Assessment of the spatial distribution of cereal yields on sandy soil related to the application of soil-improving cropping systems (SICS).

Sandy soils occur in different regions throughout the world. In spite of poor quality, they are being used in crop production. The use of sandy soils for crop production requires soil-improving cropping systems (SICS). The aim of this study was to determine the spatial relationships of soil properties including intrinsic texture and relatively stable organic carbon, pH(KCl), cation exchange capacity, and cereal yield (grain and straw yields and plant height) in response to random application of SICS using geostatistics and maps. A 4-year field experiment included the following crop rotation: oat, wheat, wheat and oat and SICS: the control (C) and SICS: liming (L), leguminous catch crops for green manure (LU), farmyard manure (M), and farmyard manure+liming+leguminous catch crops together (M + L + LU). The use of the soil properties as auxiliary variables in the cross-semivariograms improved the prediction of the spatial distribution of the cereal yield, compared to the semi-variograms. The cokriging maps showed positional similarity between the cereal yield, the application of some SICS, and soil textural fractions. The application of M and M + L + LU providing the greatest amounts of organic matter and nitrogen was an effective measure in increasing cereal yields in sub-areas with low contents of sand, compared with the C, L, and LU variants. This increase in the yield was most pronounced in the last study year with an adequate rainfall amount and distribution during the growing season. The similar spatial effects of the SICS M and M + L + LU suggest that the application of M can be in part replaced by incorporation of atmospheric nitrogen-fixing legume catch crops and liming with maintenance of the same productivity and nitrogen supply. The spatial interrelations of the yield response, soil texture, and SICS type will help in selection of the most effective SICS in terms of cereal productivity, depending on local soil conditions.

Effects of Application of Recycled Chicken Manure and Spent Mushroom Substrate on Organic Matter, Acidity, and Hydraulic Properties of Sandy Soils.

Soil organic matter is a key resource base for agriculture. However, its content in cultivated soils is low and often decreases. This study aimed at examining the effects of long-term application of chicken manure (CM) and spent mushroom substrate (SMS) on organic matter accumulation, acidity, and hydraulic properties of soil. Two podzol soils with sandy texture in Podlasie Region (Poland) were enriched with recycled CM (10 Mg ha-1) and SMS (20 Mg ha-1), respectively, every 1-2 years for 20 years. The application of CM and SMS increased soil organic matter content at the depths of 0-20, 20-40, and 40-60 cm, especially at 0-20 cm (by 102-201%). The initial soil pH increased in the CM- and SMS-amended soil by 1.7-2.0 units and 1.0-1.2 units, respectively. Soil bulk density at comparable depths increased and decreased following the addition of CM and SMS, respectively. The addition of CM increased field water capacity (at -100 hPa) in the range from 45.8 to 117.8% depending on the depth within the 0-60 cm layer. In the case of the SMS addition, the value of the parameter was in the range of 42.4-48.5% at two depths within 0-40 cm. Depending on the depth, CM reduced the content of transmission pores (>50 µm) in the range from 46.3 to 82.3% and increased the level of residual pores (<0.5 µm) by 91.0-198.6%. SMS increased the content of residual pores at the successive depths by 121.8, 251.0, and 30.3% and decreased or increased the content of transmission and storage pores. Additionally, it significantly reduced the saturated hydraulic conductivity at two depths within 0-40 cm. The fitted unsaturated hydraulic conductivity at two depths within the 0-40 cm layer increased and decreased in the CM- and SMS-amended soils, respectively. The results provide a novel insight into the application of recycled organic materials to sequester soil organic matter and improve crop productivity by increasing soil water retention capacity and decreasing acidity. This is of particular importance in the case of the studied low-productivity sandy acidic soils that have to be used in agriculture due to limited global land resources and rising food demand.

Spatial variability of saturated hydraulic conductivity and its links with other soil properties at the regional scale.

Saturated hydraulic conductivity (K) is a key property for evaluating soil water movement and quality. Most studies on spatial variability of K have been performed soil at a field or smaller scale. Therefore, the aim of this work was to assess (quantify) the spatial distribution of K at the larger regional scale in south-eastern Poland and its relationship with other soil properties, including intrinsic sand, silt, and clay contents, relatively stable organic carbon, cation exchange capacity (CEC) and temporally variable water content (WC), total porosity (FI), and dry bulk density (BD) in the surface layer (0-20 cm). The spatial relationships were assessed using a semivariogram and a cross-semivariogram. The studied region (140 km2) with predominantly permeable sandy soils with low fertility and productivity is located in the south-eastern part of Poland (Podlasie region). The mean sand and organic carbon contents are 74 and 0.86 and their ranges (in %) are 45-95 and 0.002-3.75, respectively. The number of individual samples varied from 216 to 228 (for K, WC, BD, FI) to 691 for the other soil properties. The best fitting models were adjusted to the empirical semivariogram (exponential) and the cross-semivariogram (exponential, Gaussian, or linear) used to draw maps with kriging. The results showed that, among the soil properties studied, K was most variable (coefficient of variation 77.3%) and significantly (p < 0.05) positively correlated with total porosity (r = 0.300) and negatively correlated with soil bulk density (r = - 0.283). The normal or close to the normal distribution was obtained by natural logarithmic and root square transformations. The mean K was 2.597 m day-1 and ranged from 0.01 up to 11.54 m day-1. The spatial autocorrelation (range) of K in the single (direct) semivariograms was 0.081° (8.1 km), while it favourably increased up to 0.149°-0.81° (14.9-81 km) in the cross-semivariograms using the OC contents, textural fractions, and CEC as auxiliary variables. The generated spatial maps allowed outlining two sub-areas with predominantly high K above 3.0 m day-1 in the northern sandier (sand content > 74%) and less silty (silt content < 22%) part and, with lower K in the southern part of the study region. Generally, the spatial distribution of the K values in the study region depended on the share of individual intrinsic textural fractions. On the other hand, the ranges of the spatial relationship between K and the intrinsic and relatively stable soil properties were much larger (from ~ 15 to 81 km) than between K and the temporally variable soil properties (0.3-0.9 km). This knowledge is supportive for making decisions related to land management aimed at alteration of hydraulic conductivity to improve soil water resources and crop productivity and reduce chemical leaching.

The SMOS-Derived Soil Water EXtent and equivalent layer thickness facilitate determination of soil water resources.

The assessment of water resources in soil is important in understanding the water cycle in the natural environment and the processes of water exchange between the soil and the atmosphere. The main objective of the study was to assess water resources (in 2010-2013) in the topsoil from satellite (SMOS) and in situ (ground) measurements using the SWEX_PD approach (Soil Water EXtent at Penetration Depth). The SWEX_PD is a result of multiplying soil moisture (SM) and radiation penetration depth (PD) for each pixel derived from the SMOS satellite. The PD, being a manifold of the wavelength λ0 equal to 21 cm, was determined from the weekly SMOS L2 measurement data based on the real and imaginary part of complex dielectric constant. The SWEX_PD data were compared with soil water resources (WR) calculated from the sum of components derived from multiplication of soil moisture (SM) and layer thickness in nine agrometeorological stations located along the eastern border of Poland. Each study site consisted of seven neighbouring Discrete Global Grid pixels (nodes spaced at 15 km) including the central ones with agrometeorological stations. The study area included different types of soils and land covers. The agreement between the water resources obtained from the SWEX_PD and ground measurements (WR) was quantified using classical statistics and Bland-Altman's plots. Calibrated Layer Thickness (CLT = dbias) from 8 to 28 cm was obtained with a low values of bias (close to zero), limits of agreements, and confidence intervals for all the SWEX_PD, depending on the pixel location. The results revealed that the use of the SWEX_PD for assessing soil water resources is the most reliable approach in the study area. Additionally, the data from Bland-Altman plots and the equation proposed in these studies allowed calculation of the Equivalent Layer Thickness (ELT = [Formula: see text]), which corresponds to the water resources derived from the SMOS satellite at the same time as (SM) measurements performed in the agrometeorological stations. The ranges of the mean, standard deviation, minimum, maximum, and coefficient of variation (CV) of ELT among all pixels and stations were 8.28-28.7 cm, 3.27-12.66 cm, 3.03-10.87 cm, 19.23-94.97 cm, and 24.72-98.79%, respectively. The ranges of the characteristics depended on environmental conditions and their means were close to the values of the calibrated layer thickness. The impacts of soil texture, organic matter, vegetation, and their interactive effects on the differentiation and agreement of soil water resources obtained from SWEX_PD vs. data from ground measurements in the study area are discussed. Further studies are required to address the impact of the environmental factors to improve the assessment of soil water resources based on satellite SM products (retrievals).

Structural and functional microbial diversity of sandy soil under cropland and grassland.

BACKGROUND: Land use change significantly alters soil organic carbon content and the microbial community. Therefore, in the present study, the effect of changing cropland to grassland on structural and functional soil microbial diversity was evaluated. The specific aims were (i) to identify the most prominent members of the fungal communities and their relevant ecological guild groups; (ii) to assess changes in the diversity of ammonia-oxidizing archaea; (iii) to determine the relationships between microbial diversity and selected physical and chemical properties. METHODS: We investigated microbial diversity and activity indicators, bulk density and the water-holding capacity of sandy soil under both cropland and 25-year-old grassland (formerly cropland) in Trzebieszów, in the Podlasie Region, Poland. Microbial diversity was assessed by: the relative abundance of ammonia-oxidizing archaea, fungal community composition and functional diversity. Microbial activity was assessed by soil enzyme (dehydrogenase, ß-glucosidase) and respiration tests. RESULTS: It was shown that compared to cropland, grassland has a higher soil organic carbon content, microbial biomass, basal respiration, rate of enzyme activity, richness and diversity of the microbial community, water holding capacity and the structure of the fungal and ammonia-oxidizing archaea communities was also altered. The implications of these results for soil quality and soil health are also discussed. The results suggest that grassland can have a significant phytosanitary capacity with regard to ecosystem services, due to the prominent presence of beneficial and antagonistic microbes. Moreover, the results also suggest that grassland use may improve the status of soil organic carbon and nitrogen dynamics, thereby increasing the relative abundance of fungi and ammonia-oxidizing archaea.

Determining the effect of exogenous organic materials on spatial distribution of maize yield.

Knowledge on spatial distribution of crop yield in relation to fixed soil fertilisation with exogenous organic materials is essential for improving precise crop and soil management practices within a field. This study assessed the effect of various application rates and types of exogenous (recycled) organic materials (EOMs) containing different organic matter and nitrogen contents vs. mineral nitrogen on the yield of maize by means of linear regressions (trends), spatial kriging-interpolated maps, and Bland-Altman statistics. The experiments were conducted in 2013 and 2014 on two soils, i.e. loam silt in Braszowice (Poland) and clay silt loam in Pusté Jakartice (Czech Republic) under a cross-border cooperation project. The organic materials included compost from manure, slurry, and straw (Ag), industrial organic compost from sewage sludge (Ra), animal meal from animal by-products (Mb), and digestate from a biogas fries factory (Dg). The following 3 application rates of each EOM were adjusted according to the reference 100% = 200 kg N ha-1: 50 (50% N from EOM and 50% mineral N), 75 (75% N from EOM and 25% mineral N), and 100 (100% N from EOM). 100% mineral N was applied on control plots. All treatments were carried out in 4 replicates. The linear regressions between the EOM application rates and the maize yield were in general ascending in the Braszowice soil and descending in the more productive Pusté Jakartice soil. The spatial kriging-interpolated maps allowed separating zones of lower and higher yields with EOMs compared to the control. They were attributed in part to the different EOM application rates and soil water contents. The Bland-Altaman statistics showed that addition of 50% of N from EOMs in 2013 caused a decrease and an increase in the maize grain yield in Braszowice and Pusté Jakartice, respectively, whereas the inverse was true with the 75 and 100% EOM additions. In 2014, the yield of maize for silage increased with the increasing EOM application rate in Braszowice and decreased in Pusté Jakartice, but it was smaller on all EOM-amended plots than in the control. As shown by the limits of agreement lines, the maize yields were more even in Pusté Jakartice than Braszowice. These results provide helpful information for selection of the most yield-producing EOM rates depending on the site soil conditions and prevalent weather conditions.

Assessment of promising agricultural management practices.

iSQAPER project - Interactive Soil Quality Assessment in Europe and China for Agricultural Productivity and Environmental Resilience - aims to develop an app to advise farmers on selecting the best Agriculture Management Practice (AMPs) to improve soil quality. For this purpose, a soil quality index has to be developed to account for the changes in soil quality as impacted by the implementation of the AMPs. Some promising AMPs have been suggested over the time to prevent soil degradation. These practices have been randomly adopted by farmers but which practices are most used by farmers and where they are mostly adopted remains unclear. This study is part of the iSQAPER project with the specific aims: 1) map the current distribution of previously selected 18 promising AMPs in several pedo-climatic regions and farming systems located in ten and four study site areas (SSA) along Europe and China, respectively; and 2) identify the soil threats occurring in those areas. In each SSA, farmers using promising AMP's were identified and questionnaires were used to assess farmer's perception on soil threats significance in the area. 138 plots/farms using 18 promising AMPs, were identified in Europe (112) and China (26).Results show that promising AMPs used in Europe are Crop rotation (15%), Manuring & Composting (15%) and Min-till (14%), whereas in China are Manuring & Composting (18%), Residue maintenance (18%) and Integrated pest and disease management (12%). In Europe, soil erosion is the main threat in agricultural Mediterranean areas while soil-borne pests and diseases is more frequent in the SSAs from France and The Netherlands. In China, soil erosion, SOM decline, compaction and poor soil structure are among the most significant. This work provides important information for policy makers and the development of strategies to support and promote agricultural management practices with benefits for soil quality.

Spatial relationships among cereal yields and selected soil physical and chemical properties.

Sandy soils occupy large area in Poland (about 50%) and in the world. This study aimed at determining spatial relationships of cereal yields and the selected soil physical and chemical properties in three study years (2001-2003) on low productive sandy Podzol soil (Podlasie, Poland). The yields and soil properties in plough and subsoil layers were determined at 72-150 points. The test crops were: wheat, wheat and barley mixture and oats. To explore the spatial relationship between cereal yields and each soil property spatial statistics was used. The best fitting models were adjusted to empirical semivariance and cross-semivariance, which were used to draw maps using kriging. Majority of the soil properties and crop yields exhibited low and medium variability (coefficient of variation 5-70%). The effective ranges of the spatial dependence (the distance at which data are autocorrelated) for yields and all soil properties were 24.3-58.5m and 10.5-373m, respectively. Nugget to sill ratios showed that crop yields and soil properties were strongly spatially dependent except bulk density. Majority of the pairs in cross-semivariograms exhibited strong spatial interdependence. The ranges of the spatial dependence varied in plough layer between 54.6m for yield×pH up to 2433m for yield×silt content. Corresponding ranges in subsoil were 24.8m for crop yield×clay content in 2003 and 1404m for yield×bulk density. Kriging maps allowed separating sub-field area with the lowest yield and soil cation exchange capacity, organic carbon content and pH. This area had lighter color on the aerial photograph due to high content of the sand and low content of soil organic carbon. The results will help farmers at identifying sub-field areas for applying localized management practices to improve these soil properties and further spatial studies in larger scale.

Linking Microbial Enzymatic Activities and Functional Diversity of Soil around Earthworm Burrows and Casts.

The aim of this work was to evaluate the effect of earthworms (Lumbricidae) on the enzymatic activity and microbial functional diversity in the burrow system [burrow wall (BW) 0-3 mm, transitional zone (TZ) 3-7 mm, bulk soil (BS) > 20 mm from the BW] and cast aggregates of a loess soil under a pear orchard. The dehydrogenase, ß-glucosidase, protease, alkaline phosphomonoesterase, and acid phosphomonoesterase enzymes were assessed using standard methods. The functional diversity (catabolic potential) was assessed using the Average Well Color Development and Richness Index following the community level physiological profiling from Biolog Eco Plates. All measurements were done using soil from each compartment immediately after in situ sampling in spring. The enzymatic activites including dehydrogenase, protease, ß-glucosidase and alkaline phosphomonoesterase were appreciably greater in the BW or casts than in BS and TZ. Conversely, acid phosphomonoesterase had the largest value in the BS. Average Well Color Development in both the TZ and the BS (0.98-0.94 A590 nm) were more than eight times higher than in the BWs and casts. The lowest richness index in the BS (15 utilized substrates) increased by 86-113% in all the other compartments. The PC1 in principal component analysis mainly differentiated the BWs and the TZ. Utilization of all substrate categories was the lowest in the BS. The PC2 differentiated the casts from the other compartments. The enhanced activity of a majority of the enzymes and increased microbial functional diversity in most earthworm-influenced compartments make the soils less vulnerable to degradation and thus increases the stability of ecologically relevant processes in the orchard ecosystem.

Impact of Faba Bean-Seed Rhizobial Inoculation on Microbial Activity in the Rhizosphere Soil during Growing Season.

Inoculation of legume seeds with Rhizobium affects soil microbial community and processes, especially in the rhizosphere. This study aimed at assessing the effect of Rhizobium inoculation on microbial activity in the faba bean rhizosphere during the growing season in a field experiment on a Haplic Luvisol derived from loess. Faba bean (Vicia faba L.) seeds were non-inoculated (NI) or inoculated (I) with Rhizobium leguminosarum bv. viciae and sown. The rhizosphere soil was analyzed for the enzymatic activities of dehydrogenases, urease, protease and acid phosphomonoesterase, and functional diversity (catabolic potential) using the Average Well Color Development, Shannon-Weaver, and Richness indices following the community level physiological profiling from Biolog EcoPlate™. The analyses were done on three occasions corresponding to the growth stages of: 5-6 leaf, flowering, and pod formation. The enzymatic activities were higher in I than NI (p < 0.05) throughout the growing season. However, none of the functional diversity indices differed significantly under both treatments, regardless of the growth stage. This work showed that the functional diversity of the microbial communities was a less sensitive tool than enzyme activities in assessment of rhizobial inoculation effects on rhizosphere microbial activity.

Soil microbial functional and fungal diversity as influenced by municipal sewage sludge accumulation.

Safe disposal of municipal sewage sludge is a challenging global environmental concern. The aim of this study was to assess the response of soil microbial functional diversity to the accumulation of municipal sewage sludge during landfill storage. Soil samples of a municipal sewage sludge (SS) and from a sewage sludge landfill that was 3 m from a SS landfill (SS3) were analyzed relative to an undisturbed reference soil. Biolog EcoPlatesTM were inoculated with a soil suspension, and the Average Well Color Development (AWCD), Richness (R) and Shannon-Weaver index (H) were calculated to interpret the results. The fungi isolated from the sewage sludge were identified using comparative rDNA sequencing of the LSU D2 region. The MicroSEQ® ID software was used to assess the raw sequence files, perform sequence matching to the MicroSEQ® ID-validated reference database and create Neighbor-Joining trees. Moreover, the genera of fungi isolated from the soil were identified using microscopic methods. Municipal sewage sludge can serve as a habitat for plant pathogens and as a source of pathogen strains for biotechnological applications.

Symbiotic activity of pea (Pisum sativum) after application of Nod factors under field conditions.

Growth and symbiotic activity of legumes are mediated by Nod factors (LCO, lipo-chitooligosaccharides). To assess the effects of application of Nod factors on symbiotic activity and yield of pea, a two-year field experiment was conducted on a Haplic Luvisol developed from loess. Nod factors were isolated from Rhizobium leguminosarum bv. viciae strain GR09. Pea seeds were treated with the Nod factors (10⁻¹¹ M) or water (control) before planting. Symbiotic activity was evaluated by measurements of nitrogenase activity (acetylene reduction assay), nodule number and mass, and top growth by shoot mass, leaf area, and seed and protein yield. Nod factors generally improved pea yield and nitrogenase activity in the relatively dry growing season 2012, but not in the wet growing season in 2013 due to different weather conditions.

Community level physiological profiles (CLPP), characterization and microbial activity of soil amended with dairy sewage sludge.

The aim of the present work was to assess the influence of organic amendment applications compared to mineral fertilization on soil microbial activity and functional diversity. The field experiment was set up on a soil classified as an Eutric Cambisol developed from loess (South-East Poland). Two doses of both dairy sewage sludge (20 Mg·ha(-1) and 26 Mg·ha(-1)) and of mineral fertilizers containing the same amount of nutrients were applied. The same soil without any amendment was used as a control. The soil under undisturbed native vegetation was also included in the study as a representative background sample. The functional diversity (catabolic potential) was assessed using such indices as Average Well Color Development (AWCD), Richness (R) and Shannon-Weaver index (H). These indices were calculated, following the community level physiological profiling (CLPP) using Biolog Eco Plates. Soil dehydrogenase and respiratory activity were also evaluated. The indices were sensitive enough to reveal changes in community level physiological profiles due to treatment effects. It was shown that dairy sewage amended soil was characterized by greater AWCD, R, H and dehydrogenase and respiratory activity as compared to control or mineral fertilized soil. Analysis of variance (ANOVA) and principal component analysis (PCA) were used to depict the differences of the soil bacterial functional diversity between the treatments.

Macro-porosity and leaching of atrazine in tilled and orchard loamy soils.

Atrazine is the most commonly detected herbicide in the groundwater. Leaching of atrazine largely depends on soil management practices. The aim of this study was to examine leaching of atrazine in tilled and orchard silty loam soils. The experimental objects included: conventionally tilled field (CT) with main tillage operations including pre-plow (10 cm)+harrowing, mouldboard ploughing (20 cm), and a 35 year-old apple orchard (OR) with a permanent sward. To determine leaching of atrazine soil columns of undisturbed structure were taken with steel cylinders of 21.5 cm diameter and 20 cm high from the depth of 0-20 cm. All columns were equilibrated at water content corresponding to field capacity (0.21 kg kg(-1)). Atrazine suspended in distilled water was dripped uniformly onto the surface of each column. Then water was infiltrated and breakthrough times of leachates were recorded. Atrazine concentration in the leachates was determined by means of HPLC Waters. Macro-porosity and percolation rate were higher in OR than CT soil. Cumulative recovery % of the atrazine applied was 1.267% for OR and approximately one third more from the CT soil but the rate of leaching (per unit of time) was greater from the OR soil. The lower leaching under OR than CT can be due to a greater SOM and the presence of earthworm burrows with organic burrow linings that could adsorb atrazine and contribute to preferential flow allowing solutes to bypass parts whereas the greater rate of leaching due to a greater infiltration rate. The results indicate potential of management practices for minimizing atrazine leaching.