Soil properties of major irrigated rice areas in the Philippines

Issue Date

7-2016

Abstract

The productivity of irrigated lowland rice (paddy) fields is controlled by soil properties. Hence, this study was conducted to assess the soil pH, organic matter (OM) and available phosphorus (P) levels, and soil texture in the major lowland areas of the Philippines. It also determined the factors that control the levels or nature of soil properties. Thirty-two lowland soils were collected from the country's characterized paddy soils. Results showed that paddy soils had slightly acid to very strongly acid pH due to the removal of basic cations during crop uptake as these soils are continuously producing high rice yields. Most Laguna, Bicol, and Mindanao soils had high OM contents (5.8%) due to high precipitation, shallow water table, and poor drainage characteristics of such soils. Most Central Luzon soils had low and medium OM contents (3.8%) due to the region's low precipitation. Soil OM contents were also controlled by the amount of clay. The Villasis (Pangasinan), Sta. Rosa City b (Laguna), Polangui (Albay) and San Miguel (Iloilo) soils had the highest amounts of available P (37 mg/kg) because they had medium acid to neutral soil pH ranges that allow P availability. Meanwhile, most Central Luzon soils had low available P levels (5.4 mg/kg) due to their strongly acidic pH that cause P precipitation. Soils on floodplains and natural levees have high silt contents, while soils on back swamps have low sand and high clay contents. The study confirms that paddy soil properties are controlled by farm practice, precipitation level and landforms, and are related with each other. Incorporation of rice biomass, especially biochar, and organic fertilizers from outside sources is recommended for paddy soils with low available P levels and strongly acidic pH and for sandy soils with limited water retention.

Source or Periodical Title

Asia Life Sciences

ISSN

0117-3375

Volume

25

Issue

1

Page

291-309

Document Type

Article

Frequency

semi-annually

Physical Description

Illustration; tables; references

Language

English

Subject

Rice; Soil chemistry; Soil composition

En – AGROVOC descriptors

IRRIGATED RICE; IRRIGATED LAND; PADDY SOIL; SOIL CHEMICOPHYSICAL PROPERTIES; ORGANIC MATTER; PHOSPHORUS; PHILIPPINES

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