Fragment size and diversity of mulches affect their decomposition, nutrient dynamics, and soil microbiology

Gaitanis, D.; Lukac, M.; Tibbett, M.

doi:10.1101/2022.07.21.500764

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bioRxiv · 10.1101/2022.07.21.500764

Fragment size and diversity of mulches affect their decomposition, nutrient dynamics, and soil microbiology

Gaitanis, D.·Lukac, M.·Tibbett, M.

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Abstract

Plant-based mulch has been proposed as a sustainable way of maintaining soil fertility. However, the role of mulch diversity, quality, and size in decomposition dynamics, and their effect on crop yield are not fully explored. We investigated how mulch quality, proxied by the constituent plant species diversity, and residue size drive mulch decomposition, crop nutrition, and yield. A rhizotron experiment was set up with barley as a model crop, with the addition of mulch of two particle sizes (1.5 and 30 cm) and four different plant residue mixes (17, 12, 6, and 1 species) in a fully factorial design. Soil nutrient dynamics were measured at advanced decomposition stages, together with residue quality, arbuscular mycorrhizal fungal (AMF) root colonization, and crop yield. Residue mass loss was significantly affected by its chemical composition. Long residues retained significantly higher C and N content, than short residues. Crop yield was not affected by residue type or size. Residue size significantly affected barley growth rate, influencing seed protein content. Soil available K was significantly increased by residues with a higher initial C:N ratio. Short residues resulted in higher soil Zn. Residues of higher diversity resulted in higher AMF root colonization of the barley plants. Generally, long residue mulches maintain soil fertility for a longer period than short ones, without a deleterious effect on crop yield. Further investigation should evaluate the effect of continuous application of long residue mulches on soil fertility and microbial populations.

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Gaitanis, D., Lukac, M., Tibbett, M.. 2022-07-22. Fragment size and diversity of mulches affect their decomposition, nutrient dynamics, and soil microbiology. https://doi.org/10.1101/2022.07.21.500764

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