Predicting Slash Pine Response to Nitrogen and Phosphorus Fertilization

Abstract

Abstract The Cooperative Research in Forest Fertilization (CRIFF) soil groups based on soil drainage class and depth to and nature of the B horizon, were as good as or better than Soil Conservation Service soil series or Coile soil units at predicting slash pine ( Pinus elliottii var. elliottii Engelm.) response to N and P fertilization. Some CRIFF soil groups demonstrate much greater uniformity of response than others. Within these soil groups, soil properties and foliar analyses were used to better predict fertilizer response. The properties valuable for predicting response varied from soil group to soil group, but those most consistently valuable were measures of available soil water, extractable soil P, the amount of silt plus clay in the surface soil, and foliar N and P. A model with from two to four significant variables was developed for each CRIFF soil group. The coefficients of determination (R 2 ) for these models ranged from 0.52 to 0.99.