Effects of boron distribution on sugar beet crop yield in two Tunisian soils

Boron is an important micronutrient required for the growth of various types of plants. Both a deficiency in boron and its toxicity may lead to marked yield reduction and quality loss of many crop species. The range between these extremes is quite narrow. Therefore, the management of boron in soil has become a worldwide agricultural problem in the recent years. Facing this situation, the present research was undertaken in order to better understand boron distribution effect on sugar beet crop yield in two soils of Dour Ismail irrigated perimeter (North Tunisia). Two pits P1 and P2 were dug in field plots that had not received any boron fertilization. We followed the dynamic of the available boron and its depth distribution according to the three sugar beet cycle stages. Soil samples were taken from different horizons of the profile and analyzed for the main physicochemical properties. Both studied soils are Stagnic Fluvisols (Clayic) and the water used for irrigation comes from Oued Medjerda River. Our results showed that the highest boron values were recorded in surface horizons of the two studied soils. These amounts decreased with depth following different patterns according to the sugar beet cycle stages. The boron vertical distribution was similar to the total organic carbon and clay contents but was greatly affected by some soil properties such as pH, carbonate calcium content, and salinity. Sugar beet yield in P2 (100 t ha(-1)) was less than that of P1 (114 t ha(-1)) indicating a problem of boron availability.