Relatively few studies have been performed to characterize municipal solid waste (MSW) at household level. This is due in part to the difficulties involved with collecting the data and selecting an appropriate statistical sample size. The previous studies identified in this paper have used statistical tools appropriate for analysing data collected at a material recovery facility or landfill site. This study demonstrates a statistically sound and efficient approach for characterizing MSW at the household level. Moreover, a household approach also allowed for consideration of the socio-economic conditions, level of waste generation, geography, and demography. The study utilized two-stage cluster sampling within strata in Kathmandu Metropolitan City (KMC) to measure MSW for 2 weeks. In KMC, the average household solid waste generation was 161.2 g capita ^—1 day^{— 1}with an average generation rate between 137.7 and 184.6 g capita^—1 day^—1 for a 95% confidence interval and 14.5% relative margin of error. The results show a positive relation between income and waste production rate. Organic waste was the biggest portion of MSW, and hazardous waste was the smallest of the total. Sample size considerations suggest that 273 households are required in KMC to attain a 10% relative margin of error with a 95% confidence interval.

Soil degradation due to loss of soil organic carbon is a serious concern in semiarid agroecosystems. Biochar and other organic char products have long been known to increase soil organic carbon. In this study, three-year field observations were carried out on use of coal char (CC) and biochar (BC) as soil amendments in unirrigated semiarid rangeland soil. Coal was pyrolyzed at three different temperatures of 650, 750, and 800 °C to form CC650, CC750, and CC800, respectively, and BC was obtained from a local commercial producer. Manure, CC, and BC were incorporated in soil at 10% (v/v). Analyses of plant growth (aboveground biomass) and soil properties were performed and compared with the control treatment without char. In all three years, CC applied with manure (CC650M) produced significantly greater grass biomass, by 95, 42, 101%, and BC applied with manure (BCM) increased grass biomass by 89, 39, 52% in 2018, 2019, and 2020, than the controls in the respective years. Soil tests a year after application of char indicated significantly increased soil organic matter (OM) with CC and BC treatments (1.60–2.93%) compared with the control (1.37%). However, further detailed studies are required to investigate CC and BC interactions with soil in unirrigated semiarid rangelands.

Sustainable use of croplands is facing a challenge to maintain organic carbon (C) in soil. Pyrolyzed coal or coal char (CC) is a porous C material produced from the pyrolysis of coal containing high organic C, large surface area, and low bulk density like biochar (BC). This study evaluates corn (Zea mays L.) grain yield and selected soil properties in soil amended with CC and BC at two rates (22 and 44 Mg ha⁻¹) with farmyard manure (FM) (66 Mg ha⁻¹) and without FM addition. This field experiment was performed in sandy loam soil at the University of Wyoming’s Sustainable Agricultural Research and Extension Center (SAREC), Lingle, WY, USA. Two years of field study results indicated CC and BC applied at 22 Mg ha⁻¹ with FM resulted in significantly greater average corn grain yields (13.04–13.57 Mg ha⁻¹) compared to the no char’s treatment (11.42 Mg ha⁻¹). Soil organic matter (SOM) content was significantly greater in the higher application rates of CC and BC than in treatments without chars. Overall, soil nitrate nitrogen (NO₃-N), phosphorous (P), and potassium (K) were found significantly greater in CC and BC co-applied with FM treatments. Soil water-holding capacity (WHC) significantly improved in sandy loam soil (up to 27.6% more than the no-char treatment) at a greater concentration of char materials. This study suggests that char materials applied at a moderate rate (22 Mg ha⁻¹) with FM can improve soil properties and crop yield.

Research indicates arbuscular mycorrhizal fungi (AMF) inoculum potential and AMF biomass production in agricultural soil are strongly influenced by both soil moisture availability and crop rotation (CR) strategies. We hypothesized that AMF biomass production in and inoculum potential of Wyoming semiarid agricultural soil would increase when managed using CR and irrigation. To test this hypothesis, we examined AMF activity (AMF biomarker fatty acid, and AMF infection of roots) in two differently managed soils (no-CR soil and two-year CR soil) in a field experiment. Furthermore, in a greenhouse experiment, we examined AMF activity in the same two CR treatment soils under different irrigation regimes (wet, irrigated to 60% field capacity, and dry, irrigated to 15% field capacity). Notably, the two-year CR soil had greater amounts of AMF biomarker fatty acid and greater inoculum potential, and higher percentage of AMF root colonization compared to no-CR soil. Despite the fact that the CR soil had more AMF propagules, it was less than the undisturbed non-agricultural native sage-grassland soils previously reported. Overall, the findings suggest that high levels of irrigation can inhibit the activity of AMF adapted to semiarid soil conditions and CR can increase activity of AMF in soils from semiarid regions.

Carbon-rich products such as biochar and coal char have emerged as promising soil amendments to improve soil properties and support plant growth in semiarid climates. Coal char is produced from the pyrolysis of coal, while biochar is a biomass-derived product from pyrolysis. A two-year field study was conducted to evaluate the comparative impacts of coal char, biochar, inorganic fertilizer, and manure amendments on soil properties, plant growth indices, and soil and plant nutrient dynamics in a semiarid, sandy clay loam soil in Wyoming, USA. The study demonstrates the value of multivariate approaches for capturing the complex, interactive effects of amendments and plant covariates on crop performance. Results show that, while char and amendment treatments did not significantly alter soil pH, EC, or CEC, both char type and fertilizer amendments significantly affected soil nutrient availability and plant tissue nutrient concentrations. Multivariate multiple linear regression (MMLR) showed coal char at 22–44 Mg ha⁻¹ increased yield by up to 4.4 t ha⁻¹, with higher Normalized Difference Red Edge (NDRE) and leaf sulfur (S) concentrations associated with reduced sugar loss to molasses. Our results suggest that coal char has potential as a sustainable amendment for improving sugar beet productivity in semiarid, sandy clay loam soils, especially when integrated with inorganic fertilizer and manure. Further research is needed to assess the variability of coal char and biochar and their cumulative impacts on soil health and productivity across different cropping systems.