To enhance yield and produce high-quality olive products, it is crucial to implement accurate and balanced fertilization programs. Like other crops, olive trees require the application of specific macro and micronutrients in addition to basic fertilization. This study aimed to evaluate the effects of foliar fertilizer applications containing K as well as N, K, Ca, and B, in addition to basic fertilization, on the yield and quality parameters of the Gemlik olive (Olea europaea L. cv. Gemlik) variety, known for its high economic value and use in black table olives and oil production, during two consecutive seasons in 2021–2022. The research evaluated the effects on olive fruit yield, fruit nutrient content (N, Ca, P, Na, K, Mg, Zn, Fe, Cu, and Mn), oil yield, and quality. In addition to traditional basic fertilization (NPK fertilizer), foliar fertilizers containing K as well as N, K, Ca, and B nutrients were applied before flowering and after fruit set. These applications were organized using a randomized block design with three replicates, each consisting of three trees. The results showed that foliar fertilizer applications, in addition to basic fertilization, had a significant impact on the yield and quality parameters. Specifically, foliar K applications positively affected olive yield in the second year. Moreover, foliar fertilizer applications improved the fruit nutrient content, oil quality (K-232, K-270, peroxide, acidity, and total phenol), and oil composition (%). Therefore, it is recommended that foliar fertilizers are applied during similar periods under similar conditions. However, ensuring the continuity of an optimal fertilization management plan is crucial for olive, as it is a perennial plant.

Farklı demirli gübrelerin maydanoz bitkisinde demir alınım miktarlarına etkisinin belirlenmesi amacıyla yapılan bu araştırmada, bikarbonatlı ve bikarbonatsız koşullarda iki farklı demir gübresi kullanılarak toplam 6 farklı uygulama denemesi yapılmıştır. (Kontrol, Fe-EDTA, Fe-Sülfat, Kontrol+HCO3-, Fe-EDTA+HCO3-, Fe-Sülfat+HCO3-). Araştırma sonucunda bikarbonat içeren uygulamalarda Fe-EDTA önemli etki göstermiş ve bitki demir içeriğini olumlu yönde etkilemiştir. Yaprak ve sapta bikarbonatlı ve bikarbonatsız koşullarda en yüksek demir ve aktif demir sonuçlarını Fe-EDTA uygulaması vermiştir. En yüksek verim bikarbonatsız koşullarda Fe-Sülfat, bikarbonat uygulamasında Fe-EDTA’da saptanmıştır. Sonuç olarak şelatlı demir gübrelerinin bikarbonatlı ortamlarda ortaya çıkan olumlu etkisi bir kez daha belirlenmiştir.

Globally, rising coffee consumption has led to an increase in coffee grounds waste. This study evaluated the feasibility of using spent coffee grounds (SCG) as an alternative fertilizer in agriculture from an environmental perspective. To this end, various application rates of coffee grounds (0, 7.5, 15, and 30 t ha⁻¹) were tested to determine their effects on the yield and nutrient content of red radish, as well as on selected physical and chemical soil properties. Coffee grounds applications significantly increased the organic matter content and the amounts of N, P, K, Mg, and Zn in loamy sand soil following radish cultivation. Compared with the control, 30 t ha⁻¹ of SCG raised soil organic matter by 50% and enhanced P, Mg, and Mn contents by 27.5%, 14.6%, and 55.5%, respectively. SCG treatments significantly improved the P, Mg, Zn, and Mn contents in radish leaves and tubers, as well as K and vitamin C levels in the tubers. Notably, the 30 t ha⁻¹ dose increased tuber Mg and Mn contents by 32% and 55%, respectively, while the 15 t ha⁻¹ dose increased vitamin C content by 35%. However, these applications did not affect radish tuber yield, dry matter content, leaf N, Fe, and Cu levels, or tuber N, Ca, and Fe concentrations. Consequently, the application of spent coffee grounds enriched the mineral profile of radish, an important nutritional source, thereby enhancing its overall nutritional value. The findings indicate that spent coffee grounds applications to soil can improve the mineral content of both plants and soil while also enhancing soil properties, suggesting significant potential as an alternative fertilizer. Additionally, repurposing large quantities of coffee grounds in agriculture contributes to sustainable soil fertility and offers environmental benefits.

Zeytin karasuyu, yüksek kirlilik yükü ve içerdiği polifenollerden dolayı fitotoksik etkilere sahip fakat bununla beraber organik bileşikler ve bitki besin elementleri yönünden de zengin bir atık su özelliğindedir. Bu nedenle belli düzeyde bir arıtımdan geçtikten sonra toprak ıslah maddesi olarak kullanılabilme potansiyeli bulunmaktadır. Bu çalışmada; zeytinyağı üretimi sırasında ortaya çıkan ham karasu ve iki farklı yöntem (ekonomik ön arıtma ve ileri arıtma tekniği) ile arıtılmış karasu kumlu tın bünyeli bir toprağa 50, 100 ve 150 m3 ha-1 dozlarında uygulanmış ve toprağın C ve N-dinamiği ile bazı kimyasal özelliklerinde meydana getirdiği değişimler incelenmiştir. Deneme laboratuvar koşullarında 90 günlük bir inkübasyon denemesi olarak yürütülmüştür. Gerek arıtılmış ve gerekse arıtılmamış zeytin karasu uygulamaları toprağın toplam organik-C (TOC), toplam N (TON), çözünebilir-C (ÇÖZ-C), mikrobiyal biyokütle-C ve-N (MB-C ve MB-N), alınabilir P ve K miktarlarını artırmış fakat N-immobilizasyonundan dolayı inorganik-N (İNOR-N) havuzunu küçültmüştür. En yüksek MB-C/TOC, ÇÖZ-C/TOC ve MB-N/TON oranları karasu uygulamalarının ilk dozlarında, en yüksek İNOR-N/TON oranları ise, kontrol ve en yüksek ham karasu uygulamalarında saptanmıştır. Bu sonuçlar karasuyun 50 ve 100 m3 ha-1 uygulamalarında topraktaki mikrobiyal biyokütlenin arttığını fakat 150 m3 ha-1 karasu uygulamasında topraktaki C ve N-dinamiğinin olumsuz etkilendiğini ortaya çıkarmıştır. Fenol ve organik C yükünün azaltıldığı arıtılmış karasuların100 m3 ha-1’ı geçmeyecek dozlardaki uygulamalarının bu atığın değerlendirilmesinde iyi bir geri dönüşüm stratejisi olabileceği düşünülmektedir.

Introduction: Optimizing fertilization strategies in Melissa officinalis L. requires an integrated assessment of biomass production and secondary metabolite synthesis. Methods: This study evaluated the effects of organic and organomineral fertilization on herbage yield, essential oil (EO) yield, and leaf rosmarinic acid (RA) content under field conditions in Ödemiş (Türkiye) during the warm and dry 2024 growing season. A split-plot design was used, with two cultivars (Melis and Quedlinburger) assigned as main plots and six fertilization treatments (G0–G5) as subplots, evaluated across two harvest times (H1 and H2). Results: Fertilization significantly affected all parameters (p < 0.01). The highest fresh herbage yield was obtained with G3 (ammonium sulfate combined with humic and fulvic acids) at H1, reaching 15.41 t ha ^- ¹ in Quedlinburger. Organomineral fertilization (G5; 12-12-12, 50% organic matter) maximized EO yield at H1, reaching 118.10 L ha ^- ¹ in Melis, and maintained higher mean RA content than the control across both harvests (62.47 and 53.41 mg g ^- ¹ at H1 and H2, respectively; mean across cultivars), corresponding to 69–99% higher RA content than the control. A marked phenological shift was observed, with EO content declining by ~50% from H1 to H2, while RA content also decreased by ~20% across harvests but remained highest under G5 treatment, which may be associated with changes in carbon allocation between the terpenoid (MEP) and phenylpropanoid pathways. Multivariate analysis supported these findings, with principal component analysis explaining 88.2% of total variance and clustering identifying G5 and G3 as the most effective treatments. Discussion: Overall, integrated nutrient management enhanced both yield and phytochemical quality under heat and water-deficit conditions.