Application of PistachioWaste as Organic Manure in Sustainable Agriculture

Plant residuals and waste products of agricultural crops form organic fertilizer sources that are traditionally used as organic manure. From 230000 t of dry pistachios produced in 2014, more than 766000 t waste was generated and a large part was to pistachio orchards in fertile regions to be used as organic manure. This study investigated the positive and negative effects of the used of pistachio waste as organic fertilizer over two consecutive years in the form of statistical designs for compound decomposition (overtime). The results indicate that if pistachio waste accumulates without being disinfected, it is a suitable environment for the growth and activity of Aspergillus and Penicillium fungi. The presence of aflatoxin G2 was confirmed in the pistachio waste (0.028 μg), but this contamination did not exist in the soil of the orchard to which the pistachio waste was added. The addition of waste to soil significantly reduced the EC and pH and increased the levels of Zn, P, and K by 270%, 195%, and 89.5%, respectively, in comparison with the control. The level of B did not differ significantly at between treatments. The results suggest that adding pistachio waste to soil enriches it with elements that are directly absorbable by pistachio trees, but it is necessary for the waste to be disinfected with proper fungicides to prevent development of toxin contamination. Furthermore, to recover the decomposability of soil, application of waste to orchards with intervals of twice or three times a year is recommended.