Determinants of total and available phosphorus in forested Alfisols and Ultisols of the Ozark Highlands, USA
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Geoderma Regional. 5: 117-126.
Phosphorus is an important nutrient limiting forest growth in many parts of world, and soil P forms and concentrations may be associated with a host of soil and environmental attributes in a complex soil landscape. The objective of this study was to identify key environmental and soil properties influencing total and available soil P concentrations in a mixed oak (Quercus L.)-hickory (Carya Nutt.) forest ecosystem. Soil samples and soil characterization data were obtained from fifty pedons sampled at the Missouri Ozark Forest Ecosystem Project (MOFEP) located in south-central Missouri, USA. Additional soil chemical analyses were conducted to measure total P, available P (Mehlich-3 P and Bray-1 P), and citrate bicarbonate dithionite (CBD) extractable Fe, Al, and Mn content. Classification and regression tree (CART) analysis was applied to explain relationships between P concentrations and environmental and soil properties. Total P concentration in the soils studied ranged from 15.6 to 410 mg kg-1 and the range of available P concentration was 0.29 to 30.6 mg kg-1. The CART analysis identified variables, primarily soil attributes, explaining 48, 71, and 65% of the variability associated with total P, Mehlich-3 P, and Bray-1 P concentrations, respectively. Extractable Mn was the most important explanatory variable in all CART models (explaining 28-33% of soil P variation). The CART analysis provided a concise framework for coupling soil and environmental variables to understand and identify locations within a complex soil landscape that may be susceptible for nutrient depletion. Furthermore, findings of this research highlight a need to more thoroughly evaluate relationships between Mn and P forms and concentrations in soil.
KeywordsAlfisols Available phosphorus Classification and regression tree analysis Forest soils Soil nutrients Total phosphorus Ultisols
Singh, Gurbir; Goyne, Keith W.; Kabrick, John M. 2015. Determinants of total and available phosphorus in forested Alfisols and Ultisols of the Ozark Highlands, USA. Geoderma Regional. 5: 117-126. https://doi.org/10.1016/j.geodrs.2015.05.001.