M. A. Ebrahimizade, A. M. Hassanli ,
Volume 12, Issue 44 (summer 2008)
Abstract
Root depth is one of the main parameters affecting soil moisture availability held within the plant root zone. This study was conducted to evaluate the trend of corn root development during the growing season in different irrigation methods with two water qualities, and distribution of roots in soil profile. The experiment was a split plot design with three main treatments (subsurface drip(SSD), surface drip(SD) and furrow irrigation(FI)) and two sub main treatments (municipal effluent and fresh water) in two consecutive years conducted in Korbal plain, Fars province. Root monitoring was carried out with the observation of soil profile root depth measurement. Samples were taken during the growing season 16 times, each with a 7 day interval. Measurement of root weight in different soil layers was carried out using monoliths of soil washed with water pressure using 50 mesh sieves. Although the longest roots were observed in plots irrigated with SSD and the shortest in FI, the final root length was not significantly affected by irrigation methods and water qualities. In this research, a model showing the trend of root length average growth was developed and tested in the experiment conditions. The average final main root depth for all treatments was 77 cm. Irrigation volume using root depth monitoring could be reduced compared to linear model, Borg & Grimes and CROPWAT model for root depth estimation. Irrigation water on the base of soil moisture deficit within the root zone in each irrigation event could be reduced when the real root depth is considered compared with the conventional general models giving a final root depth. Results showed the total dry root weight in SSD was more than that in SD and FI methods. However, water quality did not show a significant effect on dry root weight. The most root concentration in SSD was measured in depth of 20-40 cm, while in SD and FI the most concentration was in surface layer (0-20 cm). In the SSD, the roots were distributed more evenly compared with SD and FI methods. The concentration of roots in all treatments below 65 cm was not significant.
