Spatial variability of soil physical properties in a cultivated field such as; bulk density (BD), penetration resistance (PNT), saturated hydraulic conductivity (Ks), field capacity (FC) and permanent wilting point (PWP), were determined by geostatistical method. While BD values varied between 1.12 and 1.41 gcm -3 , PNT resistance (0.66 to 1.88 MPa), clay content (31.48 to 43.97%), Ks (1.46 to 3.37 mm h -1 ), FC (30.40 to 39.66%) and PWP (19.22 to 24.42%) values showed variations with soil cultivation. In kriging interpolation for the spatial variability of soil properties, the biggest r 2 and cross validation r 2 values were determined with spherical model for PNT, Ks, FC values, and exponential model for clay, BD and PWP. Spatial dependences of the properties, except BD, were found to be strong in the field. Ks values significantly increased with increasing BD (0.340*), and decreasing clay content (-0.905**) and PNT (-0.288*) values in the field. Spatial variations of soil physical properties in the field are generally controlled by the particle size distribution as a fundamental factor. Heterogeneity and variation of soil physical parameters in a field due to soil plowing should be taken into consideration for a successful agricultural management.

Effects of farmyard manure treatments on some soil structural parameters such as, aggregate stability (AS), geometric mean weight (GMWD) and mean weight (MWD) diameters, fragmentation (D) and mass (Dm) fractal dimensions, bulk density (BD) and organic C (OC) contents of aggregates were determined in a clay soil. Application of 67 Mg ha-1 farmyard manure to Vertic Haplustoll soil decreased AS 12.14% compared with the control. Manure treatment increased the proportion of microaggregates in the fractions <1.00 mm in size and decreased the proportion of macroaggregates in the fractions >1.00 mm in size. While OC contents of aggregates increased between 22.8% and 123.4%, BD values decreased between 0.8% and 16.6% with the manure treatment. Fragmentation (D) and mass (Dm) fractal dimensions were increased with decreasing numbers of macroaggregates of the clay soil. GMWD (1.16 mm) and MWD (1.86 mm) obtained in the manure treatment were lower than that in the control treatment (1.20 mm and 1.95 mm, respectively). Although OC content of the aggregates increased with the manure treatment, the number of macroaggregates of clay soil decreased with decreasing AS.

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 15cm 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 15cm 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 (333.4cmh(-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.

Saturated hydraulic conductivity (Ks) is an important variable in hydrological cycle processes. Determination of Ks in soils is a difficult and time consuming process. The objective of this study was to determine Ks in soils by pedotransfer (PTF) models derived using soil moisture constants and physical properties. Ks values were determined in 30 different soil samples using constant head permeability method. According to path analyses results, direct effects of some soil properties on Ks in soils were in the following order; permanent wilting point (PWP) > bulk density (BD) > clay (C) > silt (Si) > field capacity (FC). Soil physical properties generally had the highest indirect effects on Ks through PWP. Prediction of Ks by the second order PTF models was significant using only C, Si and DB (r=0.868**) and using only FC and PWP (r=0.796**) in the models. Using moisture constants with the other soil physical properties in the second order PTF model increased significance level of the relation between predicted and measured values of Ks (r=0.955**). Besides soil physical properties, having moisture constants in PTF models showed that saturated Ks values can be predicted more accurately in soils having similar physical boundary conditions such as texture, bulk density etc.

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 manure (M), hazelnut husk (HH), tobacco (TW) and tea (TEW) wastes on penetration resistance (PR) values in a clay field were determined after 8 months of organic wastes were incorporated into soil at four different rates (0, 2, 4 and 6 %) in a randomized plot design with three replicates. While bulk density (BD), relative saturation (RS) and PR values decreased, mean weight diameter (MWD), total porosity (F), gravimetric water (W) and organic matter (OM) contents of the clay soil increased with increasing the application rates of organic wastes. While the lowest PR (0.72 MPa) was determined in the highest application rate of HH which had the highest C:N ratio, the highest PR (1.72 MPa) was in the control. According to the control treatment, decreases in mean values of PR by the organic waste applications were in the following order; HH (52.10%) > TEW (42.07%) > TOW (30.73%) > M (25.17 %). PR values gave significant negative correlations with F (-0.551**), W (-0.439**) and MWD (-0.509**), and significant positive correlations with BD (0.550**) and RS (0.374*). Total porosity showed the highest direct effect (62.39%) on PR. The higher indirect effects of the other properties on PR were also obtained via F. Applications of the same doses of different organic wastes had different effects on the PR values with changing the structure of clay soil due to their C:N ratios.

The levels of Tobacco mosaic virus (TMV) in a clay soil were monitored for more than two years after tobacco waste (TOW) application. It was incorporated to 15 cm soil depth at four different rates (0, 33, 67 and 100 ton ha(-1)) in three replicates. Surface soil samples were collected 8, 16, 23 and 30 months after TOW application. The DAS-ELISA method was used to determine the level of TMV in the soil. ELISA absorbance values of TMV were influenced by soil physical properties, plant growth and climatic conditions. The ELISA values were significantly correlated with relative saturation (0.596**), total porosity (-0.502**), organic carbon content (-0.475**) and soil pH (-0.349*). According to path analysis, soil pH showed the highest direct effect (59.7%) on the ELISA values. The highest indirect effects of soil pH and relative saturation on ELISA values were mediated by total soil porosity. Increasing total soil porosity, infiltration rate and mean monthly precipitation decreased the concentration of TMV in the clay soil. Growing lettuce and beans or the presence of host plants in the field increased TMV concentration.

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.

Arazilerin mevcut potansiyellerinde degerlendirilmesi tarimsal uretim ve dogal kaynaklarinin surdurulebilirliginde temel esastir. Bu nedenle oncelikle mevcut toprak kaynaklarinin tespiti yapilmalidir. Yesilirmak ve Kizilirmak Deltalari Turkiye’nin onemli tarim merkezlerindendir. Ancak ozellikle erozyon ve topraklarin amac disi kullanimi bu onemli tarim merkezlerinin surdurulebilirligini tehdit etmektedir. Bu calismada, Samsun Ilindeki toplam 957.900 ha arazi varliginin, % 51.92’ sinin siddetli erozyona maruz kaldigi, potansiyel tarim topraklarinin amac disi ve yanlis kullaniminin ise % 18 oldugu belirlenmis ve toprak sorunlarinin cozum olanaklari irdelenmistir

Saturated hydraulic conductivity (Ks) is an important variable in all models that deal with the hydrological cycle. Determination of Ks in soils is a difficult and time consuming process. The objective of this study was to determine saturated hydraulic conductivity in soils by pedotransfer (PTF) models derived using some moisture constants and soil physical properties. Saturated hydraulic conductivity values were determined in 30 different soil samples using constant head permeability method. According to path analyses results, direct effects of some soil properties on Ks in soils were in the following order; permanent wilting point (PWP) > bulk density (BD) > clay (C) > silt (Si) > field capacity (FC). Soil physical properties generally had the highest indirect effects on Ks through PWP. Saturated hydraulic conductivity predicted by the second order PTF models was highly significant using only C, Si and DB (r=0.868**) and using only moisture constants, FC and PWP (r=0.796**) in the models. Using moisture constants with the other soil physical properties in the second order PTF model increased significance level of the relation between predicted and measured values of Ks (r=0.955**). Besides soil physical properties, having moisture constants in PTF models showed that saturated Ks values can be predicted more accurately in soils.

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 20 cm intervals through to 80 cm 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 0-60 cm 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 20-40 cm 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 (r = 0.793**), EC values (r = 0.421**) and soil pH (r = -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.

Hazelnut husk was applied at the rates of O-(control), 2, 4 and 6 % to a sandy clay loam soil in order to investigate effect of hazelnut husk on some chemical and physical soil properties during its mineralization period for 16 weeks. Experiment was conducted at 4 different incubation periods (1, 4, 8 and 16 weeks) under the same laboratory conditions. Hazelnut husk treatments increased organic carbon content. electrical conductivity, aggregate stability, volumetric water content, total porosity and lowered bulk density of the soil over the control treatment. During the 16 weeks incubation period, organic carbon content for hazelnut husk treatments decreased while the electrical conductivity values of the soil increased. Organic carbon content gave a significant negative relationship (-0.984**) with electrical conductivity value. Mean bulk density of the soil significantly decreased from 1.25 g cm(-3) for control to 1.05 g cm(-3) for 6 % hazelnut husk treatment. Increases in the mean porosity and the mean volumetric water content for 6 % hazelnut husk rate over the control were 14.3 and 26.2 %, respectively. The highest aggregate stability was determined with 6 % of hazelnut husk application rate in the eight week. Aggregation in soils slowed down after eight weeks and disaggregation occurred for all application rates in the last incubation period due to possibility of more substrate demands of bacteria and bacterial attack on products which bind soil particles together.

Bu calismada Ondokuz Mayis Universitesi Kurupelit Kampus alaninda yer alan toprak serilerinin Atterberg limitleri, hacimsel buzulme, dogrusal buzulme, dogrusal uzama katsayilari (COLE) ve kivam indeksleri (Ic) gibi mekaniksel ozellikleri belirlenmis, bu ozellikler dikkate alinarak topraklarin islenebilirlikleri degerlendirilmistir. En yuksek likit limit (LL, %88.67) ve plastik limit (PL, %42.28) degerleri Oyumca serisinde, en dusuk LL (%57.55) ve PL (%30.11) degerleri ise Aksu serisi topraklarinda belirlenmistir. LL ve plastiklik indeksi (PI) degerlerine gore butun topraklar fazla plastik inorganik killer grubunda siniflandirilmistir. Incesu ve Kurupelit serilerindeki topraklar smektit grubu kil mineralince daha zengin olmalari nedeniyle diger serilerdeki topraklara gore daha yuksek buzulme limiti ve hacimsel buzulme degerleri gostermislerdir. COLE degerlerine gore Incesu, Oyumca ve Kurupelit Serilerindeki topraklar cok yuksek, Muzmullu ve Aksu Serilerindeki topraklar ise yuksek sisme-buzulme potansiyeline sahiptirler. Topraklarin PI degerleri %27.44 ile %47.22 arasinda degismis ve Aksu < Kurupelit < Muzmullu < Oyumca < Incesu siralamasiyla artmistir. Genis PI degerlerine sahip Incesu ve Oyumca serilerindeki topraklar cok islakken islendiklerinde balciklasma tehlikesi daha fazladir. OMU Kurupelit kampusunde yer alan toprak serilerinde en uygun toprak isleme icin maksimum nem icerigi, kivam indeksinin yaklasik 1.0’e esit olmasini saglayan tarla kapasitesindeki nem degerleri veya PL’in %90’indaki nem degerleri olarak belirlenmistir.

In this study, effects of rice husk (RH) application on mechanical properties and cultivation of a clay textured soil were investigated with and without barley planting. A rate of 5% (w/w) rice husk as a dry weight basis was added to a clay textured soil by alone (RH) and with 5 kg N/da of ammonium sulphate (RHN) in order to increase the biological activity and the decomposition rate of rice husk in soil. Rice husk applied soils including control treatment were incubated at field capacity under greenhouse conditions for 2 months. After this period, barley was sown in a half number of the pots. All pots having barley planted and without planted were incubated together for 6 more months. Study was carried out in a factorial experimental design on barley planting and without planting pots in 3 treatments (control, RH and RHN) with 3 replications. At the end of the study, liquid limit (LL), plastic limit (PL), plasticity index (PI), consistency index (Ic), field capacity (FC), permanently wilting point (PWP) and organic matter (OM) contents of soils were determined. The highest values were determined for LL in RH+nitrogen+barley planting (RHNP), for PL in RH application without planting and for PI in control application with barley planting (CP). Barley planting increased LL and PI values of soil significantly. LL values of soils significantly correlated with PL (0.664**), PI (0.880**) and PWP (0.948**). PL values of soils significantly correlated with OM (0.699**) and PWP (0.821**). PI values of soils significantly correlated with FC (0.654**) and PWP (0.713**). Ic values gave the significant correlations with PL (0.908**), OM (0.787**), FC (-0.611**) and PWP (0.615**). Ic values in all RH treatments were higher than that in control treatments. It was concluded that clay textured soil in control treatment can have deformation when it is cultivated at the field capacity without RH application; however clay soils can be cultivated without deformation after application of RH.