Phosphorus nutrition of rice in relation to flooding and temporary loss of soil-water saturation in two lowland soils of Cambodia

• Published in: Plant and soil Vol. 207; no. 2; pp. 121 - 132
• Main Authors: Seng, Vang, Bell, R. W., Willett, I. R., Nesbitt, H.J.
• Format: Journal Article
• Language: English
• Published: Dordrecht Kluwer Academic Publishers 01-12-1999; Springer; Springer Nature B.V
• Subjects: Acid soils; Agricultural and forest climatology and meteorology. Irrigation. Drainage; Agricultural and forest meteorology; Agrology; Agronomy. Soil science and plant productions; Availability; Biological and medical sciences; Clay; Clay soils; Crop growth; Fertilizers; Field capacity; Flooded soils; Floods; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Lowlands; Moisture content; Phosphorus; Plants; Reduction; Rice; Rice soils; Rice straw; Sand soils; Sandy soils; Saturation; Soil chemistry; Soil erosion; Soil organic matter; Soil pH; Soil water; Soils; Straw; Water balance and requirements. Evapotranspiration; Water regimes; Water stress; Cambodia; Asia; Water; Monocotyledones; Nutrition; Growth; Alfisols; Phosphorus; Bioavailability; Flooding; Cereal crop; Oryza sativa; Absorption; Soil water properties; Gramineae; Limiting factor; Angiospermae; pH; Nutrient; Spermatophyta; Lowland
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1023/a:1026452029146

In the rainfed lowlands, temporary loss of soil-water saturation during crop growth is a common factor limiting rice (Oryza sativa L.) yield but its effects on phosphorus (P) availability are poorly understood. Rice plants were transplanted into pots containing soils that were either continuously flooded, maintained at field capacity or flooded and then dried to field capacity for 3 weeks during the vegetative stage. A black clay soil (Kandic Plinthaquult) and a sandy soil (Plinthustalf) from south-east Cambodia were compared with or without amendments by rice straw and P fertilizer. Under continuously flooded conditions, the growth of rice was vigorous without straw addition and there was a strong response of rice growth to the addition of P fertilizer. The soil underwent reduction, which increased pH from 4.2 to 5.5 or 6.0, in the black clay or sandy soil, respectively. By contrast, a loss of soil-water saturation 3 weeks before panicle initiation (PI) markedly impaired the growth of rice. This was not through any effect of water stress, and the growth reductions were not as strong as with continued loss of soil-water saturation from transplanting to PI. Fluctuations in soil pH and Eh corresponded closely to changes in soil-water regimes. Growth reductions were attributed to reduced shoot P levels resulting from the decline in P availability during the loss of soil-water saturation. The addition of rice straw stimulated soil reduction and lessened changes in soil pH and Eh during the loss of soil-water saturation in both soils. Straw addition enhanced P uptake by the rice plants during loss of soil-water saturation, but its beneficial effects could not be attributed to the direct addition of P, N or K to the soils. Thus the application of rice straw may be effective in lessening the effects of temporary loss of soil-water saturation on rice growth in lowland rice soils by minimising the decline in P availability.