Effects of Shallow Water Tables on Height Growth and Phosphorus Uptake by Loblolly and Slash Pines

In southern Mississippi, the heights of loblolly and slash pines at age 20 were positively correlated with the phosphorus content of the foliage and with depth in the soil to gray (chromas 52) mottles. Slash pine was taller than loblolly at equivalent levels of foliage phosphorus, but the rate of height increase as foliage phosphorus increased was the same for both species. Neither species was productive when the winter water table was at the surface. Phosphorus soil tests were not useful in predicting height even though phosphorus was a growth limiting nutrient. As the available phosphorus content of the soils studied is very low, the soil depth or volume of soil available for root exploration is more important than small differences in soil phosphorus. Additional keywords: Gray mottles, phosphorus soil test, soil-site, soil water.