Extended waterlogging (WL) conditions can alter soil enzyme activities and their role in maintaining healthy soils. We assessed the effects of soil moisture regimes (field capacity [FC] and WL) and phosphorus (P) rates (0, 15, 30, 45 kg available P ha^–1) on (i) soil enzymes and microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), and microbial biomass P (MBP); and (ii) dissolved organic carbon (DOC) and total dissolved nitrogen (TDN). The treatments were tested in a 4-month greenhouse experiment using intact soil columns under annual ryegrass (Lolium multiflorum). WL decreased the activity of β-glucosidase and acid phosphomonoesterase but increasedN-acetyl-β-glucosaminidase in soils. These changes were associated with changes in MBC, DOC, MBN, and TDN, but not MBP. Anoxic conditions in WL soil promote the activity of anaerobes and contribute to the reduction of Fe oxyhydroxides and the release of DOC, TDN, and P in the soil solution. The activity of the extracellular enzymes decreased in WL with additions of slurry indicating adequate supply of C, N, and P. Our results also showed that both enzyme activities and microbial biomass were restricted in the upper soil layer with limited downward movement along the soil profile. We can conclude that since these enzymes control the hydrolysis of cellulose, phosphomonoester, and chitin, soil moisture influences the direction and magnitude of C, N, and P in manured and waterlogged soil cultivated with ryegrass.

Soil amendment effects on the mobility of potentially toxic elements (PTEs) have been hardly investigated under snowmelt flooding conditions. This research quantifies and compares the loadings of arsenic (As), copper (Cu), nickel (Ni), selenium (Se), vanadium (V), and zinc (Zn) to snowmelt from unamended, alum-, gypsum-, and Epsom salt-amended soils from a manured agricultural field and a non-manured agricultural field. In the fall of 2020, amendments were surface applied at a rate of 2.5 Mg ha⁻¹ to field plots with four replicates. Runoff boxes were installed at the plots’ edge to collect winter snow. In the spring of 2021, the snowmelt in each box was pumped out, and volume was recorded until all snow in the boxes had melted. Concentrations of PTE and other cations and pH were measured in a subsample of the snowmelt. The snowmelt from the manured field had higher Ni, Se, and V loads than that from the non-manured field. There were no significant differences in snowmelt PTE loads between the amended soils and the unamended controls at each field. Although not statistically significant, the Epsom salt-amended treatment resulted in a 75% reduction in Se loading and a 44% reduction in V loading, while the gypsum-amended treatment showed a 38% reduction in Ni loading compared to the unamended treatment in the manured soil. Overall, our findings from a single season using both manured and non-manured fields suggest that alum, gypsum, and Epsom salt additions did not significantly alter the mobility of the studied PTEs during the spring snowmelt period.

Wireless underground sensor networks (WUSNs) are gradually being applied to smart agriculture for soil information collection and monitoring of crop growth environments. WUSN can avoid the inconvenience caused by tillage and other machine operation activities on farmland and obtain multi-level and multi-dimensional parameters in the underground soil environment, which is crucial for soil moisture monitoring of crops. However, WUSN has no universally applicable transmission protocol standards in the field. Therefore, the research of different soil compositions on the placement of wireless sensor network nodes can provide scientific guidance to obtain soil moisture information of agricultural fields, which is important for the development of precision agriculture. In this paper, low-power WUSN nodes were designed, based on the modified Frisian transmission model and the complex refractive index Fresnel model. We proposed an adaptive optimization model and also proposed an improved genetic algorithm that automatically adjusts the fusion parameter according to soil and distance factors, making the prediction of signal attenuation under different soil components more accurate. We used the adaptive optimized model for signal prediction, comparing it with the modified Friis prediction model and the complex refractive index Fresnel prediction model. The results showed that the proposed adaptive optimization model with an automatic parameter is convenient to predict the signal attenuation, and the adaptive optimization model made the prediction error stay really low. To compare with other sensors in the soil environment, the temperature of the distributed fiber-optic temperature sensor was tested, which was predicted by the adaptive model. The result shows that the adaptive model is more favorable to the prediction of signal attenuation in WUSN than distributed fiber-optic temperature sensors.

The savanna (Cerrado) of northeastern Brazil has undergone significant transition in land use to expand agricultural activities. In this region, soils are highly weathered, with phosphorus (P) commonly bound to aluminum (Al) and iron (Fe), creating conditions that demand the supply of P fertilizers to build soil fertility. Conservation systems, such as integrated agroforestry, can increase the inorganic P lability. The aim of this study was to evaluate soil P availability in components of an integrated agroforestry system. Four systems were studied from a 3-year experiment: eucalyptus (E. urophylla ×E. tereticornis) rows (ER), sabiá (Mimosa caesalpiniifolia) rows (SR), inter-planted maize, and inter-planted soybean in addition to an area of native Cerrado (NC) used as a control. Inter-planted soybean and maize components showed an increase in available P in relation to NC, as a response to a liming-induced increase in soil pH and phosphate fertilization. Eucalyptus and sabiá row components showed an increase in available P in soil because of higher P recycling promoted by forest species and lower P adsorption onto Fe and Al due to the high concentrations of organic matter. Phosphorus forms, following a descending order for all components of the agroforestry system, are P–Al > P–Fe > P–Ca. This information can be used to improve management and soil quality of agricultural production in the Cerrado of the Brazilian northeast region.

Continuous monitoring of water quantities in different soil horizons is necessary to understand the behavior of infiltrated water in the soil. Under certain conditions, using measurements of natural ground gamma radiation can help us estimate soil water content measurements over a 100 m² surface within a 15 cm depth. A CS725 sensor can provide up to four daily estimates of soil water content by detecting the natural emission of gamma radiation. However, in boreal forest environments, gamma radiation mitigated by the water in the thick humus layers (litter, fermented, and humic horizon) can bias the underlying mineral soil water content measurements. The objective of this research was to evaluate the accuracy of methods that incorporate variables describing the surface humus layer into calculations of the underlying mineral soil water content, by measuring the soil’s natural gamma emission with the CS725. Using raw gamma radiation values obtained by CS725 sensors deployed over various boreal soils, we tested two functions. The first one included variables describing the humus layer and the other excluded these variables (manufacturer’s method). The function that included the descriptive humus layer variables showed superior results compared to the function without. The results of this study suggest that the CS725 sensor can adequately estimate mineral soil water content within ±10% absolute of the reference water content when examined with the following humus variables: humus layer thickness, fractioned composition, bulk density, and linear gamma radiation attenuation.

Cultivated land is prone to cracking during the high-temperature season, resulting in accelerated water evaporation, incomplete soil structure, and waste of resources caused by pollutants entering the soil. In this study, image analysis technology was used to compare the effects of two kinds of fibers on the drying and shrinkage characteristics of silt under the same volume. The results show that during cracking process, water evaporation can be divided into three phases: constant rate stage, deceleration rate stage, and residual stage. The crack rate of 0.08% basalt fiber-treated soil and 0.06% carbon fiber-treated soil is reduced by 27.66% and 27.98%, respectively. The addition of fibers acts like a bridge, narrowing the concentration of crack width from 0.2–0.8 to 0–0.6 mm, increasing short cracks of 0–5 mm and decreasing long cracks larger than 5 mm, thus reducing the soil cracking rate. With rough surface and high elastic modulus of fibers, the addition of fibers enhances the friction between soil particles to limit the movement of soil mass, and bears part of the tensile stress when cracking. It increases the tensile strength between the soil mass and effectively reduces the crack rate. It is found that the improvement effect of basalt fiber is relatively better and the economic benefit is higher under the same volume.

Despite the increasing use of portable, low-cost spectrometers in estimating soil properties, there is lack of documentation regarding the factors contributing to the lower performance of these spectrometers when compared to conventional ones. This study investigates potential factors influencing performance of the Nanoquest, a low-cost spectrometer, in estimating soil organic carbon (SOC) and total nitrogen (TN). To conduct the study, five different models (cubist, partial least squares regression, support vector machines, random forest, and generalised boosted models) were tested for the estimation SOC and TN and a fivefold cross-validation analysis was conducted for model hyperparameter optimization. The Nanoquest achieved a Lin’s concordance correlation coefficient (CCC) value of 0.84 and an R² value of 0.74 for SOC. For TN, CCC values of 0.86 and an R² value of 0.78 were obtained. To understand the impact of the spectral range and spectral resolution on SOC and TN estimation, the ASD spectra were digitally resampled to match the Nanoquest spectral range and resolution. This resampling resulted in a slight decrease in model performance for the spectral range and a more pronounced decrease for the spectral resolution.

Incorporation of soil health concept into professional practice, supported by integration into postsecondary programs, may lead to the successful maintenance and improvement of Canadian soils. The Canadian Society of Soil Science (CSSS) has identified the need to promote the teaching of the soil health concept to instructors of soil science and related courses across Canada. In summer 2023, a 37-question survey was emailed to CSSS members with the objectives of (1) gauging the understanding and interest among instructors of soil science (and related) courses across Canada in soil health, (2) describing the current status of the soil health concept in Canadian postsecondary soil science (and related) courses, and (3) assessing the need for an open access repository of educational resources focused on soil health. Survey results of 46 respondents suggest that inclusion of the concept in courses has been increasing steadily for the last 20 years, with estimated 1400 students being exposed to the concept annually in 30 courses in 6 majors, where 60% had soil in the course title. The main reasons for not including soil health in courses included lack of time and experience. Creation of a Canadian soil health repository of teaching materials would provide resources to 28% respondents (13/46) who do not include the soil health concept into their courses. Respondents indicated that the soil health concept is useful in teaching because it requires integration of a range of basic soil disciplinary concepts, a process that might be best implemented through active learning strategies.

Loss on ignition (LOI) is a common method for determining organic matter in soils. Mineral soil organic carbon content has been shown to be approximately 50%–58% of the organic matter in many soils, but the carbon fraction of LOI can actually be much lower—particularly in Spodosols. We leveraged data available in the International Soil Carbon and National Ecological Observatory Networks to evaluate departures from the common 50% rule. We offer empirical equations that more accurately predict C:LOI with depth and genetic horizon in Spodosols. These equations enable more accurate soil C stock appraisals than using assumed C:LOI ratios.

Silver nanoparticles (AgNPs) are present in biosolids from wastewater treatment facilities, a common soil amendment. Exposing earthworms (Eisenia fetida) to AgNP and AgNO₃ in soil with 0 and 7.5 g biosolids kg⁻¹ for 28 days showed AgNO₃ was more lethal to earthworms in artificial soil (LC20 ≤ 325 mg Ag kg⁻¹) than natural soil (LC20 ≥ 573 mg Ag kg⁻¹). In contrast, AgNPs were more lethal in natural soil (LC20 ≤ 425 mg Ag kg⁻¹) than artificial soil (LC20 ≥ 653 mg Ag kg⁻¹). Earthworm response to silver in artificial soil may not reflect toxicity in biosolids-amended natural soils.