EURASIAN JOURNAL OF SOIL SCIENCE

266 - 274

Authors: Idowu Ezekiel Olorunfemi, Johnson Toyin Fasinmirin, Adefemi Samuel Ojo

Cation exchange capacity (CEC) is a good indicator of soil productivity and is useful for making recommendations of phosphorus, potassium, and magnesium for soils of different textures. Soil water holding capacity (SWHC) defines the ability of a soil to hold water at a particular time of the season. This research predicted CEC and SWHC of soils using pedotransfer models developed (using Minitab 17 statistical software) from basic soil properties (Sand(S), Clay(C), soil pH, soil organic carbon (SOC)) and verify the model by comparing the relationship between measured and estimated (obtained by PTFs) CEC and SWHC in the Forest Vegetative Zone of Nigeria. For this study, a total of 105 sampling points in 35 different locations were sampled in the study areas. Three sampling points were randomly selected per location and three undisturbed samples were collected at each sampling point. The results showed success in predicting CEC and SWHC from basic soil properties. In this study, five linear regression models for predicting soil CEC and seven linear regression models for predicting SWHC from some soil physical and chemical properties were suggested. Model 5 [CEC = -13.93+2.645 pH +0.0446 C (%)+2.267 SOC (%)] was best for predicting CEC while model 12 [SWHC (%)=36.0- 0.215 S (%)+0.113 C (%)+10.36 SOC (%)] is the most acceptable model for predicting SWHC.

279 - 284

Authors: Sergey V. Makarychev, Andrey G. Bolotov

The goal of this study was to reveal the quantitative interrelations between the thermophysical indices (thermal conductivity and thermal diffusivity) and physical soil properties such as; moisture content, density and detachability. According to the research targets, the soil samples including different genesis and soil particle size distribution were taken in different soil and climatic zones of the Altai Region. These were the sod-podzolic sandy loam soils of the dry steppes, chernozems and chestnut soils of light and medium loamy particle size distribution of temperately arid zone, and the heavy loamy gray forest soils and clayey chernozems of the Altai foothills and low mountains. The samples of undisturbed structures in different soil horizons were studied. To measure the thermophysical properties in laboratory setting, a pulse method of a two-dimensional heat source was used. The method takes into account the patterns of temperature field equalization in an unbounded medium after the heat source termination. A feature of this process is the occurrence of peak temperature at the investigated point of the medium at a given instant. The knowledge of this temperature and time enables to determine the soil thermal capacity, thermal conductivity and thermal diffusivity.

294 - 298

Authors: Nutullah Özdemir, Ömrüm Tebessüm Kop-Durmuş, İrem Zorba

This study was carried out to determine the effects of rice husk compost (RC), town waste compost (TW) and tobacco waste (TB) on bicarbonate extractable phosphate content (P) in soils having different pH levels under greenhouse conditions. Soil samples used in this study were taken from surfaces (0-20 cm) of agricultural fields around Samsun, Northern Anatolia. The experiment was conducted according to split plot design with four doses of organic matterials (0, 2.5, 5.0 and 7.5, %). After a month of mixing organic matterials into soils, lettuce were grown in the medias. According to the results, RC, TW and TB applications into acidic (Tepecik), neutral (Kampüs) and alkaline (Çetinkaya) soils increased extractable P content. It was observed that effectiveness of organic matterials changed depend on soil reaction, type and dose of organic matterials. All organic wastes were more effective on increment of bicarbonate extractable phosphate content in neutral soil pH when compared the other soil pH levels.

307 - 313

Authors: Erkan Kasırğa, Mehmet Ali Demiral

In order to investigate the effect of salt stress on mineral nutrients, one year-old olive (Olea europaea L. cv. Gemlik) seedlings were exposed to increasing levels of NaCl salinity (4 dS m-1, 8 dS m-1 and 12 dS m-1, respectively) in pot culture and Na, K, Ca, Mg, N, P, Cl, Fe, Mn, Zn concentrations, ratios of K/Na and (K+Ca+Mg)/Na of the plants were ascertained. Sodium and Cl concentrations of plant parts increased with the salinity and the level in the aerial parts of the plants were lower than that of root. Salinity led to a general decrease in K concentrations in the all organs with the exception of subsoil trunk. Calcium concentrations of the plant parts decreased significantly by salinity with the exception of roots and subsoil trunk. Salinity affected Mg concentrations only in trunk and leaves. Treatments significantly decreased the ratios of K/Na and (K+Ca+Mg)/Na of all the plant organs. Compared to control application the highest salinity level (12 dS m-1) decreased the N concentrations of all the plant organs statistically except roots. Similarly salinity increased the concentrations of P in all plant parts except trunks compared to control treatment. Concentrations of all the micronutrients detected in the study were found lower in aerial parts than the roots.

322 - 331

Authors: Magboul Sulieman, Abd El-Azeem Sallam

Until now, there is no method can be used to accurately assess the particles size distribution as well as textural classes of gypsiferous soils for proper interpretation of physical behavior of these soils, and most laboratory methods involve pretreatment to remove gypsum from the samples. Therefore, the results of the particle size distribution do not reflect the size distribution of the whole soil. This study aimed to develop an alternative method to determine particle size distribution for some gypsiferous soils selected from Al-Ahsa governorate, Saudi Arabia. Five samples from different profiles with different gypsum content were selected to evaluate the modified method. Sand fractions were separated with three disaggregation methods: 1) drying sieving, 2) shaking for 5 hours in a 7:3 ethanol: water solution, and 3) sonication for 3 minutes in a 7:3 ethanol: water solution. The statistical analysis results revealed that the sonication for 3 minutes in a 7:3 ethanol: water solution was the most effective method for separating sand fractions as compared to dry sieving and shaking. Meanwhile, there was slight difference in separating sand fractions between sonication for 3 minutes and shaking for 5 hours. The particle size distribution by the developed method showed increasing in total sand content as compared to standard particle size method. Likewise, comparison of the CEC/clay ratio between the two methods also indicated that the developed method yielded clay contents more consistent with other property data for the same horizons. Consequently, the textural classes obtained from the two methods were different. Therefore; we concluded that the determination of particle size distribution for gypsiferous soils (≤ 40% gypsum) using this developed method will improve the understanding and ability to proper interpret of physical behavior of these unique soils. We highly recommended using this developed method to separate soil particles from the gypsiferous soils.