Soil Syst., Volume 8, Issue 3 (September 2024) – 6 articles

Nanoclay, a processed clay, is utilized in numerous high-performance cement nanocomposites. This clay consists of minerals such as kaolinite, illite, chlorite, and smectite, which are the primary components of raw clay materials formed in the presence of water. In addition to silica, alumina, and water, it also contains various concentrations of inorganic ions like Mg²⁺, Na⁺, and Ca²⁺. These are categorized as hydrous phyllosilicates and can be located either in interlayer spaces or on the planetary surface. Clay minerals are distinguished by their two-dimensional sheets and tetrahedral (SiO₄) and octahedral (Al₂O₃) crystal structures. Different clay minerals are classified based on the presence of tetrahedral and octahedral layers in their structure. These include kaolinite, which has a 1:1 ratio of tetrahedral to octahedral layers, the smectite group of clay minerals and chlorite with a 2:1 ratio. Clay minerals are unique due to their small size, distinct crystal structure, and properties such as high cation exchange capacity, adsorption capacity, specific surface area, and swelling behavior. These characteristics are discussed in this review. The use of nanoclays as nanocarriers for fertilizers boasts a diverse array of materials available in both anionic and cationic variations. Layered double hydroxides (LDH) possess a distinctive capacity for exchanging anions, making them suitable for facilitating the transport of borate, phosphate, and nitrate ions. Liquid nanoclays are used extensively in agriculture, specifically as fertilizers, insecticides, herbicides, and nutrients. These novel nanomaterials have numerous benefits, including improved nutrient use, controlled nutrient release, targeted nutrient delivery, and increased agricultural productivity. Arid regions face distinct challenges like limited water availability, poor soil quality, and reduced productivity. The addition of liquid nanoclay to sandy soil offers a range of benefits that contribute to improved soil quality and environmental sustainability. Liquid nanoclay is being proposed for water management in arid regions, which will necessitate a detailed examination of soil, water availability, and hydrological conditions. Small-scale trial initiatives, engagement with local governments, and regular monitoring are required to fully comprehend its benefits and drawbacks. These developments would increase the practicality and effectiveness of using liquid nanoclay in desert agriculture. Full article

The combined application of biochar and fertilizer has become increasingly popular for improving soil quality and crop productivity. However, the reported research results regarding the effects of biochar on soil properties and crop productivity have contradictory findings, indicating the requirement for further scientific research. Therefore, this study aimed to investigate the effects of a combined application of water hyacinth biochar (WHB) and NPS fertilizer on soil physicochemical properties and wheat yield under deficit irrigation conditions in acidic silty loam soil in Ethiopia. Four different biochar rates (0, 5, 10, and 20 t ha⁻¹), three fertilizer rates (0, 100, and 200 kg NPS ha⁻¹), and two irrigation regimes (50 and 100% of crop requirement) were evaluated to assess soil properties and wheat yields. The results showed that biochar amendment significantly reduced soil bulk density by 15.1–16.7%, and improved soil porosity by 6.8–8.6% and moisture content by 10.3–20.2%. Additionally, the combined application of biochar and fertilizer improved soil pH (0.26–0.87 units), NH₄⁺–N (73.7–144%), NO₃⁻–N (131–637%), and available phosphorus (85.8–427%), compared to the application of fertilizer alone. As a result, wheat dry biomass and grain yield increased by 260 and 173%, respectively. Furthermore, the combined application of WHB and fertilizer resulted in a comparable wheat dry biomass and grain yield even with a 50% reduction of irrigation water. Therefore, WHB has a significant potential to improve soil physicochemical properties and wheat yield when it is applied in combination with fertilizer, and it can reduce the water requirement for wheat production. Full article

A methodology has been developed to assess the presence and dissipation of herbicides of a wide range of polarities in soil using in-tube solid-phase microextraction (IT-SPME) coupled online to capillary liquid chromatography (capLC). The compounds investigated were tritosulfuron (TRT), triflusulfuron-methyl (TRF), aclonifen (ACL), and bifenox (BF), with log octanol-water partition coefficients (log K_ow) ranging from 0.62 to 4.48. The method provided suitable linearity at concentration levels of 0.5–4.0 µg/g for TRT and TRF, and 0.2–1.0 µg/g for ACL and BF, and intra- and interday precision (expressed as relative standard deviation) ≤4% and ≤8%, respectively. The mean recoveries ranged from 90% to 101%, and the limits of detection (LODs) and quantification (LOQs) were in the intervals of 0.05–0.1 µg/g and 0.1–0.4 µg/g, respectively. The accuracy of the method was also satisfactory. The proposed approach was successfully applied to assess the degradation of the tested herbicides in different types of soil (agricultural, urban and forest) after being exposed to different laboratory and outdoor conditions. The results obtained showed a greater persistence of the most apolar compounds ACL and BF, with percentages of degraded herbicide ≤31% regardless of the soil characteristics. In contrast, a significant degradation of highly polar herbicides TRT and TRF was observed in soils with the lowest organic matter, even after a few days of exposure. For example, the percentages of remaining TRT and TRF in this kind of soil after 20 days were ≤65%; the half-life time of TRF was only 24.8 days. These results indicate that the proposed approach can be considered as an effective tool for a better understanding of soil pollution. Full article

Agricultural residues are generated during the production and processing of agricultural crops. Under modern date palm plantation practices, field operations generate huge quantities of residues, which are discarded with little valorization. The date palm agro-industry produces significant amounts of waste. The accumulation of these residues can cause ecological damage to the oasis ecosystems. There is a lack of comprehensive data on long-term research studies that aim to assess the impact of date palm waste management practices. Composting and/or pyrolysis of date palm residues showed benefits for improving soil physical and chemical properties, particularly in sandy soils. This claim holds particular significance for arid and semi-arid regions, which are characterized by low fertility and are susceptible to soil degradation, accentuated by ongoing climate change. This review summarizes the existing literature concerning the valorization of date palm residues with regards to compost and pyrolysis processes, as well as the impact of their application on soil quality. Further research is required to assess the effects of using date palm residues for better soil amendment management. Research should focus on composting and biochar technologies for date palm residues and their application in arid and semi-arid regions to combat soil erosion and degradation. Increasing the beneficial uses of date palm residues could lead to sustainable and economic growth in dry areas. Full article

Reusing the by-products from wood pulp processing can promote the efficient use of resources. In this sense, the objective of this research was to determine the agronomic efficiency of CaCO₃ and Na₂SO₄ by-products from wood pulp processing to establish criteria for their use and avoid undesirable side effects when applying these materials to the soil. Six treatments in proportions of 1; 0.9; 0.75; 0.5, 0.25, and 0, of CaCO₃/Na₂SO₄, respectively, were incubated at a constant temperature and humidity for 15 days. The first proportion consisted of 100% CaCO₃, while M1 mixed 90% CaCO₃ and 10% Na₂SO₄, M2: 75% CaCO₃ and 25% Na₂SO₄, M3: 50% CaCO₃ and 50% Na₂SO₄, M4: 25% CaCO₃ and 75% Na₂SO₄, with the last proportion comprised of 100% Na₂SO₄. Samples of 40 g from two soil series, Licantén (Inceptisol) and San José (Andisol), were used. The rates applied for each treatment were 0, 1, 2, 4, and 8 g of material per kg of dry soil. At the end of the incubation period, pH in water, pH in CaCl₂, exchange bases (Ca²⁺, Mg²⁺, K⁺ and Na⁺) and extractable sulfur were determined. The results showed that the San José soil had a pH buffering capacity three times higher than that of the Licantén soil. The linear increase in pH was thus explained by the soil type in relation to the applied rate of CaCO₃. The analysis of the increase in the exchangeable Na percentage (ESP) showed that the soils increased up to about 70% of their ESP with the highest added rate of Na₂SO₄. The application of a mixture of 25% Na₂SO₄ and 75% CaCO₃ resulted in an increase in the ESP close to 15%; therefore, it is not recommended to use mixtures with a Na₂SO₄ content higher than 25% in these soils. Finally, we affirm that for M2 the maximum recommended dose for application should be 4 Mg ha⁻¹, i.e., 3 g of material per kg of soil. Full article