Alkali soils have undesirable properties for crop production. However, these problematic areas can be reclaimed and regained for cultivation. Mulch materials have been used in the past to decrease salinity damage in saline soils. But information about using mulch materials for alkali soil reclamation is rare. The aim of this study was to determine the combined effects of different levels of gypsum applied with straw or pumice mulch materials on the reclamation of an alkali soil. Results obtained from soil extracts during the leaching water cycles showed that gypsum and mulch materials caused significant differences in sodium adsorption ratio (SAR) and electrical conductivity (EC) values. Major reclamation parameters of soil samples were also determined after the addition of 140 cm of leaching water. The exchangeable sodium percentage (ESP) significantly decreased from 18.43 in the initial soil to as low as 2.31 in 0-15 cm soil depth samples and 10.53 at 15-30 cm (P < 0.05). The various treatments were related to significant decreases in SAR, EC, and lime content in reclaimed soils. The amount of water stable aggregates (WSA) increased significantly after reclamation. Although hydraulic conductivity values also increased, the increase was not statistically significant. The fastest water flow rate was observed in the 100% gypsum requirement (GR) and straw mulch treatment. In contrast, the slowest water flow rate was found in the 50% GR and unmulched treatment, and the differences in means were significant. Overall, the 100% GR and straw mulch treatment was most effective in decreasing soil alkalinity, improving soil structure, and reducing reclamation time.

No abstract

No abstract

A greenhouse experiment was conducted to investigate the response of tomato plants (Lycopersicon lycopersicum L.) to salinity and to determine the interactive effects of salinity and nitrogen fertilisation on yield, nitrogen uptake, water use efficiency (WUE), and root-zone salinity during early plant growth. Furthermore, the effects of salinity and N fertilisation were evaluated by measurement of carbon isotope discrimination (Δ). Tomato plants were grown in pots filled with 8 kg (dry weight equivalent) of Krumbach sandy loam. Salinity treatments were imposed by irrigation water containing Na, Ca, and Mg salts and having electrical conductivity of 0, 3, 6, 9, and 12 dS/m at 25�C. 15N-labelled urea (10 atom % excess) was also applied at 0, 80, 160, and 240 mg N/kg soil. Increasing salinity reduced plant growth; fresh and dry weights of shoots and roots decreased significantly, except for the non-fertilised plants. The maximum growth reduction in shoots occurred due to salinity–N fertilisation relationships at 12 dS/m (59.4% reduction compared with 0 dS/m in 160 mg N/kg). Root growth was less affected than shoots. Vegetative growth and N content increased with increasing nitrogen treatment. However, salinity generally reduced N uptake by plants. Δ was negatively correlated with WUE at all salinity levels in young tomato plants. Similar correlations were also obtained between WUE and Δ at various N treatments; the result suggests that Δ is a useful tool for assessing stress conditions. Smaller Δ values were obtained when salinity or N level increased. Increasing N fertiliser increased WUE in plants, whereas increasing salinity increased WUE at 3 dS/m and decreased WUE to some extent at other salinity levels. Electrical conductivity of the root-zone increased due to increasing salinity and time, whereas pH decreased. It was concluded that the early stage of development was a salt sensitive period for tomato plants.

The objective of this research was to investigate the morphology, genesis and classification of organic soils formed on depression and flat land around Lake Yenicaga, west-central Turkey. Formation of the area has been influenced by tectonic and karst processes. This peatland is important in this area due to its extensive use as a horticultural plant growth medium resulting from positive physical and chemical properties. Organic soils in the study area were formed in nutrient-rich conditions and it is classified as typical basin peat. Four representative pedons were excavated in the study area based on extensive observations performed with random grid method using an auger. Samples were taken from horizons in each profile for laboratory analyses. Organic matter contents ranged from 12.5 to 91.5% across all four pedons. Fiber contents were between 4.3 and 91.5%, and N ranged from 0.56 to 2.19%. Cation exchange capacity ranged from 37 to 222 cmol kg -1 , bulk density from 0.09 to 0.78 g cm -3 , lime from 0.15 to 2.62%. The pH and EC e values ranged from 5.38 to 7.92 and 0.50 to 3.80 dS m -1 , respectively. Sand, silt and clay contents of the organic soils ranged between 0. 75-3.92, 40.70-74.77 and 24.15-57.30%, respectively. Differences in organic soils were found to depend on the environment, botanical origins, decomposition degrees, and groundwater composition. The organic soils of the research area were classified in the typic, hemic and hydric subgroups of Medifibrists (Soil Taxonomy 1999).