Micronutrient, phosphorus and pH influences on growth and leaf tissue nutrient levels of Prosopis alba and Prosopis glandulosa

Abstract

Nitrogen fixing trees of the genus Prosopis occur on many semiarid lands of the world, where they show potential for food and fuel production. Semiarid soils tend to be alkaline and low in organic matter, N, P and micronutrients. For both native woodlands and plantations, it is important to understand the response of Prosopis to changing fertility regimes and to develop quantitative relationships between leaf tissue mineral nutrient concentrations and productivity. The growth of two contrasting Prosopis species was compared on an inert artificial soil mixture with four lime [Ca(OH) 2] treatments to vary soil pH from 6 to 9 in the greenhouse. At each lime level a factorial design, with and without phosphorus and micronutrient additions, was used. Dry biomass was related to leaf tissue levels of N, P, K, Ca, Na, Mg, Mn, Fe, Zn, Cu and soil pH. Phosphorus was the element most limiting growth. Micronutrient additions produced little change in biomass at the lower lime levels, but at the high lime levels they increased biomass in the P amended plants. At high pH (8.9), zinc appears to play a role in decreasing toxic Na levels. It was the micronutrient most correlated with enhanced biomass production. A significant negative correlation between phosphorus and zinc tissue concentrations occurred and it appears that phosphorus can reduce zinc uptake by Prosopis.