Ali Hassanli - Department of Natural Resources and Environment, College of Agriculture, Shiraz University, Shiraz, I. R. Iran; School of Natural and Built Environments, University of South Australia, Adelaide, SA, Astralia
Sh. Ahmadirad - Department of Natural Resources and Environment, College of Agriculture, Shiraz University, Shiraz, I. R. Iran
S. Beecham - School of Natural and Built Environments, University of South Australia, Adelaide, SA, Australia

ABSTRACT- A detailed understanding of crop rooting systems will facilitate water use reduction, optimized nutrient uptake and irrigation scheduling more efficiently. A field experiment was conducted during ۲۰۰۵-۲۰۰۶ to investigate sugar beet rooting depth growth, irrigated with three irrigation methods (subsurface drip, surface drip and furrow) and two water qualities (recycled wastewater: EC= ۱.۵۲ dS m-۱ and fresh water: EC=۰.۵۱ dS m-۱) in order to improve irrigation water management. A local rooting depth model was developed and three empirical models describing the root growth were evaluated. A significant reduction in sugar beet root depth was observed in the plots irrigated with furrows compared to those irrigated with the pressure irrigation methods. However, no significant difference (p<۰.۰۵) in root depth was observed for the crops irrigated with recycled wastewater and fresh water. A good correlation (R۲ = ۰.۹۹) between root depth and time was observed. The results also showed that using a locally developed rooting depth model to predict the soil water depletion may lead to water savings of between ۲۰% and ۳۴% when compared to the empirical models developed in other regions. The highest root yield obtained was ۸۰ tha-۱ by surface drip irrigation with recycled waste water and the lowest was ۴۱.۴ t ha-۱ by furrow irrigation with fresh water.

Keywords:, Root depth models, Root depth monitoring, Recycled wastewater, Sugar beet