Spatial relationship between peach tree productivity and soil properties in a newly reclaimed orchard

ABSTRACT

The construction of banks and surface soil cutting involved in newly reclaiming orchards may cause spatial variability in soil properties, which could cause poor fruit tree productivity. This study examined spatial relationships between variations in peach tree properties and soil properties around each tree and assessed the possibility of site-specific field management for individual trees in a newly reclaimed orchard. Three and four years after reclamation in 2016, the 0.1-ha field located in Kyoto, Japan was divided into 32 grid cells at 5-m intervals for all individual peach trees and 128 grid cells at 2.5-m intervals for measuring soil properties around each tree (field scale). The 128 grid cells were each further divided into five positions at 0.71-m intervals for assessing selected soil properties (grid-cell scale). The soil data were geostatistically analyzed by calculating the nugget/sill ratios and anisotropy ratios (degree of variation in relation to direction) and drawing kriged maps. Coefficients of variation of soil properties at the grid-cell scale were much higher than those at the field scale. Pearson’s correlation analysis at the field scale indicated that the tree productivity was most strongly correlated with relative altitude, followed by the degree of soil reduction, time-domain reflectometry electrical conductivity (TDR-EC), subsoil pH (H₂O), and TDR-volumetric water content. Tree productivity tended to be lower at lower elevations, where the degree of soil reduction, TDR-EC, subsoil pH (H₂O), and soil water content tended to be high. Poor productivity appeared to be related to wet injury. Semivariograms of the soil properties related to soil water showed strong spatial dependence and had nugget/sill ratios of ≤24.0%. Kriged maps and anisotropy ratios further indicated that most tree property values decreased from southeast to northwest and showed variations similar to those of the soil properties related to soil water. Fine-scale mapping of soil properties in the orchard could reveal spatial soil-property variations around individual peach trees, and the result would imply the importance of soil management practices on a per-tree basis. Our findings could help to improve tree productivity in the northwestern area by increasing soil drainage for individual trees.

KEY WORDS:

• Fine-scale geostatistics
• isotropic and anisotropic semivariograms
• kriging
• scale dependence
• spatial variation

Acknowledgments

The authors are grateful to technical staff members Mr. K. Kusumi, Mr. T. Kurosawa, Ms. M. Yasuda, and Mr. T. Konishi of the experimental farm, Kyoto University, for managing the experimental field and providing data on fruit harvest and information on field reclamation. The authors thank Dr. K. Ohigashi, Institute for Agro-Environmental Sciences, National Agriculture and Food Research Organization, for technical support regarding the spatial autoregressive model.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/00380768.2022.2163837

Additional information

Funding

No funding was received from any agency for this work.