Initial Soil Properties Research Articles

Assessing long-term impacts of cover crops on soil organic carbon in the central US Midwestern agroecosystems.

Cover crops have been reported as one of the most effective practices to increase soil organic carbon (SOC) for agroecosystems. Impacts of cover crops on SOC change vary depending on soil properties, climate, and management practices, but it remains unclear how these control factors affect SOC benefits from cover crops, as well as which management practices can maximize SOC benefits. To address these questions, we used an advanced process-based agroecosystem model, ecosys, to assess the impacts of winter cover cropping on SOC accumulation under different environmental and management conditions. We aimed to answer the following questions: (1) To what extent do cover crops benefit SOC accumulation, and how do SOC benefits from cover crops vary with different factors (i.e., initial soil properties, cover crop types, climate during the cover crop growth period, and cover crop planting and terminating time)? (2) How can we enhance SOC benefits from cover crops under different cover crop management options? Specifically, we first calibrated and validated the ecosys model at two long-term field experiment sites with SOC measurements in Illinois. We then applied the ecosys model to six cover crop field experiment sites spanning across Illinois to assess the impacts of different factors on SOC accumulation. Our modeling results revealed the following findings: (1) Growing cover crops can bring SOC benefits by 0.33 ± 0.06 MgC ha-1 year-1 in six cover crop field experiment sites across Illinois, and the SOC benefits are species specific to legume and non-legume cover crops. (2) Initial SOC stocks and clay contents had overall small influences on SOC benefits from cover crops. During the cover crop growth period (i.e., winter and spring in the US Midwest), high temperature increased SOC benefits from cover crops, while the impacts from larger precipitation on SOC benefits varied field by field. (3) The SOC benefits from cover crops can be maximized by optimizing cover crop management practices (e.g., selecting cover crop types and controlling cover crop growth period) for the US Midwestern maize-soybean rotation system. Finally, we discussed the economic and policy implications of adopting cover crops in the US Midwest, including that current economic incentives to grow cover crops may not be sufficient to cover costs. This study systematically assessed cover crop impacts for SOC change in the US Midwest context, while also demonstrating that the ecosys model, with rigorous validation using field experiment data, can be an effective tool to guide the adaptive management of cover crops and quantify SOC benefits from cover crops. The study thus provides practical tools and insights for practitioners and policy-makers to design cover crop related government agricultural policies and incentive programs for farmers and agri-food related industries.

Effects of the Ratio of Substituting Mineral Fertilizers with Manure Nitrogen on Soil Properties and Vegetable Yields in China: A Meta-Analysis

Substituting mineral fertilizers (MFs) with manure nitrogen (N) can not only reduce environmental pollution, but also improve soil quality. However, the effects of various manure N substitution ratios (SRs, the ratio of manure N over total N applied) on soil properties and vegetable yields in China are poorly studied. Here, through a meta-analysis of 667 observations, we assessed the effects of three manure N SRs (low (SR ≤ 35%), medium (35% < SR ≤ 70%), and high (SR > 70%)) on vegetable yields and soil properties (soil organic carbon, SOC; soil total nitrogen, STN; microbial biomass carbon (C) and nitrogen (N), MBC/N; and available phosphorus and potassium, (AP/AK)) in the 0-20 cm soil under different climatic conditions, initial soil properties, and management practices. The results show that the SOC and STN contents increased by 28.5% and 21.9%, respectively, under the medium SRs compared to the MF, which were the highest among the three SRs. Both soil MBC and MBN increased with the increase in the SRs, and the increased ratios in the high SRs reached 203.4% and 119.3%, respectively. In addition, the AP also increased with the increase in the SR, but the AK was not significantly changed with the low and medium SRs compared with the MF. Overall, the medium SR produced the highest vegetable yield among the three SRs with an increase of 18.6%. Additionally, a random forest analysis indicated that the N application rate, planting years, and mean annual precipitation were the most important factors influencing vegetable yield. In conclusion, the SR of 35-70% is more conducive to increasing soil nutrient contents significantly and improves vegetable yields in Chinese vegetable fields.

Effects of Afforestation on Soil Carbon and Nitrogen Accumulation Depend on Initial Soil Nitrogen Status

AbstractLong‐term carbon (C) sequestration in terrestrial vegetation and soil is mediated by soil nitrogen (N) supply. Afforestation is regarded as a global‐scale solution to climate change; thus, resolving the role of N in either facilitating or reducing the long‐term C benefits of this practice has essential implications to maximize its C sink potential. The impacts of afforestation on soil C, N, and their stoichiometric ratio have been widely explored but what regulates these impacts remains unclear at regional and global scales. In this study, we conducted an intensive field sampling investigation including 610 pairs of afforested and control plots in northern China and extensively compiled a global data set containing 211 afforested‐control pairs worldwide to evaluate responses of soil N concentrations and C:N ratios to afforestation and further explored their major regulator. We identified a soil N threshold, the inflection point where afforestation changes from increasing to decreasing soil C and N, which was 0.86 (95% CI: 0.81–0.91) kg N m−2 in 0–1 m depth. Changes in soil C:N ratios with afforestation were mediated by initial relative abundance of soil C and N and types of mycorrhiza associated with planted trees. Increases in soil C:N were mostly driven by trees with ectomycorrhizal associations but did not change for those associated with arbuscular mycorrhizal fungi. These results provide a data‐based understanding on soil C and N dynamics following afforestation and its underlying mechanisms and further highlight the importance of site selection based on initial soil properties in future afforestation.

Tree species identity is the predominant modulator of the effects of soil fauna on leaf litter decomposition

Soil fauna is one of the key drivers of the litter decomposition at both local and global scales, yet the role of tree species in mediating the effects of soil fauna on litter decomposition remains elusive. We conducted a field experiment using litterbags with three different mesh sizes that allowed access of microfauna (0.1 mm), micro- and mesofauna (2 mm), and total soil fauna (5 mm) to evaluate the decomposition of foliar litter of two tree species associated with arbuscular mycorrhizal (AM) fungi and three tree species associated with ectomycorrhizal (ECM) fungi in six Danish common garden sites. We also assessed how differences in initial litter quality, soil properties, and microbial community composition among the tree species may affect litter decomposition as well as soil fauna effects on litter decomposition. Results showed that (1) litter mass loss varied significantly among different mesh sizes and tree species, with litter decomposition rates (k) ranging from 0.273 to 3.482; (2) the access of mesofauna significantly increased litter k of 0.658 for AM and 0.396 for ECM tree species with no access of soil fauna 255 and 92%, respectively, while the access of both meso- and macrofauna increased k by 265 and 108% for AM and ECM trees, respectively; (3) tree species identity, mycorrhizal association, initial litter quality, soil properties, microbial community composition, and ambient soil fauna biomass were all significantly influencing factors on litter decomposition, but tree species identity was the dominant factor regardless of litterbag mesh size; and (4) the effects of mesofauna on litter decomposition were predominantly controlled by tree species identity, initial litter Mg concentration and lignin:N ratio, while the small additional impact of macrofauna access was not well explained by any of the assessed factors. Overall, our results suggest that tree species affect litter decomposition via different stimulation of soil fauna functioning, and that AM and ECM associated tree species differ in the degree to which soil fauna stimulates litter decomposition. However, the pattern was not entirely consistent as litter decomposition rates for the ECM associated lime were stimulated to the same extent as rates for the AM associated tree species ash and maple. Overall, our results suggested that soil meso- and macrofauna communities may enhance tree species effects on litter decomposition as well as incorporation of litter C into mineral soil.

LABORATORY MODEL DESIGN FOR DEEP SOIL MIXING METHOD

One of the most critical problems in the construction sector is the inadequate bearing capacities of subsoils. To solve this problem, various soil improvement methods are employed. Soil improvement is defined as the improvement in soil properties to the desired level by using various methods when the soil is not suitable for superstructure loads. Various types of soil improvement methods exist, and their application depends on the construction site, soil properties, earthquake zone, application time, and cost. One of the most widely used methods recently is the deep soil mixing method. In this study, a laboratory-scale deep soil mixing device is first developed; subsequently, the effects of injection pressure, mixing time, and dosing parameters on application are investigated. Deep soil mixing columns are prepared using different injection pressures, mixing times, and dosages and then subjected to the unconfined compression test. Results show that the effects of injection pressure, cement dosage, and mixing time on the unconfined compressive strength of deep soil mixing samples vary based on the initial soil properties.

Photosynthesis and Leaf Traits of Tree Species Influenced by Green Manure Associated with Soil Treatments

ABSTRACT The use of green manure (GM) associated with soil decompaction treatments has shown to be an alternative to improve soil attributes. This study associated the use of GM with tree species nitrogen-fixing and non-nitrogen-fixing (N-fixing and non-N-fixing, respectively), hypothesizing that non-N-fixing species are more beneficial by GM. The experiment was carried out in a disabled clay extraction deposit. Previously, chemical analysis and mechanical resistance to soil penetration was registered in order to characterize the initial soil properties of the experimental site. The soil treatments were scarification (SCA), scarification + harrowing (SCAH), and subsoiling + harrowing (SUBH) with presence/absence of GM (+GM and -GM, respectively) and four native tree species, N-fixing (Dalbergia ecastophyllum (L.) Taub., Inga laurina (Sw.) Willd., and non-N-fixing (Psidium cattleianum Sabine and Schinus terebinthifolius Raddi), were planted. Growth and leaf traits were measured after 6 and 12 months. The response patterns of leaf attributes were well defined in the non-N-fixing species. Over time, GM increases the level of chlorophyll (Chl) in N-fixing species and, consequently, improves the maximum quantum yield for photosystem II (PSII) primary photochemistry (φPo), quantum yield for PSII electron transport (φEo), the number of active reaction centers (RC/CSo), and the performance index (PI/abs). GM increased these same photochemical parameters in non-N-fixing species after 12 months. The samples cultivated in the SCA and SUBH treatments showed a better performance. The species responded in different ways to GM, which improved the leaf traits in non-N-fixing species. GM improved the leaf traits of N-fixing species. The positive effect of GM over time give us a good alternative for fertilization in revegetation areas. Furthermore, our findings shown that the subsoiling promotes the highest soil decompaction, which associated with GM, can be efficiently used in projects of revegetation of degraded areas.

Hybrid gradient boosting with meta-heuristic algorithms prediction of unconfined compressive strength of stabilized soil based on initial soil properties, mix design and effective compaction

In the investigation, hybrid Gradient Boosting (GB) with four optimization techniques named Simulated Annealing (SA), Random Restart Hill Climbing (RRHC), Particle Swarm Optimization (PSO) and Evolution Strategy Optimization (ESO) are used to develop machine learning models for predicting unconfined compressive strength (UCS) of stabilized soils based on initial soil properties, mix design and effective compaction. The results show that the hybrid model GB_PSO can successfully predict the UCS of stabilized soils with high performance R2 = 0.9655, RMSE = 0.1633 MPa for testing part. The feature importance analyses are performed with using GB_PSO based Permutation Importance of Sklearn library and Shapley Additive Explanations (SHAP value), which reveal that maximum dry density (MDD), linear shrinkage (LS), and Gravel content are the most important characteristics in the UCS prediction performance of the GB_PSO model. The partial dependence plot (PDP) analysis consisting of PDP 1D and PDP 2D show respectively the impact way of each feature on the UCS and the interactions between initial soil properties, mix design and effective compaction in the UCS improvement of stabilized soil. The PDP analysis show that (i) the LS is the most important criterion in determining the success of improving the UCS of stabilized soil, (ii) the predominance of effective compaction over other conditions on the improvement of UCS. The present investigation can be considered to be new insights for better understanding process of stabilized soil and UCS improvement.

Defining the Boundary Conditions for Seismic Response Analysis—A Practical Review of Some Widely-Used Codes

The first step for learning any calculation code for seismic response analysis is an adequate understanding of how to properly set the boundary conditions and the properties of the soil model at the initial stage, i.e., before the shaking event. To pursue this aim, nine different computer codes suitable for seismic response analyses of soil profiles have been reviewed. An ideal twenty-meter soil column with visco-elastic linear behavior, subjected to a pulse-like input motion, has been reproduced with the different codes with the scope to practically show the differences and peculiarities of each of them. In the definition of the soil properties in the small-strain range, special attention has been devoted to the definition of the damping ratio, usually defined in non-linear codes as viscous damping according to the Rayleigh formulation. This simple one-dimensional exercise has been considered as a useful benchmark for verifying the rightness of the application of the boundary conditions and setting the initial soil properties. The same analysis can be easily reproduced by beginner users and, therefore, constitutes a starting point in the learning phase of new and/or more sophisticated 2D and 3D calculation codes for seismic site response analysis.

GIS AND STATISTICAL EVALUATION OF SOIL QUALITY OF SIDI YAHYA, GHARBPLAIN (MOROCCO)

The study of soil quality in irrigated areas is necessary to evaluate the sustainability of the agricultural production system. Indeed, the assessment of this quality is based on the physicochemical and biological characterization of soil parameters, as well as the knowledge of their spatial distribution and their evolution over time. This work aims to make a diagnosis of the current situation of soil quality of SidiYahya in the Gharb plain, Morocco. For this, sampling was carried out from 33 sites distributed over the studied plain during 2019. In this study, different soil properties including specifically texture, pH, electrical conductivity (EC), organic matter (OM), phosphorus (P2O5), and potassium (K2O) were measured while exchangeable sodium percentage (ESP) was calculated using the standard formula. Based on the observed soil properties a map was prepared by using a geographic information system (GIS), which was based specifically on the inverse distance weighted (IDW) spatial interpolation method. Data were processed using different statistical tools like descriptive statistics, correlation, and principal component analysis (PCA). Results of the study revealed that 70% of the soils have a heavy clayey texture with a predominance of vertisols (55%). Further, the study area soil is mainly alkaline (70%), poor in organic matter (61%) and phosphorus (52%), while very rich in potassium (70%), and non-saline (88%) contents. Soil pH was reported to be the least variable whereas sand, phosphorus, and salinity were the highest variable. IDW allowed mapping the soil properties by moving from punctual information to whole extent information. Furthermore, correlations were found between various soil properties by using PCA, 3 principal components (PCs) were able to extract 76% of the information from the 9 initial soil properties. Collected soil samples were grouped into 3 groups, based on their scores on the 3 PCs. Based on these two kinds of information, delineation of management zones can be established for a site-specific supply of agricultural inputs leading to better management of soil and water resources for securing their sustainable use.

What Determines Ion Content of Lumbricid Casts: Soil Type, Species, or Ecological Group?

Most soils possess a large supply of nutrients, but these reserves cannot be mobilized by plants, as they exist in a bound form. Therefore, it is need to understand mechanisms that naturally increase the acquisition of nutrients by plants. Earthworms are crucial soil engineers that play a key role in soil functioning. In this study we have estimated the impact of three factors, earthworm species, ecological group, and soil type, on the ion content of casts of Eisenia nordenskioldi, E. ventripapillata, E. nana, Lumbricus rubellus, and Aporrectodea caliginosa. Laboratory experiments were performed in microcosms on three soil types. We analyzed five water-soluble cations and six anions in the earthworm casts by capillary zone electrophoresis to determine their content in casts compared to soil. For three of the five species studied this is the first information obtained on the matter. The obtained data demonstrated that soil type has the biggest impact on the observed changes in the cast ion content, probably due to the differences in the initial concentrations and soil properties. Within each soil type, the observed effects were mostly species-specific, and the species belonging to the same ecological group (endogeic and epi-endogeic) did not have similar effects. The exposure to different earthworm species resulted in pronounced differences in the concentrations of magnesium, calcium, ammonium, and chloride, while the soil type had the highest impact on sulfate, fluoride, acetate, and sodium ions. Therefore, the terms ‘ecological group’ and ‘functional group’ are not equivalent for earthworm casts, and replacing an earthworm species with another belonging to the same ecological group may result in changes of the soil ion composition.

Effects of cropping system and varieties on the rice growth and yield in acid sulphate soils of tidal swampland

Swampland plays a critical function in agriculture, specifically in growing rice production. The study aimed to determine the effects of cropping systems and varieties on the rice growth and yield in acid sulfate soil of tidal swampland. The experiment was conducted in a potential acid sulphate soils in Kapuas Regency, Central Kalimantan Province. The experiment was arranged in a split plot design with three replications. The main plot consisted of three HYV’s of rice, namely Inpara 8, Inpari 32, and Margasari. The subplot consisted of five cropping systems, namely, Jarwo 2:1A, Jarwo 2:1B, Jarwo 2:1C, Hazton, and Tegel. The plot size was 4 m x 5 m. The variables observed included initial soil properties, plant growth, and yield components. The jajar legowo cropping system in this study was not able to increase rice yields in acid sulphate soil. There was an interaction effect of cropping systems and varieties on the plant height and number of tillers at vegetative phase. At generative and pre-harvest phases, there was significant single effect of variety and cropping system in the planting height and number of tillers, respectively. Both cropping system and variety significantly affected the number of panicles per hill, while panicle length, grain per panicle and grain yield were only affected by variety. There was no significant effect of both factors on the number of filled grains per panicle. Inpara 8 variety achieved the highest grain yield, which was 6.78 ton.ha-1 or equivalent to 4.34 ton.ha-1 of 14 % water content.

​Effects of Application of Soil Amendments on Concentrations of Heavy Metals and Quality of Berseem Grown on Soil Irrigated with Sewage Water

The pot culture experiment for two consecutive years was conducted at Department of Soil Science and Agricultural Chemistry, MPKV, Rahuri to study the influence of various soil amendments on concentrations of heavy metals viz. Cd, Cr, Ni and Pb in berseem fodder crop. The pots were filled with soil irrigated with sewage water for more than thirty five years. The soil was treated with different amendments viz. FYM, gypsum, fly ash and their combinations. All the pots were supplied with recommended dose of chemical fertilizers by maintaining five plants per pot. The experiment was laid out in CRD with eight treatments and three replications. Initial soil properties were pHe 8.38, ECe 4.1 dSm-1, organic carbon 7.6 g kg-1, calcium carbonate 83.8 g kg-1, heavy metals viz. Cd, Cr, Ni and Pb were 0.35, 2.60, 2.23, 10.34 mg kg-1, respectively. Total four cuttings of berseem in each year were taken and analyzed for heavy metal concentrations. Two years pooled mean showed that, there was significant effect of different soil amendments on decreasing concentration of cadmium, chromium and lead as compared to control. Pooled mean of both years showed that the combined application of FYM + gypsum + fly ash each @ 10 g kg-1 soil (T8) registered significantly lower concentration of Cd, Cr and Pb in berseem as compared to rest of the treatments, but found at par with treatment (T5) FYM + gypsum each @ 10 g kg-1 soil. The reduction in concentrations of these heavy metals were higher in treatments where FYM was applied either alone or in combination with other amendments followed by gypsum and fly ash. Pooled mean values of two years showed significantly higher crude protein content due to application of FYM + gypsum + fly ash each @10 gkg-1 soil (T8) and at par with treatment T5. Pooled mean of two years showed numerically higher crude fiber due to treatment T8 (application of FYM + gypsum + fly ash each @ 10 g kg-1 soil) followed by T5 (application of FYM + gypsum each @ 10 g kg-1 soil). Significantly higher Acid Detergent Fiber (ADF) was recorded in T2 (application of FYM @10 g kg-1 soil) followed by T3 (application of gypsum @ 10 g kg-1 soil) treatment.

Soil type affects not only magnitude but also thermal sensitivity of N2O emissions in subtropical mountain area

It is a concern whether the effect of soil type on N2O emissions has to be considered for regional mitigation strategies and emission estimates in mountainous areas with inherent spatial heterogeneities of soil type. To date, there were few field experiments which investigated soil type effects on N2O emissions. Thus a 2-year field study was conducted to measure N2O emissions and soil environmental variables from three different soils that were formed from similar parental rock under the same climate. Seasonal N2O fluxes ranged from 0.18 to 0.40 kg N ha−1 for wheat seasons and 0.40 to 1.50 kg N ha−1 for maize seasons across different experimental soils. The intra- and inter-annual variations in N2O emissions were mainly triggered by temporal dynamics of soil temperature and moisture conditions. On average, seasonal N2O fluxes for acidic soils were significantly lower than for neutral and alkaline soils in cold-dry wheat seasons while significantly greater than for neutral and alkaline soils in warm-wet maize seasons. These determined differences of N2O emissions were mainly caused by differences of initial soil properties across different soils. Moreover, seasonal N2O fluxes were positively correlated with soil pH in wheat seasons, but negatively correlated in maize seasons. The temperature sensitivity coefficient (Q10) of soil N2O emissions for acidic soil (4.06) were significantly greater than those for neutral (1.82) and alkaline (1.15) soils. Overall, N2O emissions for acidic soils were not only higher than those for neutral and alkaline soils but also more sensitive to changing temperature. The present study highlights that soil type is needed to be carefully considered for regional estimate and proposing mitigation strategy of N2O emissions especially in subtropical mountain regions with inherent great heterogeneity of soil type.

Does biochar application improve soil aggregation? A meta-analysis

Biochar as a potential soil amendment has been widely used in agricultural soils for improving soil physical properties. However, the effects of biochar addition on soil aggregation are inconsistent in many individual studies. Therefore, we conducted a meta-analysis of 641 comparisons from 119 published studies to assess the combined effects of biochar application on soil aggregation through biochar attributes, initial soil properties, and experimental conditions. Overall, our results indicate that biochar application significantly improved soil aggregation by 16.4 ± 2.5 %, regardless of biochar/experimental/soil conditions. The response ratio (lnR) of biochar-induced soil aggregation had significant variability across different studies. In the context of biochar attributes, there was a higher favorable influence of wood biochar with higher pyrolysis temperature (> 600 °C). With the amount of biochar increased, the effects of biochar on soil aggregation significantly improved (P < 0.001). Considering experimental conditions, the advancement of soil aggregation was more significant over a longer period of time (> 3 years). In particular, the wet sieving method (18.2 %) is better than the dry sieving method (4.05 %) for assessing soil aggregation. Moreover, soil aggregation intensified in neutral and acidic soil, while alkaline soil was not significantly changed. Also, biochar amendment strengthened soil aggregation in the loam-textured (19.9 %) soils relative to sandy soils (13.4 %). Our meta-analysis demonstrates that biochar as a soil amendment can improve soil aggregation through the combination of experimental conditions with specific biochar, and soil properties.

Spatio-temporal Changes and Associated Uncertainties of CENTURY-modelled SOC for Chinese Upland Soils, 1980–2010

Detailed information on the spatio-temporal changes of cropland soil organic carbon (SOC) can significantly contribute to the improvement of soil fertility and mitigate climate change. Nonetheless, information and knowledge on the national scale spatio-temporal changes and the corresponding uncertainties of SOC in Chinese upland soils remain limited. The CENTURY model was used to estimate the SOC storages and their changes in Chinese uplands from 1980 to 2010. With the Monte Carlo method, the uncertainties of CENTURY-modelled SOC dynamics associated with the spatial heterogeneous model inputs were quantified. Results revealed that the SOC storage in Chinese uplands increased from 3.03 (1.59 to 4.78) Pg C in 1980 to 3.40 (2.39 to 4.62) Pg C in 2010. Increment of SOC storage during this period was 370 Tg C, with an uncertainty interval of −140 to 1110 Tg C. The regional disparities of SOC changes reached a significant level, with considerable SOC accumulation in the Huang-Huai-Hai Plain of China and SOC loss in the northeastern China. The SOC lost from Meadow soils, Black soils and Chernozems was most severe, whilst SOC accumulation in Fluvo-aquic soils, Cinnamon soils and Purplish soils was most significant. In modelling large-scale SOC dynamics, the initial soil properties were major sources of uncertainty. Hence, more detailed information concerning the soil properties must be collected. The SOC stock of Chinese uplands in 2010 was still relatively low, manifesting that recommended agricultural management practices in conjunction with effectively economic and policy incentives to farmers for soil fertility improvement were indispensable for future carbon sequestration in these regions.

Quantifying the effects of spatial-temporal variability of soil properties on crop growth in management zones within an irrigated maize field in Northwest China

Spatial and temporal variability of soil properties, irrigation schedules, and fertilization management play an important role in crop growth and yield in agricultural systems. However, how to improve and accurately predict crop yield in different management zones (MZs) within a large-scale field are important but rarely discussed. In this study, coefficient of variation, linear correlations, partial least squares discriminant analysis and quantile regression were used to quantify relationships between crop and soil properties, and determine key explanatory factors of yield, and to identify suitable ways to improve crop yield among MZs. At the temporal scale, coefficients of variation of crop growth parameters (LAI and biomass), and correlations of crop growth parameters with soil water content and available nitrogen varied during crop growth stages in MZs across years. Crop–soil correlations varied with time and were most pronounced in heading and filling stages when LAI and biomass approached maximum values, respectively. At the spatial scale, 22 explanatory factors belonging to four categories: soil physical properties, initial soil properties, soil water and nitrogen dynamics, and topography were compared. Results showed that among the four categories, initial soil properties had the greatest influence on yield across the whole field, whereas soil water and nitrogen dynamics were the most influential for individual MZs. Key explanatory factors of yield varied across MZs in 2017 and 2018. Although key explanatory factors varied across years within a MZ, some remained unchanged, especially soil physical properties. Based on the quantile regression results, the same key explanatory factors might appear in MZs, but the reference ranges were different. For more sustainable and efficient agricultural production, distributed integrated management, including soil amelioration before sowing, and irrigation and N fertilization scheduling during the crop growth period should be implemented in MZs based on the spatial-temporal variability of soil properties.

Effect of Levels of Coconut Shell Biochar and Farm Yard Manure on Soil Properties under Upland Rice Cultivation

An field experiment were conducted at ZAHRS, UAHS, Shivamogga, during summer 2018 to know the effect of biochar and Farm Yard Manure (FYM) on soil properties. The experiment was planned in Randomized Complete Block Design (RCBD) with 16 treatments consisting of four levels of biochar at 2, 4, 6 and 8 t ha-1 and two levels of FYM at 5 and 10 t ha-1 which were applied alone and in combinations. The recommended dose of fertilizer was applied commonly to all the treatments with three replications. The result revealed that combined application of 8 t ha-1 biochar + 10 t ha-1 FYM with Recommended Dose of Fertilizer (RDF) (100:50:50 kg ha-1) to soil significantly decreased the soil Bulk density (1.30%) and Permanent wilting point (2.13%) and increased the soil porosity (50.94%), Maximum water holding capacity (37.30%), Field capacity (19.71%) and water stable aggregates (67.40%) as compared to initial soil properties of experimental site. Significantly increased the soil pH (initial acidic (5.88) to neutral at harvest (7.05)), Electrical Conductivity (EC) (0.37 dS m-1), Cation Exchange Capacity (CEC) (17.86 [cmol (p+ kg-1)]), available Nitrogen (340.24 kg ha-1), Phosphorus (79.54 kg ha-1), Potassium (252.46 kg ha-1) and Sulfur (13.55 mg kg-1). Soil Diethylene triamine penta acetic acid (DTPA) extractable micronutrients, soil enzymes and microbial biomass compared to absolute control and RDF alone treatments.

Litter share and clay content determine soil restoration effects of rich litter tree species in forests on acidified sandy soils

Many West-European forests are located on degraded and acidified soils. Soil acidification has resulted in hampered ecosystem functioning and lower delivery of ecosystem services. Forest management, particularly the choice of tree species, can accelerate or counteract soil acidification by the quality of litter input. The positive impact of so called ‘rich litter’ on the soil nutrient status and belowground ecosystem functioning has already been evidenced in common gardens. Here, we evaluate the effect of the rich litter species black cherry (Prunus serotina Ehrh.) in mixed forest stands dominated by pedunculate oak (Quercus robur L.). We study the effects using a replicated set-up of 10 established forest stands (age 30 to 90) in Belgium, the Netherlands and Germany along an edaphic gradient in sandy soils on Pleistocene aeolian deposits. We hypothesize that black cherry has a positive effect on the soil nutrient status and aim to answer the following research questions: (i) does admixture of black cherry increase soil pH and base saturation? (ii) what proportion of rich litter admixture is needed in a poor litter matrix to observe significant improvement of the soil nutrient status? and (iii) does the magnitude of the rich litter effect interact with initial soil properties? The results of this study indicate that admixture of black cherry enhances the forest floor turnover and enriches topsoil chemical conditions significantly. Thickness of the litter layer decreases from a mean of 7 cm under oak to a mean of 4.5 cm under cherry and correspondingly base saturation increases to a maximum of 25%, NO3− concentration to 26 mg/mg and organic matter content to 8%. However, large shares of rich litter admixture (>30% basal area) are needed to improve topsoil conditions. Moreover, we find that rich litter effects are more pronounced on sandy soils with higher fine particle (loam + clay) content. This suggests that the actual impact of restoration efforts in acidified forest soils is a product of the trinity “litter quality – litter share – site quality”.

Effects of afforestation of agricultural land with grey alder (Alnus incana (L.) Moench) on soil chemical properties, comparing two contrasting soil groups

BackgroundNatural afforestation of former agricultural lands with alder species is common in Europe. Symbiotic nitrogen fixation by actinomycetes associated with alder species has been widely used for improvement of soil properties of abandoned agricultural lands, but relatively little is known of the interactions of these processes with soil type and chemical composition. We conducted a space-for time study with soil sampling under and outside grey alder tree canopies on two different soil groups to explore effects of colonisation of former agricultural lands by alder on soil properties.ResultsThe results were analysed using analysis of variance. During the first 25 years after afforestation of former agricultural lands there was a significant increase in content of Ctot, Ntot, K+, Fe3+, Mn2+ and available P in the topsoil (0–10 cm and 11–20 cm) of Dystric Arenosols soils, which are deficient in organic matter. Such trends were not evident in organic matter rich Endostagnic Umbrisols soils, in which exchangeable K+ concentration decreased and exchangeable Fe3+ and Al3+ concentration increased.ConclusionsThe results show that the effects of grey alder on soil chemical properties depend on initial soil properties. The invasion of agricultural land by grey alder leads to spatial variability of soil chemical properties creating a mosaic pattern.

Initial soil properties of the restored degraded area under different vegetation cover in UB Forest, East Java, Indonesia

Forest ecosystem degradation due to conversion into agricultural land is increasingly widespread in tropics. This study aimed to determine the initial properties of forest soils in some restoration areas under different vegetation cover. The restoration sites were divided into three areas, namely intensive agricultural land (PI), abandoned coffee plantation (KTT), and remnant protected forest (HLS). In each restoration area, soil samples were taken at top 20 cm depth of soil from five sampling points with three replications. As a comparison, soils were also sampled from the reference sites (RS). Soil samples were then analyzed for some soil properties in the laboratory such as soil physical properties (soil aggregate, bulk density, soil moisture), soil chemical properties (organic matter, pH, electrical conductivity), and soil biological properties (soil bacteria). Results showed that soil physical and chemical properties measured in restoration areas were significantly different from RS (p<0.05). Soil physics properties among three restoration areas were not statistically different (p>0.05), but the soil chemical properties were statistically different. This soil chemical difference was presumably caused by spatial variation and vegetation cover. The diversity of soil bacteria in all studied areas was not statistically different (p<0.05) even though the environmental conditions in each area were different. Among soil properties showed interactions that affected each other based on multivariate data analysis. Forest conversion into agricultural land use had a negative impact on soil properties and tends to decrease soil quality and health.