World's First Soil Fertility Index Based on Microbial Health Developed

A research group led by Professor Motoki Kubo at the College of Life Sciences, Ritsumeikan University, announced on December 10, 2012, that they developed the world's first soil fertility index (SOFIX(R)) based on the assessment of soil biological characteristics.

Generally, there are three quantitative diagnoses for soil health. Chemical assessment takes into consideration such properties as nutrients and pH buffering effect, while physical properties include water retaining capacity and air permeability. The third, biological properties such as microbial organic degradation and resistance to diseases and pests, has been technically difficult to assess. As a result, organic farming, which excludes the use of chemical fertilizer, has depended solely on experience for the preparation of suitable soil, making it difficult to ensure a stable yield.

SOFIX is based on a new method for measuring the amount of microorganisms in the soil and the degradation and circulation of nitrogen and phosphate caused by microbial activity. The method can provide a scientist's "prescription" for soil preparation using organic fertilizer, thus contributing to an improvement in organic farming productivity.

The method was tested from December 2011 to July 2012 by growing tomatoes in chemically fertilized soil and soil with SOFIX-prescribed cow manure as fertilizer. Both soils produced about the same yield, but the sugar content of tomatoes grown in the organically fertilized soil came out higher. By popularizing the SOFIX-based soil assessment and developing more optimal organic fertilizers, the research group hopes to reduce the cost of organic farming to 30% less than that of chemical farming.

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