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Biochar, as a soil conditioner, has been widely used to promote the growth of maize, but most of the current research is short-term experiments, which limits the research on the long-term effects of biochar, especially the physiological mechanism of biochar on maize growth in aeolian sandy soil is still unclear. Here, we set up two groups of pot experiments, respectively after the new biochar application and one-time biochar application seven years ago (CK: 0 t ha -1 , C1: 15.75 t ha -1 , C2: 31.50 t ha -1 , C3: 63.00 t ha -1 , C4: 126.00 t ha -1 ), and planted with maize. Subsequently, samples were collected at different periods to explore the effect of biochar on maize growth physiology and its after-effect. Results showed that the plant height, biomass, and yield of maize showed the highest rates of increase at the application rate of 31.50 t ha -1 biochar, with 22.22% increase in biomass and 8.46% increase in yield compared with control under the new application treatment. Meanwhile, the plant height and biomass of maize increased gradually with the increase of biochar application under the one-time biochar application seven years ago treatment (increased by 4.13%-14.91% and 13.83%-58.39% compared with control). Interestingly, the changes in SPAD value (leaf greenness), soluble sugar and soluble protein contents in maize leaves corresponded with the trend of maize growth. Conversely, the changes of malondialdehyde (MDA), proline (PRO), catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) manifested an opposite trend to the growth of maize. In conclusion, 31.50 t ha -1 biochar application can promote the growth of maize by inducing changes in its physiological and biochemical characteristics, but excessive biochar application rates ranging from 63.00-126.00 t ha -1 inhibited the growth of maize. After seven years of field aging, the inhibitory effect of 63.00-126.00 t ha -1 biochar amount on maize growth disappeared and changed to promoting effect.

The effects of biochar on soil improvement have been widely confirmed, but its influence on soil microorganisms is still unclear. Elucidating the complex relationship and the community assembly processes of microorganisms under biochar addition is important to understand the ecological effects of this substance. We performed a one-time addition of biochar on aeolian soils and planted maize (Zea mays L.) continuously for 7 years. Afterwards, soil samples were collected, and the 16S/ITS rRNA gene sequencing technology was used to study changes in microbial community structure, network characteristics, and community assembly processes in the aeolian soils. We found that biochar addition significantly increased the maize yield and changed the soil microbial community composition (β-diversity), but had no significant effect on the microbial α-diversity. The addition of 31.5–126.0 Mg ha−1 of biochar led to a reduction of the rhizosphere bacterial network’s edge number, average degree, and robustness, but had no significant effect on the fungal network properties. The bacterial community was controlled by deterministic processes, while fungi were mainly controlled by stochastic processes. The addition of 126.0 Mg ha−1 of biochar led to a transformation of the bacterial community’s assembly processes from deterministic to stochastic. These results indicate that the stability of the rhizosphere bacterial community’s complex network in aeolian soils diminishes under biochar addition, together changed the bacterial community’s assembly processes. Fungi can instead effectively resist the environmental changes brought by biochar addition, and their network remains unchanged. These findings help clarify the effect of biochar addition on microbial interaction and assembly processes in aeolian soils characteristic of arid regions.Key points• Biochar addition led to changes in the microbial community composition• Biochar addition reduced the network’s stability of rhizosphere bacteria• Biochar addition changed the processes of the bacterial community assembly

Aeolian sandy soil is barren and readily leads to low fertilizer utilization rates and yields. Therefore, it is imperative to improve the water and fertilizer retention capacity of these soils. In this paper, three kinds of biochar (rice husk, corn stalk, and bamboo charcoal) and bentonite were used as amendments in the first year of the experiment. In the second year, only corn stalk biochar was applied. The effects of biochar and bentonite on the physicochemical and biological characteristics of aeolian sandy soil and corn agronomic traits were studied through a 2-year field experiment, and the carbon sequestration and emission reduction potential of biochar in aeolian sandy soil were explored. The results showed that the input of biochar and bentonite effectively improved water content and reduced soil bulk density. Compared with the same treatment in the first year, the content of water-stable aggregates with particle sizes greater than 0.25 mm, mean weight diameter and geometric mean diameter of the corn stalk biochar mixed with bentonite treatment significantly increased in the second year. Biochar and bentonite significantly increased the soil organic matter content, pH, cation exchange capacity (CEC) and available nitrogen, phosphorus and potassium contents, and CEC increased by 150.4%. Soil available phosphorus increased 2.6 times compared with that of the fertilizer treatment. Soil alkali-hydrolyzable nitrogen content increased by 211.5%, respectively. The plant height, leaf area index and ground dry matter mass also increased significantly, and the corn yield increased by 36.6% in response to the mixed application of 1.9 t/hm 2 corn stalk biochar and 12 t/hm 2 bentonite. The contents of urease, sucrase and catalase increased first and then decreased with crop growth through the jointing, silking and maturity stages. The microbial carbon content increased 2.4 times in the second year when corn stalk biochar was applied compared with that in the first year. The carbon sequestration potential of biochar application was equivalent to offsetting CO 2 emissions by approximately 100 million tons per year of the study.

Aim In arid and semi-arid regions, soil phosphorus (P) deficiency often limits the development of agriculture. Intercropping is considered as a key mode to improve P use-efficiency in P poor soils. This study aimed to investigate the effect of P fertilization and intercropping on plant growth, nitrogen (N) and P uptake of millet and soybean across three soil types. Methods A greenhouse pot experiment was conducted, and three factors were designed, including P supply levels (0, 30, and 150 mg kg –1 ), planting modes (monocultured millet, monocultured soybean, and intercropped millet-soybean), and soil types (the loess soil, Aeolian sandy soil, and mixed soil). Plant P uptake, root organic acid contents and phosphatase activity were used to characterize the P-utilization potential of plants. Key results Both P supply and intercropping increased plant dry mass, but no significant interaction between P and planting modes was observed. Maize N and P uptake under intercropping was greater than that under monoculture in most treatments. Soybean secreted more kinds of carboxylate than millet. Both P30 and intercropping enhanced exudation of tartrate, succinate, malate, and malonate by roots. Soil alkaline phosphatase activity in the mixed soil was higher than that in the loess soil. Conclusions Adding P and intercropping can promote plant growth, N and P uptake. Increased soil phosphatase activity and carboxylate secretion by roots were the key mechanisms for soil P mobilization. This study can provide a feasible scheme for agricultural production in arid and semi-arid areas.

Aeolian soil erosion is responsible for erosional landforms, or deflation patches, that are ubiquitous in the Kangerlussuaq region of West Greenland. Deflation patches are identifiable as bare regions within a mosaic of shrub and graminoid tundra, and have the potential to alter regional carbon cycling and vegetation dynamics. Understanding the spatial distribution of deflation patches is an important first step in establishing the drivers, controls, and ecological impacts of wind erosion in the region. Using high-resolution WorldView-2 satellite imagery, we created a land cover classification and percentage vegetation cover map to investigate the regional distribution and variability of deflation patches. Across the study area, deflation patches account for 22 percent of the terrestrial land surface and occur in greater density closer to the Greenland Ice Sheet (GrIS). Farther away from the GrIS, local topography plays a larger role in determining the distribution of deflation patches, with wind erosion tending to occur on steep south-southeast-facing slopes. Parallels between the distribution of deflation patches and local wind patterns suggest that katabatic winds are an important driver behind deflation patch occurrence. Within deflation patches, graminoid cover increases with distance from the GrIS, due either to a lesser degree of erosion or to a longer recovery time. In the context of recent circumpolar shrub expansion, deflation might locally limit the dominance of shrubs by creating habitat more suitable for graminoids and is an important factor to consider when predicting vegetation changes in West Greenland.

Humic acid (HA) is considered a promising soil amendment for improving soil fertility. However, the effects of HA application on the microbial community, especially in aeolian sandy soils of semi-arid regions, remain insufficiently elucidated. To address this gap, a field experiment was conducted to investigate the changes in soil properties, bacterial and fungal diversity, and community structure in a buckwheat field in the fourth year after a single application of lignite humic acid (L-HA) at 0 (L-HA0), 2 (L-HA1), 4 (L-HA2), and 6 (L-HA3) ton·ha−1 in an aeolian sandy soil in Inner Mongolia, China. The results demonstrated that four years after L-HA application, there was a significant (p < 0.05) decrease in soil pH, accompanied by an increase in soil water content and nutrient levels, including organic matter and total N, available P, and K. Additionally, the application of L-HA enhanced microbial biomass C and N and stimulated enzyme activities, such as urease and invertase, with these effects being more pronounced at higher application rates (L-HA2 and L-HA3). However, HA addition did not significantly (p < 0.05) affect soil microbial biomass P or alkaline phosphatase activity. The L-HA amendment enhanced the α-diversity indices of soil bacteria but did not significantly (p < 0.05) affect soil fungal diversity. The addition of L-HA induced significant changes in the composition of the soil microbial community at both the phylum and genus levels, with significant variability in microbial responses observed across the different L-HA application rates. The incorporation of L-HA notably enriched the composition of bacterial and fungal communities at the phylum level, particularly those involved in carbon cycling, including the bacterial phyla Proteobacteria and Actinobacteriota and the fungal phyla Ascomycota and Rozellomycota. At the genus level, higher L-HA application rates, specifically L-HA2 and L-HA3, exerted statistically significant (p < 0.05) effects on most bacterial and fungal genera. Specifically, these treatments increased the abundance of bacterial genera, such as Rokubacterium and fungal genera, including Plectosphaerella, Tausonia, Talaromyces, and Clonostachys. Conversely, the relative abundance of the bacterial genera Vicinamibacter and Subgroup_7, as well as the fungal genus Niesslia, was significantly reduced. Redundancy analysis (RDA) indicated that bacterial community compositions were closely associated with soil parameters, such as available P (AP), microbial biomass carbon (SMC), microbial biomass nitrogen (SMN), microbial biomass phosphorus (SMP), and invertase, while all tested soil parameters, except for alkaline phosphatase, significantly influenced the fungal community structure. Given that the changes in these soil parameters were highly correlated with the amounts of L-HA addition, this suggests that the impacts of long-term L-HA amendment on the soil bacterial and fungal communities were linked to alterations in soil physicochemical and biological properties.

The Maowusu Desert is still suffering from serious ecological and environmental security issues such as wind erosion and desertification, influenced by both natural and human factors. The amendment of aeolian sandy soil with soft rock material presents an effective erosion control strategy, leveraging the complementary structural and compositional properties of both materials to enhance soil stability and rehabilitate degraded environments. However, there are few studies that investigate the effect of soil surface electrochemical properties and particle interaction forces on the structural stability of compound soils with soft rock and sandy soil. This decade-long field study quantified the electrochemical properties and interparticle forces and their synergistic effects on structural stability across five soft rock-to-aeolian sandy soil blend volume ratios (0:1, 1:5, 1:2, 1:1, 1:0) within the 0–30 cm soil profile. The results showed that the soil organic matter (SOM), specific surface area (SSA), and cation exchange capacity (CEC) significantly increased with the incorporation of soft rock material. For five different proportions, with the addition of soft rock and the extension of planting years, the content of SOM increased from 5.65 g·kg−1 to 11.36 g·kg−1, the CEC varied from 4.68 cmol kg−1 to 17.91 cmol kg−1, while the σ0 importantly decreased from 1.8 to 0.47 c m−2 (p < 0.05). For the interaction force at 2.4 nm between soil particles, the absolute value of van der Waals attractive force increased from 0.10 atm to 0.38 atm, and the net force decreased from 0.09 atm to −0.30 atm after the incorporation ratios of soft rock from 0:1 to 1:1. There was a significant negative correlation between the resultant net force between the particles of compound soil and the SSA and CEC. These results indicate that the addition of soft rock material positively improves the surface electrochemical properties and internal forces between aeolian sandy soil particles, further enhancing its structural stability. This study establishes a foundational theoretical framework for advancing our mechanistic understanding of aeolian sand stabilization and ecosystem rehabilitation in the Mu Us Desert.

Soil aggregates are the material basis of soil structure and important carriers of nutrients. Long-term application of organic and inorganic fertilizers can affect the composition of soil aggregates to varying degrees, which in turn affects the distribution and storage of soil nutrients. We report the results of a 15-year long-term field-based test of aeolian sandy soil and used the wet sieve method to analyze the stability of water-stable aggregates, as well as the distribution characteristics of nutrients in different particle size aggregates. Our results show that long-term application of organic fertilizer (M3) and combined organic–inorganic treatments (NPK1-M1, NPK1-M2, and NPK1-M3) help to increase the amount of organic carbon, inorganic carbon, and cation exchange in the macro-aggregates, and the improvement rates are 92–103%, 8–28%, and 74–85%, respectively. The organic content of the fertilizers also promotes the formation of macro-aggregates, and the stability of aggregates increase from 0.24 to 0.45. In contrast, the application of inorganic fertilizers (NPK1, NPK2, and NPK3) has no marked effect on the formation and stability of macro-aggregates; the application of inorganic fertilizers can merely maintain the organic carbon content of the soil. Correlation analysis shows that the application of organic fertilizers and chemical (inorganic) fertilizers containing phosphorus and potassium can markedly increase the content and reserves of available phosphorus and potassium across all aggregate sizes, and there is a significant positive correlation between these parameters and the amount of applied fertilizer (p < 0.05). Aggregates of various sizes in aeolian sandy soils in arid areas have the potential for greater nutrient storage. Therefore, organic fertilizers can be used in the agricultural production process to improve soil structure and fertility.

Understanding the distribution of water and nitrate nitrogen in the soil profile is crucial for the reasonable operation of fertigation, and it is also fundamental for controlling and regulating nitrate nitrogen in the root zone, thereby meeting a crop’s requirements. The application rates of fertilizer and water directly influence this distribution of water and nitrate nitrogen. However, the effects in Aeolian sandy soil, a type of developing soil bordering deserts, remain ambiguous. In this study, field experiments for different drip fertigation treatments in Aeolian sandy soil were conducted to investigate the soil water distribution, as well as that of nitrate nitrogen. A completely randomized experimental design was implemented, encompassing three levels of irrigation amount: low (W1), medium (W2), and high (W3), and three levels of nitrogen application rate: low (F1), medium (F2), high (F3). After the completion of each irrigation treatment, soil samples were extracted at 10–20 cm intervals. The soil water and nitrate nitrogen contents in the profiles of these samples were measured. The experimental results revealed that increasing the nitrogen application rate facilitated the retention of greater amounts of water and nitrate nitrogen in the soil profile. However, with an increase in the nitrogen application rate, both soil water and nitrate nitrogen exhibited a radial tendency to move away from the drip emitter. Some moved upward and accumulated in surface soil near a ridge furrow, while some moved downward and remained in a deeper area approximately 30 cm horizontally from the emitter at depths of 40–60 cm. The uniformity of the water distribution decreased with increasing nitrogen application under low water conditions, with a reversal of this trend observed in medium and high water treatments. The effect of nitrogen application level on the uniformity of the nitrate nitrogen distribution was not significant. There was no significant correlation between the average soil water content and nitrate nitrogen content along the horizontal direction, however, a positive correlation existed in the vertical direction. In the whole profile, increasing the nitrogen application enhanced the correlation under low water conditions, but under medium and high water conditions, this trend was the opposite. This implies that, to avoid nitrate nitrogen leaching or limiting in a specific area, a moderate nitrogen application level is advisable. Under low water conditions, nitrogen application showed a positive effect on the nitrate nitrogen content, and a higher application is recommended. In cases of substantial water irrigation or rainy years, the nitrogen application rate should be decreased.

Background No-tillage (NT) is a widely used field management to reduce soil erosion and degradation and is suggested to be beneficial for enhancing soil carbon (C) sequestration capacity. Nonetheless, the effects of NT on soil total carbon (TC) content in aeolian sandy soils are not extensively explored, and the underlying mechanisms are not clear. In our field experiments, the influence of NT and conventional tillage (CT) on sandy soil was studied. Methods We estimated the changes in soil TC in response to NT practice in a Cyperus esculentus L. field located at semi-arid Horqin sandy land, China. To unravel the underlying mechanisms, plant traits, soil properties and soil microbial characteristics were measured in parallel. The variations in soil bacterial community structure were investigated by 16S rRNA amplicon sequencing. The functionality of soil bacterial community was predicted based on OTU tables by using PICRUSt2. Results NT increased soil TC content in this sandy agroecosystem within a short-term experimental period, compared to CT. The underlying mechanisms might rely on three aspects. First, NT increased soil TC content through increasing photosynthesis and plant biomass, and thus, the plant-derived dissolved organic C. Second, NT increased the C immobilized in soil microbial biomass by increasing microbial C demands and C use efficiency. Third, NT increased the dominance of oligotrophic members in bacterial communities by decreasing available nutrient levels, which is associated with the recalcitrance and stability of the soil organic carbon. Conclusions The present study enriched our knowledge on the changes in the plant-soil-microbe continuum in response to NT in a semi-arid sandy agroecosystem. Still, this study provides a reference for modifying tillage practices to benefit crop yield as well as soil C sequestration.