| Immature municipal solid waste (MSW)-biosolid composts were evaluated as potential biological weed control agents in vegetable crop row-alleys. Ivyleaf morningglory (Ipomoea hederacea L.) was used to determine a compost maturity bioassay. A 20 g (dry weight) of MSW compost:50 ml water extract resulted in the widest percent seed germination range to varying compost maturities.; Ivyleaf morningglory, barnyardgrass (Echinochloa crusgalli L.), common purslane (Portulaca oleracea L.), and corn (Zea mays L.) seeds were used in the bioassay to determine the relative potential of 3-day, 4-week, and 8-week-old composts (containing 2474, 1790, and 1776 mg{dollar}cdot{dollar}kg{dollar}sp{lcub}-1{rcub}{dollar} acetic acid, respectively) to inhibit germination and reduced seedling growth. Extract from 8-week-old compost was the most phytotoxic (delayed and reduced germination) to seeds of 14 important economic weed species.; Immature and mature composts were applied as mulch in pot culture to determine the effect on weed seed emergence. Compost (3-day-old) delayed ivyleaf morningglory emergence by 4 days and decreased emergence by 50% than no mulch. Seed emergence of eight weed species covered with 2.5 or 10 cm of either mature or immature (8-week-old) compost decreased as compared with a control. Reduction and delayed germination from immature compost were more prominent with the thinner layer (2.5 cm) than with mature compost.; Compost thicknesses of 3.8 (49 t{dollar}spcdot{dollar}ha{dollar}sp{lcub}-1{rcub}{dollar}), 7.5 (99 t{dollar}spcdot{dollar}ha{dollar}sp{lcub}-1{rcub}{dollar}), 11.3 (148 t{dollar}spcdot{dollar}ha{dollar}sp{lcub}-1{rcub}{dollar}), and 15 cm (198 t{dollar}spcdot{dollar}ha{dollar}sp{lcub}-1{rcub}{dollar}) were applied to vegetable crop row-alleys. Immature compost applied at 7.5 cm or thicker completely inhibited weed growth for 240 days after treatment under low weed pressure. Complete weed control by 4-week-old compost only lasted 65 days under higher weed pressure, especially with yellow nutsedge (Cyperus esculentus L.). Weed cover was reduced by 50% with 11.3 cm of compost than the control, 240 DAT.; Acetic acid levels in 4-week-old compost were 1221 and 4128 mg{dollar}spcdot{dollar}kg{dollar}sp{lcub}-1{rcub}{dollar} in the two field experiments. Immature compost provided effective weed control in vegetable crop row-alleys due to physical and chemical effects (short-chain fatty acids). Eight months later, compost matured, and was used as a soil amendment that increased snap bean yields. |
