The use of agricultural chemicals has adversely affected soil health and the environment. Organic farming practices, particularly vermicompost (VC), are gaining attention for their potential to improve soil fertility and crop productivity. This study investigated VC rate applications on lettuce growth, yield, soil fertility, nutrient dynamics, enzyme activity, biological parameters, and biochemical aspects under greenhouse conditions in Samsun, Turkey during 2022–2023. Experimentally, VC was applied at rates of V1: 1%, V2: 2%, and V3: 4% w/w, with a control group without VC application, V0: 0% w/w. Batavia lettuce, which is sensitive to environmental conditions and nutrient deficiency, was subjected to these treatments in a randomized complete block design, replicated thrice. Results showed consistent improvements in plant dry weight across all VC treatments, with the 2% application rate (V2) yielding the highest increase in lettuce yield (56.43%). Soil pH varied across treatments, with V1 being slightly alkaline and V3 showing high electrical conductivity and increased nitrogen content. Phosphorus content increased in all treatments, while potassium varied, with V3 having the highest values. Soil enzyme activities increased with VC concentrations, with V3 showing the highest urease activity. Pearson correlations confirmed positive associations with growth parameters and soil enzymatic activity. These findings highlight vermicompost as a sustainable solution for lettuce production and soil improvement.

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.

Calcareous soils, typically characterized by low fertility, low organic matter and nitrogen content, and often deficient in phosphorus, zinc, and iron, as well as having low microbial activity, require the development of sustainable soil conditioners to improve fertility. To address these shortcomings and promote sustainable agriculture, biochar, especially with acidic character, may offer a promising solution. This study investigates the effects of modified biochar by H 2 SO 4 and ZnSO 4 on soil properties and wheat yield under field conditions. For this purpose, biochar (B), acidified biochar (AB), Zn enriched biochar (BZn), and acidified-Zn enriched biochar (ABZn) were applied to the field at two different doses (0.5 and 1.0%) together with the control treatment (Ck) without biochar application. AB 1.0% was determined as the most effective treatment in decreasing soil pH (0.15 units), while B1.0% was determined as the most effective treatment in increasing organic carbon and cation exchange capacity, 13% and 32%, respectively. The effect of the treatments varied for specific nutrients. The highest antioxidant enzyme activities were found in acidified biochars where the lowest yields were obtained. Compared to the Ck, the highest catalase (CAT) (32%) was determined in ABZn 1.0% , ascorbate peroxidase (APX) (56%) and glutathione peroxidase (GPX) (36%) were determined in ABZn 0.5% , and superoxide dismutase (SOD) (28%) was determined in AB 0.5%. The highest proline (PRO), with the least decrease in yield, was found in the AB 1.0% application, which is 205% more than Ck. B and BZn treatments all increased the grain yield, and the highest increase was 20% in B 1.0% when compared to the Ck.

Bu çalışmada; kimyasal gübre ve iki farklı organik gübre (kompost ve kül solüsyonu) uygulamalarının, domateste fide kalitesi üzerine etkileri araştırılmıştır. Çalışmada fide kalitesini belirlemek amacı ile; gövde çapı(mm), fide boyu(cm), yaprak sayısı(adet), yaprak klorofil içeriği (CCI), yaprak alanı(cm2), kök uzunluğu(cm), toplam fide kuru ağırlığı(g) ve nispi büyüme hızı (NBH) gibi parametreler incelenmiştir. Yapılan çalışma sonucunda kompoze gübre uygulaması; gövde çapı (3.2mm), yaprak sayısı (6 adet), yaprak klorofil içeriği (14.7 CCI), yaprak alanı (49.42 cm2), kök uzunluğu (21 cm) ve toplam fide kuru ağırlığı (0.287g) parametreleri bakımından ön plana çıkmış olup, kontrol hariç tüm gübre uygulamalarında istatistiki (p≤0.05) olarak benzer değerlerin elde edildiği belirlenmiştir. Çalışma sonucunda organik gübre uygulamalarının kompoze gübre ile rekabet edebilir olduğu belirlenmiştir. Nitekim, odun külü kullanımının nispi büyüme hızını (0.110 g g-2gün-1) arttırmasının yanı sıra fide boyu (16.5 cm) üzerine etkileri istatistiksel olarak önemli bulunmuştur. Sonuç olarak odun külü kullanımının fidelerde boy kontrolü sağlamış olması domates fidesi yetiştiriciliğinde odun külü kullanımını ön plana çıkarmıştır.

Gazlaştırma işlemiyle elde edilen biyoçarlar genellikle alkali karaktere sahip olduklarından yüksek kireç içeren topraklara uygulanması bitki besin elementlerinin yarayışlılığını olumsuz etkilemektedir. Bu çalışma ile kumlu tınlı bünyeye sahip kireçli bir toprağa orijinal (alkali) ve asitle modifiye edilmiş biyoçar uygulamalarının toprakta pH, EC ve DTPA ile ekstrakte edilebilir mikro element içeriğine etkileri araştırılmıştır. İnkübasyon denemesinde orijinal (BpH9.4) ve farklı pH düzeylerinde asitleştirilmiş biyoçarlar (BpH6.5 ve BpH3.6) kullanılmıştır. Biyoçarlar dört farklı dozda (%0, %1, %2 ve %4) toprağa karıştırılarak 20-24oC’de inkübasyona bırakılmıştır. Tarla kapasitesi nem düzeyinde yürütülen inkübasyon denemesinin 30. ve 90. gününde toprak örneklemeleri yapılmıştır. Inkübasyon süresi uzadıkça toprakların pH ve EC değerlerinin arttığı belirlenmiştir. Toprak pH’sındaki en fazla artış kontrole kıyasla BpH9.4 uygulamasında (0.46 birim), en fazla azalış ise BpH3.6 (0.19 birim) uygulamasında olmuştur. Genel olarak BpH9.4 uygulaması toprak EC değerini azaltırken, BpH6.5 ve BpH3.6 uygulamaları artırmıştır. Kontrole kıyasla EC değerindeki en fazla artış BpH3.6 uygulamasında (%342) belirlenmiştir. İnkübasyon süresi uzadıkça toprakların pH, EC ve DTPA ile ekstrakte edilebilir Fe içeriği artarken, Cu, Mn ve Zn içerikleri azalmıştır. BpH3.6 uygulamasında DTPA ile ekstrakte edilebilir Fe (%49), Mn (%43) ve Zn (%16) içerikleri, BpH6.5 uygulamasında ise DPTA ile ekstrakte edilebilir Cu içeriği (%19) kontrole kıyasla artmıştır.