Biochar Application Can Improve Most of the Chemical Properties of Acidic Soils: A Global Meta-Analysis

Stable gullies provide a suitable habitat for functional insects and reduce the threat of pests on crops in farmland of Northeast China

AbstractGullies with lower altitudes compared to the surrounding environment are widely distributed in farmland of the watershed and their numbers are still expanding. However, it is still unclear how these gullies regulate the functional insects in farmland. In this study, land use types combined with the herbaceous plant, herbicide application, soil moisture, topography and climatic factors during crop growth were considered to understand how gullies influence the dynamics of functional insects in farmland from a watershed (240 ha) of Northeast China. The primary findings demonstrate that the richness and abundance of functional insects are generally greatest in gullies, particularly in stable gullies, and decrease in the following order: forest belts, grasslands, and farmlands within the watershed. Notably, the ratios of beneficial insects to pests (BI/Pest) in terms of richness and abundance were lower in gullies before July but reversed after July, in comparison to farmland. Stable gullies exhibited higher BI/Pest abundance and diversity ratios than developing gullies. The richness and abundance of functional insects were higher in the middle sections of gullies compared to their heads and tails. Furthermore, the ratios of BI/Pest were generally lower in farmlands than in any gully position. Functional insect dynamics were mainly determined by season, followed by plant abundance and biomass in the gullies, and rarely by soil moisture in the both watershed and single gullies scales. Generally, the richness and abundance of functional insects in farmland were mainly influenced by gullies, especially influenced by the gully middle position. Insect composition in farmland influenced by stable gullies was stronger than by developing gullies, and stable gullies were more beneficial in reducing the threat of pests to crops in the farmland of the watershed.

Middle concentration of microplastics decreasing soil moisture-temperature and the germination rate and early height of lettuce (Lactuca sativa var. ramosa Hort.) in Mollisols

Extraction and decontamination of microplastics from high organic matter soils: A simple, cost-saving and high efficient method

Microplastics change the leaching of nitrogen and potassium in Mollisols

Microplastic migration and distribution in the terrestrial and aquatic environments: A threat to biotic safety

Crops Change the Morphology, Abundance, and Mass of Microplastics in Mollisols of Northeast China

Degradation of microplastics (MPs) by both physicochemical and biological processes in the natural environment is determined by the enzymes inside the soil, and which was severely influenced by crop growth and straw amendment (SA). However, it is still unclear how crop growth and SA influence degradation of MPs in soils. In this study, both catalase and sucrase were measured, and the stereomicroscope combined with microscopic infrared spectroscopy and scanning electron microscope (SEM) was used to detect the morphology and quantity of low-density polyethylene microplastic (LDPE-MP) and low-density polypropylene microplastic (LDPP-MP), after crop growth (maize and soybean, with and without SA, 1 and 2% MP) in an outdoor pot experiment, in the Mollisols. The results showed that the growth of the crops changed the morphology, functional groups (e.g., methylene, carbonyl), total mass, and abundance ratio of MPs of different sizes. These were possibly caused by enzymes that were significantly influenced by crop types, abundance, and types of MPs in the soils. Maize growth decreased the mass of LDPE-MP and LDPP-MP by 28.7 and 32.7%, respectively, and 2% (w/w) of LDPP-MP addition in soil decreased mass of 9%, which was higher than that in 1% (w/w) LDPP-MP addition in soil. Soybean growth with SA decreased the mass of LDPE-MP and LDPP-MP by 36.6 and 20.7%, respectively, than the control treatment (CK). Compared with CK, both crop growth and SA changed the abundance of MPs of different sizes and decreased the mean size of MPs. The LDPE-MP could be more easily degraded by enzymes in the soils compared to LDPP-MP when the MP size was smaller with surface roughness. Generally, both maize and soybean growth can accelerate MP change in soils, and MP change process was mainly determined by SA, MP types, and the dose effect of MP.

Nutritional requirements and precise fertilization of wine grapes in the eastern foothills of Helan Mountain

Field management changes the distribution of mesoplastic and macroplastic in Mollisols of Northeast China

Heterogeneity of plastic residue was determined by both mulch film and external plastic pollutants in the farmland of Northeast China

Effect of biochar application method and amount on the soil quality and maize yield in Mollisols of Northeast China

AbstractThere have been many studies on soil quality and crop yield using different biochar application amounts, but few studies have focused on the combination of different methods and amounts of biochar application in moderately degraded Mollisols. In this study, the methods of mixing biochar evenly with the soil of the plough layer (0–20 cm depth) [homogeneous biochar application (HO)] and burying biochar above the soil plow pan (under 20 cm depth) (heterogeneous biochar application (HE)) were used to reveal how biochar application methods influenced soil quality, crop yield and agronomic characteristics in moderately degraded Mollisols (soil organic matter (SOM), 30.33 g kg−1). The biochar application amounts were 0 (control), 10 (level 1), 20 (level 2), and 40 (level 3) t ha−1 in both the HO and HE treatments. The results showed that, compared with control, HO3 significantly increased maize yield in the first year, and HO2, HO3, HE2 and HE3 continuously increased maize yield in the next three years but not significantly. HO1 and HE1 had the lowest maize yield. HO2 tended to delay maize leaf senescence. There was a positive linear relationship between soil quality index (SQI) and biochar application amount in HO. Compared with other treatments, the pH, EC, SOM, available phosphorus, sucrase and catalase activities were highest in HO3. However, the effects of HE on soil quality and crop productivity were limited at first but gradually increased with time. Overall, HO3 was beneficial for improving the soil quality and crop productivity in Mollisols for short-term cultivation (3-year), while HE showed an effect over time. Graphical Abstract

Microbial Community and Their Potential Functions after Natural Vegetation Restoration in Gullies of Farmland in Mollisols of Northeast China

Although huge numbers of gullies have been widely formed and have severely decreased the quality of farmlands in mollisols, it is still unclear how the microbial community distributes after natural vegetation restoration (NVR), which highly relates to the ecological functions in the farmland. In this study, both the microbial community and their potential ecological functions after NVR were reviewed, together with the environmental factors relating to microbial evolution which were detected in two gullies of mollisols situated on farmland in Northeast China. The main results showed that NVR improved the microbial diversity and complexity of the co-occurrence network in gullies, and promoted bacterial community composition to be similar between the gully and deposition area. Moreover, the soil organic matter (SOM) regulated the microbial diversity by balancing soil available phosphorus (AP), soil moisture (SM), and pH, thus stimulating the key bacterial biomarkers of gullies (Rhizobiales, Microtrichales, TRA3-20) and regulating the bacterial composition, as well as indirectly enriching the function of bacteria to perform denitrification, C fixation, and phosphorus transport in gullies. In addition, abundant Dicotyledons in gullies mainly regulate the fungal community composition, and increased fungal richness in 0–20 cm soil depth, but decreased bacteria richness in 0–20 cm soil depth. Our findings revealed the repair mechanism of NVR on soil bacterial and fungal communities, especially on bacterial functionality, which should be given further attention in nutrient cycling across eroding mollisols in gullies.

Non-biodegradable microplastics in soils: A brief review and challenge