Feride Candemir

Effects of Different Agricultural Wastes on Some Soil Quality Indexes in Clay and Loamy Sand Fields

Effects of manure (M), hazelnut husks (HH), tea waste (TEW), and tobacco wastes (TOW) on some soil quality indexes were monitored for more than 2 years in a clay field and a loamy sand field. While soil organic carbon (OC) contents were around 2% after 30 months in clay, they were generally less than 2% after 7 months in loamy sand. Organic wastes generally increased aggregate stability (AS) and field capacity and decreased bulk density (BD) of the soils. Soil pH decreased with TEW and increased with M treatment. Tobacco wastes exerted the greatest effect on AS, EC, and nitrate (NO3) nitrogen (N). Hazelnut husks and TEW had the greatest effect on soil respiration in clay and loamy sand soils, respectively. While BD and pH increased, the other indicators generally decreased between the first and the last sampling. Soil quality can be improved in coarse-textured soils using TEW and HH and in fine-textured soils using TEW and M.

Accumulation of Tobacco mosaic virus (TMV) at different depths clay and loamy sand textural soils due to tobacco waste application

The effects of tobacco waste (TW) application to the soil surface on the accumulation of Tobacco mosaic virus (TMV) in clay and loamy sand textural soils at various depths were investigated in two different fields. The tobacco waste had been found to be infected with TMV. Eighteen months after TW application to the soil surface, soils were sampled at 20xa0cm intervals through to 80xa0cm depth. The DAS-ELISA method was performed to determine infection of soil with TMV. The viruses persisted in clay soil for a long period compared with loamy sand soil. There was no accumulation of TMV at any depth of loamy sand soil in Experimental Field 2. TMV adsorption to soil particles in 0–60xa0cm depth of clay soil was determined in all TW treatments in Experimental Field 1. The highest ELISA Absorbance (A405) values in all treatments were determined in the 20–40xa0cm soil depth that had the highest clay content. ELISA A405 values of TMV at different depths of clay soil gave significant correlations with clay content (ru2009=u20090.793**), EC values (ru2009=u20090.421**) and soil pH (ru2009=u2009−0.405**). Adsorption of TMV to net negatively charged clay particle surfaces increased with increasing EC values of soil solution. Decreasing soil pH and infiltration rate increased adsorption of TMV to clay particles. Higher infiltration rate and lower clay content in loamy sand soil caused leaching of TMV from the soil profile.

Influencing Factors and Prediction of Hydraulic Conductivity in Fine-Textured Alkaline Soils

Hydraulic conductivity is an essential parameter in hydrological cycle studies. Determination of saturated hydraulic conductivity (Ks) in fine-textured, especially alkaline, soils is a difficult process and takes time. In this study, the effects of some soil properties on Ks in fine-textured alkaline soils were determined, and Ks values were predicted using pedotransfer (PTF) models. Ks, which varied between 0.011 and 0.625 cm h−1 in 64 different soil samples, significantly decreased with increasing exchangeable Na percentage (ESP), sodium absorption ratio(SAR), exchangeable Na (exch. Na), and clay content of soils. The correlation coefficients were divided into a series of direct and indirect effects of the soil properties on Ks by path coefficients. The direct effects of selected properties on Ks were in the following order; exch. Na (42.6%) > ESP (37.0%) > clay (21.3%) > CEC (16.8%) > SAR (9.7%) > pH (8.4%) > silt (6.4%) > electrical conductivity (EC) (0.8%). The highest indirect effect on Ks was obtained with EC (43.0%) mediated by exch. Na. Accuracy and reliability of PTFs were assessed with the average of root mean square error (RMSE) and R2 values in the training and testing data sets, respectively. Using clay and silt fractions together with EC, exch. Na, ESP, or SAR in the second order equations significantly increased the accuracy and reliability of PTFs. Exchangeable Na was one of the most important soil properties that affected Ks directly in these soils. Using soil chemical properties in PTFs with soil physical properties showed that saturated Ks values can be predicted more accurately in fine-textured alkaline soils.

Effects of agricultural wastes on the hydraulic properties of a loamy sand cropland in Turkey

Abstract This study was carried out to determine the proper amount of application for manure (M), hazelnut husk (Corylus avellane L.) (HH), tobacco (Nicotiana tabacum L.) (TO) and tea (Camellia Sinensis (L.)) (TE) wastes based on hydraulic property improvement of a loamy sand cropland in Turkey. The effects of agricultural wastes on field capacity (FC), permanent wilting point (PWP), available water content (AWC), relative saturation (RS) and initial infiltration rate (IR) were determined for a loamy sand soil 7 months after agricultural wastes were incorporated to 15 cm soil depth at four different rates (0, 2%, 4% and 6%, weight:weight) in a randomized plot design experiment with three replicates. While increases in soil OM content for the M application rates were generally lower, TE and HH treatments including high organic carbon (OC) contents resulted in high soil organic matter (OM) increases. Organic wastes generally increased the values of soil hydraulic properties, with increased aggregate stability (AS) and total porosity (F) and reduced bulk density (BD). The highest AS and F values were obtained with 6% HH and 6% TE applications, respectively. Due to different mineralization rates of the organic wastes attributable to their carbon: nitrogen (C:N) ratios, the same application rate had different effects on the soil’s hydraulic properties. Manure, having the lowest C:N ratio, generally had a lower effect on AS and BD. Increased IR due to increases in AS and F by the agricultural waste treatment, especially at 4 and 6% HH, reduced the AW content to 15 cm compared with 2% HH. This indicates that the significant application of higher C:N ratio wastes is not suitable in terms of AW, due to significant improvement of IR. While the highest FC (17.3%) and AWC (10.7%) values were found in the 6% TE application, the highest PWP (7.2%) and IR (333.4 cm h−1) were in the 6% TO and 6% HH applications, respectively. To improve soil physical and hydraulic properties, 6% TO and M, 4% TE and 2% HH applications are suggested for loamy sand cropland.