Disposal of Agro-Industrials Wastes as Soil Amendments

Abstract

We investigated the fertilizing potential of three agro-industrial wastes (Compost (C), Dehydrated Manures (DM) and Digestate (D)) on soil properties, on seeds germination and the plants growth. Results showed that the addition of wastes modified several soil properties as pH, Electrical Conductivity (EC), Water Retention Capacity (WRC) and Soil Organic Matter (SOM). Hence, SOM increase from 1.5% in unamended soil to 2, 2.3 and to 3.1% in soils amended with (D), with (DM) and with (C) respectively. A fast SOM biodegradation was illustrated in presence of compost where we noted a decrease of 20% of initial organic matter content. Besides, wastes improve strongly microbial and respirometric soil activities mainly in presence of DM and D. These same wastes stimulate seeds germination of two standard plants species (Tomato (Lycopersicon esculentum) and Alfalfa (Medicago sativa)). The growth levels of three cultivated plants species (Wheat (Triticum durum), Sorghum (Sorghum bicolor) and Alfalfa (Medicago sativa)) were enhanced in presence of wastes than those irrigated with water.

Anaerobic co-digestion of rabbit manure and sorghum crops in a bench-scale biodigester

“…As previously mentioned, no reports on rabbit and sorghum digestate quality have been reported in the open literature constituting this a novel information. Nonetheless, the average values of total solids, K and P for the digestate under study are within the range reported by Vaneeckhaute et al (2013b) and Mekki et al (2013) for digestates of pig manure with energy maize and agriculture wastes, respectively. Table 3 also presents the average value and deviation of all the other analyzed parameters (C, N and H content).…”

“…Table 3 also presents the average value and deviation of all the other analyzed parameters (C, N and H content). Taking into account the value of total C and N determined by elemental analysis, the digestate presents a C/N ratio of 8.1, similar to that reported by Mekki et al (2013), and less than the encountered for the feed stream. Table 3 shows a reduction in the VS content and the carbon content of the digestate with respect to the VS and C in the substrate (see Table 2).…”

“…Liquid substrate and liquid digestate samples were characterized as follows. For both type of samples, total solids (TS) content was determined according to Mekki et al (2013) and Smith et al (2007) standard method. Indeed, a known weight of each liquid sample was introduced into a porcelain crucible followed by drying at 105 °C until constant weight.…”