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    IMPLICATION OF GROUNDWATER FLUCTUATION ON THE SEASONAL SALT DYNAMIC IN THE HARRAN PLAIN, SOUTH-EASTERN TURKEY
    (Wiley, 2010) Cullu, M. A.; Aydemir, S.; Qadir, M.; Almaca, A.; Ozturkmen, A. R.; Bilgic, A.; Agca, N.
    Inefficient farm-level water management aggravates groundwater fluctuation and salt accumulation particularly in and and semi-arid irrigated agriculture Inappropriate water management practices in the Harran Plain are a good example. A study was carried out to investigate the effect of groundwater fluctuation on the seasonal salt dynamic in four widespread soil series in the Harran Plain with different natural drainage, south-eastern Turkey Four profiles were excavated and soil samples were collected seasonally up to 100 cm depth with 10 cm intervals Similarly. irrigation and groundwater samples were collected from the fields where soil sampling was carried out Significant seasonal variations in the salt dynamic were observed with the fluctuation levels of the groundwater. Total salt content at I m soil depth remained constant during the year, however salt fluctuation throughout the root zone in the growing season exceeded the threshold values of corn, wheat and cotton, commonly grown crops in the region. of 1.7, 6.0 and 7.7 dS m(-1) respectively. However. soils with less water fluctuation showed lower salt accumulation in the root zone from May to October. Results also confirmed that soils can be non-saline, but groundwater salinity which may not be point specific, requires special attention. Copyright (C) 2009 John Wiley & Sons, Ltd
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    Influence of different nitrogen sources and leaching practices on soil chemical properties under tomato vegetation in a greenhouse
    (2008) Bozkurt, Sefer; Agca, N.; Odemis, B.
    A greenhouse study was carried out to determine the effects of different nitrogen sources and leaching practices on soil chemical properties. Tomato (Lycopersicon esculentum) was used as a test plant. All plots were fertilized equally for nitrogen, phosphor and potassium whereas nitrogen was applied at five different NH4+N/NO3-N ratios (N1 = 100/0; N2 = 75/25; N3 = 50/50; N 4 = 25/75; N5 = 0/100). No nitrogen applied plots (N 0) were also added to experiment. The changes and their relationships of soil soluble ions (Ca2+, Mg2+, Na+, K +, CO32-, HCO3-, Cl -, SO42-), EC and pH were determined in soil samples taken from three soil layers (0-5, 5-15 and 15-45 cm) at the beginning and the end of the study. Soil samples were also taken before and after the soil leaching to determine the effects of leaching on the parameters mentioned above. Soil pH had different correlations with N treatments among soil layers and showed rising trends with soil depths which had statistically significant differences at p<0.05 level in all treatments. Soil leaching caused statistically significant differences on soil pH at p<0.05 level. There were increases in EC values in all N treatments over the study period. However, soil leaching decreased soil EC values in all plots. All cations were affected by all treatments and their interactions. The study showed that the chemical properties of soil especially soil pH was affected by the forms of N fertilizers. © 2008 Asian Network for Scientific Information.
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    Yield responses of cauliflower (Brassica oleracea L. var. Botrytis) to different water and nitrogen levels in a Mediterranean coastal area
    (Taylor & Francis As, 2011) Bozkurt, S.; Uygur, V.; Agca, N.; Yalcin, M.
    Global warming along with the increasing population and fresh water shortages necessitates a specific fertilization programme under water-scarce conditions. This study was conducted to investigate the effects of different irrigation and nitrogen levels on yield, growth components and water use characteristics of cauliflower (Brassica oleracea L. var. Botrytis cv. Tetris-F-1) cultivated in a field for three consecutive years from 2005 to 2007 in the Eastern Mediterranean region of Turkey. Four irrigation (Kcp) levels with a drip irrigation system based on adjustment coefficients (0, 0.75, 1.0 and 1.25) of pan evaporation were used. Nitrogen (N) treatments were consisted of four different nitrogen rates (0, 75, 150 and 225 kg N ha(-1)). The following yield and quality parameters were determined: curd weight, curd diameters, number of leaves per crop, above ground biomass (AGB) and curd/AGB ratio. Fertilizer use efficiency (FUE) and leaf mineral contents were also determined to clarify the productivity of N treatments. According to the results; the amount of irrigation water and/or total received water affects the plant water consumption, consequently, crop yield in a field grown cauliflower. The highest yield was obtained in Kcp(1.0) irrigation level which represents full irrigation treatment. The excess water applications had negative effect on yield and AGB of cauliflower. Highest yield was obtained at 225 kg N ha(-1). The water use efficiency and irrigation water use efficiency values increased with decreasing irrigation rate. However, lower Kcp coefficients resulted in lower total yield. The FUE in irrigation treatments showed linear increases from non irrigation to full irrigation plots. However, excessive irrigation caused a decrease in FUE. It can be recommended that the Kcp1.0 crop-pan coefficient with 225 kg ha(-1) nitrogen application can be used to achieve the highest yield for field grown cauliflower in the Eastern Mediterranean coastal region of Turkey.