Mehmet Işik

Soil erosion is a major threat to the sustainable productivity of arable lands, making the accurate prediction of soil erodibility essential for effective soil conservation planning. Soil erodibility is strongly controlled by intrinsic soil properties that regulate aggregate resistance and detachment processes under erosive forces. In this study, machine learning (ML) models, including the Multi-layer Perceptron Regressor (MLP), Random Forest (RF), Decision Tree (DT), and Extreme Gradient Boosting (XGBoost), were applied to predict the soil erodibility factor (K-factor). A comprehensive set of soil properties, including soil texture, clay ratio (CR), organic matter (OM), aggregate stability (AS), mean weight diameter (MWD), dispersion ratio (DR), modified clay ratio (MCR), and critical level of organic matter (CLOM), was analyzed using 110 soil samples collected from the northern part of Adana Province, Türkiye. The observed K-factor was calculated using the RUSLE equation, and ML-based predictions were spatially mapped using Geographic Information Systems (GISs). The mean K-factor values for arable, forest, and horticultural land uses were 0.065, 0.071, and 0.109 t h MJ⁻¹ mm⁻¹, respectively. Among the tested models, XGBoost showed the best predictive performance, with the lowest MAE (0.0051) and RMSE (0.0110) and the highest R² (0.9458). Furthermore, the XGBoost algorithm identified the CR as the most influential variable, closely followed by clay and MCR content. These results highlight the potential of ML-based approaches to support erosion risk assessment and soil management strategies at the regional scale.

The aim of the study examines the effects of contrasting greenhouse microclimates on nutrient uptake, dry matter yield (DMY), and water use efficiency (WUE) in maize (Zea mays L.) during the early vegetative stage, under limited irrigation conditions. The study addresses the question of how microclimatic factors, particularly airflow and the humidity of the greenhouse, affect plant growth and nutrient dynamics under deficit irrigation conditions. The experiment was established at the Research and Application Greenhouses of the Department of Soil Science and Plant Nutrition, Çukurova University, Adana, Türkiye. Two greenhouse environments were compared: first with a whitewashed glass surface and active ventilation, and second with a transparent glass surface without ventilation. Three irrigation levels were applied based on available water capacity: 50%, 75%, and 100%, with three replications. Maize P2105 was used in the experiment, and plants were harvested following 40 days of deficit irrigation management. Research findings show that a microclimate greenhouse plays a critical role in maize growth and WUE under limited irrigation. In the ventilated and lime-whitewashed greenhouse, total dry matter yield reached 18.08 g pot−1, and water use efficiency peaked at 4.76 g mm−1 under 75% irrigation, approximately three times higher than values observed in the non-ventilated greenhouse. Additionally, nitrogen and phosphorus uptake was significantly enhanced, reaching 277.87 mg pot−1 and 20.85 mg pot−1, respectively. The optimized microclimate also significantly promoted the accumulation of other macro and micronutrients; the highest potassium (1239.56 mg pot−1) and magnesium (235.61 mg pot−1) uptakes were recorded under ventilated conditions, while shoot Mn concentration significantly increased to 37.71 mg kg−1 compared to the unventilated control. These results suggest that optimized airflow and humidity conditions substantially improve physiological efficiency and nutrient acquisition under water-limited environments. Microclimate engineering is therefore recommended as a sustainable strategy to mitigate drought stress in greenhouse-based crop production.

This study investigates the long-term effects of mineral and various organic fertilizer (animal manure, compost, and mycorrhizae) applications on yield, nutrient uptake, and soil properties of faba bean (Vicia faba L.). A long-term field experiment was established in 1996 at the Cukurova University Research Centre in Adana/Türkiye. Since then, for each cropping season: Control (no fertilizer), Mineral fertilizer (NPK), Animal Manure (25 t ha⁻¹), Compost (25 t ha⁻¹), and Compost (10 t ha⁻¹) + Arbuscular Mycorrhizal Fungi treatments were applied. In the present study, faba beans were grown in winter 2021 and harvested in spring 2022. At harvest, shoot and root dry weight, as well as seed yield, were measured. Plant tissue mineral nutrients were determined, and plant total nitrogen and carbon uptake were calculated. When dry weight data were examined, the highest values for shoot (11.35 t ha-1), grain (9.77 t ha-1), and total dry matter (22.23 t ha-1) were obtained in the compost treatment, while the lowest values were 6.81, 5.32, and 13.09 t ha-1 in the control treatment, respectively. The highest nitrogen (N) concentration in plant tissues was 5.26% in compost+mycorrhiza treatment, while the highest grain nitrogen content was 0.37 t N ha-1 in compost application. In terms of carbon (C) accumulation, compost-treated plants stored 8.65 t C ha-1, equivalent to 31.73 t CO₂ ha-1. In comparison, control plots stored only 5.49 t C ha-1 (20.13 t CO₂ ha-1). Fertilizer application significantly increases shoot K, P, and Zn concentrations, and root P and Zn concentrations. In conclusion, organic fertilizers, such as compost and animal manure, have a positive influence on both plant yield and nutrient quality. These results demonstrate that long-term organic fertilization significantly enhances biomass, seed yield, and mineral nutrient concentration, especially under compost and compost + mycorrhizae treatments. Organic fertilizers fixed significantly more CO2 than control treatments, which is important for combating climate change driven by greenhouse gases.

The study identifies the soil physical properties most influenced by long-term fertilizer application, offering valuable insights into sustainable agricultural practices. Therefore, the aim of this study is to determine the effects of fertilizer application on soil physical properties by identifying key properties that require monitoring for improvement. A long-term field experiment was initiated (in 1996) on the Typic Xerofluvents soil series, which is generally low in organic carbon contents, and high in soil pH and calcium carbonate. The experiment was established under wheat-maize crop rotations with three replicates in which control (CO), mineral fertilizer (MF), animal manure (M25), compost (C25), compost and arbuscular mycorrhiza fungi (C10 + AMF) were applied. After the harvest, soil samples at 0–15 cm and 15–30 cm were collected and analyzed. Organic fertilizers such as M25, C25, and C10 + AM significantly increased soil organic matter (SOM) by 2.47, 2.19 and 1.86%, water stable aggregates (WSA), and air permeability (k _a ) at both depths. The organic fertilizer treatments significantly increased field capacity (FC), permanent wilting point (PWP_v), available water content (AWC_v) at 0–15 cm; bulk density (ρ_b), and total porosity (TP) at 15–30 cm. Furthermore, fertilizer application significantly improved crop yield. WSA had a strong positive correlation with SOM, while the principal component analysis showed that FC_v, PWP_v, AWC_v, MiP, and MaP explained the highest variation, whereas ρ_b, TP, and k _a made lesser contributions. In terms of k _a , hydraulic conductivity (K), SOM, WSA, and other soil parameters, CO outperformed MF; however, it fared badly when compared to organic fertilizers. Compost enhanced k _a and K, whereas manure improved SOM, ρ_b, and soil moisture; suggesting that if one of these properties is to be improved, a decision must be taken.

This study aimed to investigate the effects of P and mycorrhiza application on cotton root and shoot morphological parameters, P uptake and dry matter yield. The hypothesis to be tested is mycorrhiza and P applications increase cotton growth yield and P uptake. The experiment was established under greenhouse conditions in May 2022 and harvested in July 2022, as a pot experiment. In the experiment, two P levels (0 mg P2O5 kg-1, and 50 mg P2O5 kg-1) three mycorrhizae species (control (without mycorrhiza), indigenous mycorrhiza (IM) and Rhizophagus Clarus (Rh. Clarus)) inoculated with May 505-cotton (Gossypium hirsutum L.) variety were used with three replications. Before harvesting, plant height and stem diameter were measured, at harvest; shoot, root, and total dry matter weight (DW) were obtained. The P content of the root and shoot parts of the plant was determined by ICP-OES. Plant root morphological characteristics were determined, and Mycorrhizal Dependency (MD) was calculated by the DW yield of cotton. The JMP8 statistical program was used for ANOVA analysis and LSD test. Results showed that there was no statistically significant difference in terms of plant height, but P and mycorrhiza treatments made a significant difference in terms of stem diameter. In addition, mycorrhiza application made a significant difference in plant dry weight yield. As a total dry weight yield, the IM application has 45.1 g pot-1 and Rh. Clarus had 47.38 g pot-1 total DW yields. The results showed that mycorrhiza and P applications increased root growth parameters. In addition, P and mycorrhiza treatments improved root morphological characteristics on average. The cotton was found to be an 8.0 to 12.3% MD, and MD was lower in P-treated pots (8.1%) compared to non-P-treated pots (11.3%). Mycorrhiza inoculation and 50 mg P2O5 kg-1 dual applications seem to be suitable for cotton growth.

Soybeans, as an industrial plant, are used in many industries. Since soybeans fix nitrogen through the rhizobium bacteria, P fertilization is one of the biggest requested fertilizers in their production. In this context, under long-term experimental conditions, the aim is to investigate the effect of increasing doses of P application on soybean yield and nutrient uptake. The hypothesis is that optimum P fertilizer doses increase soybean yield and P uptake. A field experiment was established in 1998 on the soil Arık soil series. Four doses of P fertilizers were applied, such as 0, 50, 100, and 200 kg P2O5 ha-1 with three replications before each cultivation term. Arısoy soybean (Glycine max L.) species seeds were sown in May 2024 and harvested in November 2024. At harvest, root, shoot dry weights, and yield were determined. Plant mineral nutrients (K, P and Zn) concentrations were analyzed by ICP-OES. ANOVA statistical analysis was realized by the JMP 8-pack program, and the less significant difference (LSD) test was carried out. Research results have shown that there is no significant difference in root dry matter and yield, but there is a significant difference in shoot dry matter yield. Especially when soybean grain yield was examined yield increased due to increasing doses from P0 to P200 (1596, 2390, 2431 and 2512 kg ha-1) fertilization, respectively. Furthermore, increasing doses of P fertilization statistically increased grain P concentration in a linear manner. Overall, for soybeans, 100 kg P2O5 ha-1 phosphorus fertilization is given an optimum dose for optimum growth. It was determined that the 100 kg P2O5 ha-1 application is the optimum application in soybean cultivation growth and nutrient uptake under long-term field experiments.

Phosphorus (P) fertilizers are produced from rock phosphate (apatite); however, they are low-mobility in soil for plant nutrient absorption and uptake. In addition, the rock phosphate quantity is a limited source for future P fertilizer. At the same time, high phosphorus fertilization will cause environmental pollution (such as eutrophication in rivers). Also, a great proportion of applied P fertilizer remains in the soil, reducing the viable soil organisms. Therefore, the effect of different doses of P on some properties of soil (physical, chemical, and biological) is not entirely understood in the literature under long-term experiment conditions. Also, phosphorus fertilizer applications indirectly decrease the plant growth and yield. Under long-term experimental conditions, this research aims to understand the effect of increasing P doses on some physical, chemical and biological properties of the soil. The hypothesis to be tested is that under long-term field experiment conditions, increasing doses of phosphorus fertilizer negatively affect the soil properties. The field experiment was established in 1998 and has continued uninterruptedly to the present time under maize and wheat rotations. Four doses of P fertilizers were applied; such as 0, 50, 100 and 200 kg P2O5 ha-1 application with three replications. P2105 Maize (Zea mays L.) species seeds were sown in June 2022 and harvested in November 2022. At harvest, the soil samples were taken at 0-15 cm and 15-30 cm depth in each plot. Soil pH, EC and available P were analyzed as soil chemical properties. The number of mycorrhizal spores and Soil Organic Matter (by walkley-black method) were determined as soil biological properties. Furthermore, soil bulk density (BD), water stable aggregated (WSA) and mean weight diameter (MWD) were analyzed as soil physical properties. Phosphorus application in increasing doses negatively affects the soil physical properties (such as WSA, MWD and BD) under long-term field experiment condition. The research finding showed that depending on increasing P doses application soil WSA and MWD were decreased but BD was increased. While depending on increasing P doses application soil organic carbon is increased, however, the numerical value of mycorrhizal spores and root colonization was decreased. The results are revealed that for sustainable and eco-friendly crop production, 50 and 100 kg P2O5 ha-1 P fertilizer can be used in maize production.

Tr en Mısır (Zea Mays L.) bitkisi dünyada en çok üretilen tahıllardan birisidir. Mısır üretiminde en çok kullanılan gübrelerden biri olan fosfor (P) önümüzdeki 50-100 yıl içerisinde tükeneceği varsayılmakta ve bu da bitkisel üretimi kısıtlayacaktır. Bu sebeple çalışmanın amacı; artan dozlarda P uygulamasının bitkinin P alımı ve P kullanım etkinliğini belirlemektir. Deneme 1998 yılında Çukurova Üniversitesi Araştırma ve Uygulama Çiftliğinde Arık toprak serisi üzerinde kurulmuş olup halen devam etmektedir. Söz konusu çakılı deneme düzenli olarak her ekim dönemi öncesi kontrol (0 kg da-1 P2O5), P5 (5 kg da-1 P2O5), P10 (10 kg da-1 P2O5) ve P20 (20 kg da-1 P2O5) olacak şekilde uygulanmış olup, bitkinin ihtiyaç duyduğu temel azot ve potasyum gübre gereksinimleri toprak analiz sonuçlarına göre belirlenmiştir. Deneme P2088 mısır çeşidi kullanılarak Mayıs 2017’de kurulmuş ve Eylül 2017’de de hasat edilmiştir. Hasat zamanı bitki farklı aksamları (kök, kök üstü aksam ve dane) kuru ağırlık verimleri alınmıştır. Kuru yakma metodu kullanılarak ICP-OES aleti ile bitki farklı aksamları P konsantrasyonları analiz edilmiştir. Elde edilen veriler ile Agronomik Etkinlik (AE), Fizyolojik Etkinlik (FE), Agro-Fizyolojik Etkinlik (AFE), Geri Kazanım Etkinliği (GKE) ve Gübre Kullanım Etkinliği (KE) hesaplanmıştır. Araştırma bulgularına göre; artan dozlarda P uygulamalarının farklı bitki aksamları kuru madde verimini ve P konsantrasyonunu arttırmaktadır. Ancak artan dozlarda P uygulamalarının AE, FE, GKE ve KE hesaplamalarına etkisine bakıldığında P10 uygulamasının istatistiksel olarak en iyi uygulama olduğu görülmektedir. Sonuç olarak araştırma bulguları P10 yani 10 kg da-1 P 2O5 dozu uygulamasının Mısır bitkisinin gübrelemesinde optimum doz olduğunu göstermektedir. Maize (Zea Mays L.) plant is one of the most produced cereals around the world. Phosphorus (P), which is one of the most used fertilizers in maize production. P is not a renewable resource and in next 50-100 years, it may be finish. Moreover, less P fertilization may limit crop yield and production capacity. The purpose of study is to investigate the effects of different P dosses on P uptake and its usage efficiency upon maize plant under long term P fertilizer filed experiment. Long-term field experiment was established in 1998, since then regularly each year control (without fertilization), 5, 10 and 20 kg P2O5 da-1 P (as triple superphosphate) doses are applied as a basic fertilizers. P2088 maize genotype was used as plant material. Maize seeds were sown in June 2017 and were harvested in October 2017. After harvest, yield, shoot and root dry weight were determined. P concentrations of each parts were determined by ICP-OES. Agronomic Efficiency (AE), Physiological Effciency (PE), Agrophysiological Effciency (APE), Apparent Recovery Effciency (ARE) and Utilization Effciency (EU) were calculated. According to the research findings; increasing doses of P applications increase different plant parts dry matter yield and P concentration. However, it is seen that P10 application is statistically the best application on AE, FE, GKE and KE calculations. It was determined that under field condition application of P10 kg da-1 P2O5 dose was the optimum dose for maize production.

Çalışmanın amacı uzun süreli çakılı deneme koşullarında artan dozlarda P uygulamasının toprak C, N ve P içeriği ve elementlerin kendi aralarındaki etkileşimlerini araştırmaktır. Test edilen araştırma hipotezi ise; artan dozlarda P uygulaması toprak C, N ve P konsantrasyonlarını arttırmakta ve buna bağlı olarak bitkisel üretim artmaktadır. Deneme Çukurova Üniversitesi Ziraat Fakültesi Araştırma ve Uygulama Çiftliğinde 1998 de Arık toprak serisinde çakılı deneme olarak kurulmuş ve günümüze kadar buğday-mısır rotasyonu olarak devam ettirilmektedir. Söz konusu çalışmada her üretim sezonu öncesi 0 kg P2O5 ha-1 (P0), 50 kg P2O5 ha-1 (P50), 100 kg P2O5 ha-1 (P100) ve 200 kg P2O5 ha-1 (P200) konuları üç tekerrürlü olarak uygulanmaktadır. Çalışma Kasım 2017 de Adana-99 çeşidi Buğday (‎Triticum aestivum L.) ekilerek kurulmuş olup Mayıs 2018 de hasat edilmiştir. Hasat ile birlikte farklı toprak derinliklerinden (0-15 ve 15-30 cm) ve farklı bölgelerden (rizosfer ve rizosfer olmayan) toprak örnekleri alınarak analize hazır hale getirilmiştir. Toprak organik C (OC), inorganik C (IC), toplam C ve N içeriği ve P konsantrasyonları tayin edilmiştir. Araştırma Bulguları gösteriyor ki; her iki derinlikte rizosfer (R) ve rizosfer olmayan (NR) bölgelerde P içeriği bakımından istatistiksel olarak dikkate değer bir fark olup; kontrole kıyasla en iyi uygulama P200 uygulamasında elde edilmiştir. Artan P doz uygulaması ile toprak P içeriği doğrusal bir şekilde artmıştır. Toprak OC içeriği bakımından ise rizosfer ve rizosfer olmayan bölgelerde (15-30 cm derinlikte) istatistiksel olarak dikkate değer bir fark olup, kontrole kıyasalar en iyi uygulama P200 uygulamasında sağlanmıştır. Ayrıca, artan P doz uygulamasına bağlı olarak ortalama toprak OC, toplam N ve C içeriği artış göstermekte olup sonuçlar hipotezimizi destekler niteliktedir.