M. Najafi-Ghiri, H. R. Owliaie,
Volume 18, Issue 69 (fall 2014)
Abstract
Although addition of amendment materials to soil is not for changing of soil K status, secondary effects of these materials can be important in K distribution among soluble, exchangeable and non-exchangeable forms. In this research, effect of addition of 2% zeolite, 2% vermicompost and 1% zeolite+ 1% vermicompost on 10 calcareous soils of Fars province belonging to five orders was investigated. The experiments were done as a randomized complete block with three replicates. Samples were incubated at 22±2 °C and 50% of saturated moisture content for 90 days. Then different forms of K were determined in the samples. Zeolite application induced 279 mg kg-1 increase in exchangeable K and 24 mg kg-1 decrease in non-exchangeable K, but it had not a significant effect on soluble K. Although vermicompost application increased soluble and exchangeable K, its effect was more sensible for soluble K (139 mg kg-1). Zeolite+vermicompost application increased all forms of K. Increase in soluble K with vermicompost application may increase risk of K leaching but zeolite application can preserve K in exchangeable phase and inhibit K leaching and fixation.
M. Najafi-Ghiri, A. R. Mahmoodi, S. Askari,
Volume 19, Issue 72 (summer 2015)
Abstract
Potassium (K) is an important cation in saline soils of arid lands, and its content, distribution and availability may be affected by native plants. To study the effect of halophyte species on different K forms in Korsia region located in western Darab (Fars province), three dominant halophyte species including Juncus gerardi, Halocnemum strobilaceum, and Salsola rigida were selected. Sampling was done from soils in canopy and between plants at the depth of 0-15 (surface) and 15-30 cm (subsurface) in triplicate. Soil physical and chemical properties including soil texture, organic matter, calcium carbonate, pH, cation exchange capacity, saturation percentage and electrical conductivity and different K forms including soluble, exchangeable and non-exchangeable were determined. Results indicated that organic matter, CEC, pH, and EC were affected by plant species. Juncus gerardi increased exchangeable K and decreased soluble K, but it had no effect on non-exchangeable and HNO3-extractable K. Halocnemum strobilaceum significantly increased soluble, exchangeable and HNO3-extractable K in surface and subsurface soils rather than soils between plants. This finding may be due to K uptake by plants from subsoils and also transfer of soluble K from soils between plants to roots. Salsola rigida had no effect on K status. Generally, soils between plants had more soluble and exchangeable K in surface than subsurface horizon. The studied halophyte species showed differences in growth and development pattern, soluble salts and K absorption and secretion, grazing by livestock, returned organic matter to soil, soluble salts and K reserves in their organs, and water uptake and thereby water and K diffusion from soil far from rhizosphere to roots, which may have different effects on K distribution in soils. Juncus gerardi, as regards effects on decreasing salinity and soluble K and increasing exchangeable K, may be recommended as a suitable species for remediation of the studied soils.
M. Najafi-Ghiri,
Volume 20, Issue 77 (Fall 2016)
Abstract
The status of soil K forms and its relationship with K content in wheat grain at harvest period may be important for nutrient fertility management. For this purpose, 40 surface (0-20 cm) and subsurface (20-40 cm) soil samples and also grain samples from wheat fields of Darab region were randomly sampled in 2014. Then physicochemical properties of the soils and the contents of soluble, exchangeable and non-exchangeable K and contents of K in wheat grains were determined. Results indicated that content of soluble, exchangeable and non-exchangeable K in the studied soils ranged 15-70, 91-443 and 396-1182 mg kg-1, respectively. Significant relationships were obtained between soil K forms and clay, calcium carbonate and CEC. Although it is expected that content of easily available K (soluble and exchangeable K) was low at late stage of wheat growth, most soils had sufficient K content. The positive and significant relationship among different K forms was indicative of the K forms equilibration at the time of wheat harvesting. Although there is not a relationship between K content in wheat grain and soil K forms, it was shown that K content of wheat grain was correlated with soil exchangeable K and clay content in fine-textured soils (clay > 30%). It means that ammonium acetate may be a suitable extractant for estimation of soil K status and plant available K of heavy-textured soils in the studied region.
M. Najafi-Ghiri, Y. Kiassi, F. Khademi, A. R. Mahmoodi, H. R. Boostani, Dr M. Mokarram, M. J. Gholami,
Volume 22, Issue 3 (Fall 2018)
Abstract
Little information is available regarding the effect of road on the adjacent vegetation and soil. The current investigation was done to study the effect of Darab-Bandar Abbas road on vegetation, soil properties and nutrient availability of the adjacent soils. For this purpose, eighteen soil samples in three different regions from the roadside and the adjacent land (50m from the road edge) were collected and the vegetation type and density were determined. Soil properties and the availability of N, P, K, Fe, Mn, Zn and Cu were also determined. Roadside soil had more organic matter and sand contents and less clay content and pH in comparison to the adjacent lands. The mean contents of N, Fe, Zn and Cu available in the roadside soils were 0.13%, 4.2, 3.2 and 0.7 mg kg-1, respectively; these were significantly more than those of the adjacent lands (0.06%, 2.8, 0.6 and 0.3 mg kg-1, respectively). Vegetation of roadside was more varied, consisting of Artemisia sieberi and Astragalus fasciculifolius. Vegetation cover in the roadside (13.8%) was significantly more than that of the adjacent lands (8.5%). Generally, it could be concluded that roadside soils had a suitable moisture condition and fertility for the vegetation development and this could be considered in the soil conservation management of the roadside soils.
M. Najafi-Ghiri, H.r. Boostani, A. R. Mahmoodi, F. Dehghanpoor, M. Besh,
Volume 23, Issue 4 (winter 2020)
Abstract
Astragalus fasciculifolius is one of the most distributed plant species in the arid and semiarid regions of southern Iran. It may be well grown on roadside. This investigation was carried out to study the effect of road and its traffic intensity on the soil physicochemical properties and plant nutrients availability of roadside and to monitor the concentration of nutrients in the aerial parts of Astragalus fasciculifolius. Thirty soil and plant samples from roadside and 100 m distance from road were randomly collected and some physicochemical soil properties and nutrients availability were determined. Concentrations of the nutrients in the aerial parts of the plants were also determined. The results indicated that roadside soils had more sand and calcium carbonate equivalent than the adjacent lands. Soils of the main roadside had less K and more Fe, Mn, Zn and Cu than the adjacent lands; this difference in local road was observed only for Fe and Cu. Nutrients concentration in the aerial parts of the plants was affected by road, and P, K, Mn and Zn showed significant increases in the roadside plants. Concentrations of P, Fe, Zn and Cu in plants grown in main roadside and concentrations of Fe and Zn in plants grown in the local roadside were correlated with their contents in the soils. The effect of roads on soil properties change and nutrients availability may be related to the addition of road bed and emission of vehicles. Generally, it could be concluded that roadside soils had more suitable water and nutrition conditions for the growth of Astragalus fasciculifolius, as compared to the soils of the adjacent lands.
