Cm Layer Of Soil Research Articles

16-Year fertilization changes the dynamics of soil oxidizable organic carbon fractions and the stability of soil organic carbon in soybean-corn agroecosystem

Oxidizable organic carbon is a valuable indicator of soil quality, early changes in soil organic carbon (SOC) content, and changes in stabilities of SOC induced by soil fertilization practices. To improve SOC accumulation under soybean-corn cropping system in flat farmland on the Loess Plateau, we examined the effects of nine fertilization treatments [bare land (BL), control (CK), nitrogen (N), phosphorus (P), N + P (NP), manure (M), M + N (MN), M + P (MP), M + N + P (MNP)] on dynamics of SOC and four fractions of oxidizable organic carbon (OC) [very labile (CVL), labile (CL), less labile (CLL) and recalcitrant (CNL)], and stability of SOC over the period of 1997 to 2013. Although SOC content in treatments without fertilization or with inorganic fertilization remained relatively stable between 1997 and 2013, long-term no fertilization or inorganic fertilization caused a depletion of the very labile C (CVL) fraction and increased the stability of SOC. Long-term application of manure promoted an accumulation of SOC in the topsoil between 1997 and 2013, mainly by sequestering labile C (CVL and CL) in the 0–20-cm soil layer, and the dynamics of SOC and CVL contents under these treatments fitted a logistic regression model, which decreased the stability of SOC between 2008 and 2013. SOC content in the subsoil (20–40 cm) under cultivation with organic fertilization increased between 1997 and 2006, but then decreased between 2007 and 2013. Organic fertilization increased CVL and CL contents in the 20–40-cm layer between 1997 and 2010, but then decreased them between 2010 and 2013, and increased the stability of SOC between 2011 and 2013. Our findings indicated that manure fertilization was more effective in promoting SOC enrichment of the soil surface layers by increasing CVL, relative to inorganic fertilization and no fertilization, whereas long-term manure fertilization was associated with a risk of decreasing labile carbon in the 20–40-cm layer and the stability of SOC in the 0–20-cm layer. Manure fertilizer should thus be used cautiously in farmland on the Loess Plateau to guarantee long-term soil carbon stock.

Assessment of Nutrient Leaching in Flooded Paddy Rice Field Experiment Using Hydrus-1D

Solute runoff and leaching are two direct pathways of nutrient pollution from paddy fields into water systems. Due to the dynamic nature of paddy fields, solute transport and transformation processes are complex and difficult to understand. Therefore, in this study, nitrogen (N) transport in flooded paddy rice fields with conventional irrigation (flooding irrigation) in the Tanjung Karang Rice Irrigation Scheme (TAKRIS), Sawah Sempadan, were observed and modelled using the Hydrus-1D numerical model during two consecutive rice growing seasons. Based on solute transport analysis results, it was observed that 50.3% to 48% of percolated N was accumulated in the top 40-cm soil layer, while 49.7% to 52% of leachate N was lost below the 40-cm soil layer (40–100 cm) during the off and main seasons, respectively. About 85% of N leaching loss was in the form of NO3−. NO3− was absorbed by rice roots within 0–40 cm and the denitrified root zone; however, there was still a large quantity of NO3− which remained below the root zone, which was quickly transported downward along with the leachate water. The NH4+ concentration in subsurface water was lower than the NO3− concentration due to various processes that removed NH4+ from the topsoil layer (0–40 cm), such as ammonium volatilisation, nitrification, and plant uptake. The total leaching loss of N was 34.9 and 27.9 kg/ha during the off and main seasons, respectively. The simulated and observed water flow and nutrient leaching were in a good agreement (R2 = 0.98, RMSE = 0.24). The results showed that Hydrus-1D successfully simulated the solute movement under different soil depths during the study period.

Surface rock effects on soil moisture retrieval from L-band passive microwave observations

The L-band (1.41 GHz) passive microwave remote sensing technique is the approach used by the first satellites dedicated to soil moisture measurement, the European Space Agency's (ESA) Soil Moisture and Ocean Salinity (SMOS), and the Soil Moisture Active Passive (SMAP) mission developed by the National Aeronautics and Space Administration (NASA). These satellites aim to provide global soil moisture maps for the top ~5 cm layer of soil with an accuracy better than 0.04 m3/m3. However, with a passive microwave observing resolution of ~40 km, non-soil targets such as surface rock may possibly confound the brightness temperature observations and degrade the accuracy of retrievals for many SMOS and SMAP pixels across the world. Since the microwave contribution of rock is not well accounted for in current soil moisture retrieval algorithms, simply ignoring its existence may be detrimental to the performance of resultant soil moisture products. Using a combination of model simulations and airborne field campaign data from central Australia, this study has determined that a rock cover fraction threshold of up to 0.4 can be tolerated before the 0.04 m3/m3 soil moisture target accuracy is potentially exceeded under extreme dry or wet conditions. However, this threshold reduces to 0.2 when assessed in terms of a brightness temperature impact >4 K. These rock fraction thresholds have subsequently been applied to the Ecoclimap rock cover map, identifying the SMOS and SMAP pixels globally that are likely to be adversely affected if rock is unaccounted for. The results show that approximately ~3.3% of all SMOS and SMAP pixels may have brightness temperature impacts exceeding 4 K from surface rock, with Asia being the most affected, having ~6.0% affected pixels. These values reduce to ~1.5% of SMOS and SMAP pixels globally, and ~3.1% for Asia, when assessed in terms of soil moisture errors expected to possibly exceed 0.04 m3/m3 when not accounting for surface rock.

Wheat Grain Enrichment with Zinc Through Using Zinc Fertiliser and Preceding Plant Residues Incorporation

Abstract Micronutrients and particularly zinc (Zn) deficiency affects crops productivity and human health, therefore improving Zn concentration within plant tissues might be regarded as an aim of sustainable agriculture. In this respect, a field experiment was carried out to examine the potential influence of preceding crop residues including bean and wheat incorporation into the soil as a way to improve zinc accumulation within subsequent wheat (Triticum aestivum L.) grain. The experiment was initiated at autumn 2014 and in the first year, a piece of farm land in Dehaghan-Isfahan-Iran was divided into two equal parts devoted to wheat and bean cultivation. At the end of the harvest season, aboveground plant residues were incorporated to 0-30 cm layer of soil. In the next year, the entire farm devoted to wheat production. The applied treatments included: control, zinc sulfate (60 kg/ha), wheat residues, bean (Phaseolus vulgaris L.) residues, wheat residues + zinc sulfate and bean residue + zinc sulfate. The results of analysis of variance showed the highly significant differences between treatments in terms of grain zinc, protein, phytic acid to zinc molar ratio (PA/Zn), quantitative yield and soil electrical conductivity (EC). Soil pH and organic carbon (OC) were not affected by treatments while soil EC significantly increased by using plant residues. The highest grain yield (3.8 t/ha), grain protein (10.3 mg/kg) and zinc concentrations (36 mg/kg) were obtained by using bean residues plus ZnSO4 while the lowest quantities were related to control treatment. The treatments had no significant impact on grain acid phytic concentration but phytic acid / zinc molar ratio was affected by treatments and the lowest ratio (which is a positive attribute) was measured from plots containing bean residues plus ZnSO4 while the highest occurred in control plots.

Influence of rainwater harvesting and soil anti-seepage on soil water infiltration, distribution and use efficiency in hilly orchard.

Rainwater harvesting and soil anti-seepage technology is a new technology based on the ridge film mulching and furrow rainwater harvesting. To explore the application effects of rainwater harvesting and soil anti-seepage technology, four different treatments including control (CK), loessal soil with compacted anti-seepage treatment (L1), red clay with anti-seepage treatment (R1), and red clay with compacted anti-seepage treatment (R2) were set up in a "Fuji" hillside orchard in Mizhi Demonstration Station of northern Shaanxi Province. Soil bulk density, stable infiltration rate, soil water content, fruit quality and yield, and water use efficiency were measured. Results showed that R2 had the best anti-seepage efficiency with the highest bulk density (1.61 g·cm-3), the minimum water holding capacity, and the least stable infiltration rate (0.02 mm·min-1). The empirical formula of Kostiakov equation was suitable for describing water infiltration characteristics. Throughout the growing season, soil moisture for 0-60 cm soil depth in the rainwater harvesting ditch could be improved by the different anti-seepage treatments. R2 had the highest soil water content all the time and could satisfy the suitable water content standard for growth and development of apple trees in the dry season. Under the anti-seepage treatment, there was an "low humid layer" with 20-30 cm of soil layer under 60 cm soil depth, but the variation tendency of soil water content from "low humid layer" to 200 cm soil layer was stable and slightly higher than that in CK. Rainwater harvesting and soil anti-seepage treatments could increase fruit yield and water use efficiency, and improve the quality of fruit. Compared with that in CK, the fruit yield, the rate of good fruit, and water use efficiency of R2 treatment increased by 19.2%, 26.5%, and 24.5%, respectively. Therefore, rainwater harvesting and soil anti-seepage technology was recommended as the effective agricultural measurement in the apple production in loess hilly areas of northern Shaanxi Province.

FUKUSHIMA FALLOUT IN SAKHALIN REGION, RUSSIA, PART 1: 137CS AND 134CS IN GRASSLAND SOILS

The caesium-134 and caesium-137 radionuclides released into the atmosphere as a result of the Fukushima accident were dispersed over the entire Northern Hemisphere. To assess the risks associated with the exposure due to Fukushima fallout, a comprehensive radiological survey was performed in the Russian Far East. One of the objectives of the project was to determine the densities of ground contamination by 137 Cs and 134 Cs on Sakhalin and Kuril Islands that constitute the Sakhalin oblast, an administrative region of Russia. In 2011, soil samples were collected at grasslands on Sakhalin, Kunashir and Shikotan Islands and results of the 2011 survey were published earlier. In the present study, activities of 137 Cs and 134 Cs were measured in soil samples obtained on Kunashir, Iturup, Urup and Paramushir Islands in 2012. From the studies carried out in 2011–2012, it was estimated that the Fukushima-derived 134 Cs inventory at 37 undisturbed grassland sites in the Sakhalin oblast varied from 8 Bq m −2 to 345 Bq m −2 (as of 15 March 2011). For this date, the inventory of the 137 Cs radionuclide originated from the Fukushima NPP was assumed to be the same as that of the 134 Cs radionuclide. The southern Kuril Islands were the most contaminated due to Fukushima fallout. In 2011 and 2012, Fukushima-derived radiocaesium was detected only in the top 5 cm layer of soil at all sites, excluding one, where ~20% of the 134 Cs inventory was found at a depth of 5–10 cm. In the period September 2011– September 2012, the inventory of 134 Cs declined by ~26% at four plots selected for long-term observations. The decline in the 134 Cs inventory closely corresponded to the reduction (29%) of 134 Cs activity due to radioactive decay. Pre-accidental inventory of 137 Cs in the top 20 cm layer of soil ranged from 53 Bq m−2 to 3630 Bq m −2 . The mean reference inventory of pre-accidental 137 Cs for 13 representative sites was amounted as 2600 Bq m −2 . Hence, the Fukushima accident added relatively small quantities of radioactivity to the reference preaccidental inventory of 137 Cs in grassland soils in the Sakhalin region: about 3% (~80 Bq m −2 ) on the average and 15% (~350 Bq m −2 ) at the maximum. Such small additional radioactive contamination is absolutely safe from a radiological point of view.

Mediterranean cork oak wooded grasslands: synergies and trade-offs between plant diversity, pasture production and soil carbon

Mediterranean wooded grasslands that emerge from silvopastoral activities are multifunctional systems that result in high biodiversity and offer ecosystem services such as forage production and soil carbon sequestration. During 3 years, ten grazed wooded grassland fields were studied in the Berchidda–Monti long-term observatory, located in NE Sardinia, Italy, with the aim of exploring the synergies and trade-offs between biodiversity and selected ecosystem services. Positions below and outside the canopy of three cork oak trees in each field were randomly selected to compare seasonal pasture production, pasture utilization rate by animals, botanical composition, biodiversity indicators (Shannon index and plant species richness) and soil organic carbon. In autumn, dry matter production of pasture was similar in the two positions; in two winters out of three it was greater below the trees than outside, and in spring it was greater outside than below the trees. While plant species richness and Shannon index were not significantly influenced by the position, the overall wooded grassland plant species richness was 31% higher than that outside of the tree crown. The soil organic carbon content in the 0–40-cm soil layer was also higher below the trees. Our findings highlight that if the main purpose of the wooded grasslands is to provide forage for grazing animals rather than conserving and/or enhancing plant diversity and soil fertility, the presence of trees constrains the overall forage productivity, although the greater forage availability in winter under the trees can contribute to improve the seasonal distribution of forage production.

Soil enzyme activities and microbial biomass response to crop types on the terraces of the Loess Plateau, China

Soil microbes play a critical role in the recycling of soil nutrients and soil fertility. Different crop types greatly influence the soil environment, including the carbon and nitrogen biogeochemical cycles, and the effects may be particularly important on the terraces of the Loess Plateau. In this study, the characteristics of soil physicochemical properties and microbial activity were investigated under different crop types to establish relationships among soil microbial biomass, enzyme activities, and physicochemical properties. Soils under four typical crops (potato, corn, apple, and intercropping (apple and potatoes)) grown on terraces constructed during a similar period were examined at an experimental site on the Loess Plateau, with 5-year abandoned land as the control. The activities of soil invertase, urease, and alkaline phosphatase, soil microbial biomass carbon (MBC), soil microbial biomass nitrogen (MBN), and the ratio MBC/MBN, and their relationships with soil physicochemical properties were investigated using redundancy analysis and partial redundancy analysis. (1) For soil physicochemical properties, including organic carbon, total nitrogen, total phosphorus, nitrate nitrogen, and available phosphorus, the lowest concentrations were in abandoned land and the highest contents were under apple and intercropping; (2) the activities of soil invertase were in the order intercropping > corn > apple > potato > abandoned land, whereas the activities of soil urease in apple and intercropping were more than twofold higher than those in abandoned land; (3) soil microbial biomass carbon and the ratio of MBC/MBN were highest in abandoned land, which indicated that abandoned land had a high proportion of bacterial to fungal biomass; (4) soil microbial activity was affected by the application of organic manure under terrace crop systems. The contents of soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), and available phosphorus (AP) in abandoned land were significantly lower than those under all crop types; thus, directly abandoned farmland was not favorable for soil microbial activity in the typical loess hilly-gully region. Soil TP, moisture (MS), and NO3−–N were identified as the key factors affecting soil microbial activity in the 0–20-cm soil layer, and soil TP, AP, NH4+–N, and NO3−–N were the significant factors in the 20–40-cm layer.

The migration and transformation regular study of metal manganese in surface soil of Yiwang Industrial Park in Shanxi Province, China

ABSTRACTAll kinds of industries can produce a large amount of the heavy metal Mn emission, especially in the Mn steel plant production process. The assessment of Mn pollution in industrial areas is vital to human health and soil conservation. First, there are 120 samples of 0–5 cm and samples 9 of 0–40 cm of the surface soil collected from outside. Next, the soil column test is applied to study the migration and speciation regularity of Mn in 0–40 cm of soil layer, and then a forecasting model is established to verify and evaluate the Mn pollution in the study area. After the exogenous Mn enters the soil, Mn soon transforms into a more stable form in soil at 0–20 cm depth. But the residual amounts of Mn in deep soil increases with the increase of exogenous Mn. The main speciation of Mn in surface soil includes residual, oxide-bound, and organic-bound forms. Carbonate-bound form is sensitive to the increase of exogenous Mn. The exogenous Mn content has less influence on the content of oxide-bound and organic-bound forms in soils below 20 cm. The prediction model can be used to evaluate the degree of pollution of Mn in surface soil of the study area.

Динаміка родючості ґрунтів орних земель Гощанського району Рівненської області

Динаміка родючості ґрунтів орних земель Гощанського району Рівненської області

Dynamics of Soil Properties and Plant Composition during Postagrogenic Evolution in Different Bioclimatic Zones

The postagrogenic dynamics of acidity and some parameters of humus status have been studied in relation to the restoration of zonal vegetation in southern taiga (podzolic and soddy-podzolic soils (Retisols)), coniferous-broadleaved (subtaiga) forest (gray forest soil (Luvic Phaeozem)), and forest-steppe (gray forest soil (Haplic Phaeozem)) subzones. The most significant transformation of the studied properties of soils under changing vegetation has been revealed for poor sandy soils of southern taiga. The degree of changes in the content and stocks of organic carbon, the enrichment of humus in nitrogen, and acidity in the 0- to 20-cm soil layer during the postagrogenic evolution decreases from north to south. The adequate reflection of soil physicochemical properties in changes of plant cover is determined by the climatic zone and the land use pattern. A correlation between the changes in the soil acidity and the portion of acidophilic species in the plant cover is revealed for the southern taiga subzone. A positive relationship is found between the content of organic carbon and the share of species preferring humus-rich soils in the forest-steppe zone.

Long-term nitrogen fertilization impacts soil fungal and bacterial community structures in a dryland soil of Loess Plateau in China

Nitrogen (N) fertilization is a key factor that affects soil biogeochemical properties and microbial community structures across ecosystems. However, we know less about the responses of soil microbial community dynamics and biogeochemical properties to long-term N fertilization practices in a loess dryland soil in Northwest China. We sampled dryland soils at the 0–20-cm soil layer from a long-term field experiment (initiated in 2004) conducted in Northwest China, which has three treatments (i.e., N0 (control), N160 (160 kg N ha−1 year−1), and N320 (320 kg N ha−1 year−1). We determined soil biogeochemical properties and used 454 pyrosequencing of internal transcribed spacer (ITS) regions (for fungi) and V1–V3 regions of 16S rRNA (for bacteria) genes to explore soil microbial communities. Increased concentrations of soil organic carbon (SOC), total N (TN), nitrate N and microbial biomass N, and decreased soil pH were found in N-fertilized treatments and probably due to N fertilizer additions. However, N fertilization had no significant effect on soil microbial biomass C, available phosphorus, available potassium, and electrical conductivity. N fertilization did not affect the fungal species number, but it decreased the abundance of phylum Zygomycota and increased genus Fusarium. The predominant bacterial phyla in N0 were Bacteroidetes, Firmicutes, and Fusobacteria, but in N160 and N320 were Acidobacteria, Actinobacteria, and Proteobacteria. At the bacterial genus level, N fertilization decreased the relative abundances of Bacteroides, Fusobacterium, and Faecalibacterium and increased other genera (e.g., Bacillus, Lactococcus, Rhodoplanes, Steroidobacter). However, there was no difference in community structure between N160 and N320. The bacterial community structure had close correlation to soil properties SOC, TN, and pH, while no correlations were observed between fungal community structure and these soil properties, which indicated that soil bacterial community structure was easily changed by soil properties as affected by N fertilization. N fertilization changed soil biogeochemical properties and thereby altered soil fungal community compositions and bacterial community structure, but it did not impact the fungal diversity. These results demonstrated that a reasonable rate of N fertilizer applied to wheat field can improve soil fertility and microbial communities.

Pupation Behavior and Predation on Drosophila suzukii (Diptera: Drosophilidae) Pupae in Maine Wild Blueberry Fields

Drosophila suzukii (Matsumura; Diptera: Drosophilidae) is an invasive vinegar fly and pest of soft fruits in North America, including wild blueberries (Vaccinium angustifolium Aiton) in Maine. Despite its presence in the continental United States for 9 yr, little is known about its natural enemy complex. Here we report the results of a 3-yr study designed to identify naturally-occurring predators in Maine's wild blueberry fields. Experiments were conducted to determine pupation site and pupation depth to understand D. suzukii's predation vulnerability. Predation rates in the field of fully-exposed, caged, and buried pupae were measured. Pitfall traps were deployed to identify the potential predator assemblage, and laboratory experiments were conducted to determine how many pupae were consumed by commonly occurring ground beetle species (Carabidae) and field crickets (Gryllus pennsylvanicus Burmeister). The most commonly collected predators were ants, ground beetles, harvestmen, and field crickets. Significantly more pupae were found to occur in the soil compared to blueberry fruit, with most pupae in the top 0.5 cm layer of soil. Pupal predation rates in the field were high, with higher rates of predation on exposed pupae compared to buried pupae. Laboratory studies revealed that ground beetles and field crickets are likely predators of D. suzukii pupae.

Drip Irrigation Affects the Morphology and Distribution of Olive Roots

Under field conditions, this study investigated the influence of the irrigation amount on olive root morphology and spatial distribution. Soil samples were taken with an auger at distances of 30, 60, and 90 cm from the tree trunks in four directions. The roots were analyzed using an Epson Twain Pro root scanning system. The results indicated that under different irrigation treatments, the indicators of root morphology of different varieties showed different responses to the irrigation amount. The root length density (RLD), root surface area (RSA), and root volume (RV) of Arbosana first increased with increasing irrigation amount but then decreased; however, those of Arbequina monotonically increased with increasing irrigation amount. The root average diameter of the two varieties was inversely proportional to the irrigation amount. In the vertical dimension, the RLD and RSA of each treatment decreased with increasing soil depth and were mainly distributed in the surface soil (0–20 cm in depth). The RLD and RSA in the vertical direction (VD) of the drip irrigation belt were higher than those of the belt in the parallel direction (PD), and the range was 12% to 86%. Compared with the roots of the 0- to 20-cm soil layer, the roots of the 20- to 40-cm and 40- to 60-cm soil layers were more influenced by the irrigation amount. Horizontally, the RLD and RSA decreased with increasing radial distance. The 30-cm radial area contained most roots, the proportion of roots in this region increased with increasing irrigation capacity. The influence of irrigation quantity in the PD of the drip irrigation belt was greater than that in the VD. The results suggest that irrigation does not change the root spatial distribution pattern but does promote root growth. The two varieties had different responses to irrigation. In terms of soil moisture levels after irrigation, 75% of field capacity is appropriate for ‘Arbosana’, whereas 100% is advisable for ‘Arbequina’. To improve water use efficiency, moisture should be irrigated within the 30-cm radial distance from the trunk, and irrigation depth is not easy to more than 20 cm. This study provides a scientific basis for the efficient water management of olive trees.

The statistical structure of the field of surface soil layer moisture from ground-based and satellite observations

The following data was used: the archives of measurements of available water capacity carried out at Roshydromet network of stations and satellite measurements of relative humidity of the upper soil layer from ASCAT data (from the MetOp satellites). The statistical structure of the field of available water capacity in the upper 10- and 20-cm soil layers is assessed. The correlations between the Earth remote sensing data and data from agrometeorological stations are revealed. The procedure of automatic data checking from ground-based observations is developed. The algorithm is suggested for statistically optimal conversion of the Earth remote sensing data to the estimate of moisture content in the upper soil layer.

Distribution of pesticide residues in soil and uncertainty of sampling

ABSTRACTPesticide residues were determined in about 120 soil cores taken randomly from the top 15 cm layer of two sunflower fields about 30 days after preemergence herbicide treatments. Samples were extracted with acetone-ethyl acetate mixture and the residues were determined with GC-TSD. Residues of dimethenamid, pendimethalin, and prometryn ranged from 0.005 to 2.97 mg/kg. Their relative standard deviations (CV) were between 0.66 and 1.13. The relative frequency distributions of residues in soil cores were very similar to those observed in root and tuber vegetables grown in pesticide treated soils. Based on all available information, a typical CV of 1.00 was estimated for pesticide residues in primary soil samples (soil cores). The corresponding expectable relative uncertainty of sampling is 20% when composite samples of size 25 are taken. To obtain a reliable estimate of the average residues in the top 15 cm layer of soil of a field up to 8 independent replicate random samples should be taken. To obtain better estimate of the actual residue level of the sampled filed would be marginal if larger number of samples were taken.

Effects of supplemental irrigation by measuring soil moisture on water consumption chara-cteristics and radiation utilization in wheat

Field experiments were conducted during 2013-2014 and 2014-2015 winter wheat growing seasons by using Jimai 22 as test material. Five treatments were designed: W0(non-irrigation during growth season), W1(non-irrigation at overwintering, but irrigated to 65% of field capacity (FC) at jointing and 70% of FC at anthesis in 0-40 cm soil layer), W2(irrigated to 70% of FC at overwintering, 65% of FC at jointing and 70% of FC at anthesis in 0-40cm soil layer, respectively) and W3(irrigated to 75% of FC at overwintering, 65% of FC at jointing and 70% of FC at anthesis in 0-40cm soil layer, respectively), W4(irrigated 60 mm at overwintering, jointing and anthesis stages, respectively). The aim was to clarify the effects of supplemental irrigation on water consumption characteristics and photosynthetically active radiation utilization in wheat. Results showed that the total irrigation amount and its ratio to total water consumption in each treatment were ranked as W4＞W3＞W2＞W1＞W0. However, the percentage of water consumption in soil to total water consumption was presented as W0＞W1, W2＞W3, W4. The total water consumption, water consumption from anthesis to maturity were ranked as W4＞W2, W3＞W1＞W0. The order of photosynthetically active radiation (PAR) capture ratio was W4＞W2, W3＞W1＞W0, but the order was contrary in PAR reflect ratio among the treatments. The net accumulation of dry matter was ranked as W4＞W2＞W3＞W1＞W0 in the two growing seasons. During the two winter wheat growing seasons, the grain yield in W2 was higher than in the other treatments, except W4, but the irrigation efficiency and water use efficiency in W2 were the highest. Concerning both the high-yield and high-water use efficiency in this experiment, the most appropriate irrigation regime was W2 treatment.

Soil improvement promoted micro-ecology of farmlands for ginseng cultivation

This study has revealed the change of the soil micro-ecology of farmlands, which used for ginseng cultivation, brought by comprehensive soil improvement. The process of soil improvement was described as follows： soil was sterilized using trichloronitromethane, and then perilla seeds were planted. After growing up, the perillas were turned over into the field and fermented, then organic fertilizer was added. Rotary tillages were carried out during the intervals. Physical and chemical properties of treated soil were measured, as well as microbial diversity, which was illustrated using 16s high through-put sequencing. The survival rate and growth data of ginseng seedlings were recorded. The analysis showed that after improvement, the soil organic matter content was increased and soil bulk density was decreased, compare to the controls, and the fertility in 0-20 cm of soil layer was increased in the treatment. Additionally, the soil microbial diversity was changed greatly. In detail, alpha diversity of the soil decreased after soil improvement while the beta diversity increased. In order to verify the achievement of soil improvement, ginseng seedlings were planted. Compared to the untreated land blocks, the survival rate of ginseng on improved blocks was increased up to 21.4%, and the ginseng physiological index were all better than the controls. Results showed that comprehensive soil improvements including soil sterilization, green manure planting and organic fertilization application effectively improved the soil micro-ecology in farmlands. This study will pave the way for the future standardization of ginseng cultivation on farmlands.

Natural 13C abundance and soil carbon dynamics under long‐term residue retention in a no‐till maize system

AbstractResidue retention and reduced tillage are both conservation agricultural practices that may enhance soil organic carbon (SOC) stabilization in soil. We evaluated the long‐term effects of no‐till (NT) and stover retention from maize on SOC dynamics in a Rayne silt loam Typic Hapludults in Ohio. The six treatments consisted of retaining 0, 25, 50, 75, 100 and 200% of maize residues on each 3 × 3 m plot from the crop of previous year. Soil samples were obtained after 9 yrs of establishing the experiment. The whole soil (0–10 and 10–20 cm of soil depths) samples under different treatments were analysed for total C, total N, recalcitrant C (NaOCl treated sample) and 13C isotopic abundance (0–10 cm soil depth). Complete removal of stover for a period of 9 yrs significantly (P < 0.01) decreased soil C content (15.5 g/kg), whereas 200% of stover retention had the maximum soil C concentration (23.1 g/kg). Relative distribution of C for all the treatments in different fractions comprised of 55–58% as labile and 42–45% as recalcitrant. Retention of residue did not significantly affect total C and N concentration in 10–20 cm depth. 13C isotopic signature data indicated that C4‐C (maize‐derived C) was the dominant fraction of C in the top 0–10 cm of soil layer under NT with maize‐derived C accounting for as high as 80% of the total SOC concentration. Contribution of C4‐C or maize‐derived C was 71–84% in recalcitrant fraction in different residue retained plots. Residue management is imperative to increase SOC concentrations and long‐term agro‐ecosystem necessitates residue retention for stabilizing C in light‐textured soils.

Integrated spatial assessment of wind erosion risk in Hungary

Abstract. Wind erosion susceptibility of Hungarian soils was mapped on the national level integrating three factors of the complex phenomenon of deflation (physical soil features, wind characteristics, and land use and land cover). Results of wind tunnel experiments on erodibility of representative soil samples were used for the parametrization of a countrywide map of soil texture compiled for the upper 5 cm layer of soil, which resulted in a map representing threshold wind velocity exceedance. Average wind velocity was spatially estimated with 0.5′ resolution using the Meteorological Interpolation based on Surface Homogenised Data Basis (MISH) method elaborated for the spatial interpolation of surface meteorological elements. The probability of threshold wind velocity exceedance was determined based on values predicted by the soil texture map at the grid locations. Ratio values were further interpolated to a finer 1 ha resolution using sand and silt content of the uppermost (0–5 cm) layer of soil as spatial co-variables. Land cover was also taken into account, excluding areas that are not relevant to wind erosion (forests, water bodies, settlements, etc.), to spatially assess the risk of wind erosion. According to the resulting map of wind erosion susceptibility, about 10 % of the total area of Hungary can be identified as susceptible to wind erosion. The map gives more detailed insight into the spatial distribution of wind-affected areas in Hungary compared to previous studies.