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"Soil - chemistry"
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Different kinds of soil
Introduces children to the composition of soil, its layers, and what organic and inorganic matter is found in soil. Comparisons of soil particles help describe different types of soil, soils from different climates, how soil type effects plant and animal life, and the value of fertile soil.
Book
Combined use of biochar and zinc oxide nanoparticle foliar spray improved the plant growth and decreased the cadmium accumulation in rice (Oryza sativa L.) plant
The contamination of large areas of arable land with cadmium (Cd) is a serious concern worldwide and environmentally feasible amendments are necessary to minimize Cd accumulation in cereals such as rice (
Oryza sativa
L.). A pot study was, therefore, conducted to evaluate the efficiency of foliar spray of different levels (0, 50, 75, 100 mg/L) of zinc oxide nanoparticles (ZnO NPs) alone or combined with biochar (1.0%
w
/
w
) on Cd content in rice plants grown on an aged Cd-polluted soil. The results showed that ZnO NPs alone or combined with biochar improved the biomass and photosynthesis of rice plant. The ZnO NPs significantly diminished the Cd concentration and enhanced the Zn concentrations in shoots and roots either alone or in combination with biochar. Foliar spray of 100 mg/L ZnO NPs significantly diminished the Cd content in rice shoot and rice roots by 30% and 31%, respectively. The Cd concentrations in rice shoot and root diminished by 39% and 38% after 100 mg/L ZnO NPs combined with biochar, respectively. The ZnO NPs in combination with biochar increased the soil pH from 8.03 to 8.23 units. Soil AB-DTPA-extractable Cd significantly reduced with the amendments applied over the control. Foliar spray of ZnO NPs combined with biochar could be used to grow rice plants especially in areas where Cd concentration is high and Zn deficiency is high.
Journal Article
Nutrient-induced acidification modulates soil biodiversity-function relationships
Nutrient enrichment is a major global change component that often disrupts the relationship between aboveground biodiversity and ecosystem functions by promoting species dominance, altering trophic interactions, and reducing ecosystem stability. Emerging evidence indicates that nutrient enrichment also reduces soil biodiversity and weakens the relationship between belowground biodiversity and ecosystem functions, but the underlying mechanisms remain largely unclear. Here, we explore the effects of nutrient enrichment on soil properties, soil biodiversity, and multiple ecosystem functions through a 13-year field experiment. We show that soil acidification induced by nutrient enrichment, rather than changes in mineral nutrient and carbon (C) availability, is the primary factor negatively affecting the relationship between soil diversity and ecosystem multifunctionality. Nitrogen and phosphorus additions significantly reduce soil pH, diversity of bacteria, fungi and nematodes, as well as an array of ecosystem functions related to C and nutrient cycling. Effects of nutrient enrichment on microbial diversity also have negative consequences at higher trophic levels on the diversity of microbivorous nematodes. These results indicate that nutrient-induced acidification can cascade up its impacts along the soil food webs and influence ecosystem functioning, providing novel insight into the mechanisms through which nutrient enrichment influences soil community and ecosystem properties.Nutrient enrichment is a major global change component. Here the authors show that soil acidification induced by nutrient enrichment, rather than changes in mineral nutrient and carbon availability, modulates soil biodiversity-function relationships
Journal Article
Meta-analysis of the impacts of global change factors on soil microbial diversity and functionality
Biodiversity on the Earth is changing at an unprecedented rate due to a variety of global change factors (GCFs). However, the effects of GCFs on microbial diversity is unclear despite that soil microorganisms play a critical role in biogeochemical cycling. Here, we synthesize 1235 GCF observations worldwide and show that microbial rare species are more sensitive to GCFs than common species, while GCFs do not always lead to a reduction in microbial diversity. GCFs-induced shifts in microbial alpha diversity can be predominately explained by the changed soil pH. In addition, GCF impacts on soil functionality are explained by microbial community structure and biomass rather than the alpha diversity. Altogether, our findings of GCF impacts on microbial diversity are fundamentally different from previous knowledge for well-studied plant and animal communities, and are crucial to policy-making for the conservation of microbial diversity hotspots under global changes.
It is often assumed that various types of anthropogenic change reduce microbial diversity and function. Here, the authors do a meta-analysis showing that global change factors affect microbial diversity inconsistently; negative effects are most likely for global change factors that affect soil pH.
Journal Article
Evaluating the impacts of microplastics on agricultural soil physical, chemical properties, and toxic metal availability: An emerging concern for sustainable agriculture
Microplastics (MPs) are an emerging environmental issue that might endanger the health of agricultural soil. Even though several research on the particular toxicity of MPs to species have been carried out, there is little information on MPs’ impacts on soil physicochemical properties and heavy metals (HMs) availability of HMs contaminated and without contaminated soils. This study examined the changes in soil characteristics for both HMs contaminated and without contaminated soils by five distinct MPs, including Polyethylene (PE), Polyethylene terephthalate (PET), Polystyrene Foam (PS), Polyamide (PA), and a combination of these four types of MPs (Mixed MPs), at two different concentrations (0.2% and 1%; w/w), where soil incubation experiments were setup for this studies and the standard analytical techniques employed to measure soil characteristics and toxic metal availability. After the ending of soil incubation studies (90 days), significant changes have been observed for physicochemical properties [bulk density, porosity, water holding capacity, pH, electrical conductivity (EC), organic carbon (OC), and organic matter (OM)]. The soil nutrients change in descending order was found as NH 4 + -N> PO 4 3+ > Na > Ca > NO 3 - > Mg for lower concentrations of MPs compared to higher concentrations. The HMs availability is reducing with increasing MPs concentration and the descending order for metal availability was as follows Pb > Zn > Cd > Cr > Cu > Ni. Based on MP type, the following descending order of MPs PS > Mix (MPs) > PA > PET > PE, respectively act as a soil properties influencer. Usually, effects were reliant on MPs’ category and concentrations. Finally, this study concludes that MPs may modify metal movements, and soil quality; consequently, a possible threat will be created for soil health.
Journal Article
Metallic micronutrients are associated with the structure and function of the soil microbiome
The relationship between metallic micronutrients and soil microorganisms, and thereby soil functioning, has been little explored. Here, we investigate the relationship between metallic micronutrients (Fe, Mn, Cu, Zn, Mo and Ni) and the abundance, diversity and function of soil microbiomes. In a survey across 180 sites in China, covering a wide range of soil conditions the structure and function of the soil microbiome are highly correlated with metallic micronutrients, especially Fe, followed by Mn, Cu and Zn. These results are robust to controlling for soil pH, which is often reported as the most important predictor of the soil microbiome. An incubation experiment with Fe and Zn additions for five different soil types also shows that increased micronutrient concentration affects microbial community composition and functional genes. In addition, structural equation models indicate that micronutrients positively contribute to the ecosystem productivity, both directly (micronutrient availability to plants) and, to a lesser extent, indirectly (via affecting the microbiome). Our findings highlight the importance of micronutrients in explaining soil microbiome structure and ecosystem functioning.
Soil micronutrients may be important for belowground biota and associated functions. Here, the authors identify the relationships between metallic micronutrients and soil microbial communities and functions across 180 sites, and validate them in a soil incubation experiment.
Journal Article
Factors affecting variations of soil pH in different horizons in hilly regions
Soil pH is a key factor that controls soil nutrient availability, soil microbial activities, and crop growth and development. However, studies on the soil pH variations of cultivated lands in different horizons at the regional scale remain limited. In this work, 348 soil samples were collected from three soil horizons (A, B, and C) at 120 sites over the hilly region of Chongqing, southwestern China. Six topographic indicators, four climate parameters, and parent material were considered. Classification and regression trees (CARTs) were applied to investigate the relationships between soil pH and the variables in the A, B, and C horizons. Model performances were evaluated by root mean square error (RMSE), relative root mean square error (RRMSE), and coefficient of determination (R2). Results showed that soil pH increased obviously from the A to C horizons. Soil pH was predicted well by the forcing factors with the CART models in all horizons. RMSE, RRMSE, and R2 varied between 0.37 and 0.435, between 5.93 and 7.23%, and between 0.71 and 0.80, respectively. The relative importance of the studied variables to soil pH differed with the horizons. Annual temperature range (ATR), terrain wetness index (TWI), and Melton ruggedness number were critical factors that controlled soil pH variability in the A horizon. Parent material, precipitation of warmest quarter (PWQ), ATR, and TWI were important variables in the B horizon. Parent material, PWQ, ATR, and precipitation were key factors in the C horizon. The results are expected to provide valuable information for designing appropriate measurements for agricultural practices and preventing soil acidification.
Journal Article