Aeolian Sandy Soil Research Articles

生猪粪水液态肥高量还田对黑土和风沙土养分含量的影响

生猪粪水液态肥高量还田对黑土和风沙土养分含量的影响

Experimental Study on Ecological Restoration of Glycyrrhiza Uralensis in Yulin Sandy Grassland

Aeolian sandy grassland area is the main geomorphic type in the north of Yulin. The ecological environment is fragile and the problem of desertification is serious, which needs to be controlled urgently. The introduction of herbs is considered to be an effective means to control the sandy beach area. In this paper, licorice was selected as the indicator crop, and the introduction performance of licorice under different treatments in Yulin Sandy Grassland was observed through field experiment. The results show that: (1) after treatment, the physical structure of aeolian sandy soil is effectively improved. Compared with the control, the moisture content, temperature and porosity of aeolian sandy soil increased in varying degrees, which were 31.62%, 5.12% and 5.26% respectively, and the soil bulk density decreased by 4.08%. (2) After treatment, the chemical structure of aeolian sandy soil was significantly improved, the electrical conductivity, soil organic matter and nutrients were significantly increased, which were 22.63%, 21.09% and 4.66% respectively, and the pH decreased by 2.51% compared with the control group. (3) The treatment group could effectively improve the plant height, rejuvenation rate and coverage of Glycyrrhiza uralensis by 14.95%, 29.79% and 41.40% respectively.

Biochar-mediated changes in the microbial communities of rhizosphere soil alter the architecture of maize roots.

Aeolian sandy soil is a key resource for supporting food production on a global scale; however, the growth of crops in Aeolian sandy soil is often impaired due to its poor physical properties and lack of nutrients and organic matter. Biochar can be used to enhance the properties of Aeolian sandy soil and create an environment more suitable for crop growth, but the long-term effects of biochar on Aeolian sandy soil and microbial communities need to be clarified. Here, a field experiment was conducted in which biochar was applied to a maize (Zea mays L.) field in a single application at different rates: CK, 0 Mg ha−1; C1, 15.75 Mg ha−1; C2, 31.50 Mg ha−1; C3, 63.00 Mg ha−1; and C4, 126.00 Mg ha−1. After 7 years of continuous maize cropping, verify the relationship between root architecture and soil microbial communities under biochar application using a root scanner and 16S/ITS rRNA gene sequencing. The application of biochar promoted the growth of maize. Specifically, total root length, total root surface area, total root volume, and root biomass were 13.99–17.85, 2.52–4.69, 23.61–44.41, and 50.61–77.80% higher in treatments in which biochar was applied (C2, C3, and C4 treatments) compared with the control treatment, respectively. Biochar application increased the diversity of bacterial communities, the ACE index, and Chao 1 index of C1, C2, C3, and C4 treatments increased by 5.83–8.96 and 5.52–8.53%, respectively, compared with the control treatment, and significantly changed the structure of the of bacterial communities in rhizosphere soil. However, there was no significant change in the fungal community. The growth of maize roots was more influenced by rhizosphere bacteria and less by fungal community. A microbial co-occurrence network revealed strong associations among rhizosphere microorganisms. The core taxa (Module hubs taxa) of the bulk soil microbial co-occurrence network were closely related to the total length and total surface area of maize roots, and the core taxa (Connectors taxa) of the rhizosphere soil were closely related to total root length. Overall, our findings indicate that the application of biochar promotes the growth of maize roots in aeolian sandy soil through its effects on bacterial communities in rhizosphere soil.

Wind erodibility indices of aeolian sandy soils impacted by different vegetation restoration: a case study from the Shannan valley of the Yarlung Zangbo River

Wind erodibility indices of aeolian sandy soils impacted by different vegetation restoration: a case study from the Shannan valley of the Yarlung Zangbo River

Long-term fertilization altered microbial community structure in an aeolian sandy soil in northeast China.

Soil microorganisms play crucial roles in nutrient cycling and determining soil quality and fertility; thus, they are important for agricultural production. However, the impacts of long-term fertilization on soil microbial community remain ambiguous due to inconsistent results from different studies. The objective of this study was to characterize changes in bacterial and fungal diversity and community structures after 12 years of different fertilization in aeolian sandy soil by analyzing 16S rRNA and ITS rRNA gene sequences and the soil properties to discover the driving factors. Eight different fertilizer treatments have been set up since 2009: no fertilizer (CK), chemical N fertilizer (N), chemical N and P fertilizer (NP), chemical N, P and K fertilizer (NPK), pig manure only (M), pig manure plus chemical N fertilizer (MN), pig manure plus chemical N and P fertilizer (MNP), pig manure plus chemical N, P, and K fertilizer (MNPK). The results indicated that the long-term application of chemical fertilizer reduced soil pH, whereas the addition of pig manure alleviated a decrease in soil pH value. Chemical fertilizer plus pig manure significantly improved soil available nutrients and soil organic carbon. Long-term MNPK fertilization resulted in changes in bacterial diversity due to effects on specific bacterial species; by contrast, all fertilization treatments resulted in changes in fungal diversity due to changes in soil properties. Principal component analysis indicated that fertilization had a significant effect on soil microbial community structure, and the effect of chemical fertilizer combined with pig manure was greater than that of chemical fertilizer alone. Soil available phosphorus, total phosphorus, and pH were the most important factors that influenced bacterial taxa, whereas soil pH, total phosphorus, organic carbon, ammonium nitrogen and nitrate nitrogen were the most important factors influencing fungal taxa after 12 years of fertilization in aeolian sandy soil.

Effect of Aeolian Sand Powder Addition on Frost Resistance of Concrete Pavement.

In order to solve the problem of exploring the freeze-thaw characteristics of modified aeolian sand mixed with cement and silt, the authors propose a freeze-thaw cycle test of modified aeolian sand under the condition of mixing 5% cement and silt with different contents. In this experiment, under freeze-thaw conditions, its intensity decay and mass volume change law and the changes of freeze-thaw characteristics were comprehensively characterized by multiple indicators. The result shows that, after two freeze-thaw cycles, the compressive strength and peak strain of the improved aeolian sand were positively correlated with the silt content. With the increase of the number of freeze-thaw cycles, the compressive and antidestruction capacity of the improved aeolian sand with high silt content and low silt content decreased significantly. 15% silt content improves the structural stability of aeolian sand. It is proved that the authors' experiment can intuitively and effectively reflect the change law of soil strength after freezing and thawing of such improved aeolian sandy soil, which has displayed significance.

The role of groundwater depth in semiarid grassland restoration to increase the resilience to drought events: A lesson from Horqin Grassland, China

Grassland degradation in the semiarid area of China is often attributed to overgrazing and expansion of irrigated agriculture without the consideration of groundwater. However, falling groundwater levels in the region have caused many problems for grassland ecology. In this paper,the typical sandy grassland- the Tongliao part of Horqin grassland was selected as the study area to study the spatial distribution of normalized difference vegetation index (NDVI) and the relationship between the NDVI and groundwater depth (GD) of each grassland pixel was studied. The temporal variation of the NDVI and its correlations with precipitation were investigated. The relationship between GD and vegetation species diversity in grassland was analyzed based on the vegetation survey. The results of the relation between GD and NDVI and vegetation species showed that GD can buffer the impact of increase in drought events on the vegetation because GD affected the composition and diversity of vegetation species. As the GD increases, the mean NDVI showed a trend of increasing first and then decreasing, and basically remained unchanged when the GD was greater than 3.5 m. The species diversity of grassland decreased with increasing GD and was not related to GD when GD was greater than 3.5 ∼ 4 m. Falling groundwater levels will cause great changes in the structure of grassland; specifically, azonal vegetation will gradually die and 3.5 m may be the critical GD needed to maintain the incomplete extinction of grassland azonal vegetation in the aeolian sandy soil. Correlation analysis proved that the correlation between NDVI and precipitation was significantly enhanced when GD increased sharply from 3 m to 6 m after 1999. This research indicates that the control of grassland degradation should pay attention to controlling the groundwater exploitation to recover a reasonable groundwater level, which was found to be necessary in the support of diverse and climate resilient of vegetation.

Responses of moss biocrusts respiration to simulated grazing and trampling disturbance with different intensities on the fenced forestland of Loess Plateau, China

The changes in soil properties caused by grazing and trampling are important reasons for the changes in soil respiration rates, carbon fixation, and emission. However, the effects of different intensities of grazing and trampling on biocrusts respiration rate are unclear. In this study, we simulated grazing and trampling disturbances of 10%, 30%, 50%, and 70% intensity on moss biocrusts developed in aeolian sandy soil on Loess Plateau, with undisturbed moss biocrusts serving as a control. The changes in respiration rate of moss biocrusts were monitored continuously, and its responses to different disturbance intensities were analyzed. The results showed that: 1) moderate disturbance stimulated moss biocrusts respiration, while heavy disturbance inhibited that. The respiration rate of moss biocrusts was increased by 41.1% and 22.2% at disturbance intensities of 10% and 30%, but was decreased by 8.9% and 15.3% at disturbance intensities of 50% and 70%, respectively. 2) The trampling disturbance significantly changed soil temperature but did not affect soil water content. In comparison to the control, soil temperature of biocrusts was decreased by 0.4 and 1.2 ℃ at disturbance intensities of 10% and 30%, but it was increased by 1.1 and 1.0 ℃ at disturbance intensities of 50% and 70%, respectively. 3) The respiration rate of moss biocrusts showed a significant exponential relationship with soil temperature and a linear positive relationship with soil water content under different disturbance intensities. However, the correlation between respiration rate of moss biocrust and the characteristics of moss biocrust was not significant. Soil temperature and water content could explain 70.6%-96.3% and 49.1%-70.0% of the total variation of respiration rate of moss biocrusts, respectively. In conclusion, grazing and trampling affected the respiration rate of moss biocrusts, with short-term moderate grazing and trampling would have positive effects. On the other hand, excessive grazing and trampling would reduce the rate of moss biocrust respiration. As a result, future studies on soil carbon balance of the Loess Plateau should consider the effects of grazing and trampling on biocrust respiration.

Effects of drilling waste combined with exogenous organic matter on physicochemical properties of aeolian sandy soil and growth of spinach

An indoor potted experiment was carried out to study the application effects of water-based waste drilling mud (WBDM) and drill cuttings combined with humic acid and woody peat in aeolian sandy soil.We analyze their effects on the growth of spinach, in order to provide a reference for the resource utilization of drilling waste and the improvement of aeolian sandy soil. A total of three individual experiments were set up: 4 treatments in the basic group, taking aeolian sandy soil as the control (CK), mixing aeolian sandy soil and drill cuttings at a mass ratio of 1:1, then added with 0, 2%, and 4% WBDM (dry basis) respectively. The basic group treatment was added with 1% humic acid, 1% humic acid+3% woody peat mixture respectively, as the humic acid group and woody peat group. The results showed that in the basic group, drilling waste application significantly increased soil organic matter content (SOM), pH and electrical conductivity, the 2% WBDM significantly promoted the growth of spinach. Humic acid and woody peat reduced soil pH and increased SOM content and electrical conductivity. Plant growth indicators such as plant height, total leaf area, fresh weight and dry weight of the humic acid group were higher than the corresponding treatments in the basic group. The mixed addition of humic acid and woody peat did not affect plant growth. The treatment with the best performance was to add 2% WBDM to the humic acid group, and the SOM was 13.1 g·kg-1, spinach's plant height, total leaf area, fresh weight and dry weight significantly increased by 49.7%, 93.4%, 83.3%, and 34.6% than CK after 40 days of sowing. The application of drilling waste with organic matter could significantly increase SOM content and promote spinach growth. Aeolian sandy soil + drill cuttings + WBDM (2%) + humic acid (1%) was the best combination mode.

Effect of Long-Term Fertilization on Aggregate Size Distribution and Nutrient Accumulation in Aeolian Sandy Soil.

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.

Characterising the diversity and functionality of the microbial community within biocrusts associated with different vegetation communities and soil habitats

In arid and semi-arid ecosystems, the biocrust serves as an important biological interface in the topsoil. Although the biocrust and vascular plant and soil are closely related, microbial diversity and functional characteristics in biocrusts of different vegetation communities and soil habitats, especially in watershed conditions, is poorly understood. In this study, biocrust samples were collected from two different soil substrate habitats, the loess and the aeolian sandy soil, as well as three plant communities consisting of Stipa bungeana, Artemisia ordosica, and Populus simonii, with the farmland soil acting as the control at the small watershed scale in the interlaced water and wind eroded area of Northern Shaanxi, China. To characterise the microbial diversity and functionality within biocrusts, a total of 4705 and 219 16S and 18S rDNA OTUs, respectively, were classified using high-throughput sequencing. Proteobacteria, Actinobacteria, and Bacteroidetes were dominant in prokaryotic community, whereas Ascomycota and Basidiomycota were dominant in fungal community in biocrusts. Principal coordinate analysis and hierarchical clustering demonstrated significant differences in prokaryotic and fungal communities between farmland soil and biocrusts, and soil parent materials could be a major factor in shaping the difference in the microbial communities of biocrusts relative to the vegetation types. Soil pH and carbon were dominant environmental factors that affected the prokaryotic and fungal communities in biocrusts. Hence, we demonstrated that the biocrust can significantly improve the topsoil properties in the study region, while their prokaryotic and fungal communities are largely determined by soil properties and environmental parameters.

Soil properties, root morphology and physiological responses to cotton stalk biochar addition in two continuous cropping cotton field soils from Xinjiang, China.

Long-term and widespread cotton production in Xinjiang, China, has resulted in significant soil degradation, thereby leading to continuous cropping obstacles; cotton stalk biochar (CSB) addition may be an effective countermeasure to this issue, with effects that are felt immediately by root systems in direct contact with the soil. In this study, we assess the effects of different CSB application rates on soil nutrient contents, root morphology, and root physiology in two soil types commonly used for cotton production in the region. Compared with CK (no CSB addition), a 1% CSB addition increased total nitrogen (TN), available phosphorus (AP), and organic matter (OM) by 13.3%, 7.2%, and 50% in grey desert soil, respectively , and 36.5%, 19.9%, and 176.4%, respectively, in aeolian sandy soil. A 3% CSB addition increased TN, AP, and OM by 38.8%, 23.8%, and 208.1%, respectively, in grey desert soil, and 36%, 13%, and 183.2%, respectively, in aeolian sandy soil. Compared with the aeolian sandy soil, a 1% CSB addition increased TN, OM, and AP by 95%, 94.8%, and 33.3%, respectively, in the grey desert soil , while in the same soil 3% CSB addition increased TN, OM, and AP by 108%, 21.1%, and 73.9%, respectively. In the grey desert soil, compared with CK, a 1% CSB application increased the root length (RL) (34%), specific root length (SRL) (27.9%), and root volume (RV) (32.6%) during the bud stage, increased glutamine synthetase (GS) (13.9%) and nitrate reductase (NR) activities (237%), decreased the RV (34%) and average root diameter (ARD) (36.2%) during the harvesting stage. A 3% CSB addition increased the RL (44%), SRL (20%), and RV (41.2%) during the bud stage and decreased the RV (29%) and ARD (27%) during the harvesting stage. In the aeolian sandy soil, 1% CSB increased the RL (38.3%), SRL (73.7%), and RV (17%), while a 3% caused a greater increase in the RL (55%), SRL (89%), RV (28%), soluble sugar content (128%), and underground biomass (33.8%). Compared with the grey desert soil, a 1% CSB addition increased the RL (48.6%), SRL (58%), and RV (18.6%) in the aeolian sandy soil, while a 3% further increased the RL (54.8%), SRL (84.2%), RV (21.9%), and soluble sugar content (233%). The mechanisms by which CSB addition improves the two soils differ: root morphology changed from coarse and short to fine and long in the grey desert soil, and from fine and long to longer in the aeolian sandy soil. Overall, a 3% CSB addition may be a promising and sustainable strategy for maintaining cotton productivity in aeolian sandy soil in the Xinjiang region.

Geo-accumulation Index Method to Optimize the Evaluation Method of Polymetallic Environment Quality: Taking Developed Agricultural Areas as an Example

An accurate and reasonable soil pollution assessment method is the premise of regional soil pollution assessment. Triangular fuzzy numbers were introduced into the geo-accumulation index method, combined with α-cut technology and the Latin hypercube sampling (LHS) stochastic simulation method, to evaluate the accumulation of heavy metals in five different soil types (moisture soil, aeolian sandy soil, cinnamon soil, loessal soil, and alluvial soil), with large differences in heavy metal (Cd, Hg, As, Pb, and Cr) content in the study area. This method can avoid the inaccuracy of the evaluation results caused by the traditional geological accumulation index method in the selection of background values and the great difference between local and whole heavy metal contents in the study area and can comprehensively and truly represent the regional soil heavy metal pollution status, thus providing a theoretical basis for scientific decision-making. The results showed that the improvement in the method will not affect the evaluation results when the heavy metal content difference is small, that is, when the evaluation results of the geological accumulation index at all points are within a certain interval level or when the evaluation results of the geological accumulation index at all points are less than 0. The traditional and geological cumulative index method based on the evaluation with triangular fuzzy numbers provides results for a certain level, which is determined by the heavy metal content in the study area average; conversely, differences in the heavy metal content of soil sampling points throughout the study area can result in a decrease or increase in the recorded heavy metal contents in larger areas, making the evaluation result inaccurate. Combined with the LHS sampling method, the possibility of changing the evaluation results into various pollution levels can greatly improve the limitations of traditional evaluation methods and make the evaluation results more reasonable and accurate. Combined with the geographic information system (GIS) method, the regional heavy metal pollution accumulation concentration can also be visualized.

Cyanobacteria and moss biocrusts increase evaporation by regulating surface soil moisture and temperature on the northern Loess Plateau, China

Soil evaporation is a three-stage process and plays a vital role in soil physical, chemical, and biological processes, as well as global climate change. As an important living skin, biocrusts strongly influence most soil properties and support fundamental ecosystem functions. Although there are many studies concerning biocrust effects on surface soil hydrological processes, it still remains unclear how biocrusts impact soil evaporation and their potential effects on the water budget in drylands. In this study, we selected aeolian sandy soil (bare soil) and three types of biocrusts, specifically cyanobacteria (cyano), cyanobacteria and moss mixed crusts (cyano-moss), and moss crusts (moss), on the northern Chinese Loess Plateau. By utilizing weighing micro-lysimeters in simulated and ∼4 months in-situ field evaporation experiments, we investigated all evaporation stages containing stages I–II and III, as well as the soil evaporation rate (E) of all treatments. The soil moisture (θ) and temperature (T) at 2 cm and 10 cm depths were also measured in field. Our results showed that biocrust types strongly influenced E in the ranked order of moss > cyano-moss > cyano > bare soil. The cumulative evaporation amount (Ec) of all types of biocrusts was significantly higher than that of bare soil in simulated experiments. Particularly, moss increased Ec by 15.7% compared with bare soil. The results of in-situ field measurements illustrated that the E of cyano, cyano-moss, and moss was increased by 42.4%, 55.5%, and 46.9%, respectively, compared with the bare soil, and these increasing effects became more pronounced after rainfall events. Additionally, all types of biocrusts markedly increased θ and decreased T at 0–10 cm depth of soil, but cyano and cyano-moss increased T (by up to 5.7 °C) at 2 cm depth during the non-rainfall periods. The increasing effects of biocrusts on E were reasonably attributed to their higher contents of fine particles and organic matter, as well as their higher field capacity in contrast to bare soil. All these regulations of biocrusts on soil properties further reshaped soil water and temperature regimes and finally changed soil evaporation. In conclusion, biocrusts may greatly intensify surface soil water loss due to their higher E. However, their greater θ and lower T in comparison to bare soil may partially offset these negative effects in return, and they may have feedback impacts on surface soil water and heat balances in drylands.

Growth stability of four drought resistant plant species in different regions

There are abundant germplasm resources of drought resistant trees in China. It is difficult for foresters to evaluate and screen excellent germplasm that is suitable for various drought adverse circumstances. In this study, four tree species from different provenances, namely Amygdalus davi-diana, Prunus sibirica, Salix gordejevii, and Caryopteris mongolica, were used as test materials. Four soil regions, namely Dalad Banner, Siziwang Banner, Kouhezi town and Liujiazi town of Kulun Banner in the Central and Eastern Inner Mongolia Autonomous Region were selected as multi-point experiment sites to analyze the growth and physiological status of different tree species and provenances. The additive main effects and multiplicative interaction model was used to evaluate the regional adaptability and stability of the germplasm. The growth and physiological indices of four tree species differed between provenances and locations. Soil conditions (potassium content, nitrogen content, and pH) and climate conditions (annual average temperature, precipitation, and potential evaportranspiration) in different locations all influenced the growth of different provenance species. Concerning tree species, S. gordejevii and C. mongolica are more adapted to the sandy loam and chestnut soil of Dalad Banner and Siziwang Banner. A. davidiana and P. sibirica L. are more adapted to the loess and aeolian sandy soil of Kouhezi town and Liujiazi town. Concerning tree provenances, A. davidiana of Tuzuo, P. sibirica of Ningcheng and Yuanzhou, S. gordejevii of Lanqi, and C. mongolica of Jingbian displayed higher regional stability and better growth adaptability, indicating their suitability for afforestation in similar areas.

Effects of adding different proportions of soft rock on the dynamic change of the quality of aeolian sandy soil

Evolution process of quality of soft rock and sand compound soil and exploration of its stability were studied. In the present study different proportions (1 : 1, 1 : 2, 1 : 5, 0 : 1) of soft rock and sand compound soil as the research object were selected. Tthe particulate organic carbon, microbial organic carbon, effective phosphorus, quick-acting potassium, nitro nitrogen and ammonium nitrogen in the compound soil were analyzed. Results showed that after 9 years of planting, the organic carbon content of particles with 0 : 1 treatment was the lowest, at 1.73 g/kg, and the treatment of 1 : 5 and 1 : 1 increased significantly by 74.74 and 94.90%, respectively. In the 20 - 30 cm soil layer, the lowest organic carbon content of particles with 1 : 2 treatment was 1.92 g/kg, and there was no significant difference between the other three treatments, with 0 : 1, 1 : 5 and 1 : 1 treatment increased by 46.20, 29.27 and 34.07%, respectively compared to 1 : 2 treatment. With developed root system, the biomass of the root system was greater than the biomass left on the ground after harvest, and the average content of organic carbon of the particles increased first and then decreased later. The microbial community in the compound soil was significantly improved, and the carbon content of microorganisms in the treatment of 1 : 1, 1 : 2 and 1 : 5 was significantly higher than that of whole sand by 85, 165 and 143%, respectively, after multi-year of cultivation. The soil root microbial community showed a benign development. With the increase of planting years, the incorporation of soft rock accelerates the process of natural succession of soil quality. Compared with sandy land, compound soil has significantly improved storage of available phosphorus and available potassium nutrients. Compound soil has been cultivated for 9 years compared with 6 years, with the ratio of 1 : 1, 1 : 2, 1 : 5 and 0 : 1, the effective phosphorus content increased significantly by 141, 181, 169 and 63% respectively, the available potassium content increased significantly by 141, 181, 169 and 63% respectively. Compound soil has been cultivated for 9 years compared with 6 years, with the ratio of 1 : 1, 1 : 2, 1 : 5, and 0 : 1, the nitrate nitrogen content increased significantly by 40, 130, 135 and 120%, respectively. Nitro nitrogen is easily soluble in water, and the higher the proportion of sand in the compound soil, the easier the loss of nitrous nitrogen content in the soil. After multiple years of cultivation, the ammonium nitrogen content in the compound soil decreased, with a significant decrease of 35 (p &lt; 0.05), 34 (p &lt; 0.05), 45 (p &lt; 0.05) and 37% (p &lt; 0.05), respectively. Due to the disruption of harvest, the exposure of the surface soil is high, which causes ammonium nitrogen to evaporate. Bangladesh J. Bot. 50(3): 837-845, 2021 (September) Special

Two irrigation events can achieve relatively high, stable corn yield and water productivity in aeolian sandy soil of northeast China

To achieve relatively high, stable corn (Zea mays L.) yield and water productivity (WPc) in aeolian sandy soil in the corn belt of northeast China (CBNC), a 4-year field experiment was conducted from 2017 to 2020 to evaluate the effects of irrigation on yield and WPc. The field experiment included four treatments: no irrigation (NI), single irrigation (SI), two irrigation events (TI), and full irrigation (FI) at the Lishu Experimental Station, Jilin Province, China. The results showed that, the TI and FI treatments improved the relative soil water content (RSWC) of the corn root zone and the aboveground biomass relative to the NI and SI treatments. The corn yield in the SI, TI, and FI treatments was 16–187%, 19–438%, and 17–409% greater than that of the NI treatment, respectively. The coefficient of variation of yield from 2017 to 2020 in the NI, SI, TI, and FI treatments were 47%, 23%, 4%, and 2%, respectively. The TI and FI treatments increased evapotranspiration relative to the NI and SI treatments. The TI and FI treatments increased the WPc by 10–396% and 24–324% compared with the NI treatment. No difference in WPc was observed between the TI and FI treatments. The irrigation water productivity (WPI) of the TI treatment was 35% and 46% higher than that of the FI treatment in 2017 and 2020, respectively, while no difference was observed in 2018 and 2019. Therefore, the TI treatment is recommended to improve the yield and WPc of corn in the aeolian sandy soil of the CBNC.

Effects of crude oil pollution on soil moisture infiltration with loessial soil and aeolian sandy soil

Crude oil may block soil pores, affect soil water repellency, and change soil water movement. In this study, soil column simulation was used to study the effects of different crude oil pollution levels (0, 0.5%, 1%, 2%, 4%) on the water infiltration processes in loessial soil and aeolian sandy soil. The results showed that soil wetting front speed and infiltration rate of those two soils decreased with increasing crude oil content. The time needed for wetting front reaching the bottom of the soil column was the longest under 4% crude oil polluted soil, which was 4 times and 48 times longer than that of no crude oil polluted soil for loessial soil and aeolian sandy soil, respectively. The cumulative infiltration of loessial soil decreased with increasing crude oil content, while it increased to the max and then decreased as the crude oil content increased in aeolian sandy soil. The cumulative infiltration curves of aeolian sandy soil with high crude oil contents (2% and 4%) presented "up-tail" phenomenon. Kostiakov infiltration model and Philip infiltration model could better fit the infiltration process than Green-Ampt model for loessial soil with different crude oil content. However, the two models could only well fit the infiltration process for aeolian sandy soil with low crude oil content (0, 0.5%, 1%). Crude oil pollution could significantly affect soil water infiltration process, especiall in aeolian sandy soil.

Effect of Saline Water for Drip Irrigation on Microbial Diversity and on Fertility of Aeolian Sandy Soils

Saline water is widely distributed in the arid environment and sometimes represents the only source of irrigation water to restore and reconstruct vegetation. However, the effects of saline water on the bacterial diversity and fertility level of aeolian sandy soil are not well understood. In this study, we investigated a vegetation belt along the Tarim Desert Highway that has been constructed as a windbreak and consists of desert shrubs and was irrigated with saline water at six levels of salinity along the Tarim Desert Highway. The bacterial diversity was studied using Biolog Eco, a phospholipid fatty acid analysis, and a polymerase chain reaction–denaturing gradient gel electrophoresis, and the soil fertility was calculated and expressed as the integrated fertility index. The soil bacterial diversity (in terms of carbon metabolism, genes, and fatty acid species) was significantly affected by the level of salinity, and the microbial activity was low under high salinity. Fertility was also markedly affected by the degree of salinity and by the depth of soil, being lower at higher salinity levels and in the top layer (0–5 cm), and was also correlated to both the metabolic diversity index of soil microorganisms and the diversity index of fatty acids of soil microorganisms. The genetic diversity index of soil microorganisms shared a polynomial relation with fertility and contributed to it positively and significantly. Therefore, using less saline water for drip irrigation could avoid salt accumulation in soil and arrest its compaction, promote the formation of soil aggregates and the build-up of nutrients, and increase microbial activity, thus playing a crucial role in promoting the circulation, conversion, and utilization of nutrients in aeolian sandy soils and improving the soil quality. The judicious use of saline water, therefore, deserves serious consideration in irrigation practices.

Response of the characteristics of organic carbon mineralization of soft rock and soil composed of sand to soil depth.

The addition of soft rock to aeolian sandy soil can improve the level of fertility and ability of the soil to sequester carbon, which is of substantial significance to improve the ecological environment of the Mu Us sandy land and supplement newly added cultivated land. S oft rock and sand were combined using the ratio (v/v) of 0:1 (CK), 1:5 (S1), 1:2 (S2), and 1:1 (S3). The process of mineralization of organic carbon at different depths (0–10 cm, 10–20 cm, and 20–30 cm) in the combined soil was studied by 58 days of incubation indoors at a constant temperature. The content of soil nutrient s increased significantly under the S2 and S3 treatments and was higher in the 0–10 cm soil depth. The mineralization of rate of soil organic carbon (SOC) of different combination ratios can be divided into three time periods: the stress mineralization stage (1–7 d), the rapid mineralization stage (7–9 d) and the slow mineralization stage (9–58 d). At the end of incubation, the rates of mineralization of SOC and accumulated mineralization amount (Ct) were relatively large in the 0–10 cm soil depth, followed by the 10–20 cm and 20–30 cm soil layers , indicating that the stability of SOC in the surface layer was poor, which is not conducive to the storage of carbon. The content of potentially mineralizable organic carbon (C0) in the soil was consistent with the trend of change of Ct. Compared with the CK treatment, the cumulative organic carbon mineralization rate (Cr) of the S2 and S3 treatment s decreased by 7.77% and 6.05%, respectively; and the C0/SOC decreased by 22.84% and 15.55%, respectively. Moreover, the Cr and C0/SOC values in the 10–20 cm soil depth were small, which indirectly promoted the storage of organic carbon. With the process of SOC mineralization, the contents of soil microbial biomass carbon (SMBC) and dissolved organic carbon (DOC) tended to decrease compared with the initial contents, with larger amplitudes in the 20–30 cm and 10–20 cm soil depth s, respectively. SOC, total nitrogen, available potassium, SMBC and DOC were all closely related to the process of mineralization of organic carbon. Therefore, the accumulation of soil carbon could be enhanced when the proportion of soft rock and sand composite soil was between 1:2 and 1:1, and the 10–20 cm soil depth was relatively stable. These results provide a theoretical basis for the improvement of desertified land.