Soil Water Regime Research Articles

Reed Fescue Cultivation Basic Techniques Influence on Organics and Nutrients Accumulation in the Soil

The article presents the results of many years research on the new valuable reed fescue bluegrass crop attracting to the fodder production of the region. Rational combinations of the main crop-forming factors were established: timing, sowing methods and their effect on the fescue productivity when used for seed and fodder purposes, ensuring the receipt of 400 to 800 kg/ha of seeds and from 20 to 30 t/ha of green mass. Reed fescue, when optimizing the conditions of the soil water and nutritional regime, timing, sowing methods and norms, is able to influence the fertility and the content of basic nutrients in the soil, by accumulating the root mass by the years of life from 5.0-6.0 to 17.7-20.4 t/ha of dry roots, which contributes to the introduction of 52-73 to 123-187 kg of nitrogen, 10-38 - phosphorus and 149-204 kg/ha of potassium.

Model of soil moistening during wide-row crops drip strip irrigation

The study is devoted to modeling the soil moisture zone formation during agricultural crops drip strip irrigation, taking into account the system-dynamic processes of moisture distribution during irrigation and in the inter-irrigation period. The working hypothesis of the study was the assumption that, due to the point method of water supply and the radial subsurface moisture distribution, the replenishment of soil moisture reserves within the boundaries of the humidification zone occurs unevenly and this must be taken into account when developing irrigation techniques for agricultural crops. The model characterizes the moisture distribution in the soil depending on the water supply volume and the transformation of zones with differentiated moisture reserves during the inter-irrigation period established for the crop. The study uses experimental data to check the moisture distribution features in the soil after irrigation and to assess the soil moisture saturation degree by zones of the moisture contour on the date when the need for the next vegetation irrigation was established. The results of the study substantiated the need for the introduction of new parameters characterizing the soil moisture distribution during drip strip irrigation, which must be taken into account for the formation of an optimal soil water regime, focused on the cultivated crop biological needs.

Soil Penetration Resistance and Sugarcane Rooting Under Subsuperficial Drip Irrigation Levels

Knowledge of the soil water regime in a dynamic equilibrium condition (steady state) of the emitter–soil–plant system is essential to evaluate the adopted irrigation management, aiming to maximize the water use efficiency in irrigation. Thus, our objective was to determine the integrated effect of four irrigation levels on the soil moisture (θv) distribution pattern, mechanical soil penetration resistance (PR), and sugarcane rooting. Irrigation levels were established based on the percentage of reference evapotranspiration (ETo), as follows: 40% (W1), 70% (W2), 100% (W3), and 130% (W4) of ETo. From the soil moisture profile and PR versus θv regression models, PR profiles for each irrigation level were estimated. At the end of the crop cycle, trenches were opened to assess sugarcane root system. According to the results, the water dynamic in the soil profile resulted in a soil-wetting pattern that did not match the sugarcane rooting profile. For treatments W3 and W4 the wetting pattern indicated water loss through deep percolation. For all treatments and considering the entire soil profile, the PR values ranged from < 2 to 10 MPa. Also, the roots were superficially spread and limited to the first 0.35 m in depth for all irrigation depths applied. Although the soil wetting by irrigation reduced the strength of the cohesive layer, this reduction was insufficient to allow the deepening of plant roots. The su garcane root development was limited to the region of the soil profile defined by a PR value approximately equal to 2.0 MPa.

ОСОБЕННОСТИ МОДЕЛИРОВАНИЯ РАСПРЕДЕЛЕНИЯ ВОДНЫХ РЕСУРСОВ НА СИСТЕМАХ ДВОЙНОГО РЕГУЛИРОВАНИЯ ВОДНОГО РЕЖИМА ПОЧВ

The aim of the research is to develop a modeling methodology for solving problems associated with the creation of simulation models and means of information and technological support for the tasks of allocating water resources on drainage systems for double regulation of the water regime of soils. The methodological and informational basis of the work was formed by the experience of creating and operating existing means of information technology support for the design and operation of double regulation drainage systems, the provisions of normative and technical documents on the automation of systems, as well as the design features of drainage and humidification and drainage systems. irrigation systems. As a result of studies of the problem of distribution of water resources on a specific system, the main stages were determined: the allocation of its blocks for which a system of water resources regulation is being developed, the allocation of subsystems in the structure, classification of tasks in subsystems, construction of an information model of the system, construction of a complex of models. To solve the problem associated with the development of simulation models and means of information technology support for the tasks of water resources distribution on dual control systems, it is proposed to use the method of contour modeling of water resources management regimes. The essence of the methodology consists in identifying characteristic contours in the structure of the water distribution network, for which you can use standard modeling algorithms and tools (quickly adjusted to the parameters of these contours) and sequentially calculating the parameters of the distribution of water resources for each of them. In this connection, the main control loops have been determined: the control loop «Water consumer № 1, 2 ... n», «Group of water consumers № 1, 2 ... n», «Section of the system № 1, 2 ... n» and «System». The proposed technique allows you to select typical control loops and then, in the selected standard loop, select characteristic control loops, along which simulation modeling of the processes of regulating the distribution of water resources over all control loops is carried out. The carried out simulation modeling of regulation processes throughout the «system» can be used by the maintenance service of the double regulation drainage system as variations in solutions when controlling the operation of regulatory structures, pumping stations and other structures of the system used to control water distribution.

Drainage reconstruction in the zone of excessive moisture during the cultivation of blueberries on poorly water-permeable clay soils

To ensure efficient agricultural production in the humid regions of Ukraine, drainage of wetlands is one of the first places. The area of drained lands is make up to 9.7% of the total arable lands in Ukraine. In 1990, 1,976.500 hectares were used in active agricultural production, and the share of arable land on drained lands was 70.7%. Of the more than 1130 drainage systems with an area of more than 2.2 million hectares only 37% were built between 1980 and 1990, i.e. younger than 35 years. The remaining 63% of systems have been built and operated for more than 35 years. Since the 1990s, the construction of new and modernization of existing drainage systems in Ukraine has been almost non-existent. Maintenance of the systems was significantly reduced, which led to a significant deterioration in their technical condition, a change in the water regime of soils and the development of degradation processes. Traditionally, in Ukraine, a significant (1.4 million hectares) area is drained with ceramic drainage. We show the experience of reconstruction of the drainage system, which is located in the Pre-Carpathian Upland region of the Ukrainian Carpathians, the Middle Carpathian terrace plain, where a Drainage of Clay Pipes was built more than 35 years ago. The results of the analysis of the reasons of unsatisfactory drainage operation, identification of the most critical zones with the use of field research and earth remote sensing data are presented. To eliminate local wetlands, plastic drainage with a diameter of 50 mm is proposed. To increase the efficiency of its work on heavy clay soils with a filtration coefficient less than 0.01, the backfilling of the trench with local material – gravel with a fraction of 5 ... 25 mm with geotextile protection. During the construction of the new drainage, ceramic drains of the previously constructed drainage were found. They were cleaned mechanically and connected through a filter backfill to the newly built drains.

Soil Inoculation With Beneficial Microbes Buffers Negative Drought Effects on Biomass, Nutrients, and Water Relations of Common Myrtle.

Common myrtle (Myrtus communis L.) occurs in (semi-)arid areas of the Palearctic region where climate change, over-exploitation, and habitat destruction imperil its existence. The evergreen shrub is of great economic and ecological importance due to its pharmaceutical value, ornamental use, and its role in urban greening and habitat restoration initiatives. Under greenhouse conditions, we investigated the effect of soil inoculation with arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) on biomass allocation, water relations, and nutritional status of drought-stressed myrtle seedlings. Single and dual AMF (Funneliformis mosseae and Rhizophagus irregularis) and PGPR (Pseudomonas fluorescens and P. putida) soil inoculations were applied to myrtle seedlings growing under different soil water regimes (100, 60, and 30% of field capacity) for 6 months using a full factorial, completely randomized design. AMF and PGPR treatments, especially dual inoculations, alleviated negative drought effects on biomass and morpho-physiological traits, except for water-use efficiency, which peaked under severe drought conditions. Under the greatest soil water deficit, dual inoculations promoted leaf biomass (104%–108%), root biomass (56%–73%), mesophyll conductance (58%), and relative water content (1.4-fold) compared to non-inoculated controls. Particularly, dual AMF and PGPR inoculations stimulated nutrient dynamics in roots (N: 138%–151%, P: 176%–181%, K: 112%–114%, Ca: 124%–136%, and Mg: 130%–140%) and leaves (N: 101%–107%, P: 143%–149%, K: 83%–84%, Ca: 98%–107%, and Mg: 102%–106%). Our findings highlight soil inoculations with beneficial microbes as a cost-effective way to produce highly drought resistant seedling stock which is vital for restoring natural myrtle habitats and for future-proofing myrtle crop systems.

Unexpected high suppression of ammonia volatilization loss by plastic film mulching in Korean maize cropping system

Plastic film mulching (PFM) as an agronomic practice was rapidly expanded to improve crop yield and quality, mainly due to improving soil water and temperature condition. PFM has been known to increase greenhouse gas (GHG) emissions, but its influence on ammonia (NH3) volatilization loss was not properly studied. To determine the impact of PFM on NH3 emission loss, PFM and no-mulching were designed as the main treatment. In addition, chemical (NPK) and organic fertilization plots as the sub-treatment were placed under the same mulching condition. In the NPK, the recommendation level (N-P2O5-K2O=186–35–74 kg ha-1) of chemical fertilizers was only applied for maize cultivation. In the organic fertilization, the mixture of barley and hairy vetch was cultivated during the fallow season and its whole biomass as green manure was incorporated for maize cultivation. PFM considerably improved average soil water and temperature regimes during cropping season by 0.02–0.05 m3 m-3 and 0.8–1.4 ℃ over no-mulching, respectively. These improved soil properties enhanced maize grain yield by around 95–270 and 80–300% in NPK and organic fertilization plots over no-mulching, respectively. The emission loss of NH3 gas which is highly water-soluble was 70–215% higher in NPK than organic fertilization under the same mulching. However, PFM significantly decreased seasonal NH3 emission loss by approximately 40–45% over no-mulching, probably due to physical trapping in water drops under the plastic film. To verify the suppression mechanism of NH3 emission loss by PFM, the emission rates of nitrous oxide (N2O) which is a water-insoluble gas were simultaneously monitored using the closed chamber method. Different from NH3 emission loss, PFM slightly increased N2O emission without a statistical difference, regardless of fertilization background. In conclusion, PFM could be a very useful cropping practice to decrease NH3 emission loss, as well as improve soil properties and crop productivity.

Long-term effects of land use type and management on sorptivity, macroscopic capillary length and water-conducting porosity of calcareous soils

Soil hydraulic properties are often influenced by agricultural activities. Knowledge of such properties is needed to understand the effect of agricultural practices on the soil water regime and catchment hydrology. In the present study, we investigated the effects of three land use types including orchard field, OF (without plowing), annual cultivated field, ACF (with seasonal plowing), and perennial alfalfa field, PAF (without plowing) on the soil’s water-conducting porosity at equivalent pore radius interval a to b, ε(a, b), sorptivity at applied tension ψ, Sψ, and macroscopic capillary length at tension interval ψi to ψi+1, λ(ψi, ψi+1) of calcareous soils. The mentioned hydraulic attributes were calculated from infiltration data obtained from tension-disk infiltration measurements at six tensions of 0–15 cm at 75 experimental locations (25 replications per land use). In general, it can be concluded that more macropores are present in the soils of PAF than in those of ACF and OF land uses, probably due to high organic matter content, long-term no-till conditions, positive effects of alfalfa root systems, low machinery/livestock traffic, and low soluble sodium content. In ACF, conventional tillage and high machinery traffic, and in OF excessive use of Na-rich manure fertilizers and high livestock traffic resulted in less macropores compared to PAF.

Reduced nitrogen proportion during the vegetative growth stage improved fruit yield and nitrogen uptake of cherry tomato plants under sufficient soil water regime

ABSTRACT Under the current context of reducing chemical N input in agriculture, it is important to investigate better N allocation to different growth stages of crops. The plants were subjected to sufficient and reduced soil water regimes in interaction with two N application proportions applied at the vegetative and reproductive growth stages of tomato plants, respectively. In terms of the soil water impact, across the N proportion treatments, the reduced water treatments significantly decreased leaf and biomass growth by 33% and meanwhile remarkably reduced stomatal conductance of leaves, which significantly decreased water consumption by 41%. Consequently, plant WUE markedly decreased by 10.4%. The N uptake and fresh yield were considerably reduced by 37.5% and 39.3%, respectively. Regarding the N proportion effect across the soil water treatments, the lower N application of 30% at the vegetative growth stage significantly enhanced photosynthesis products allocated to fruits, which substantially improved the fresh yield by 32.9%. Furthermore, it significantly improved N accumulation by 9.0% compared to the higher N application of 70% at this stage. Conclusively, when given the certain amount of N supply, the N allocation should be reduced at the vegetative growth stage to achieve high yield and N uptake in tomato production .

Влажность сероземно-луговых почв под хлопчатником в условиях Сальянской степи Азербайджана

The article presents the results of studies on the water regime of irrigated serozem-meadow soils of the Salyan steppe under cotton-plant. The dynamics of soil moisture has been studied. Irrigation and irrigation rates for cotton have been calculated and established. The values of water consumption for total evaporation are revealed.

The prokaryotic and fungal communities of oat rhizosphere responded contrastingly to different irrigation regimes at pre- and post-anthesis stages

The transition from the vegetative stage to reproductive stage of plants and variations in soil water regimes can alter the community feedbacks of rhizosphere microbiomes by affecting the partitioning of photosynthates to roots. However, little is known about how different rhizosphere microbiota respond to the growth stages of drought-resistant crops under different irrigation regimes. To address these issues, we investigated the effects of irrigation regimes on the rhizosphere prokaryotic and fungal communities at the pre- and post-anthesis stages of oats in a semi-arid region of northeastern China. The prokaryotic and fungal community traits of the oat rhizosphere were characterized by Illumina high-throughput sequencing. The results revealed that the prokaryotic diversity was primarily regulated by oat growth stage, while the fungal diversity was mainly increased by irrigation regimes. Similarly, all prokaryotic phyla responded significantly to oat growth stages rather than irrigation regimes, while the composition of the fungal taxa was largely regulated by irrigation regimes. Approximately 2–3-fold higher proportions of the predominating pathogenic Fusarium genus were identified under dryland farming conditions than under irrigation treatment. In addition, functional predictions suggested that the contrasting responsive traits of prokaryotes and fungi were attributed to their functional guilds, which were related to oat growth stages and soil water conditions. However, the properties of the prokaryotic networks mainly responded to irrigation regimes while the fungal networks were regulated by oat growth, implying distinct determination mechanisms for microbial diversity and community stability. Our results indicate that rhizosphere prokaryotic and fungal communities differentially responded to oat growth stages and soil water history, highlighting the significance of irrigation in manipulating rhizosphere microbes in semi-arid regions.

Microbiological indication of reclaimed peat soils

In the North of the Ryazan region peat, boggy soils are common, forming part of the Ryazan Meschera. Since the late 1950-s, reclamation structures were built and drainage was carried out, after which the land was used for the cultivation of crops (mainly fodder crops). In former times, the drainage systems were supervised by economic managers, but after the economic transition in the country, control and maintenance ceased due to a lack of funding. Nowadays, soil-reclamation monitoring is carried out only at the Tinki-II site, which is located near the regional centre and is part of the ecological polygon system. The authors in the article showed the quantitative change of microorganisms of different groups in the peat soils of four reclamation sites in the Ryazan Meschera. Recently, on the region’s territory, climate change (dryness and warmth) has been established. A fundamental difference between the drainage systems was the presence of bilateral regulation of the soil water regime at the first site Tinki-II: sprinkler irrigation was in operation since the middle 1980-s, and by sluicing since the 1990-s. The authors carried out the microbiological indication of peat soils according to generally accepted methods. An indication was carried out in peat soils that had acquired signs of degradation (digestion of peat, reduction of the peat soil layer, etc.). The results indicated high microbiological activity in the soil at the Tinki-II site. Thus, there were more bacteria grown on MPA (meat-peptone agar) and SAA (starch-and-ammonia agar) than other groups, hence intensive mineralization of organic nitrogen compounds takes place. The presence of fungi of the genus Penicillium in soils indicates acidification. Azotobacter was detected in the soils, indicating an intensive nitrogen fixation process. The representatives of the Polyangium genus are dominated by cellulose-destroying bacteria, which feed on dead organic matter, cellulose. The presence of the above microorganisms groups indicated favourable development of microbiocenosis in the reclaimed peat soils.

The effects of periodically stagnant soil water conditions on biomass and methane yields of Silphiumperfoliatum

Resulting from the wide range of usages of bio-methane, anaerobic digestion has become a major issue. Beside biogenic residues, the cultivation of energy crops has significantly been expanded in Europe. Due to the increasing competition for land, sites with a low value for food production are predestined for cultivating feedstocks. Numerous studies have shown that perennial energy crops (PECs) present a valuable alternative to annual energy crops since they combine sound energy yields with substantial ecological advantages. Particularly under unprivileged sites conditions, PECs may fully leverage their strengths. Soils showing long lasting periods of soil moisture above field capacity (Stagnosols) were evaluated to be critical for silage maize cultivation as heavy harvest machinery may cause severe soil damages. Additionally, juvenile development of maize suffers from stagnant soil water.This study aimed to verify the results of a former pot experiment in which cup plant (Silphium perfoliatum) showed early sprouting, fast biomass development and higher yields under a soil water regime typical for Stagnosols. Thus, in the presented field experiment, silage maize and cup plant, were cultivated on well-drained soils (Cambisols) and on Stagnosols, and were compared concerning biomass and energy yields.On Stagnosols, the cup plant benefited likely from the higher soil water availability and produced average biomass yields of 14.3 t ha−1 a−1 being about 40% higher than on well-drained soils. The biochemical methane potential was 305 LN kg−1 VS and not affected by the soil type. Nonetheless, the methane yields per area of cup plant were still 35% lower than those of silage maize.

Improving prediction accuracy of soil water storage through reducing sampling frequency

Knowledge of spatiotemporal dynamics of soil water storage (SWS) is essential for hydrological modeling and vegetation restoration in semi-arid areas. However, characterizing the temporal stability of SWS at a regional-scale requires time-consuming and labor-intensive manual sampling. Moreover, the influence of soil depth on temporal stability of SWS is not systematic. This study aimed to investigate the influences of sampling frequency and soil depth on SWS and SWS temporal stability. We measured soil moisture at 20-cm intervals in the soil profiles to a depth of 3 m using a neutron probe at 135 locations along a 1340-m long transect on 14 dates from 2012 to 2013. Results showed that sampling frequency did not influence the mean SWS (P < 0.05), while sampling frequency significantly affected temporal stability characteristics including Spearman’s rank correlation coefficient (rs), standard deviation of mean relative difference (SDRD), the number of locations with SDRD < 5%, and the representative locations. Temporal stability of SWS increased with the increasing soil thickness and depth, which increases the possibility of the number of representative locations in deep soil. Although the mean SWSs of all soil depths can be predicted accurately at each sampling frequency, the prediction accuracy improved when sampling frequency was reducing. The values of R2 ranged from 0.769 to 0.978 at 15-day sampling frequency, and from 0.987 to 0.998 at 45-day sampling frequency. Soil moisture stability may be more important than the soil water regime during prediction of soil moisture. These findings can provide guidelines for optimizing soil moisture sampling strategies and benefit management of water resources in semi-arid watershed.

Modelling of soil moisture change during the operation of the “Frigate” sprinkler

The irrigation process is one of the most important elements of technologies for growing crops on irrigated soils. The tasks of ensuring optimal soil water regime, eliminating gravita-tional water losses outside the zone of active moisture exchange and promoting the fullest use of plants of bioclimatic potential of the region require modeling of soil moisture dynamics in the process of wetting, as well as structures and technologies related to irrigation facilities. Soil moistening in the south of Ukraine is carried out mainly by sprinkling with the use of a Frigate sprinkler, which is largely close to the natural processes of moisture in soil structures, especially with the use of the latest Xi-Wob sprinklers, which provide uniform irrigation and uniform droplet size. The aim of the article is to develop a model of soil moisture change, which will determine the moisture content in both the root and near-surface layers of the soil and prognoses the movement parameters of the "Frigate" sprinkler elements. The designs of sprinklers currently available allow to provide uniform intensity of spraying of drops on all working area of "Frigate" sprinkler, therefore it is possible to choose a separate point for modeling. The data obtained for one point can be extended to the entire work area. The Darcy equation is used to mathematically describe the movement of water in the soil. The finite difference method was used to solve the Darcy equation based on the initial and boundary conditions. Assuming that within each soil element the humidity changes linearly, and replacing the partial derivatives of moisture in depth and time with the analogues, the discretized model of soil moisture dynamics in the final differences was obtained, which allows you to predict moisture at any time due to hydro-soil characteristics in previous time and boundary conditions. Discretization of the Darcy equation made it possible to obtain a model of the dynamics of the humidity of the root layer in the space of states. It turned out to be nonlinear due to the hydrophysical characteristics of the soil and was linearized by transformation into the Taylor series. The developed mathematical model of soil moisture change in the space of states allows to determine the moisture content in both the root and near-surface soil layer depending on its hydrological characteristics, type of cultivated plants, volume of water entering the fields from irrigation systems or in the form of random precipitation used to predict the movement parameters of the "Frigate" sprinkler elements.

Responses of N2O Production and Abundances of Associated Microorganisms to Soil Profiles and Water Regime in Two Paddy Soils

Soil moisture is one of the critical factors affecting N2O emissions. The water regime affects the physical and chemical properties of paddy soil in different soil layers, which, in turn, affects N2O emissions and microbial growth. However, there are few reports on the effects of different soil layers and soil moisture conditions on N2O emission characteristics and microbial mechanisms. A 21-day microcosm experiment was performed to research the effects of soil moisture levels (60%, 100%, and 200% water holding capacity, WHC) and different soil layers (0–10, 10–20, and 20–40 cm) on N2O emissions in hydromorphic and gleyed paddy soils. Function microbes involved in nitrification and denitrification were determined by quantitative PCR. Moreover, the abiotic variables pH, Eh, and exchangeable Fe2+, Fe3+, NH4+-N, and NO3−-N were also analyzed. Results showed that N2O emissions of gleyed paddy soil were significantly higher than that of hydromorphic paddy soil, which was consistent with the result of the abundance of nitrifier and denitrifier in the two paddy soils. Soil depth, water content, and their interaction significantly affected N2O emission (p &lt; 0.05). Cumulative emissions of N2O from each layer of the two paddy soils at 100% and 200% WHC were significantly higher than that under 60% WHC (p &lt; 0.05). N2O emissions decreased significantly with the increase of soil depth (p &lt; 0.05), which was consistent with the change in the abundance of soil nitrifier (AOB and AOA) and denitrifier (nirK and nosZ) function genes with soil depth. The abundance of AOB, AOA, and nirK and nosZ genes decreased significantly with soil depth (p &lt; 0.05), but did not respond significantly to the water regime. Based on the results of redundancy analysis, the contents of Fe2+ and Fe3+ were positively correlated with N2O emissions and the abundance of AOB, AOA, and nirK and nosZ genes. These results indicate that N2O emissions and the abundance of associated microbes are selectively affected by soil moisture and soil layers in the two paddy soils.

Physiological response, phytohormone signaling, biomass production and water use efficiency of the CAM plant Ananas comosus under different water and nitrogen regimes

The objective of this study was to investigate and unravel the mechanisms for the impact of soil water regimes and N application rates on growth, physiological responses, phytohormone signaling, water use efficiency (WUE) and nitrogen recovery efficiency (NRE) of crassulacean acid metabolism (CAM) plant pineapple. The experimental treatments included three soil water regimes (90%, 70% and 50% of soil water holding capacity, representing well watered, mildly and moderately water stressed conditions) and N application rates (109, 218 and 473 mg kg-1 soil). Results showed that the well watered and mildly water stressed treatments increased the shoot dry biomass by 70.7–110.9% and the plant water use by 25.7–30.4%, consequently, the plant WUE was significantly improved compared to the moderately water stressed treatment. The specific leaf N content was significantly and positively correlated with plant carbon (C) accumulation that was increased by 66.9–89.9%, implying that the enhanced specific leaf N content in the well watered and mildly water stressed treatments could have facilitated the carbon fixation, thus increased the shoot biomass accumulation. Moreover, the well watered and mildly water stress treatments significantly increased leaf δ18O, indicating the significantly higher transpiration in line with the markedly increased plant water use due to both the large leaf water concentration and the characteristic diel pattern of stomatal conductance associated with CAM. The enhanced leaf δ13C and plant WUE in the well watered and mildly water stress treatments were ascribed to the enhanced specific leaf N content and the improved leaf relative water content. The moderately water stressed treatment decreased leaf and root water potential while significantly intensified root endogenous ABA due to water deficit. The [ZR], [IAA] and [GA3] in the leaves and roots interacted complicatedly with water and N rates. The well watered and mildly water stressed treatments enhanced ability of the roots to absorb water and nutrients from the soil, resulting in the significantly higher N and 15N accumulation. Conclusively, in the production of Ananas comosus maintaining high soil water supply is critical to achieve improved growth, water and fertilizer-N use efficiencies.

Effect of slope position on soil properties and soil moisture regime of Stagnosol in the vineyard

Abstract Hillslope hydrology in agricultural landscapes is complex due to a variety of hydropedological processes and field management possibilities. The aim was to test if there are any differences in soil properties and water regime along the hillslope and to compare vineyard rows (vine) with inter-rows (grass) area for those properties. The study determined that there are significant differences in the contents of soil particle fractions, pH, and humus content along the slope (P &lt; 0.0001), with lower confidence level in bulk density (P &lt; 0.05). Differences between row and inter-row space were significant for the pH, humus, and silt content, but for sand and clay content, and bulk density differences were not determined. The study determined differences in soil water content among five slope positions (P &lt; 0.0001), and between row and inter-row vineyard space (all with P &lt; 0.05). Where in the upper slope positions (e. g., P1) soil water content was higher than on lower slope positions. Higher soil water content was observed at higher slope positions, associated with clay content. However, it can be concluded that the retention of moisture on the slope is more influenced by local-scale soil properties (primarily soil texture) and variability of the crop (row/inter-row) than the position on the slope.

Short-term effects of compost amendments to soil on soil structure, hydraulic properties, and water regime

Abstract Despite the increasing interest in applying composts as soil amendments worldwide, there is a lack of knowledge on short-term effects of compost amendments on soil structural and hydraulic properties. Our goal was to study the effect of compost and vermicompost-based soil amendments on soil structure, soil water retention characteristics, aggregate stability and plant water use efficiency compared to that of mineral fertilizers and food-waste digestate and examine if these effects are evident within a short time after application. We set up a pot experiment with spring wheat using a sandy and a loamy soil receiving either mineral fertilizer (MF); dewatered digestate from anaerobic digestion of food waste (DG), vermicomposted digestate (VC_DG); sewage sludge-based compost (C_SS) and sewage sludge-based vermicompost (VC_SS). We then monitored and calculated the soil water balance components (irrigation, outflow, evaporation, transpiration, and soil water content). At harvest, we measured shoot biomass, soil texture, bulk density, water retention characteristics and aggregate stability. The irrigation use efficiency (IE) and the plant water use efficiency (WUE) were calculated for each treatment by dividing the transpiration and the dry shoot biomass with the amount of water used for irrigation, respectively. For the sandy soil, we used X-Ray computed tomography to visualise the pore system after applying organic amendments and to derive metrics of the pore-network such as its fractal dimension, imaged macroporosity and critical pore diameter. X-Ray tomography indicated that composting and vermicomposting resulted in more complex and diverse porous system and increased soil macroporosity. The increased fractal dimensions also indicated that compost and vermicompost can contribute to structure formation and stabilization within a short time after their application. Despite the small application rate and short incubation time, the application of organic amendments to the two different soil types resulted in improved soil water holding capacity and water use efficiency. Composting and vermicomposting appeared to have the best effect at reducing the irrigation demand and evaporation losses and increasing the water use efficiency of the plant, likely through their effect on soil structure and the pore-size distribution.

Impacts of Elevated Atmospheric CO2 and N Fertilization on N2O Emissions and Dynamics of Associated Soil Labile C Components and Mineral N in a Maize Field in the North China Plain

The elevated atmospheric CO2 concentration (eCO2) is expected to increase the labile C input to the soil, which may stimulate microbial activity and soil N2O emissions derived from nitrification and denitrification. However, few studies studied the effect of eCO2 on N2O emissions from maize field under the free-air CO2 enrichment (FACE) conditions in the warm temperate zone. Here, we report a study conducted during the 12th summer maize season under long-term eCO2, aiming to investigate the effect of eCO2 on N2O emissions. Moreover, we tested zero and conventional N fertilization treatments, with maize being grown under either eCO2 or ambient CO2 (aCO2). We hypothesized that N2O emissions would be increased under eCO2 due to changes in soil labile C and mineral N derived from C-deposition, and that the increase would be larger when eCO2 was combined with conventional N fertilization. We also measured the activities of some soil extracellular enzymes, which could reflect soil C status. The results showed that, under eCO2, seasonal N2O and CO2 emissions increased by 12.4–15.6% (p &lt; 0.1) and 13.8–18.5% (p &lt; 0.05), respectively. N fertilization significantly increased the seasonal emissions of N2O and CO2 by 33.1–36.9% and 17.1–21.8%, respectively. Furthermore, the combination of eCO2 and N fertilization increased the intensity of soil N2O and CO2 emissions. The marginal significant increase in N2O emissions under eCO2 was mostly due to the lower soil water regime after fertilization in the study year. Dissolved organic C (DOC) and microbial biomass C (MBC) concentration showed a significant increase at most major stages, particularly at the tasseling stage during the summer maize growth period under eCO2. In contrast, soil mineral N showed a significant decrease under eCO2 particularly in the rhizospheric soils. The activities of C-related soil extracellular enzymes were significantly higher under eCO2, particularly at the tasseling stage, which coincided with concurrent increased DOC and MBC under eCO2. We conclude that eCO2 increases N2O emissions, and causes a higher increase when combined with N fertilization, but the increase extent of N2O emissions was influenced by environmental factors, especially by soil water, to a great extent. We highlighted the urgent need to monitor long-term N2O emissions and N2O production pathways in various hydrothermal regimes under eCO2.