Agro-environmental assessment of composting plants in Southwestern of Morocco (Souss-Massa Region)

Purpose The region of Souss-Massa generates hugequantities of organic horticultural wastes estimated up to1,307,465 tons year-1. Fruit and vegetable producers areasked to process the organic wastes because of the GlobalGAPcertification requirements. As a result, there is aneed to assess the existing composting plants at regionalscale, to improve their efficiency, produce a high-qualitysoil amendment, free from any pathogens, and weed seeds.Methods The survey consisted of a diagnosis of thequantitative and qualitative status of the organic horticulturalwastes (axillary buds; pruned leaves), and an agroenvironmentalassessment of nine composting units.Results The analysis of macronutrients (nitrogen, phosphorus,and potassium) in the organic wastes reveals that13 million euro worth of N, P, and K can be generated bycomposting all horticultural wastes (12,000 tons of nitrogen,6000 tons of phosphorus and 14,000 tons of potassium year-1), constituting for soils an important source offertilization backup. Results of field investigations showedthat 55% of the composting plants have an area equal toone hectare. The proximity between mature piles and rawmaterials in 55.5% of cases could highly contaminate themby root knot nematode inoculum. Only 11% of compostingunits were operating on impermeable surface. The test ofcircular chromatography showed that 80% of sampledcomposts are immature, even with high operational costs.Conclusion Much effort is required to control and optimizethe maturation process. The composting activityshould be organized through a professional skilled organization,supported by scientific research and governmentsubsidies.