Effect of Spatial Variability of Plant Nutrients on Fertilizer Requirement and Yield in Table Olive Growing
摘要
The aim of this study was to determine the effect of spatial variability of plant nutrients in soil and leaf on the fertilizer requirements of table olives and yield. The olive variety was ‘Gemlik’ cultivar. An orchard was divided into variable-rate and fixed-rate fertilization parts. Variable-rate fertilization was applied to 67 trees and fixed-rate fertilization to 64 trees. The number of soil samples was 27. Soil samples were taken from 0–0.3 m and 0.3–0.6 m. Spatial variability maps of plant nutrients were produced. Fertilizer requirements of each sampling grid were calculated. Each tree was harvested and yield maps were created. Clay (C), silty clay (SiC), clay loam (CL), silty clay loam (SiCL), and silty loam (SiL) soil textures were determined. Clay loam texture was dominant at both sampling depths. pH values for the soil samples at 0–0.3 m depth varied between 6.71 and 7.82 for variable-rate fertilization and 6.98 and 7.99 for fixed rate part. Nutrient requirements were determined as 38.17 kg nitrogen (N), 19.9 kg P2O5, and 92.7 kg K2O for variable-rate applications. Pure nutrient amounts of uniform rate were 48.0 kg N, 17.6 kg P2O5, and 96.0 kg K2O for 2014. Mean yield was 7.78 kg/tree for variable-rate and 6.85 kg/tree for fixed-rate fertilization. Spatial variability in the orchards affects fertilizer requirements. Conventional fertilization should be changed because excessive use of fertilizers increases cost of production and environmental effects. Variable-rate fertilization is suggested to decrease the amount of fertilizer and increase the yield. Sensors can be used to determine spatial variability and fertilizer requirements.