Potential of rice straw quality index (SQI) in assessing crop residue material quality

Abstract

Two laboratory experiments were conducted to study the decomposition rate of straw from different rice cultivars. A correlation matrix of the initial composition of straw samples and the cumulative C release was examined to establish the relationships between residue quality parameters and decomposition rates. To describe the decomposition rate of rice (Oryza sativa L.) straw, the following equation, called Straw Quality Index (SQI), was formulated: SQI= - 56.85 + (11.68 × %N) + (1.25 × %DOM) + (2.59 × %lignin). The equation uses important descriptors of plant residue quality such as nitrogen (N), digestible organic matter (DOM), and lignin concentration. Estimates of the straw quality parameters showed a direct correlation (r2=0.84) between SQI and the cumulative carbon released from straw of 20 different rice cultivars. When the measured carbon from another batch of straw was correlated with SQI, a strong positive correlation (r2=0.94) was obtained. The results suggest that SQI is a practical tool in assessing the quality of the straw residue materials to predict their usefulness in crop-residue management systems.

Source or Periodical Title

Philippine Agricultural Scientist

ISSN

317454

Page

211-220

Document Type

Article

Subject

Decomposition, Organic material, Organic matter, Oryza sativa, Rice straw

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