Utilization Of Salt-Affected Soils By Growing Some Acacia Species

Abstract

In Pakistan most of the salt affected areas are located in the heart of its agriculturally important tract of the Indus plain. Growing conventional crops in these problem lands is not economical but these could be utilized gainfully by growing salt tolerant trees or shrubs. However, there is a need to identify suitable species for such conditions. The present study was, therefore, undertaken to evaluate the performance of some local and exotic trees, belonging to Acacia species, in salt affected soils of Pakistan. Five species of Acacia, i.e., Acacia ampliceps, A. stenophylla, A. machonochieana, A.sclerosperma, and A.nilotica were grown along with an Australian halophytic shrub Atriplex lentiformis in a field where salinity ranged from 4-25 dS m -1 . After three years of growth, A. ampliceps and A. nilotica showed markedly higher growth as compared with the other species examined. Although A. ampliceps grew well under saline environment, its maximum growth was observed under -1 (12--1 medium to high salinity levels (8-16 dS m -1 ), while Acacia sclerosperma and A. machanochieana were only populated on low salinity patches (4-8 dS m -1 ). Analysis of plant leaves, for nutrient contents, showed that the concentrations of Na + and K + ions in the Acacia species were comparatively less than those in Atriplex lentiformis. However, Acacia nilotica had comparatively higher nitrogen and phosphorus than the other Acacia species examined. On the other hand, the concentrations of Na + and K + were higher in Atriplex lentformis while the concentrations of Ca 2+ were higher in Acacia sclerosperma as compared to the other Acacia species and Atriplex. At the end of the experiment, complete soil analysis was carried out which showed that the soils on which Acacia species were grown, N, P, and K contents increased to some extent.

Phytoremediation of Saline Soils for Sustainable Agricultural Productivity

“…In contrast to these findings, Shekhawat et al (2006) did not find any appreciable change in SAR with the cultivation of Salsola baryosma, Haloxylon recurvum and Suaeda nudiflora. However, studies with different species of Acacia and Atriplex also indicated that soil SAR decreased with cultivation of these species and effect of Acacia nilotica was more pronounced than others (Ashraf et al 2006a). Similarly, results of the experiments conducted with Sporobolus arabicus, Leptochloa fusca, Suaeda fruticosa, Atriplex lentiformis and Kochia indica also confirmed that cultivation of salt tolerant plants is effective in reducing the soil SAR (Ashraf 2007).…”

“…According to Akhter et al (2004) addition of OM (8.2 g kg −1 of soil) after the cultivation of Kallar grass for 5 years, it reduced with the soil depth. Another study with Acacia species indicated that their cultivation on salt-affected soils increased the soil OM (Ashraf et al 2006a). Similarly, Aganga et al (2003) found an increase in soil OM with cultivation of Atriplex on salt-affected soils.…”

“…After 2 years of planting, a significant decrease in soil EC has been recorded which is maximum under Acacia nilotica plantation. Salinity of the soil fluctuated up to 36 months of planting but was lowest under Acacia nilotica (Ashraf et al 2006a). Shekhawat et al (2006) reported that the cultivation of Haloxylon recurvum reduced soil EC by 56 to 85% which varied with the depth of soil.…”

“…Usually, soil pH is different at different depths of soil profile which generally increases with increase in soil depth. Another study conducted with different species of Acacia and Atriplex indicated that soil pH did not change with the passage of time, which was alkaline at the outset of the trial, and was similar after three years of continuous cultivation (Ashraf et al 2006a). However, reduction in soil pH was noted by Helalia et al (1992) due to plantation with Echinochloa stagninum on saline soil.…”

“…Observations from the field studies have revealed beneficial effects of root growth in saline soils during phytoremediation. Ashraf et al (2006a) found that deep-rooted Acacia species ameliorate a low-permeability hard saline sodic soil which results in an increase in saturated hydraulic conductivity. Acacia roots penetrated as deep as 2 m as compared to 1.1 m in Atriplex.…”