Fe3O4-urea nanocomposites as a novel nitrogen fertilizer for improving nutrient utilization efficiency and reducing environmental pollution

Effect of caffeic acid and cobalt sulfate on potato (Solanum tuberosum L.) plants in the presence and absence of nanoparticles-coated urea

Potatoes (Solanum tuberosum L.) are a significant food crop cultivated around the world. Caffeic acid (CA) can enhance plant growth by promoting antioxidant activity and stimulating root development, contributing to overall plant health and vigor. Cobalt sulfate (CoSO4) boosts plant growth by promoting nitrogen (N) fixation, healthier root development, and chlorophyll synthesis, enhancing photosynthesis and overall plant health. Nanoparticle-coated urea (NPCU) improves nutrient uptake, promoting plant growth efficiency and reducing environmental impact. This study investigates the effects of combining CA, CoSO4, and NPCU as amendments on potatoes with and without NPCU. Four treatments, control, 20 μM CA, 0.15 mg/L CoSO4, and 20 μM CA + 0.15 mg/L CoSO4 with and without NPCU, were applied in four replications using a completely randomized design. Results demonstrate that the combination of CA + CoSO4 with NPCU led to an increase in potato stem length (~ 6%), shoot dry weight (~ 15%), root dry weight (~ 9%), and leaf dry weight (~ 49%) compared to the control in nutrient stress. There was a significant rise in chlorophyll a (~ 27%), chlorophyll b (~ 37%), and total chlorophyll (~ 28%) over the control under nutrient stress also showed the potential of CA + CoSO4 with NPCU. In conclusion, the findings suggest that applying CA + CoSO4 with NPCU is a strategy for alleviating potato nutrient stress.

Effects of biochar combined with MgO desulfurization waste residue on nitrogen conversion and odor emission in chicken manure composting

Aim: Chicken manure is known to produce strong odors during aerobic composting, which not only pollutes the surrounding environment but also leads to the loss of valuable nutrients like nitrogen and sulfur, thus reducing the quality of the fertilizer. Methods: In this study, we explored the use of biochar combined with MgO desulfurization waste residue (MDWR) as a novel composting additive. Our approach involved conducting composting tests, characterizing the compost samples, conducting pot experiments, and examining the impact of the additives on nitrogen retention, deodorization, and compost quality. Results: Our findings revealed that the addition of biochar and MDWR significantly reduced ammonia volatilization in chicken manure compost, demonstrating a reduction rate of up to 60.12%. Additionally, the emission of volatile organic compounds (VOCs) from chicken manure compost treated with biochar and MDWR decreased by 44.63% compared to the control group. Conclusions: The composting product treated with both biochar and MDWR (CMB) exhibited a 67.7% increase in total nitrogen (TN) compared to the blank control group, surpassing the other treatment groups and showcasing the synergistic effect of these two additives on nitrogen retention. Moreover, the CMB treatment facilitated the formation of struvite crystals. Furthermore, our pot experiment results demonstrated that the CMB treatment enhanced vegetable yield and quality while reducing nitrate content. These findings highlight the significant impact of MDWR on nitrogen retention, deodorization, and compost quality enhancement, thereby indicating its promising application prospects.

Agricultural Waste-Derived Biochar-Based Nitrogenous Fertilizer for Slow-Release Applications

The exponential increase in population demands more food to be produced by employing modern technologies. There is a worldwide increase in the use of chemical fertilizers to rapidly enhance the crop yield. Nitrogen is a crucial plant nutrient, and nitrogenous fertilizers are the most widely used fertilizers. However, the high solubility and volatility of commonly used nitrogenous fertilizers have led to low nutrient use efficiency and alarming environmental pollution. They are lost due to the volatilization of ammonia and leaching of nitrate and release of nitrous oxide, and thus, plants only absorb approximately 20-30% of the nitrogen present in fertilizers. Slow-release fertilizers have been designed to overcome these issues and supply nutrients gradually and sustainably. Biochar, a solid material rich in carbon derived from biomass, can reduce nutrient loss in soil and extend the effectiveness of fertilizers in promoting plant uptake. In the present study, a slow-release nitrogenous fertilizer is prepared using biochar obtained by pyrolysis of a banana leaf sheath (BLS) at 500 °C for 3 h. The BLS biochar and nutrient-loaded BLS (NBLS) biochar exhibited significant water absorbance capacity, water retention capacity, swelling ratio, and equilibrium water content, which would support the maintenance of water levels in soils. The lower salt index values of the prepared fertilizer showed its potential to be used as a sustainable and clean fertilizer. The prepared BLS and NBLS biochar were also characterized by various techniques such as Fourier transform infrared (FT-IR), powder X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Brunauer-Emmett-Teller (BET) methods. The FT-IR spectra of both BLS and NBLS biochar demonstrate the existence of primary, secondary, and tertiary alcohols, alkanes, alkenes, esters, and phenols. The peak at 1423 cm-1 in NBLS biochar corresponds to the vibration of NH4+ confirming nutrient loading. A minor phase change was noticed in the intensities of NBLS biochar, which may be attributed to the absorption of nutrients into the structure of biochar. TGA analysis confirmed the stability of BLS and NBLS Biochar. SEM analysis demonstrates a highly porous structure of the biochar samples due to the release of volatile matter from the biomass. The BET-specific surface area of BLS and NBLS biochar was 43.216 and 35.014 m2/g, respectively. Nutrient release studies showed an incremental increase in the nitrogen release percentage over a period of 16 h. The gradual supply of nitrogen to the plants over an extended period demonstrated by the prepared slow-release fertilizer confirms its potential to reduce the leaching loss commonly observed in conventional chemical fertilizers.

Application of green synthesized bimetallic nZVI-Cu nanoparticle as a sustainable alternative to chemical fertilizers to enhance growth and photosynthetic efficiency of rice seedlings

Application of nanomaterials in agriculture has been extensively explored over the past decade leading to a wide ambit of nanoparticle-based agrochemicals. Metallic nanoparticles consisting of plant macro- and micro-nutrients have been used as nutritional supplements for plants through soil amendments, foliar sprays, or seed treatment. However, most of these studies emphasize monometallic nanoparticles which limit the range of usage and effectivity of such nanoparticles (NPs). Hence, we have employed a bimetallic nanoparticle (BNP) consisting of two different micro-nutrients (Cu & Fe) in rice plants to test its efficacy in terms of growth and photosynthesis. Several experiments were designed to assess growth (root-shoot length, relative water content) and photosynthetic parameters (pigment content, relative expression of rbcS, rbcL & ChlGetc.). To determine whether the treatment induced any oxidative stress or structural anomalies within the plant cells, histochemical staining, anti-oxidant enzyme activities, FTIR, and SEM micrographs were undertaken. Results indicated that foliar application of 5 mg L-1 BNP increased vigor and photosynthetic efficiency whereas 10 mg L-1 concentration induced oxidative stress to some extent. Furthermore, the BNP treatment did not perturb the structural integrity of the exposed plant parts and also did not induce any cytotoxicity. Application of BNPs in agriculture has not been explored extensively to date and this study is one of the first reports that not only documents the effectivity of Cu-Fe BNP but also critically explores the safety of its usage on rice plants making it a useful lead to design new BNPs and explore their efficacy.

Iron-rich sand promoted nitrate reduction in a study for testing of lignite based new slow-release fertilisers

The N losses and agronomic performances of newly developed slow-releasing fertilisers (SRFs; Epox5 and Poly5) were tested against conventional N fertilisers, urea and diammonium phosphate (DAP), in a climate-controlled lysimeter system. The dry matter (DM) yield and N losses of SRFs were not significantly different from urea and DAP. However, nitrate leaching and nitrous oxide (N₂O) losses were unexpectedly low and therefore, it was inferred that nitrate underwent a chemical transformation. It was observed that a thick fibreglass wick interrupted drainage and created an anaerobic condition in the soil. The subsoil was found to have a high extractable total iron and it was postulated that iron played a role in the observed low level of N losses. An investigation was carried out with a factorial design using sand types and rates of N application as the main factors. Two types of sand; with high and low iron concentration and four levels of N applications; 0 (control), 50, 100 and 200 kg N ha^-1 were employed in a leaching column and nitrate and N₂O losses were measured. The nitrate leaching was significantly (P < 0.05) affected by sand types wherein a lower nitrate level was recorded for high‑iron concentration sand than for low-iron concentration sand at all N application levels. The N₂O emission was significantly (P < 0.05) lower for high-iron sand than for low-iron sand for the 200 N treatment, but not significantly different between sand types for other treatments. These observations provide evidence for the involvement of iron in nitrate transformation under anaerobic conditions and it was hypothesised path was dissimilar nitrate reduction (DNR). Further studies are recommended, to identify the underlying mechanism responsible for nitrate reduction with iron-rich sand.

Engineered Nanomaterials for Improving the Nutritional Quality of Agricultural Products: A Review

To ensure food safety, the current agricultural development has put forward requirements for improving nutritional quality and reducing the harmful accumulation of agricultural chemicals. Nano-enabled sustainable agriculture and food security have been increasingly explored as a new research frontier. Nano-fertilizers show the potential to be more efficient than traditional fertilizers, reducing the amount used while ensuring plant uptake, supplying the inorganic nutrients needed by plants, and improving the process by which plants produce organic nutrients. Other agricultural uses of nanotechnology affect crop productivity and nutrient quality in addition to nano-fertilizers. This article will review the research progress of using nanomaterials to improve nutritional quality in recent years and point out the focus of future research.