Role of organic food wastes on soil fertility and stevia crop growth and its yield

A field experiment was conducted at the Experimental farm, Soils and water Department, Faculty of Agric., Al-Azahar Univ., Assuit, Egypt, during two successive growing seasons of 2018 and 2019. The study aims to assess the influence of organic food wastes (Eggshell, Banana peels, Green pea peels and Potato peels) are sources of some nutrients and Soybean protein isolate as a source of nitrogen on the soil fertility, growth parameters, yield and quality of stevia plant under drip irrigation system.
The result showed positive increase in all growth parameters and yield of sativa plant as well as improving soil properties by adding organic food wastes. The most effective treatment was the combination of C4 treatment (50% organic-N from isolated soy protein, 12.5% banana peels, 12.5% eggshell, 12.5% green pea peels and 12.5% potato peels). The highest total chlorophyll value of 4.48 and 3.61 mg/g fresh weight in the 1stand 2nd cutting, respectively in the 1st season were obtained under C4 treatment. The corresponding values were 4.89 and 4.02 mg/g fresh weight in the 2nd season. The highest values of dry leaf yield 843 kg plot-1 and biological yield 1.60 kg plot-1 were noticed under C2 treatment in the 2nd cut in the first season. In the second season, the corresponding values were 1242 and 2.19 kg plot-1 resulted from C4 treatment in the 2nd cut. The highest values of protein content 10.73 and 13.72% in 1st and 2nd cut, respectively were realized under C4 treatment in the 1st season. The corresponding values were 15.0 and 18.11% for C4 treatment in the 2nd season. In the 1st season, the highest values of stevioside content were 8.49 and 8.98 % in the 1st and 2nd cut for C4 and C2, respectively. In the 2nd season, the highest values of stevioside content were 9.69 and 10.05 % in the 1st and 2nd cut for C2 treatments, respectively. Available N in C0 treatment Control (without applied fertilizers) had the lowest values of both seasons compared to the C4 treatment that had the highest values of both forms in both seasons. The overall results suggest that organic food wastes combination could be advised to grow stevia plant and improving soil properties of Egypt.