Soil microbial and enzyme activities in different land use systems of the Northwestern Himalayas.

Soil microbial activity (SMA) is vital concerning carbon cycling, and its functioning is recognized as the primary factor in modifying soil carbon storage potential. The composition of the microbial community (MC) is significant in sustaining environmental services because the structure and activity of MC also influence nutrient turnover, distribution, and the breakdown rate of soil organic matter. SMA is an essential predictor of soil quality alterations, and microbiome responsiveness is imperative in addressing the escalating sustainability concerns in the Himalayan ecosystem. This study was conducted to evaluate the response of soil microbial and enzyme activities to land conversions in the Northwestern Himalayas (NWH), India. Soil samples were collected from five land use systems (LUSs), including forest, pasture, apple, saffron, and paddy-oilseed, up to a depth of 90 cm. The results revealed a significant difference (p < 0.05) in terms of dehydrogenase (9.97-11.83 TPF µg g-1 day-1), acid phosphatase (22.40-48.43 µg P-NP g-1 h-1), alkaline phosphatase (43.50-61.35 µg P-NP g-1 h-1), arylsulphatase (36.33-48.12 µg P-NP g-1 h-1), fluorescein diacetate hydrolase (12.18-21.59 µg g-1 h-1), bacterial count (67.67-123.33 CFU × 106 g-1), fungal count (19.33-67.00 CFU × 105 g-1), and actinomycetes count (12.00-42.33 CFU × 104 g-1), with the highest and lowest levels in forest soils and paddy-oilseed soils, respectively. Soil enzyme activities and microbial counts followed a pattern: forest > pasture > apple > saffron > paddy-oilseed at all three depths. Paddy-oilseed soils exhibited up to 35% lower enzyme activities than forest soils, implying that land conversion facilitates the depletion of microbiome diversity from surface soils. Additionally, reductions of 49.80% and 62.91% were observed in enzyme activity and microbial counts, respectively, with soil depth (from 0-30 to 60-90 cm). Moreover, the relationship analysis (principal component analysis and correlation) revealed a high and significant (p = 0.05) association between soil microbial and enzyme activities and physicochemical attributes. These results suggest that land conversions need to be restricted to prevent microbiome depletion, reduce the deterioration of natural resources, and ensure the sustainability of soil health.

Soil organic carbon pools and carbon management index under different land use systems in North western Himalayas.

Current study was conducted to evaluate the effect of important land uses and soil depth on soil organic carbon pools viz. total organic carbon, Walkley and black carbon, labile organic carbon, particulate organic carbon, microbial biomass carbon and carbon management index (CMI) in the north Western Himalayas, India. Soil samples from five different land uses viz. forest, pasture, apple, saffron and paddy-oilseed were collected up to a depth of 1 m (0-30, 30-60, 60-90 cm). The results revealed that regardless of soil depth, all the carbon pools differed significantly (p < 0.05) among studied land use systems with maximum values observed under forest soils and lowest under paddy-oilseed soils. Further, upon evaluating the impact of soil depth, a significant (p < 0.05) decline and variation in all the carbon pools was observed with maximum values recorded in surface (0-30 cm) soils and least in sub-surface (60-90 cm) layers. CMI was higher in forest soils and lowest in paddy-oilseed. From regression analysis, a positive significant association (high R-squared values) between CMI and soil organic carbon pools was also observed at all three depths. Therefore, land use changes and soil depth had a significant impact on soil organic carbon pools and eventually on CMI, which is used as deterioration indicator or soil carbon rehabilitation that influences the universal goal of sustainability in the long run.

Land-use systems regulate carbon geochemistry in the temperate Himalayas, India.

The Himalayan ecosystem is critical for ecological security and environmental sustainability. However, continuous deforestation is posing a serious threat to Himalayan sustainability. Changing land-use systems exert a tenacious impact on soil carbon (C) dynamics and regulate C emissions from Himalayan ecosystem. Therefore, this study was conducted to determine the changes in different C pools and associated soil properties under diverse land-use systems, viz. natural forest, natural grassland, maize field converted from the forest, plantation, and paddy field of temperate Himalaya in the surface (0-20 cm) and subsurface (20-40 cm) soils. The highest total organic carbon (24.24 g kg-1) and Walkley-black carbon contents (18.23 g kg-1), total organic carbon (45.88 Mg ha-1), and Walkley-black carbon stocks (34.50 Mg ha-1) were recorded in natural forest in surface soil (0-20 cm depth), while soil under paddy field had least total organic carbon (36.45 Mg ha-1) and Walkley-black carbon stocks (27.40 Mg ha-1) in surface soil (0-20 cm depth). The conversion of natural forest into paddy land results in 47.36% C losses. Among the cultivated land-use system, minimum C losses (29.0%) from different pools over natural forest system were reported under maize-filed converted from forest system. Land conversion causes more C losses (21.0%) in surface soil (0-20 cm depth) as compared to subsurface soil. Furthermore, conversion of forest land into paddy fields increased soil pH by 5.9% and reduced total nitrogen contents and microbial population by 28.0% and 7.0%, respectively. However, the intensity of total nitrogen and microbial population reduction was the lowest under maize fields converted from the forest system. The study suggested that the conversion of natural forest to agricultural land must be discouraged in the temperate Himalayan region. However, to feed the growing population, converted forest land can be brought under conservation effective maize-based systems to reduce C loss from the intensive land use and contribute to soil quality improvements and climate change mitigation.

Influence of Anticaking Agents and Storage Conditions on Quality Characteristics of Spray Dried Apricot Powder: Shelf Life Prediction Studies Using Guggenheim-Anderson-de Boer (GAB) Model.

Apricot powder was developed through spray drying using gum arabic as an encapsulating material at a concentration of 19%. Inlet air temperature, feed total soluble solids (TSS), feed flow rate, and atomization speed were 190 °C, 23.0 °C, 300.05 mL/h, and 17,433 rpm, respectively. This study was therefore conducted to investigate the influence of anticaking agents (tricalcium phosphate and silicon dioxide) and storage conditions (ambient and accelerated) on physicochemical, micrometric, and thermal characteristics of spray-dried apricot powder (SDAP) packaged in aluminum laminates. Both tricalcium phosphate (TCP) and silicon dioxide (SiO2) improved the shelf life and quality of SDAP, with TCP being more effective, since a lower increase in water activity (aw), moisture content, degree of caking, hygroscopicity, and rehydration time was observed in TCP-treated samples followed by SiO2-treated samples than the control. Furthermore, flowability, glass transition temperature (Tg), and sticky-point temperature (Ts) of SDAP tended to decrease in a significant manner (p < 0.05) under both storage conditions. However, the rate of decrease was higher during accelerated storage. The water activity of treated samples under ambient conditions did not exceed 0.60 and had a total plate count within the permissible range of 40,000 CFU/g, indicating shelf stability of the powder. The predicted shelf life of powder obtained from the Guggenheim−Anderson−de Boer (GAB) model and experimental values were very similar, with TCP-treated samples having a predicted shelf life of 157 days and 77 days under ambient and accelerated storage conditions, respectively. However, the respective experimental shelf life under the same conditions was 150 and 75 days, respectively. Similarly, the predicted shelf life of SiO2-treated samples under ambient and accelerated storage was 137 and 39 days, respectively, whereas the experimental values were 148 and 47 days, respectively. In conclusion, TCP proved more effective than SiO2 at preserving shelf life by preventing moisture ingress.