Exploration of shrimp shell chitin as an agricultural biostimulant and its effects on soil microbial respiration

Swaffield, Alys Rose; Crew, Adrian; Bonnett, Sam

Abstract

Chitin (poly-(1→4)-β-N-acetyl-D-glucosamine) is a novel bio-stimulant derived from an inert by-product from sustainable fish production. This study observed the effect of chitin derived from shrimp shells on agricultural soil microorganism metabolism and on greenhouse gas emissions. Additions of ≤10% shrimp shell concentrations at <63µm, 63-125µm, 125-250µm, 250-500µm, 500-1000µm, and 1000-2000µm particle size fractions were added to temperate agricultural soil in mesocosms under laboratory conditions. Phenol oxidase and the hydrolase enzymes glucosidase, chitinase, and phosphatase were assayed to determine substrate utilisation in relation to soil organic matter, pH and greenhouse gas production (CO2 and CH4). Larger applications of chitin resulted in acidification and enzymatic response from glucosidase, phosphatase, whilst smaller applications and smaller particle sizes resulted in neutral soil pH and higher phenol oxidase activity. Chitin additions at 1-5% concentrations and <63-125µm particle sizes had the most complete microbial utilisation and balance between CO2 emission and CH4 sequestration, as a result of the priming effect of the chitin and successive microbial enzyme responses to the pH shift and reactivity of sites from solubilised particles. The importance of surface area and aerated lattice structure within the chitin particles was also shown. Importantly, the use of fractionation rather than chemical processing of the chitin substrate increased its solubility, reactivity, uptake and retention. The project demonstrated that use of shrimp shell by-products can achieve positive effects within soils when applied appropriately. The benefits may include creating a multiplicity of soil micro-habitats, improving nutrient retention, enhancing soil quality and promoting microbial interactions in the rhizosphere.

• Presentation Conference Type: Poster
• Conference Name: 22nd World Congress of Soil Science
• Start Date: Jul 31, 2022
• End Date: Aug 5, 2022
• Deposit Date: Sep 6, 2022
• Publicly Available Date: Sep 8, 2022
• Keywords: Shrimp, Chitin, Agriculture, Agricultural biostimulants, Biostimulants, microbial respiration, soil
• Public URL: https://uwe-repository.worktribe.com/output/9953370
• Related Public URLs: https://22wcss.org/