Randomized block trial demonstrates crab-shell chitosan effluent increases grain yield by 26% in lowland rice, highlighting a circular bioeconomy pathway for recycling biowaste.
Recycling chitosan-extraction effluent within its source catchment offers a circular-bioeconomy route for rice nutrition, though evidence remains scarce. Crab-shell feedstock from an MSME processor was converted to chitosan and the calcium-, nitrogen- and boron-rich effluent reformulated into a granular macro–micronutrient fertiliser (CMMF-CW), trialled on four smallholder paddy fields during the 2025 wet season in a six-treatment randomised complete-block design (basal NPK plus 0–2,500 kg ha⁻¹ CMMF-CW, T1–T6) across 96 plots. Versus the NPK-only baseline (T1 = 4.00 t ha⁻¹ milled rice = 6.24 t ha⁻¹ dry paddy, matching the Karawang norm of 5.5–6.5 t ha⁻¹ GKG), T6 raised milled-rice yield by 26.4% (5.06 t ha⁻¹), leaf nitrogen by 55.6%, and leaf boron by 68.0% (F = 246.8; p < 0.001; partial η² = 0.945), with rankings consistent across sites (Treatment × Site p = 0.95). Leaf calcium was the strongest yield correlate (r = 0.95); leaf zinc did not respond, consistent with homeostatic transporter regulation. Routing the effluent into its source community’s fertiliser supply closes the biowaste loop, offering a pathway for nutrient-skewed alluvial paddies. Multi-season, nutrient-matched trials remain necessary to isolate the chitosan-mediated contribution from the added nutrient load.
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Sari et al. (2026) studied this question.
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