Spatial variation of some soil properties and their relationship to tea yield in Fouman region, Guilan

Knowledge of the spatial variability of soil properties is vital for improving productivity and sustainable management of agricultural practices, as it is directly contributing to variability in crop yields. This study was conducted to investigate the spatial variability of some soil properties and their relationships with spatial variability of tea yield in the Fouman region of Guilan province. Soil samples were collected from 0 to 40 cm depth in 70 observation points. The green tea leaves were harvested at a 4 m2 plot at each site. Physicochemical soil properties and tea yield were determined according to standard methods. In order to address the cumulative impact of soil properties on tea yield, some soil physicochemical layers were subjected to delineate the study area into management zones. Soil parameters varied throughout the study area and their coefficients of variation ranged from 5.1% to 37.2% for pH and available potassium, respectively. Experimental semivariograms indicated moderate to strong spatial dependencies for all selected parameters. Spatial distribution maps, derived by kriging interpolation, showed that the spatial trend of the yield was approximately similar to pH, organic carbon and available potassium, which expresses the spatial correlation of these soil properties with the tea yield in the region. Correlation analysis revealed that tea yield was significantly positively correlated with organic carbon and available potassium (0.53 and 0.37, respectively) while negatively correlated with pH (-0.45). The results suggested the significant effect of soil properties, especially pH, organic carbon and available potassium on the tea productivity. The results indicated that the study area was successfully delineated into four distinct management zones based on spatial variability of soil properties. The spatial variations of soil properties can be used to identify the major sources of variability in crop yields and also to delineate the management zones. Therefore, the spatial variability of soil properties provides a basis of information for sustainable production in the tea gardens in the study area.