Knowledge on spatial dependence characterization of plant and soil properties can help plan and optimize research studies, and be used for commercial agricultural cultivation aiming at precision agriculture. The objective of this study was to evaluate the spatial variability and dependence of several chemical soil properties and of corn yield on a sandy loam Paleudalf. The area was treated with lime and phosphorus by plowing the fertilizers into the soil along with oat residues two months prior to soil sampling. To quantify the soil properties in the field, soil samples were collected at 6 m intervals in the east-west direction and 6 m in the north-south direction. The soil pH in water, SMP index, available phosphorus, exchangeable cations (potassium, calcium, magnesium, and aluminum), organic matter percentage, and corn yield were determined. The data were analyzed with descriptive statistics and geostatistics, by fitting semivariogram models. The spatial dependence of all studied plant and soil properties was moderate to strong. The spherical model was adjusted for pH in water, SMP value, available phosphorous, and base saturation; the gaussian model described the spatial dependence of exchangeable potassium and organic matter; and the exponential model was adjusted to corn yield and to exchangeable cations (aluminum, calcium, and magnesium), H + Al. The range of spatial dependence was 4.5 m for corn yield and very close to exchangeable aluminum, aluminum saturation, and H + Al. The range for soil pH in water, SMP value, exchangeable cations (potassium, calcium, and magnesium), effective CTC, and base saturation was 20 m. Recent soil management operations probably had a part in the increased variability of soil characteristics like phosphorus and potassium.
soil fertility; experimental unit separation; spatial dependence
