Residual effects of heavy application of poultry-droppings manure on aggregation, P-fertility and hydraulic properties of well-drained tropical soils

Tillage is one of the most important practices affecting soil physical and hydraulic properties. Its effects may vary intensely according to the tillage method. This study aims to evaluate the effects of different tillage methods (moldboard plow+disk harrow, moldboard plow+rotary tiller and chisel plow+disk harrow) and drainage (subsurface drainage and non-drainage) on soil physical properties in a clay loam soil. The experiment was conducted in split-plot in time statistical design. Soil bulk density, aeration porosity, organic matter, aggregate mean weight diameter (MWD) and water infiltration rate were measured after planting and after harvesting of winter-wheat crop. Results revealed that the tillage method had significant effect on organic matter content, such that the lowest (1.18%) and highest (1.35%) values were observed in moldboard plow/disk harrow and chisel treatment, respectively. Tillage effect was significant on saturated moisture content, MWD, aeration porosity and infiltration rate. The effect of time was significant on all investigated factors. The effect of drainage was significant on MWD and infiltration rate. Evaluating the interaction effect of tillage and drainage indicated that the contribution of drainage on changing MWD is higher than the tillage methods. Further, it was concluded that the selection of tillage method had an important role on aeration porosity and MWD in no drainage condition, so that moldboard plow makes much more aeration porosity (25.48% against 17.17%) and less MWD (2.40 against 2.80 mm) compared to chisel. According to the result, the treatment combination including drainage/after planting/moldboard plow and disk harrow had the lowest MWD and also, combined treatment of no drainage/after harvesting/chisel plow) had the highest MWD. The application of chisel is not recommended in no-drained areas having high level of groundwater, because of the highest saturated moisture content and MWD along with the lowest aeration porosity compared to moldboard plow.

Coastal saline soils are an important soil resource that, when restored, can enhance arable land and preserve the natural ecology. With the aim of improving the use of coastal saline soils, we conducted a spot survey at Bohai coastal saline land to investigate the differences in soil properties between different vegetation types. The soil physical and chemical properties of various vegetation types, including Aeluropus sinensis, Imperata cylindrica, Tamarix chinensis, Lycium chinense, Hibiscus moscheutos, Helianthus annuus, Gossypium hirsutum, and Zea mays, were examined at two depth layers: 0–20 cm and 20–40 cm, and in two seasons, spring and autumn. The soil properties were compared with bare land as a control. The results indicated that the electrical conductivity, total soil salt content, sodium adsorption ratio, and bulk density of soils with vegetation cover were lower than those with bare land. On the other hand, soil pH, organic matter content, mean weight diameter, and saturated hydraulic conductivity were higher. The redundancy analysis results revealed a substantial positive correlation between soil pH, saturated hydraulic conductivity, water content, mean weight diameter, and organic matter content, as well as a significant positive correlation between soil electrical conductivity, total soil salt content, sodium adsorption ratio, and bulk density. Soil pH, saturated hydraulic conductivity, water content, mean weight diameter, organic matter content, and soil electrical conductivity, total soil salt content, sodium adsorption ratio, and bulk density were negatively correlated. The results of the structural equation model and variance decomposition showed that soil organic matter and bulk density were the key factors affecting the degree of soil salinization, and compared with their independent effects, their combined effect on soil salinization was greater. This study’s conclusions can provide a point of reference for further research on the mechanisms of soil improvement and desalinization in coastal saline land.

Process and Mechanism for the Development of Physical Crusts in Three Typical Chinese Soils

Background: The greenhouse and field studies were carried out to assess the effect of different rates of poultry manure (PM), pig slurry (PS) and the recommended NPK fertilizer on some soil physico-chemical properties and okra yield of coarse-textured Ultisols in Nsukka, southeastern Nigeria. Methods: The PM and PS were applied at three different rates (10, 20 and 40 t ha-1) as well as no amendment as control and the recommended NPK fertilizer (300 kg/ha) and replicated five times. Soil and agronomic data collected were analyzed for variance (ANOVA) using Genstat 4.0. Result: The PM and PS significantly (p less than 0.05) improved soil pH, soil organic matter, available phosphorous, total nitrogen, aggregate stability, mean weight diameter, bulk density, porosity and saturated hydraulic conductivity in greenhouse and field studies. Significant improvement in CEC was obtained in the field study. The PM and PS significantly (p less than 0.05) improved agronomic parameters e.g. plant height, number of leaves, biomass weight and yield of okra than the control. Poultry manure showed its superiority over other amendments in improving soil and agronomic properties. The study recommended 20 t ha-1 of PM and 40 t ha-1 of PS for sustainable soil and optimum productivity of okra in Nsukka, southeastern Nigeria.

Abstract. In southern China, the island of Hainan faces land degradation risks due to a combination of soil physical, chemical, and climatic factors: soil physical properties like a high proportion of microaggregates (<0.25 mm), chemical properties such as low soil organic matter (SOM) content, and a climatic factor of frequent uneven rainfall. The cohesive force between soil particles, which is influenced by plant root properties and root-derived SOM, is essential for improving soil aggregate stability and mitigating land degradation. However, the mechanisms by which rubber plant root properties and root-derived SOM affect soil aggregate stability through cohesive forces in tropical regions remain unclear. This study evaluated rubber plants of different ages to assess the effects of root properties and root-derived SOM on soil aggregate stability and cohesive forces. Older rubber plants (>11 years old) showed greater root diameters (RDs) (0.81–0.91 mm), higher root length (RL) densities (1.83–2.70 cm cm−3), and increased proportions of fine (0.2–0.5 mm) and medium (0.5–1 mm) roots, leading to higher SOM due to lower lignin and higher cellulose contents. Older plants exhibited higher soil cohesion, with significant correlations among root characteristics, SOM, and cohesive force, whereas the random forest (RF) model identified aggregates (>0.25 mm), root properties, SOM, and cohesive force as the key factors influencing mean weight diameter (MWD) and geometric mean diameter (GMD). Furthermore, partial least squares path models (PLS-PM) showed that the RL density (RLD) directly influenced SOM (path coefficient 0.70) and root-free cohesive force (RFCF) (path coefficient 0.30), which subsequently affected the MWD, with additional direct RLD effects on the SOM (path coefficient 0.45) and MWD (path coefficient 0.64) in the surface soil. Cohesive force in rubber plants of different ages increased macroaggregates (>0.25 mm) and decreased microaggregates (<0.25 mm), with topsoil average MWD following the order control (CK) (0.98 mm) < 5Y_RF (1.26 mm) < mixed forest (MF; 1.31 mm) < 11Y_RF (1.36 mm) < 27Y_RF (1.48 mm) < 20Y_RF (1.51 mm). Rubber plant root traits enhance soil aggregate stability and mitigate land degradation risk in tropical regions, offering practical soil restoration strategies through targeted root trait selection to strengthen soil cohesion, ensure long-term agricultural productivity, and preserve environmental quality, highlighting the need for further research across diverse ecological zones and forest types.

Soil management practices influence soil physical parameters and crop productivity. No-till farming, which is a key component of conservation agriculture, is considered a sustainable alternative to conventional agriculture. The extent to which soil conservation management practices can mitigate the impacts of extreme events (heavy precipitation events and drought) remains unknown, and is examined as part of the SoilX project. This study focuses on two different tillage management practices and their effects on soil hydraulic properties, soil structure, and crop yields under current and future climate conditions. An experimental study site that is a Long-Term Field Experiment (LTE) since 2006 located in Hollabrunn, Lower Austria, was used for soil sampling and crop modelling. The site is located in a Pannonian climate, with average annual (1991-2020) precipitation of 493 mm and a mean air temperature of 9.8 °C. The soil is classified as a silt loam calcareous Chernozem under the WRB or as Typic Vermudoll under the US Soil Taxonomy. The experimental layout comprised two soil tillage treatments (conventional tillage (CT) and no-tillage (NT), both with annual crops and winter cover crops) arranged in a randomized block design. The crop model APEX (Agricultural Policy/Environmental eXtender) model was set up for both treatments to assess the impacts of CT and NT on soil physical properties and their respective hydrological properties. Field soil samples were taken from both treatments (up to 50 cm depth) and analyzed for soil bulk density, soil organic matter (SOC), water stable aggregates (WSA), unsaturated infiltration rates (determined with TDI), water retention curves, and oxygen isotopes in soil pore water. These field measurements were used to parameterize the APEX model. Field operations between 2009 and 2023 also provided model inputs on crop cultivation cycles, tillage, fertilization, sowing, crop protection, and harvesting. The yield (dry matter Mg ha-1) per plot was used for model calibration. From the soil samples obtained in 2023 differences between CT and NT were determined with respect to bulk density and soil water content, i.e. at 10 cm, the unsaturated infiltration rates were higher in CT. The future climate simulations (2050-2100) derived from regional climate models (RCMs) with different representation pathways (RCPs) were input in APEX to assess the impacts of climate change on the soil physical and hydraulic properties (SOC, infiltration rates, soil water storage) under CT and NT. The research results quantify differences in soil physical and hydraulic properties in a future climate, particularly focusing on the extreme events. The findings provide information on soil management strategies to potentially mitigate the adverse impacts of heavy precipitation events and droughts in agricultural cropping systems.

Soil organic matter (SOM) plays a significant role in modulating soil water and therefore irrigation scheduling. This relationship is especially vital in arid regions like the Mediterranean, where both SOM and water resources are scarce and increasingly threatened by the climate crisis. Soil amendments based on agricultural biowaste (e.g., compost) or byproducts of pre-existing processes (e.g., biochar) offer a cost-effective solution to boost SOM levels. However, because of this less strictly managed production process, the variability in their properties and their long-term effects on soil hydraulic behaviour, particularly after weathering, remain poorly understood. Here we compare the effect of 3 soil amendment treatments to the hydraulic properties of clay loam soil: olive tree pruning compost at 1% (C1B0), biowaste-based biochar from at 1% (C0B1), and compost-biochar mix at 1% (C1B1) against a control treatment (C0B0). Amendments were incorporated in the soil at the prescribed rates to a depth of 15 cm. To quantify the impact of the amendments in hydraulic properties of soil such as clay loam we use a modification of the hydraulic property (HYPROP2, Meter, USA) analyser (Daliakopoulos et al., 2021) after application, and 6 months after application. The assessed van Genuchten parameters are used to estimate the movement of water soil in the soil profile with HYDRUS-1D (Kool & Van Genuchten, 1991) using two distinct profiles. Simulations were validated through irrigation experiments using in-situ soil moisture measurements at 2 depths (10 and 30 cm). As shown by changes Van Genuchten parameters, results show that, compared to compost applications, biochar had a more pronounced and lasting positive effect regarding soil porosity and structure, also decreasing hydraulic conductivity and increasing field capacity. These results highlight the potential of biochar and it’s mixes to improve soil water status and contribute to the reversal of desertification processes in arid Mediterranean soils.AcknowledgementsThis work has received funding from REACT4MED: Inclusive Outscaling of Agro-Ecosystem Restoration Actions for the Mediterranean. The REACT4MED Project (grant agreement 2122) is funded by PRIMA, a program supported by Horizon 2020. MP was supported by ERASMUS+ KA131 mobility (ID 1174266). Authors IND and AK thank MINERVA Ltd. and research project “Assessment of climate change impacts on olive oil production and implementation of sustainable agricultural adaptation practices in Greece” for its support.ReferencesDaliakopoulos, I., Papadimitriou, D., & Manios, T. (2021). Improving the efficiency of HYPROP by controlling temperature and air flow. EGU General Assembly Conference Abstracts, EGU21--13082.Kool, J., & Van Genuchten, M. T. (1991). HYDRUS: One-dimensional Variably Saturated Flow and Transport Model, Including Hysteresis and Root Water Uptake, Version 3.31. US Salinity Laboratory. 

The long-term use of mineral fertilizers has decreased the soil fertility in papaya (Carica papaya L.) orchards in South China. In situ earthworm breeding is a new sustainable practice for improving soil fertility. A field experiment was conducted to compare the effects of four treatments consisting of the control (C), chemical fertilizer (F), compost (O), and in situ earthworm breeding (E) on soil physico-chemical properties and soil enzyme activity in a papaya orchard. The results showed that soil chemical properties, such as pH, soil organic matter (SOM), total nitrogen (TN), available nitrogen (AN), and total phosphorus (TP) were significantly improved with the E treatment but declined with the F treatment. On 31 October 2008, the SOM and TN with the O and E treatments were increased by 26.3% and 15.1%, respectively, and by 32.5% and 20.6% compared with the F treatment. Furthermore, the O and E treatments significantly increased the activity of soil urease and sucrase. Over the whole growing season, soil urease activity was 34.4%~40.4% and 51.1%~58.7% higher with the O and E treatments, respectively, than that with the C treatment. Additionally, the activity of soil sucrase with the E treatment was always the greatest of the four treatments, whereas the F treatment decreased soil catalase activity. On 11 June 2008 and 3 July 2008, the activity of soil catalase with the F treatment was decreased by 19.4% and 32.0% compared with C. Soil bulk density with the four treatments was in the order of O ≤ E < F < C. The O- and E-treated soil bulk density was significantly lower than that of the F-treated soil. Soil porosity was in the order of C < F < E < O. Soil porosity with the O and E treatments was 6.0% and 4.7% higher, respectively, than that with the F treatment. Meanwhile, the chemical fertilizer applications significantly influenced the mean weight diameter (MWD) of the aggregate and proportion of different size aggregate fractions. The E treatment significantly increased the MWD, but the F treatment decreased it. The MWD with the E treatment was 14.5% higher than that with the F treatment. The proportion of >2 mm size aggregates in the O and E treatments was vastly improved. In conclusion, in situ earthworm breeding in orchards performed better than traditional compost and chemical fertilizer in improving soil aggregation, chemical properties, and enzyme activity. This is a new, organic fertilizer application for improving soil structure, chemical properties, and soil enzymes due to the activities of the earthworms and the production of vermicomposting.

Soil aggregate stability under different rain conditions for three vegetation types on the Loess Plateau (China)

Influence of gully erosion on hydraulic properties of black soil-based farmland

Management and seasonal impacts on vineyard soil properties and the hydrological response in continental Croatia

Biocrust succession improves soil aggregate stability of subsurface after “Grain for Green” Project in the Hilly Loess Plateau, China

Soil is accounted as a large sink for the atmospheric carbon dioxide. Carbon dioxide emission from soil will increase by operations such as land-use change, biomass and fuel combustion, industrial production as well as tillage. Operations like tillage could accordingly intensify the soil biological activity, which per se leads to more carbon emission to atmosphere. Thus, utilizing the methods of seedbed preparation that cause low soil disturbances (conservation tillage) will prevent carbon emissions from the soil to the atmosphere; that in turn increases the content of soil organic matter; consequently, soil aggregate stability improves, against erosive factors. The research aims to assess the effects of different tillage systems (no-tillage, low tillage and conventional tillage) on the organic accumulation and the aggregate stability of the soil. The appropriate soil management and farming practices could exert a great positive influence upon crop yield. The study area is located in the eastern of Aq Qala, Iran. Three treatments of tillage systems, namely, traditional management, no-tillage and low tillagehave been examined in the study area in three replicates, based on the randomized complete block design (RCB ). In each tillage system, 10 soil samples of about 0.5 kg (wet) weight for each sample (totally 30 soil samples) were taken from two soil depths (0-25 and 25-40 cm) using a 4 cm diameter Edelman auger. Some physicochemical properties of soil such as total soil organic matter, soil texture, bulk density, and mean weight diameter were measured. Tillage systems did not have any positive effects on soil organic matter (SOM) at two different soil depths (0-25 and 25-40 cm). However, the results showed that no-till system significantly (P>0.05) increased the SOM content of the total measured soil layer (0-40 cm) in comparison with other tillage systems. There is no significant difference in the effects of soil tillage managements on soil bulk density. Moreover, all these three soil tillage systems caused nonsignificant change on soil aggregate stability against erosive factors.

Land-use effects on organic matter and physical properties of soil in a southern Mediterranean highland of Turkey

Plant roots and biochar amendment cause changes in soil structure and hydraulic properties; however, their interactive influences are still inadequately understood. A six-year field study was conducted on hillslope farmland in the Sichuan basin, China, to evaluate how honeysuckle planting and biochar application affect soil structure and hydraulic properties. Various parameters related to soil structure (soil organic matter (SOM), soil aggregate stability, bulk density were obtained in the laboratory) and hydraulic (hydraulic conductivity, and soil water retention characteristics by single porosity of van Genuchten 1980 and dual porosity bi-exponential model) properties were determined. The results showed that honeysuckle planting alone increased (SOM) content, honeysuckle planting following biochar amendment could not only enhance SOM content to a greater magnitude in top 20 cm soil but also markedly increase the SOM content in deeper soil layers (20–30 and 30–40 cm), while the application of biochar alone enhanced the SOM content in top 20 cm soil. The combination of honeysuckle planting and biochar amendment could increase soil aggregate stability. Furthermore, It was found that soil pores with size r > 125 µm were the dominant macropores in all treatments. Honeysuckle planting increased saturated soil hydraulic conductivity (Ks) significantly (p < 0.05). Biochar amendment also significantly increased Ks directly or indirectly through enhancement of SOM content. Results also showed that honeysuckle planting and biochar amendment could lead to a greater increase in saturated soil water content than saturated soil hydraulic conductivity. However, SOM showed lower value in bare land plots suggesting that both honeysuckle planting and biochar could increase SOM in soil, hence improving soil quality. Therefore, our field study demonstrated that the practice of honeysuckle planting and biochar amendment jointly in sloping farmland of purple soil could effectively strengthen soil structure and improve soil water retention.