Differentiating Biological Roles of Some Organic Amendments on Some Parameters for Sandy and Clay Soils Cultivated with Lettuce (Lactuca sativa L.) and Final Yield

Lettuce (Lactuca sativa L.) was planted in pot tests during 2020–2021 and 2021–2022 years in a randomized complete block design (RCBD) including nine treatments using soils sampled collected from Ismailia and Giza for cultivation. Treatments included usage of potassium humate (KH), vinasse (Vin), and olive mill waste (OMW) as replacements for the recommended mineral fertilizers. Effects of these alternatives on chemical, biological and physical characteristics for both lettuce and soil were studied at harvest. The combination of mineral fertilizer (NPK) with either OMW, Vin or KH in equal quantities (50%) produced the highest yields. As for Giza soil, compared with 100% NPK, the yield increased by 1.7, 1.6 and 1.6 folds using 50% NPK combined with either 50% OMW, Vin or KH, respectively. On the other hand, Ismailia soil either 50% Vin or 50% OMW with 50% NPK achieved yield of 1.8 and 1.65 folds that of 100 % NPK. Addition of 50% OMW or Vin recorded the best mean values of all tested, all parameters and improved plants growth and increased the total yield of curds besides enhancing yield and its components compared to the other treatments or the control and at the same time saved and reduced mineral fertilizer recommendation of Lettuce.