Effects of placing rice husk charcoal inside soil ridges for soil aeration and growth and yield of sweet potato in wet lowland

Effects of placing rice husk charcoal inside soil ridges for soil aeration and growth and yield of sweet potato in wet lowland fields
Islam, A. F. M. S.; Kitaya, Y.; Hirai, H.; Yanase, M.; Mori, G.; Kiyota, M. 1999

Journal of Root Crops 25(1): 85-97

To improve the growth of sweet potato in wet lowlands, rice husk charcoal was placed inside soil ridges as a soil aerating material. The effects of this material on the growth characteristics, yield, dry matter partitioning and physiological parameters of sweet potato and rhizosphere conditions were investigated. The rice husk charcoal was applied to ridges in the field in two ways: the material was placed in the central layer of the ridge without mixing with soil (mass treatment), or the material was thoroughly mixed with the ridge soil (mixture treatment). A conventional soil ridge without rice husk charcoal under wet lowland conditions was used as a control. Water depth between the ridges was kept at 20 mm above the furrow level throughout the growing period to imitate the wet soil conditions in tropical and subtropical lowlands. The dry weight of the total phytomass was greatest in the mass treatment. The fresh and dry weights of aboveground parts in the mass treatment were approximately 0.6 times higher than those in the control, while those of sub-ground parts in the mass treatment was 1.4 times greater than that the control. The photosynthetic rate, stomatal conductance and harvest index were greater in the mass treatment than in the control. The carbon dioxide concentrations in the soil ridges in the control were twice higher than the mass treatment. The higher photosynthetic rate, lower carbon dioxide concentrations in the rhizosphere soil and the lower soil water content would partly account for the better development of tuberous roots of sweet potato in the mass treatment.

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