Foliar Analysis for Predicting Quantitative Fertilizer Response: The Importance of Stand and Site Variables to the Interpretation

Abstract

Traditionally, nutrient deficiencies are diagnosed using nutrient concentrations in either plant tissue or soil. In forestry, foliar testing has generally proved superior to soil testing for identifying nutrient deficient areas (Ballard 1980). Considerable success has been achieved using foliar phosphorus (P) concentration as an index of response to P fertilization (Ballard and Pritchett 1975; Wells et al. 1973). However, total nitrogen (N) concentration in foliage has not proved particularly useful as an indicator of response to N fertilization (Mead and Gadgil 1978; Turner et al. 1977; Rosvall 1979). Some improvement in prediction of N status of forest stands has been reported using techniques such as N gradients over different age classes of tissue (Florence and Chuong 1974), N fractions in foliage (van den Driessche and Webber 1975), N-S interrelationships in foliage (Turner et al. 1977), and analysis of other biomass components such as litter (Miller and Miller 1976). While some of these techniques have been related to quantitative responses to N fertilization, none have been successfully related to quantitative responses over a range of site and stand conditions.