Comparison of several solid wastes on the growth of vegetable crops

Properties of pig manure, chicken manure, mixed sludge, fly ash, furnace bottom ash, refuse compost and commercial fertilizer were compared. Pig manare, digested sludge, furnace bottom ash and fertilizer were applied to a sandy soil for the growth of 2 vegetables: Amaranthus tricolo (Chinese spinach) and Brassica chinensis (Chinese white cabbage). Edaphic properties and heavy-metal contents of the waste-amended soils were analysed. Soils treated with pig manure and sludge possessed higher nutrient contents than ash-treated soil. Vegetables treated with pig manure gave the highest productivity and lower heavy metal contents. They also gave higher yields than those receiving fertilizer. This indicated that pig manure has a high potential as a substitute for fertilizer. Vegetables harvested from ash-treated soil had higher yields and lower heavy-metal contents than those treated with sludge. The inferior growth of vegetables harvested from sludge-amended soils seemed to correlate with the lower pH, lower organic matter and higher heavy-metal contents of the soil.