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Development and Testing of an Improved Soil‐Root Sampling Technique for Rice in Flooded Puddled Soil 1
Author(s) -
Thangaraj M.,
O'Toole J. C.
Publication year - 1986
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1986.00021962007800050040x
Subject(s) - agronomy , soil water , soil test , paddy field , environmental science , sampling (signal processing) , oryza sativa , soil science , monolith , chemistry , biology , biochemistry , filter (signal processing) , computer science , gene , computer vision , catalysis
Undisturbed, intact root and soil samples have rarely been acquired from rice ( Oryza sativa L.) grown in flooded, puddled lowland soils. Common sampling techniques used in aerobic dry soil conditions are useless under the flooded conditions of a rice field. This note presents an improved volumetric soil‐root sampling method and associated root isolation techniques for accurately measuring root length and root weight of rice in flooded soils. The metal field sampler was used to extract a soil monolith 0.2 by 0.2 by 0.5 m deep. The sampler and soil monolith were then frozen for 12 to 14 h. In a frozen state, the previously unmanageable flooded soil sample could be moved to a sample holder that facilitated cutting the monolith into sections 0.2 m by 0.2 m by 50 mm. The individual sections were treated to remove soil and organic matter from the roots. Root samples were then available for root length measurement or any other analytical procedure. Analysis of root lengths at 50‐mm vertical increments at three different growth stages of the rice crop illustrated the reliability of the sampler and analysis techniques. Coefficients of variation (CV) were less than 10% for samples between 0 and 0.25‐m depths. Below this level to 0.4 m, CV's were about 15%. We conclude that the soil‐root sampler and associated analytical techniques provide a means of overcoming the inherent problems of soil and root sampling in flooded rice fields.