PHOSPHORUS AND LIME REQUIREMENTS OF TREE CROPS IN TROPICAL ACID SOILS: A REVIEW

Abstract

YOST, R. S. & ARES, A. 2007. Phosphorus and lime requirements of tree crops in tropical acid soils: a
review. Soil P deficiency and acidity are two main limitations for trees growing on highly-weathered soils
in the tropics. Sound decisions require understanding of the growth phases in tree crops and developing
diagnosis, prediction and economic analysis to solve nutritional contrasts. Tree crops differ from annual
crops in their growth stages. The diagnostic phase can include historical information, indicator plants,
previous growth, visual symptoms, soil analysis and plant analysis, which requires proper tissue collection.
Qualitative and quantitative information can be analysed using conditional cumulative probability to
determine whether further action regarding nutrient status is needed. Predicting lime requirements for
soils to be used for growing tree crops is quite difficult because of the lack of research on the responses of
tree species to the soil acidity syndrome, which may include deficiencies of Ca, Mg and P or toxicities of Al
and Mn. Tree response is sometimes not of such economic benefit as the correction of acidity for vegetable
crops. Response curves in stands and soils are needed to establish production functions. It appears that
providing a mobile anion such as sulphate or nitrate and enough time (e.g. several months) is an effective
way to improve subsoil acidity in tropical soils.