Abstract. Steeply sloping lands are widespread in the tropics. An estimated 500 million people practice subsistence agriculture in these marginal areas. Continued population growth has led to the intensified cultivation of large areas of the sloping lands, exacerbating the problem of soil erosion. Although research shows that alley cropping and other contour agroforestry systems can stabilize the sloping lands, these systems have not been widely adopted by farmers.The Framework for Evaluating Sustainable Land Management (FESLM) has been tested in sloping land areas in the Philippines. Sustainable land management must be productive, stable, viable, and acceptable to farmers, while protecting soil and water resources. Farms on which contour hedgerow intercropping has been adopted meet the multifaceted requirements of FESLM, whereas the farmers' current practice does not. Appropriate land management measures for particular locations depend on a complex suite of social, economic, and biophysical factors, and need to be developed in participation with farmers.The role of agroforestry in sustainable management of sloping lands is the subject of networks coordinated by the International Board for Soil Research and Management (IBSRAM) in seven countries in Asia (ASIALAND) and four countries in the Pacific (PACIFICLAND). We review selected outcomes from a wealth of network data. From these results the following conclusions about the sustainability of various agroforestry systems for sloping lands can be drawn:In the Pacific, soil loss from sloping lands due to water erosion under farmers' current practices is episodic, unpredictable, and possibly not severe; Agroforestry systems that utilize legume shrubs, fruit trees, coffee (Cojfea spp.) or rubber (Hevea brasiliensis) provide useful economic returns, but are not an essential component in terms of soil protection because grass or pineapple (Ananas comosus) planted on the contour are equally effective in reducing erosion; Agricultural intensification will lead to nutrient mining, reduction of aboveground biomass, declining yields, and less soil protection unless external sources of nutrients are used; nitrogen can be effectively supplied using legumes; Cash derived from hedgerow trees and/or shrubs may provide an incentive for their adoption by farmers, as well as funds to purchase external inputs such as fertilizers; Labor may be a major constraint to the adoption of complex agroforestry systems.We also discuss the information management systems required to effectively manage and utilize the extensive sets of experimental and indigenous data being accumulated. We believe such information systems can facilitate technology transfer across and between regions, and improve the efficiency of research into agroforestry and other land-management approaches. 122

Brigalow ('Acacia harpophyllaj-Dawson gum ('Eucalyptus cambageanaj open forests are predominantly supported by solodic soils in central Queensland. This report describes relations between some physical, chemical and morphological properties of surface soils (0-0.10 m) within a virgin brigalow-Dawson gum forest. Soil property gradients were found to radiate horizontally from tree-dominated to non-vegetated areas, mdicative of a vegetationinduction process. These reflect the importance of litterfall organic matter in determining soil fertility and soil physical conditions at this site.The decomposition of litterfall is probably responsible for significant increases in soil organic carbon (C), total nitrogen (N) and total sulphur (S) concentrations with increasing vegetation canopy cover. The composition of soil organic matter appears constant across the study area, as similar soil C:N:S ratios were recorded across all vegetation canopy classes. Soil salinity, total phosphorus, mineral nitrogen, cation e.xchange capacity, exchangeable calcium and e.xchangeable potassium levels also increased with increasing vegetation canopy cover.Surface soil physical properties were also related to vegetation canopy cover. Bulk density and the < 20 jim dispersion ratio decreased while soil micro-relief and A hoYizon depth increased with increasing vegetation canopy cover. Organic C, through inverse relations with bulk density and the < 20 nm dispersion ratio, appears to enhance soil porosity and aggregate stability, indicaiing the role of organic matter in ihe siabilizaiion of larger virgin soil aggregates.The close association beiween virgin forest and surface soil fertility is seen to have implications for changes in land-use, with a decline in nutrient availability, soil aggregate stability and productivity following forest clearing.

Infiltration and deep drainage fluxes are difficult to measure directly in slowly permeable soils under furrow-irrigated upland crops such as maize (Zea mays L). This paper combines a solute mass balance model and a furrow irrigation advance model to provide an estimate of these fluxes, indirectly from simpler measurements. The models were applied to a newly cleared sodic duplex soil from the Burdekin River Irrigation Area, north Queensland, where no field measures of infiltration and deep drainage were available. The study site was sown to consecutive furrow-irrigated crops after clearing. In applying these models, measures of soil and irrigation water chloride, irrigation water applied, furrow geometry and irrigation advance were required. Estimated infiltration and deep drainage decreased with distance down the furrow from 1044 and 98 mm year-1 at 50 m to 966 and 0 mm year-1 at 260 m. In an area that received an application of gypsum (20 t ha-1) prior to planting the second crop, values ranged from 1617 and 200 mm year-1 at 50 m to 1370 and 70 mm year-1 at 260 m. Infiltration did not satisfy the estimated soil water deficit unless gypsum was applied. Where gypsum was applied, infiltration exceeded the soil water deficit and deep drainage increased. Evapo-transpiration rate and maize yield also increased. If correct, these results have local and regional implications for irrigation design and management.

Morphological, chemical and physical properties of basaltic clay soils (Vertisols-Usterts and Torrerts) from the Oxford Land System in central Queensland are described and compared over their geographical range of occurrence and also their position in the landscape. These soils are derived from undifferentiated basic lavas and interbedded pyroclastics of Tertiary age. Black earths are the dominant soil group. Position on slope had the biggest influence on depth of soil, with crest and mid-upper slope positions having more shallow (<0.9 m) soils than mid-lower and footslope positions. Soils have very high CEC and clay contents throughout the profile, are mildly alkaline at the surface and strongly so at depth, are non-saline and non-sodic (except in some footslope positions), and have an exchange complex dominated by calcium and magnesium. In the surface 0.1 m, extractable P and Zn, and total N and S levels are low and crop responses to fertilizer are probable. In comparison of 26 paired sites, where areas of native pasture and cultivation occur in close proximity, cultivated soils have lower organic C and total N, P, K and S levels than native pasture soils. This reflects a general decline in soil fertility under cultivation, and has implications for soil management and long-term soil stability.

Summary. The growth of taro plants propagated either from tissue culture plantlets or conventionally using huli (sections of corm containing the shoot apex) was followed throughout a season. The plants grown from huli began suckering 11 weeks after planting and produced an average of 5 suckers per plant. During most of the season, the huli-grown plants maintained 4–5 leaves at any one time, but had a high turnover of leaves producing 25 leaves during the 30 week period (0.8 leaves per week). At harvest the corms of the suckers contributed about one-third of the total corm weight to the entire huli stand. Plants grown from tissue culture exhibited earlier suckering (starting 8 weeks after planting) and a more profuse suckering, producing an average of about 8 suckers per plant. The tissue culture plants had a similar number and turnover of leaves on the main plant as the huli plants. However, due to the early and more profuse suckering of the tissue culture plants, the suckers contributed more to the leaf area, leaf number and yield of the entire stand than the huli suckers. The tissue culture main plants had a decreased leaf area, leaf size and shorter petiole length than the huli plants. The total corm yield of the huli and tissue culture entire stand was similar. However, the main corm of the tissue culture plants was smaller as the suckers contributed over 50% to the total corm weight of the entire stand in tissue culture plants.