Jan. 4, 2010 – Sewage sludge can be successfully converted into compost that can enhance growth and flowering of landscape plants, according to recent research in Malaysia.

Biosolid compost could be beneficial to plants. Studies are being carried out to establish the effectiveness of biosolid compost derived from sewage sludge as soil enhancers in promoting plant growth. Researchers from University Technology MARA, Sarawak, Malaysia used compost, chicken manure and topsoil to collect data to gauge the growth response in Canna (Canna orientalis), locally known as “Bunga Tasbih,” an ornamental plant.

The findings indicate that biosolid compost derived from sewage sludge has the potential to be a good soil enhancer as compared to other soil enhancers commonly used in horticultural cultivation. Biosolid compost is derived from treated sewage sludge, also known as biosolids. Biosolids are known to be high in organic content that helps improve the quality of soil. Its suitability is further enhanced due to its biologically aerobic process producing high temperatures that is caused by microbial activity during the composting processes that kill pathogenic microorganisms and helps reduce pile volume in two to three weeks.

Other studies have shown that sewage sludge composting can effectively decompose biodegradable organic matter of sewage sludge and destroy pathogens enriched in sewage sludge into a stable end product, which can be used as fertilizer or soil conditioner.

The researchers conducted a complete randomized block design experiment, replicated three times, to investigate the growth response of Canna orientalis to the compost. Six treatments were used: biosolid compost, dry aged chicken manure and topsoil, each with or without potassium. Potassium was added to gauge the effects on flowering and the number of shoots produced in each treatment over a six-month period.

The mean number of shoots by the end of the experiment ranged from 6.68 to 8.30 among the four soil treatments (compost with and without potassium, dried chicken manure with and without potassium). Over the duration of the experiment, compost fared as well or better than chicken manure with respect to mean number of shoots.

During the initial stages, the plants treated with dried chicken manure had shoots relatively longer when compared to the shoots on plants treated with the compost. At the end of the experiment, the mean height of the additional shoots, which totalled 14 in the compost treatment, was to be significantly taller than the chicken manure treatment plants, which produced only 11 shoots.

However, it was noted that the production of leaves throughout the experiment was significantly higher on the plant treated with chicken manure as compared to those treated with the compost. Flowering occurred after the fourth month of planting. The flowering of plants treated with chicken manure showed the highest percentage of early flowering, during which the compost treatment had not yet shown any flowering. It was presumed that the early flowering in the chicken manure treatment was triggered by stress that resulted in the early flowering, as plant stress is known to trigger “bolting” or unseasonably early flower production.

Despite being a late starter in flowering, the compost treatment plants showed a higher percentage of flowering, recording a 74 per cent rate at harvest as compared to 60 per cent for plants treated with chicken manure with potassium.

This study demonstrated that sewage sludge can be successfully converted into compost with beneficial qualities for landscape applications. Compost from sewage sludge showed accelerated growth and higher percentage of flowering. A point to note was that plants treated with sewage compost were able to flower profusely without the addition of potassium, a significant cost-saving consideration,

Sewage sludge compost has proven itself to be superior in propagating significantly accelerated plant growth and higher percentage in flowering, therefore qualifying as a potential plant growth enhancer for plant nurseries.