Effects of different organomineral and chemical fertilizer application rates on the nutritional status of tomato plants grown under greenhouse conditions and soil properties

The aim of this study was to investigate the effects of different organomineral and chemical fertilizer application rates on the nutritional status and soil properties of tomato plants grown under greenhouse conditions. For this purpose, two separate experiments were established. In the first experiment, the chemical fertilizer dose was kept constant and organomineral fertilizer applications were made at increasing rates (1. Control, 2. 100% KG, 3. 100% KG + 50 kg/da OMG, 4. 100% KG + 100 kg/da OMG and 5. 100% KG + 150 kg/da OMG). In the 2nd trial, the OMG fertilizer dose recommended to the producer (100 kg/da) was kept constant and KG applications were carried out at decreasing rates (1. Control, 2. 100 kg/da OMG+100% KG, 3.100 kg/da OMG+75% KG, 4.100 kg/da OMG+50% KG and 5. 100 kg/da OMG+25% KG). The recommended 100% dose of chemical fertilizer application for tomato plants was based on 40 kg/da N, 20 kg/da P2O5 and 80 kg/da K2O. OMG was implemented in both periods. The experiments were carried out in two periods, autumn and spring, in a randomized plot design with 3 replications in a gravel layout, and Özkan tomato variety was used in both seasons. Before establishing the trial plots for the study, soil samples were taken from the depths of 0-20 and 20-40 cm from the greenhouse where the trial would be conducted. At the end of each period, soil sampling was carried out to represent the plots, and leaf and fruit sampling was carried out in the middle of each period. In the study, plant nutrient element analyses (total N, P, K, Ca, Mg, Fe, Mn and Zn) and morphological characteristics (plant height, stem diameter, fruit diameter, number of bunches, etc.) as well as physical and chemical analyses (pH, EC, organic matter, total N, available P, exchangeable K, Ca and Mg) were carried out in the soils and the differences between the applications were compared statistically. In the first trial, it was determined that the 2nd application (100% KG) was generally effective on plant height, stem thickness, fresh and dry weight of stems and total N, Fe and Zn contents of leaf samples; and the 5th application (100% KG+150 kg OMG) was effective on fruit weights per plant, and the highest results were obtained. While it was determined that the fresh and dry weights of the plants, the amounts of TSS, and the P, Ca and Mg contents of the leaf samples were higher in the spring period, all other investigated plant parameters were found to be higher in the autumn period. When the soil sample analysis results are examined, it is seen that the 5th application comes to the fore in general. It was determined that the EC, exchangeable K and Ca contents of the soil samples were high in the autumn period; while the pH, total N and available P contents of the soils were high in the spring period. In the second trial, it was determined that plant height, stem thickness and fruit weight were generally higher in the 3rd (100 kg/da OMG+%75 KG) and 4th (100 kg/da OMG+%50 KG) treatments. It was determined that all applications caused an increase in the fresh and dry weights of the stems, diameters of the fruits, number of bunches on the plants and Mg contents, and the lowest values were obtained in the control application. It was determined that the N, P and K contents of the leaf samples gave the highest results in the second application (100 kg/da OMG+100% KG) and that decreasing chemical fertilizer applications with organomineral fertilizer caused a decrease. The second application gave the lowest result in terms of Ca contents of leaf samples. While the control application gave the highest results in Fe and Mn contents of the leaf samples, the 5th application (100 kg/da OMG+25% KG) gave the highest results in Zn contents. It was determined that the effect of the periods gave similar results to the 1st Experiment. When the soil sample analysis results were examined, it was determined that the second application (100 kg/da OMG + 100% KG) was generally effective on EC, total N, available P and exchangeable K contents. While it was determined that the organic matter content of the soils was low in the control application and increased with the applications, the opposite was true for the pH of the soils, with the highest values obtained in the control application and the applications made caused the pH to decrease. It was determined that EC, organic matter and exchangeable Ca contents of soil samples were high in the autumn period, while pH, total N and available P contents were high in the spring period. According to the results of the T-test and Mann-Whitney U test, which were conducted to determine whether there were differences between the two trials, it was determined that the differences in fruit diameters, total N, P and Mg contents of the plants and exchangeable K contents of the soils were statistically significant; there was no difference between the 1st and 2nd trials in terms of all other investigated parameters and the results obtained were similar to each other. As a result, when both trials were compared, it was determined that there was no application that stood out in terms of the characteristics investigated in the study and that there was difference in terms of cultivation when the periods (spring and autumn) were compared in the trials. Therefore, it was concluded that new studies are needed to clearly demonstrate the effects of organomineral fertilizer use, especially on greenhouse cultivation.