Coşkun Gülser

This study investigated the spatial variability of DTPA-extractable Fe, Mn, Zn, and Cu in a cultivated field, their relationships with selected soil properties, and the optimum number of samples required to estimate mean micronutrient concentrations precisely. Forty-nine soil samples were collected at 5-m intervals from a square grid within a 30 × 30 m cultivated plot. Mean DTPA-extractable concentrations were 71.80 mg kg⁻¹ for Fe, 350.26 mg kg⁻¹ for Mn, 2.58 mg kg⁻¹ for Zn, and 4.11 mg kg⁻¹ for Cu. The coefficients of variation were higher for Fe (20.6%) and Zn (19.2%) than for Mn (11.8%) and Cu (8.4%). Spatial variability was best described by spherical models for Fe and Mn and exponential models for Zn and Cu. The spatial correlation ranges followed the order Zn (67 m) > Cu (17 m) > Fe (15 m) > Mn (8 m). Nugget-to-sill ratios indicated strong spatial dependence for Fe (0.039%), Mn (8.03%), and Cu (11.32%) and moderate spatial dependence for Zn (42.86%). In principal component analysis, Fe, Cu, and soil organic matter (OM) had high negative loadings on PC1, whereas Zn contributed most strongly to PC2. Fe was positively correlated with soil OM and negatively correlated with Mn, Zn, pH, Ca, and Na. Mn was positively correlated with Zn and Cu, whereas Zn was positively correlated with silt and pH. Cu was negatively correlated with pH, Ca, Mg, and K. The numbers of samples required to estimate mean concentrations within allowable errors of 5%, 10%, and 20% followed the order Fe (69, 17, and 4) > Zn (59, 15, and 4) > Mn (23, 6, and 2) > Cu (11, 3, and 1), respectively. Thus, greater spatial variability in a micronutrient requires a larger sample size to estimate its field mean precisely.

Bu çalışmanın amacı, artan su stresi koşulları altında farklı piroliz sıcaklıklarında (350°C ve 550°C) üretilen çeltik kavuzu biyokömürünün marul (Lactuca sativa L.) bitkisinin verimi ve fizyolojik parametreleri ile toprak özellikleri üzerindeki etkilerinin araştırılmasıdır. Sera koşullarında, tesadüf parsellerinde faktöriyel deneme desenine göre kurulan çalışmada; üç farklı sulama rejimi (%50, %75 ve %100), iki farklı biyokömür tipi (B350 ve B550) ve üç farklı biyokömür dozu (%0, %1 ve %2) test edilmiştir. Elde edilen bulgular, artan sulama suyu seviyelerinin ve biyokömür dozlarının marulun taze ve kuru biyokütle verimi ile su kullanım randımanını istatistiksel olarak ileri düzeyde (p<0.01) artırdığını göstermektedir. Biyokömürün üretim sıcaklığının verim parametreleri üzerinde istatistiksel açıdan anlamlı bir ana etkisi bulunmamasına rağmen, %2 oranındaki biyokömür uygulaması kontrol grubuna kıyasla taze verimde %24, kuru verimde ise %30'luk bir artış sağlamıştır. Toprak özellikeri açısından değerlendirildiğinde, %2'lik biyokömür dozu toprağın değişebilir potasyum ve alınabilir fosfor konsantrasyonlarını sırasıyla %24 ve %18 oranında artırmıştır. Sonuç olarak bu çalışmada, çeltik kavuzu biyokömürünün üretim sıcaklığından bağımsız olarak %2 oranında toprağa uygulanmasının, kuraklık baskısı altındaki tarımsal sistemlerde su kullanım randımanını optimize etmek, bitki verimini korumak ve toprak verimliliğini sürdürülebilir bir şekilde artırmak için etkili, ekonomik ve çevre dostu bir strateji olduğu vurgulanmıştır.

Based on precipitation data from six weather stations covering the period 1960–2024, this study presents a retrospective analysis of drought dynamics in the Rostov Region, Russia, and evaluates the potential of the SARIMA model for forecasting moisture regime fluctuations. The Standardized Precipitation Index (SPI) was employed as the primary drought indicator. Two key phases of crop development were analyzed: the vegetation initiation period (March–May), assessed using the three-month SPI of May (SPI-3), and the full active growing season (April–September), assessed using the six-month SPI of September (SPI-6). The Mann-Kendall test revealed a non-significant positive trend in SPI-3 across all stations, while SPI-6 trends were non-significant and varied in direction. The highest frequency of drought events, based on both SPI-3 and SPI-6, occurred during 1960–1969, with a general decline in subsequent decades. The lowest drought frequency was observed during 2010–2019. Notably, the frequency of extreme droughts has shown an increasing trend, posing significant risks to agricultural productivity. Although SARIMA modeling proved useful for short-term forecasting, its application was limited by unrealistic long-term projections and deviations from climatic norms. Consequently, drought forecasts were restricted to a two-year horizon. Nonetheless, the SARIMA approach remains a valuable supplementary tool for anticipating precipitation dynamics and drought events.

Hazelnut is a nut species that is strategically important to Türkiye. Hazelnut cultivation has various cost factors, with the highest share belonging to the harvesting. Following harvesting, sucker management, and fertilization are the most significant cost factors. Due to high labor requirements and costs, sucker removal, which is recommended to be performed twice a year, is often conducted only once a year or every two years. This situation leads to reduced yield per hectare and income loss for producers. To reduce costs, some growers use herbicides to remove hazelnut suckers. However, the widespread use of herbicides causes irreversible environmental damage and can lead to erosion, particularly on sloped lands. Moreover, the continuous use of herbicides poses risks such as leaving residues in the soil, harming soil microorganisms, and threatening the health of hazelnut plants. This research aimed to determine the effects of the application frequency of a 15% salt (NaCl) solution on hazelnut sucker removal, focusing on its impact on soil EC and pH. The research was conducted at the Ondokuz Mayıs University Ali Nihat Gökyiğit Research Station from 2019 to 2021. NaCl solution applications were planned to be performed once, twice, and three times a year. The effects of application frequency on the drying rate of suckers, the number and length of newly emerged suckers, and changes in soil pH and EC were evaluated. The results revealed that applying the NaCl solution three times a year was the most effective method for sucker management and did not cause adverse changes in soil pH or EC levels.

Biochar application has gained attention as an effective soil amendment for improving soil quality and increasing crop productivity, particularly in clay-rich soils facing challenges such as compaction, poor drainage, and nutrient limitation. This two-year field study evaluated the effects of fresh and artificially aged biochar on soil chemical, physical, and biological properties and wheat (Triticum aestivum) yield. The experiment was conducted on clay soil with treatments including no biochar application as a control (CK), 5 and 10 t ha⁻¹ fresh biochar (B5, B10) and 5 and 10 t ha⁻¹ aged biochar (AB5, AB10). The results showed significant improvements in soil pH, soil organic carbon, cation exchange capacity, total nitrogen, and plant-available water capacity, particularly with higher doses of biochar. In both years, the effects of the treatments on the soil quality index area (SQI-area) were found to be statistically significant. The AB10 treatment increased SQI-area by 19% compared to the CK in the first year and by 33% in the second year. In the first year, the highest grain yield was obtained from the AB10 treatment, reaching 5.25 t ha⁻¹, which was 13% higher than the CK. In the second year, the highest yield was obtained from the B10 treatment, reaching 4.09 t ha⁻¹, which was 24% higher than the CK. Despite these positive changes, the correlation between SQI and yield was not statistically significant, suggesting that crop yield may also depend on other interacting variables. These results highlight the potential of biochar, particularly aged biochar, as a sustainable practice to improve soil health and productivity in clay soils.

Toprak kökenli vektör protozoa Polymyxa betae ile taşınan ve rhizomania hastalığına neden olan Beet necrotic yellow vein virus (BNYVV), şeker pancarı üretim alanlarında yaygın olan en tahripkar virüstür. Bu alanlarla BNYVV’nin yanı sıra Heterodera schachtii Schmidt (Şeker pancarı kist nematodu)’de şeker pancarında sık rastlanmakta olup verimde önemli kayıplara yol açmaktadır. Bu çalışma; BNYVV ve H. schachtii ile bulaşık olduğu bilinen Türkiye Şeker Fabrikaları A.Ş. Şeker Enstitüsü’ne ait Ilgın (Konya) deneme istasyonunda; rhizomania hastalığına karşı son yıllarda ıslah edilmiş farklı genotipte [Rz1, Rz1+Rz2, Rz1+Rz3, Rz2+Rz3 ve Rz1+nematoda tolerant (Rz1+NT)] şeker pancarı çeşit ve hatlarının verim ve kalite performanslarının değerlendirilmesi amacıyla tesadüf blokları deneme desenine göre dört tekerrürlü olarak 2017 ve 2018 yıllarında iki yıl süre ile yürütülmüştür. Araştırma sonucunda; pancarda yetiştiricilik açısından önemli parametreler (verim, şeker oranı, arıtılmış şeker oranı ve arıtılmış şeker verimi) dikkate alındığında, Rz1+NT genotipin, diğer genotiplerden daha iyi performans gösterdiği tespit edilmiştir. Ayrıca, rhizomania’ya dayanıklı şeker pancarı genotiplerinde virüs enfeksiyonları DAS-ELISA testine göre değerlendirilmiştir. İncelenen bu genotiplerin bazı tekerrürlerinde virüs enfeksiyonu belirlenmesine rağmen, mevcut BNYVV popülasyonu farklı genotipik özelliğe sahip çeşit ve hatların hiçbirisinde rhizomania dayanıklılığını kırmamıştır.

Coastal areas are facing increasing heavy metal pollution as a result of various anthropogenic activities, posing a serious threat to ecosystems. Modeling and understanding the sorption behavior of heavy metals in soils are essential for assessing their mobility and risk in the coastal landscapes. The aim of this study was to examine the adsorption behavior of Pb²⁺, Ni²⁺, and Zn²⁺ by common soil types of the Lower Don and the Taganrog Bay coast in Russia to better understand their potential environmental implications. The soil capacities for heavy metal adsorption and retention were determined using isothermal models. The maximum adsorption capacity and the binding strength parameter for the heavy metals were calculated, revealing significant differences among the soils. Haplic Chernozem emerged with superior values, while Gleyic Solonchak Sulfidic and Umbric Fluvisol trailed the lowest. All soils exhibited a greater adsorption capacity and binding strength for Pb compared to the other metals. The influence of soil characteristics on sorption and retention was also examined. The Pseudo-second-order model provided a more accurate description of the adsorption kinetics of heavy metals by the studied soils. The co-presence of metals in the system affected their sorption by the soils due to competition: soils adsorbed fewer metals but retained them more strongly. These findings are important for developing effective strategies to reduce heavy metal pollution in coastal ecosystems.