Nutrient contents and associated parameters for cocoa tree leaves, ripe cocoa pods and soil from 63 cocoa farms in Papua New Guinea in 2007

Brief description

Nutrient status of cocoa grown in Papua New Guinea.

Full description

Summary from associated report: Cocoa is grown by approximately 151,000 households in Papua New Guinea (PNG). Smallholders, who produce 80% of the crop, have annual yields far below the potential of 4.4 tonnes/hectare. Yields are low for many socioeconomic and agronomic reasons. The aim of this study was to determine the nutrient status of cocoa grown in PNG, and to recommend further steps to determine if there are nutrient-related constraints on productivity and how they might be overcome. Leaf and soil nutrient contents were measured and grower practices were recorded at 63 cocoa blocks (smallholders, on plantations or on research stations) across the country. A wide variety of plant species were present in blocks, with Gliricidia being the most common shade tree. Based on published ‘critical’ levels for cocoa leaf nutrient contents, nitrogen and iron deficiencies occurred in more than 89% of the blocks and phosphorus deficiencies in about 25%. Leaf magnesium concentrations were mostly adequate, except in East New Britain, where 64% of the blocks were deficient. Deficiencies of potassium, calcium, manganese, boron, copper and zinc were encountered in 2–15% of the blocks. However, the ‘critical’ levels must be regarded with caution, as the micronutrient (manganese, boron, copper, iron and zinc) values were based on surveys rather than manipulative experiments, and the macronutrient (nitrogen, phosphorus, potassium, magnesium and calcium) values were established in different places with different planting materials. Leaf potassium and phosphorus contents were related to soil type and nutrient contents. In blocks that are being well maintained and regularly harvested, it is likely that yield is being constrained by nutrient deficiencies. Management of cocoa blocks in PNG must improve dramatically for the cocoa industry to prosper, and perhaps even to survive, particularly with the recent spread of cocoa pod borer, which is drastically reducing cocoa yields. To improve management and yields, the industry requires reliable critical levels of leaf nutrient concentrations, and nutrient management recommendations appropriate to different regions, based on trials. Effective means of facilitating adoption of improved practices must also be developed.

Notes

This dataset is discussed in the publication: Nelson PN, Webb MJ, Berthelsen S, Curry G, Yinil D and Fidelis C. 2011. Nutritional status of cocoa in Papua New Guinea. ACIAR Technical Report No. 76. The Australian Centre for International Agricultural Research, Canberra. 67 pp.

This dataset is available as a spreadsheet in MS Excel (.xlsx) and Open Document formats (.ods)