Effects of strip and full-width tillage on soil carbon IV oxide-carbon (CO2-C) fluxes and on bacterial and fungal populations in sunflower

Abstract

In strip tillage system, planting lines are cultivated while the inter-row spaces are left undisturbed. The objective of this study is to determine the effects of strip tillage and full-width tillage treatments on soil carbon IV oxide-carbon (CO 2 -C) fluxes, bacterial and fungal populations in growing period of sunflower ( Helianthus annus ). A row-crop rotary hoe with C type blades was used to create three strip widths by changing the connection of blades of the rotary hoe on the flanges. Strip widths were 22.5 (T30), 30.0 (T40) and 37.5 cm (T50). The full-width tillage practice (moldboard plow + disc harrow + leveler) gave 100% surface soil disturbance (T100) and was included in the experiment to make comparisons with the strip tillage system. A randomized complete block design with three replications was used. During the growth of the sunflower, periodic measurements of CO 2 -C fluxes and bacterial and fungal populations were made. Significant (p < 0.01) differences in CO 2 -C fluxes, microbial populations, soil bulk density and total porosity were observed between the different tillage systems. Highest CO 2 -C fluxes, bacteria populations and total porosity were observed in the full-width T100 application and the lowest values were observed in the T30 treatment during flowering and harvesting periods. Increasing tillage intensity increased soil CO 2 -C fluxes and bacteria population, but decreased fungi population and soil bulk density. Key words : Carbon IV oxide-carbon flux, soil bacteria and fungi, strip tillage, full-width tillage, sunflower.