Veysel Turan’s research while affiliated with Bingöl University and other places

Legumes have a high demand for phosphorus (P) due to energetically costly biological nitrogen fixation, but they also have effective physiological and morphological strategies for P mobilization. To evaluate the inter- and intraspecific P efficiency of small-grain legumes supplied with different P recycling fertilisers, eight accessions each of alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) were cultivated in two pot experiments under greenhouse conditions until the flowering stage. To substantiate the results, some accessions were used in both experiments. Five treatments (no P, triple-superphosphate (TSP), sewage sludge ash (SSA), biowaste compost (compost), and struvite) were considered P sources. In addition to plant P uptake, the soil P pools were analysed in detail. Red clover showed higher yields and nutrient uptakes compared to alfalfa, but intraspecific effects were marginal. The addition of P resulted only partly in an increase in yield, despite the low P content in the soil. While struvite application clearly enhanced the P uptake of the plants in both experiments, SSA application had no effect compared to the control. The same treatment effect occurs with the bio-available soil P contents, which were on average 72.6 mg kg−1 after struvite and 44.3 mg kg−1 after SSA addition. Struvite as a P source was especially effective when applied to red clover. Our study aligns with previous field results and underscores the high potential of P mobilization of small-grain legumes without pronounced inter- or intraspecific differences. While struvite is suitable as a P fertiliser, the application of SSA to legumes is not recommended.

Soil is a complex and dynamic ecosystem that is home to a large number of microbial communities. These communities are composed of diverse groups of organisms, including bacteria, fungi, archaea, and protists. Among these, protists are the least studied and recognized organisms in the soil ecosystem, yet they play a significant role in maintaining soil health and ecosystem functioning. Despite their ecological importance, soil protists are often understudied, and relatively little is known about their diversity, distribution, and ecological functions. Recent advances in molecular techniques have helped to shed light on the diversity and role of soil protists in ecosystem processes, and further research in this area may have important implications for the maintenance of soil health and biodiversity. However, the initial observation of soil protists can give a basic idea of the diversity and abundance of the organisms present in the soil. Investigating soil protists is an essential step toward understanding and managing soil ecosystems, and it provides important insights into the complex interactions between microorganisms and soil nutrients. Therefore, the aim of this chapter is to provide an overview of initial observation of soil protists. Generally, two different methods are used to observe naked amoeba and active forms of ciliates and flagellates.

Arable soils irrigated with wastewater (SIWs) cause ecological and human health issues due to the presence of heavy metals (HMs). Burning rice stubble (RS) poses severe environmental and human health hazards. Converting RS into rice stubble compost (RSC) and rice stubble biochar (RSB) can overcome these issues. Here, we considered the role of RS, RSC, and RSB as individual soil amendments and combined each of them with arbuscular mycorrhiza fungi (AMF) to observe their effectiveness for HM immobilization in SIW, their uptake in pea plants, and improvements in the physicochemical properties of soil. The results revealed that adding RSB and AMF reduced the bioavailable concentrations of Pb, Cd, Ni, Cu, Co, and Zn in SIW by 35%, 50%, 43%, 43%, 52%, and 22%, respectively. Moreover, RSB+AMF treatment also reduced Pb, Cd, Ni, Cu, Co, and Zn concentrations in grain by 93%, 76%, 83%, 72%, 71%, and 57%, respectively, compared to the control. Improvements in shoot dry weight (DW) (66%), root DW (48%), and grain yield (56%) per pot were also the highest with RSB+AMF. RSB+AMF treatment enhanced soil health and other soil attributes by improving the activity of urease, catalase, peroxidase, phosphatase, β-glucosidase, and fluorescein diacetate by 78%, 156%, 62%, 123%, 235%, and 96%, respectively. Interestingly, RSB+AMF also led to the strongest AMF–plant symbiosis, as assessed by improved AMF root colonization (162%), mycorrhizal intensity (100%), mycorrhizal frequency (104%), and arbuscular abundance (143%). To conclude, converting RS into RSB can control air pollution caused by RS burning. Moreover, adding RSB with AMF to SIW can reduce HM uptake in plants, improve soil health, and thus minimize ecological and human health issues.

Amending Pb-affected soil with biochar (BH) and magnesium potassium phosphate cement (MKC) reduces Pb uptake in plants. Moreover, foliar applications of melatonin and proline are also known to reduce plant oxidative stress and Pb uptake. However, little is known about combining both techniques, i.e., adding a combo immobilizing dose (CIA = mixture of BH and MKC at 50:50 ratio) in Pb-polluted soil and foliar application of proline and melatonin for reducing Pb uptake and oxidative stress in spinach. Control, proline, melatonin, CIA, CIA+proline, and CIA+melatonin were the treatments utilized in this pot study to see their effects on reducing plant oxidative stress, Pb uptake, and improving spinach quality in Pb-polluted soil. Moreover, Pb bioavailability, enzymatic activities, and numbers of bacteria, fungi, and actinomycetes in the soil were also evaluated. The effect of CIA on reducing Pb in the soil-plant system and improving soil enzymes and microbial numbers was more pronounced than melatonin alone. The most effective treatment was CIA+melatonin reducing Pb availability in soil (77%), shoots (95%), and roots (84%), alleviating oxidative stress, and improving plant biomass (98%) and nutrients. Soil enzymatic activities and the number of microorganisms in the rhizosphere were also highest with CIA+melatonin. Results highlight the significance of CIA+melatonin, as an inexpensive approach, in remediating Pb-polluted soil and improving spinach quality. However, further research is needed to understand the significance of CIA+melatonin on different crops and various soil Pb concentrations before employing this technique commercially in agriculture and environment sectors.

Due to increasing chemical fertilizer costs, the importance of reducing the use of chemical fertilizers in agricultural areas is increasing day by day. Moreover, the European Union and many countries encourage the use of enriched plant growth and liquid fertilizers instead of chemical fertilizers. Furthermore, bioorganic liquid fertilizers produced with different contents have emerged as an alternative plant nutrition tool as soil conditioner and improver in recent years. The development of new production processes of organic fertilizers and plant nutrition enhancer can contribute to the circular economy. In addition, some agricultural wastes can be a raw material source in fertilizer production due to their rich nutrient content. As a result, bioorganic liquid fertilizers and plant nutrition enhancer applications that promote plant growth, which are developed as an alternative to chemical fertilizers, should contribute to sustainable land management by increasing their trials both in terms of low cost and in field and greenhouse conditions.

Soil polluted from Pb-acid batteries effluents (SPB) reduces the therapeutic potentials of Moringa oleifera, contaminates groundwater and surrounding soils via Pb transference. Amending SPB with P-loaded jujube twigs biochar (P-TB) can overcome these problems. Moreover, chitosan spray (CHs) on moringa, growing on SPB, can further biostimulate the production of essential phytochemicals and improve its anti-proliferative effects on human liver cancer cells (HePG2). In this pot experiment, moringa was grown on SPB (Pb = 639 mg kg–1) having control, CHs, TB, P-TB, TB+CHs, and P-TB+CHs treatments. Treatments effects on plant growth, Pb distribution in moringa leaf extract (MLE), shoots and roots, the status of plant phytochemicals and antioxidants, and concentrations of Pb and P in leachates were evaluated. Lastly, MLE was initially tested for its feasibility for human consumption through HEK 293 assay and later its antiproliferative efficacy on HePG2. Among all treatments, the P-TB+CHs exhibited the most significant results in compare to control. The P-TB+CHs resulted in the highest reduction of Pb concentrations in shoots, roots, and MLE by 79%, 70%, and 52%, whereas improved plant growth, phytochemicals, and antioxidants status. Interestingly, MLE at P-TB+CHs had Pb concentrations (3.27 mg L⁻¹) below the critical limit [5 mg kg⁻¹, WHO/FAO, 2007], was safer for consumption (HEK 293 cells viability = 133.6%), and depicted the least proliferation of HepG2 cells (35.8%). In leachates of P-TB+CHs, the concentrations of Pb (5.26 μg L⁻¹) and P (0.021 mg L⁻¹) were below the permissible limits for drinking water and preventing eutrophication, respectively. The lowest concentrations of Pb in MLE, plant parts, and leachates in P-TB+CHs were due to the formation of insoluble Pb-P compounds after Pb reacted with P present in P-TB and released P from P-TB. Hence, P-TB+CHs can remediate SPB, prevent groundwater contamination, avoid eutrophication, and boost the anti-cancer potential of moringa.

Soil receiving discharges from Pb-acid batteries dismantling and restoring units (PBS) can have a high concentration of phytoavailable Pb. Reducing Pb phytoavailability in PBS can decline Pb uptake in food crops and minimize the risks to humans and the environment. This pot study aimed to reduce the concentration of phytoavailable Pb in PBS through Aspergillus niger (A. niger)−mediated release of PO4³⁻ from fish bone [Apatite II (APII)] products. The PBS (Pb = 639 mg kg⁻¹ soil) was amended with APII powder (APII−P), APII char (APII−C), and A. niger inoculum as separate doses, and combining A. niger with APII−P (APII−P + A. niger) and APII−C (APII−C + A. niger). The effects of these treatments on reducing the phytoavailability of Pb in PBS and its uptake in fenugreek were examined. Additionally, enzymatic activities and microbial biomass carbon (MBC) in the PBS and the indices of plant physiology, nutrition, and antioxidant defense machinery were scoped. Results revealed that the APII−C + A. niger treatment was the most efficient one. Compared to the control, it significantly reduced the Pb phytoavailability (DTPA-extractable Pb fraction) in soil and its uptake in plant shoots, roots, and grain, up to 61%, 83%, 74%, and 92%. The grain produced under APII−C + A. niger were safe for human consumption as Pb concentration in grain was 4.01 mg kg⁻¹ DW, remaining within the permissible limit set by WHO/FAO (2007). The APII−C + A. niger treatment also improved soil pH, EC, CEC, MBC, available P content and enzymatic activities, and the fenugreek quality parameters. A. niger played a significant role in solubilizing PO4³⁻ from APII−C, which reacted with Pb and formed insoluble Pb-phosphates, thereby reducing Pb phytoavailability in PBS and its uptake in plants. This study suggests APII−C + A. niger can remediate Pb-polluted soils via reducing Pb phytoavailability in them.

In recent years, rapid increase in population growth, improper usage of synthetic fertilizers, organic matter depletion, nutrient imbalance, and land degradation owing to several anthropogenic activities have significantly exerted considerable pressure on agriculture which negatively influences sustainable plant production. Therefore, it is necessary to sustain the most appropriate levels of organic matter in degraded soils, which supports sustainable crop production and maintains nutrient cycling in them. Biochar has been broadly used for sustainable plant production among different organic matters due to its several advantages such as mitigating global warming, excellent soil conditioner, and as a potential amendment for various environmental applications over other soil additives. Moreover, biochar additions in agricultural soils also promoted the seed germination, growth, biomass, yield, and nutritional qualities of crops grown on biochar amended soils. Apart from these benefits, biochar also supports soil microorganisms by providing them habitat due to its porous structure and releases essential nutrients from its matrix, improving microbial communities. Thus, it is suggested that biochar could play a vital role in reducing the adverse impacts of climate change and threats to sustainable crop production.

VegetablesVegetables play a chief part in the human diet and provide the essential nutrientsNutrients and vitamins necessary to perform numerous essential physiological functions in the human body. Unfortunately, the consumption of vegetablesVegetables laden with heavy metals (HMs) is among the most imperative issues of recent years because of their toxic impacts on human health. The toxic HMs accumulated in vegetables after their release into the ecosystem through diverse natural and human-centered activities. The prolonged use of synthetic agrochemicalsAgrochemicals, irrigationIrrigationof agriculturalAgricultural lands with untreated municipalMunicipal and industrial effluents, inappropriate dumping of solid waste, and various other industrial activities are the main causative factors of HMs accumulation in productive soils. The mobility of HMsHMs in the soilSoil and their accumulation in vegetables is remarkably influenced by several soil and plant factors that control their bioavailability. Reduction in growth, biomassBiomass, yield and poor nutritional quality are the key symptoms of HMs toxicityToxicity after their absorption by the vegetables. Health risks to humans via the consumption of HMs contaminated vegetables have been investigated through different risk assessment equations. Interestingly, different novel remediation techniques such as phytoremediationPhytoremediation, immobilization, water management strategies, and applications of microbial inocula could be practiced for safer vegetable production for human consumption from HMs polluted soils.