Thursday, 13 July 2006

Influence of Nutrient Rich Organic Wastes Application to Degraded Land on Soil Properties and Establishment of Forest Tree Species.

Reddy, G.V. Prabhakara, Srinivasamurty, C.A., Nagaraja, M.S., and Vasanthi B.G. Dept. of Soil Science, UAS, GKVK, Bangalore, ID 560065, India

With the result of over exploitation, productive lands have rendered them in to un-productive degraded lands characterized with high gravelliness, dominated with courser fragments and depleted with plant nutrients. These lands require external supply of nutrients on a continuous basis for successful establishment vegetation. On the other hand, the uncontrolled urbanization and industrial expansion are leading to serious environmental problems through generating large quantity of organic wastes (sludges) characterized with high organic matter and plant nutrients. High nutrient contents in organic wastes provide an opportunity to utilize them as nutrient sources in wasteland reclamation. By keeping this in view, an attempt has been made to utilize nutrient rich industrial and domestic organic wastes for effective reclamation of degraded land through afforestaion in Eastern dry zone of Karnataka, India. Organic wastes from sugar mill, paper mill, distillery industry and municipal sludge were chosen along with Farm Yard Manure (FYM) as a control. Organic wastes were analyzed for their nutrient and heavy metal contents before application. The organic wastes were applied at 1 and 2 % on soil weight basis. Tree species such as Pterocarpus marsupium, Melia dubia, Azadirachta indica, Pongamia pinnata and Holoptelea integrifolia were planted. The growth parameters such as plant height, collar diameter were monitored at 3 months interval for 2 years. The soil samples were collected and analyzed at different interval. The organic wastes nutrient content varied with their types and also with their treatment processes. Organic carbon content ranged from 20-46 % and nutrient contents were N - 0.37 to 1.69 %, P - 0.17 to 1.64 % and K - 0.10 to 0.73 %. Nitrogen and phosphorus content was substantially high in sugar industry waste while, phosphorus, potassium, sulphur and calcium contents were higher in distillery sludge. Heavy metal contamination was recorded only in municipal and paper industry wastes. Plants growth significantly varied with organic wastes and their levels. The growth was influenced by the wastes in the order of Distillery sludge > Municipal sludge > Sugar mill sludge > FYM > Paper mill sludge > Control. In general, wastes applications at 2 % recorded higher growth compared to that of lower level. Soil nutrient status was very much influenced by the organic wastes type and their levels and no significant differences were found across species. There was substantial increase in soil organic-C, N, P2O5, K2O, Ca, S etc in municipal sludge, distillery sludge and sugar mill sludge treated plots. Slight increase in physical parameters was also observed over the sludge addition and there was a slight variation over seasons. Heavy metals were observed in municipal and paper mill sludge at higher levels and they were below the permissible limits. These results clearly suggest that the sewage sludge and agro-industries wastes can be effectively and efficiently used for wasteland reclamation.

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