Local rock phosphate deposits are a good source of phosphorus fertilizer for rice production in Cambodia

• Published in: Soil science and plant nutrition (Tokyo) Vol. 45; no. 1; pp. 51 - 63
• Main Authors: White, P.F. (International Rice Research Inst., Los Banos, Laguna (Philippines)), Nesbitt, H.J, Ros, C, Seng, V, Lor, B
• Format: Journal Article
• Language: English
• Published: Tokyo Taylor & Francis Group 01-03-1999; Japanese Society of Soil Science and Plant Nutrition
• Subjects: ABONOS FOSFATADOS; Agronomy. Soil science and plant productions; Biological and medical sciences; CAMBODGE; CAMBODIA; CAMBOYA; ENGRAIS PHOSPHATE; FOSFATO MINERAL; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Nitrogen, phosphorus, potassium fertilizations; ORYZA SATIVA; P fixation; P residual capacity; P uptake; PHOSPHATE FERTILIZERS; PHOSPHATE NATUREL; Phosphorus fertilization; ROCK PHOSPHATE; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Cambodia; Asia; Monocotyledones; Treatment efficiency; Superphosphate; Phosphorus fertilization; Cereal crop; Oryza sativa; Gramineae; Phosphate rock; Angiospermae; Spermatophyta; Application method; Economic aspect; Yield component
• ISSN: 0038-0768; 1747-0765
• DOI: 10.1080/00380768.1999.10409323

Phosphate is needed to increase yields over most of Cambodia's rice area. Imported P fertilizers are expensive and difficult to obtain for many Cambodian farmers. Local rock phosphate (PR) is potentially a viable alternative to the imported P fertilizers. Field and greenhouse experiments were conducted to compare the use of triple superphosphate (TSP) and several products developed from the local phosphate as fertilizers for rice production. The experiments were conducted over several seasons and soil types. In the field experiment, P application increased grain yields from 0 to 2.5 t ha(-1) in the first season, 1.0 to2.5 t ha(-1) in the second season and 0.5 to 1.0 t ha(-1) in the third season. In all the seasons the effect of P on grain yield was the same regardless of the type of P fertilizer applied. In the first season, however, plants receiving TSP had more than 10% higher P concentrations in their shoots than plants receiving PR. Conversely, in the final season, plants receiving TSP tended to have a lower P concentration in the straw than plants receiving PR. In the greenhouse, P fertilizer. increased shoot growth from 5 to 15 g pot(-1) on a sandy soil and from 2 to 30g pot(-1) on a clayey soil. Growth of plants receiving PR on all the soils, however, was as good as or better than that of the plants receiving TSP. The relationship between shoot growth and shoot P concentration was the same across all soil types when TSP and PR were applied but varied with the soil type when the PR product was applied. New fertilizer products developed from local rock phosphate deposits appear to be effective for rice production in Cambodia. With this technology, given the widespread P deficiency in most of the soils and the low cost of the PR product there is a potential to dramatically improve the efficiency of rice farming in Cambodia