significant.…”

“…The tillage practice (i.e. straw incorporation or mulching) represents an important factor in the decomposition process, as it affects the water regime within the soil and the contact area of residues and soil Nishigaki et al (2021).…”

Sustainable soil management and climate change mitigation

“…Recent studies suggest that 5–15% of this carbon pool is susceptible to decomposition during the thawing process triggered by global warming (Jansson & Hofmockel, 2020), which could lead to both CO 2 and CH 4 emissions. Soil management on a farm scale can affect both SOC level and CO 2 emissions, for example the incorporation of crop residue tends to increase CO 2 flux (Nishigaki et al., 2021). Soil constituents also play a critical role in regulating CO 2 and CH 4 emissions.…”

Chemical composition of cover crops and soil organic matter pools in no‐tillage systems in the Cerrado

“…Crop rotation and plant diversity in no‐tillage systems (NTS) can provide more favourable conditions for accumulating carbon (C) and nitrogen (N) in the soil profile (Alhameid et al, 2017; Eberhardt et al, 2021; Sant’Anna et al, 2017; Schmatz et al, 2017) and for nutrient cycling, increasing the productivity of agricultural systems by improving soil quality (Soares et al, 2019). Inclusion of legumes in crop rotations provides N to microorganisms that synthesize stable fractions of soil organic matter (SOM), in addition to promoting protection and stability of C, consequently reducing greenhouse gas (GHG) emissions (Nishigaki et al, 2021; Yao et al, 2019). The adoption of cover crops in cropping systems is recommended as a management strategy to increase soil C stocks (Chahal et al, 2020; Rosolem et al, 2016).…”