Productivity and Carbon Balance of Soybean-Corn Intercrops are affected by the Density of Corn

The area planted with soybean in Argentina has increased steadily in recent years along with the reduction of the area sown with cereals such as corn or sorghum. This affected negatively the soil quality, resulting in a negative carbon balance and decrease in organic matter content of the soil. The objective of this work was to evaluate the effect of corn density on grain yield, dry matter productivity and carbon balance of soybean - corn intercrops. The treatments were pure stand of soybean (PS), pure stand of corn (PC) and four intercrops varying in corn densities 1, 2, 4 and 8 plants*m-2 (named SCI1, SCI2, SCI4 and SCI8, respectively). The experiments were conducted during two seasons 2006/07 y 2007/08. RYT in 2006/7 was higher than one in all treatments while in 2007/8 in any treatment exceeded one. Possible causes of that are attributed to differences in the amount and distribution of rainfall between seasons. Thus, weather forecasts could be used to determine the chances of success of the soybean-corn intercropping. Soybean-corn intercrop may be a promising alternative in view of the sustainability of soil resources to have positive values of carbon balance mainly when corn density in intercrops is medium to high.