Soil biological and physiochemical factors limiting the growth potential of tomato planted in waterlogged volcanic soil

Abstract

Many vegetable growers in Japan practice a unique waterlogged cultivation method with ample nitrogen (N) supply and microbial supplements, reporting vigorous plant growth, no soilborne diseases, and high yields. We simulated waterlogged soil conditions in greenhouse experiments to examine effects of soil pH and redox potential (Eh) as well as microbial influence on the growth of tomato seedlings. Soil pasteurization enhanced seedling growth whether the acidic, volcanic soil was waterlogged or well-drained. Among various antimicrobials, only soil treatment with polymyxin B improved shoot growth in nonpasteurized soil. The seedlings grew best in pasteurized acidic, waterlogged soil fertilized with ample potassium nitrate (KNO₃), which maintained soil Eh above zero. In nonpasteurized soil, growth was severely stunted by raising soil pH progressively to 8.5 while Eh dropped to –194 mV. The results suggested that heat-sensitive Gram-negative soil bacteria and low soil Eh were key factors limiting the growth potential of tomato plants in waterlogged soils.

Keywords:

• heat-sensitive deleterious soil bacteria
• mineral nitrogen
• redox potential
• soil pH
• waterlogged soil

Acknowledgments

The authors thank R. Kadi, President of Aika Co., Ltd., and H. Teduka, President of T&T nursery, for supporting this research, and Jennifer S. Becker for critical review of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.