Image grey value analysis for estimating the effect of microorganism inoculants on straws decomposition

- A method was used to identify straw decomposition based on image grey values.
- Image grey values were most significantly dependent on the content of residual ash.
- The microorganism inoculants could accelerate straw decomposition.
- The microorganism inoculants could increase the final degree of mineralization.

The colour of straw changing from lighter to darker after being incorporated into soil is one of the most important reflections of the degree of straw decomposition. To quickly and accurately identify the decomposition degree of wheat straw, a high-throughput quantitative image analysis method was developed based on the colour of the straw degraded in soil over a different number of days. The correlation between these values and the contents of the chemical components in the straw was also investigated. The results indicated that the grey value representing the colour of the straw had a significant negative correlation with the content of residual ash in the straw (R2 = 0.696). The method was used to study the microorganism inoculants involved in straw decomposition. The results showed that there was a significant difference between the straw with and without microorganism inoculants in terms of the grey value after 30 days. The final colour of the straw with microorganism inoculants was much deeper than that of straw without inoculants. This suggests that the microorganism inoculants not only could accelerate the decomposition speed of the wheat straw incorporated into the soil but could also affect its final degree of mineralization.