Composted tobacco waste increases the yield and organoleptic quality of leaf mustard

Abstract

Abstract Tobacco (Nicotiana tabacum) waste is produced in many countries and is phytotoxic due to the alkaloid content; in Vietnam the waste is usually burned causing air pollution. We composted tobacco waste with chicken manure in different proportions—1 t of waste ± accelerant (C1 and C2); 0.8 t of waste + 0.2 t of chicken manure ± accelerant (C3 and C4); and 0.7 t of waste + 0.3 t of chicken manure ± accelerant (C5 and C6)—for 30 d in covered heaps. Three mixtures containing the accelerant (C2, C4, and C6) reached temperatures of ∼55 °C, that 5s, hot enough to suppress disease and weeds. Composting decreased the alkaloid content from ∼6,000 to ∼200 mg kg−1, and C4 with a C/N ratio of 19:1, was used in a field trial. The compost treatments (0, 10, 15, and 20 t ha−1) were combined fertilizer with phosphorus (40 kg ha−1), nitrogen (60 kg ha−1) and potassium (90 kg ha−1) for leaf mustard (Brassica integrifolia). The yield increased from ∼17 to ∼29 t ha−1 with the amount of compost applied, and the nitrate concentration decreased concomitantly from ∼67 to ∼42 mg NO3–N kg−1 fresh weight, presumably due to ongoing composting (nitrogen drawdown). Organoleptic evaluation showed a preference for the crops grown with the compost amendments. Whether remains to be seen whether one‐off compost applications >20 t ha−1 and repeated, large applications provide additional, long‐term production benefits, or if the benefits may be outweighed by the accumulation of persistent, phytotoxic alkaloids.