ARS | Publication request: SPATIAL VARIABILITY OF YIELD, CHLOROPHYLL CONTENT, AND SOIL PROPERTIES IN AKOREAN RICE PADDY FIELD

Submitted to: International Conference on Precision Agriculture Abstracts & Proceedings
Publication Type: Proceedings
Publication Acceptance Date: July 19, 2000
Publication Date: N/A

Interpretive Summary: Precision agriculture is a crop management strategy which seeks to address within-field variability. Already well-established in North America, Europe, and Australia, precision agriculture is now being considered in other places, including the Republic of Korea. The application of precision management principles and techniques to the diverse crops and small-scale farming systems in Korea will present new challenges. Describing within- field variability in typical Korean production settings is a fundamental first step toward the application of precision agriculture in Korea. In this study, we measured rice yield, chlorophyll content, and soil properties in a typical (approx 0.75 acre) Korean rice paddy field. Data analysis showed that there was significant variation in yield, chlorophyll content, and several soil properties, even within this small area. This finding is significant since some scientists have assumed that variability would be negligible in these small, flood-irrigated fields. Scientists working to apply precision agriculture in Korea or other Asian countries with similar cropping systems will benefit from this research since it provides them with information on the level of yield and soil variability present in typical rice production systems.

Technical Abstract: Spatial data were collected to investigate variability in rice yield, SPAD chlorophyll content, and soil properties for a 0.3 ha rice paddy field in the Republic of Korea. Descriptive statistics, semivariance analysis, and point kriging were employed to determine the magnitude and spatial range of variability in the measured parameters. The maximum rice yield was more than double the minimum yield. Several soil properties, including EC, P2O5 Ca, K, Mg, Na, and SiO2, exhibited large spatial ranges. Values of most soil properties were lower than the optimum level for rice production. Visual observation and statistical analysis indicated the presence of large-scale spatial trends over some areas of the field for several soil properties, SPAD reading, and yield. Semivariograms were fit both to the original data and to the residuals remaining after detrending with the median polishing technique. For original data, the limits of spatial dependency for rice yield and SPAD reading were 11.5 m and 6.5 m, respectively. After detrending, the limits were reduced to 7.4 m and 3.9 m. These short ranges indicate that continuous (i.e., sensor-based) measurement of these parameters is essential for proper characterization of variability. The range of spatial dependency for soil properties was variable, with several having ranges as short as 2 m and others having ranges greater than 30 m.