A decision support framework for identifying soil constraints to the agricultural productivity of tropical upland soils

Sustainable agricultural systems are based on managing soils according to their capabilities and constraints. To facilitate the identification of constraints and appropriate management strategies for upland soils, a decision support framework ‘Soil Constraints and Management Package’ (SCAMP) has been developed. Basic soil data (both field and laboratory) are entered into an Access database and are processed to output reports that identify soil constraints to productivity and that tabulate appropriate management strategies. Where spatially referenced soil data are available, maps of constraints can be readily produced in a Geographic Information System. To demonstrate the ability of SCAMP to identify soil constraints at plot scale, it was applied to soil data sets from the two major soil types (Ferralsols and Acrisols) of Gia Lai Province, Vietnam. Phosphorus (P) fixation, aluminium toxicity and low cation exchange capacity (CEC) were identified as common constraints to productivity on Ferralsols, and low plant available water capacity, compaction and low K status as common constraints to productivity on Acrisols. Field experiments were undertaken on a Ferralsol and an Acrisol to assess management strategies for minimizing these constraints in the presence of adequate N, P and K. Maize (Zea mays) yields from the Ferralsol were increased by applying a plant amendment (Tithonia diversifolia) (selected to increase soil pH and decrease P fixation) and high activity clay (selected to increase CEC). Water‐soluble P fertiliser recovery was increased in this high P‐fixing soil by placing the fertiliser in a sub‐surface band. For the Acrisol, maize was grown in mounded rows and yields were maximized by applying a super‐absorbent material (selected to increase soil water holding capacity) or a high activity clay (selected to increase the low CEC of this soil). To demonstrate the usefulness of SCAMP on a catchment/regional scale, spatially referenced soil survey data of the Herbert River catchment, Queensland, Australia, were used to produce a map identifying areas of low pH, high acidification hazard and low CEC. These applications demonstrate the usefulness of SCAMP for linking soil data to management strategies for sustainable productivity at both plot and catchment scale.