Ntonta S., Mathew I., Zengeni R., Muchaonyerwa P., Chaplot Vincent. (2022). Crop residues differ in their decomposition dynamics : review of available data from world literature. Geoderma, 419, 115855 [14 p.]. ISSN 0016-7061.
Titre du document
Crop residues differ in their decomposition dynamics : review of available data from world literature
Decomposition of crop residues may affect soil organic carbon (C) stocks, which are key for soil fertility improvement and mitigation of climate change. Numerous independent studies across the world point to contradictory results but their existence provides an opportunity to conduct a comprehensive analysis of the impact of crop type on residue decomposition. In the present study, data from 394 trials from across the world were used to assess cumulative CO2 emissions from residues of 17 crops during 0-30, 0-90 and 0-120 days (i.e. CR30, CR90 and CR120; 1-[CR30/CR120] ratio as a stability index of C emissions) and to relate the results with residue quality (C, N and lignin concentrations) and selected soil properties (texture, pH, soil organic carbon concentration). At all durations, legumes exhibited the highest CO2 emissions per gram of C added (1003 mg CO2-C gxfffd; 1C after 120 days) followed by grasses (9 4 7), oilseed crops (9 4 4) and cereals (8 4 6), with the legumes and grasses showing the lowest temporal stability of C emission as pointed out by a 1-[CR30/CR120] of 0.78 and 0.79, respectively, versus 0.82 and 0.83 for cereals and oilseed crops. At all durations, maize residues emitted the least C-CO2 (86, 275 and 495 mg CO2-C gxfffd; 1C), followed by two other lignin rich crops (cotton and sunflower), while the highest emissions were from Alfalfa residues that produced about 4 times more CO2 (e.g. 359 at CR30 and 1319 at CR120) than maize. Overall, CO2 emissions were positively correlated with soil clay concentration (r > 0.22), residue C concentration (e.g. r = 0.46 at CR90 and r = 0.37 with emission stability, P < 0.05) but negatively to residue N concentration (r = -0.26 at CR120, P < 0.05). The global trend pointed to decreased CO2 emissions with increasing residue lignin. Contrary to what is generally believed, providing the soil with high lignin and high N concentration may foster C stabilization into soils by soil microbes.
