Improvement of Compost Quality by Addition of Some Amendments (Report‪)‬

Introduction Composting is a biochemical process which involves conversion of the various components of organic wastes into relatively stable humus-like substances that can be used as a soil amendment or organic fertilizer. Even though composting is a proven-technology that can be applied on the spot, there are many aspects that should be improved in the performance of current composting facilities. One of these areas is the conservation and enhancement of the nutrients value of the product by reducing the loss of nitrogen (Jeong and Kim, 2001). The decreased ammonia loss may lead to an alleviation of the odor problem that is usually encountered in full-scale composting facilities (Switzenbaum et al. 1994). Several factors such as C/N ratio, temperature, mixing and turning and aeration rate can influence the volatilization of ammonia during composting (Morisaki et al. 1989). Gaseous nitrogen losses during composting mainly occur as ammonia, but may also occur as nitrogen and NOx (Eklind and Kirckman, 2000). Witter and Lopez-Real (1988) reported that total nitrogen loss could amount to 50% of the initial nitrogen in over 33% of the initial nitrogen during composting of poultry manure (Hansen et al. 1989). Ammonia (N[H.sub.3]) is generated from decomposition of nitrogenous material, i.e. proteins and amino acids. Its emission frequently occurs during the thermophilic stage of aerobic decomposition and tends to be high with low C/N ratio. However, when different types of organic materials are composted, a higher C/N ratio does not necessarily indicate an effective solution for preventing N loss (Baca et al., 1992; Mahimairaja et al., 1994; Brink, 1995; Eklind and Kirchmann, 2000). Both chemical form and particle size of carbon (C) source affect the availability of C to microorganisms. Glucose, a readily available C source, appeared to cause immediate immobilization of N when an appreciable amount was added to soils (Liang et al., 2006). Subair (1995) found that glucose was effective in reducing N[H.sub.3] volatilization from liquid hog manure, whereas material resistant to decomposition (sawdust) was not. Meyer and Sticher (1983) showed that N loss during composting of cattle manure and straw could be reduced by increasing the proportion of ground straw to chopped straw whilst maintaining a C/N ratio of 31.6. The juice extraction from the cane stalks and the subsequent sugar production from the cane juice provide molasses as a by-product. There is some sugar mills located in the sugar cane cultivation areas of Iran. On an annual basis, the sugar production process releases molasses by-products amounted 30000 tones, only in Haft Tappeh sugar factory. The utilization of molasses is important for the complete realization of the profit obtained by sugarcane cultivation. The market for molasses as a raw material for the domesticated meal, organic acid production and as soil amendment is fast catching up. Currently, an option for molasses utilization is as an amendment for production of organic wastes compost (Liang et al., 2006). Likewise, alkaline sludge is also a byproduct of paper mill that is annually produced to the tune of thousands cubic meter in Iran. It can be an environmental issue in addition to transportation costs, which is incurred in its disposal. However, there are ample scopes to utilize these organic wastes from industries for their use as compost amendments. The objective of present investigation was to evaluate the effectiveness of these byproducts with other amendments including the office paper and the sulfuric acid in reducing N losses and improving the quality of municipal compost.