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Purpose: to develop rational combinations of species and varieties of perennial leguminous grasses, soil water and nutrient regimes, which will contribute to obtaining stable fodder yields with high levels of protein and energy content. Materials and methods. Research is being carried out on perennial leguminous grasses on the experimental field of the institute. The experiment is three-factor and includes three options for maintaining the pre-irrigation soil moisture limit (60, 70 and 80 % of the lowest moisture capacity), three options for the soil nutritional regime (NPK₁, NPK₂ and control – without fertilizers), eight types of legumes are studied according to the third factor. The generally accepted experimental methods were used when setting up experiments and conducting research. Results. In the full germination phase there were from 294 to 386 plants of grass species per 1 sq. m. Their height before harvesting varied according to the experimental variants from 0.60 to 1.01 m in the first cutting, from 0.38 to 0.94 m in the second and from 0.25 to 0.66 m in the third cutting. The grass stand total water consumption in the year of seeding was 4.2–4.7 thous. cub. m/ha, increasing in subsequent years to 4.8–5.7 thous. cub. m/ha. The soil water regime and fertilizers had a significant impact on crop yield. In control options with a pre-irrigation limit of 60 % of the lowest moisture capacity, the green mass yield in the second year was 26.6–40.9 t/ha. With improved soil nutrition and good water supply, the yield increased to 48.2–87.8 t/ha. Sainfoin and blue-hybrid and variegated alfalfa plants responded to the improved growing conditions most actively; 54–88 t/ha of green mass were gathered from these sites during the season. Conclusions. Selection of optimal combinations of soil water and nutrient regimes, as well as the new promising perennial leguminous grasses species and varieties introduction into the field feed production in the Lower Volga region will ensure high and stable yields of fodder rich in energy and nutrients.

Purpose: scientific substantiation of the use of agro-reclamation tillage practices of light chestnut heavy loamy soils in rice cultivation with periodic irrigation by sprinkling. Materials and methods. The research was conducted at the experimental site of the All-Russian Research Institute of Irrigated Agriculture in 2022–2023 with Stalingrad 1 rice crops in a two-factor experiment: factor A (soil water regime) – two options and factor B (tillage) – three options. Generally accepted methods of laying and conducting field research were used. Results. Immediately after rice sowing, the soil density in the layer of 0.0–0.6 m, varied in the range of 1.19–1.41 t/cubic m depending on the tillage practice. The minimum value of soil density in the layer of 0.0–0.6 m was formed in the A2B3 variant and amounted to 1.23 t/cubic m. The maximum soil compaction in this layer of 1.34 t/cubic m was observed in variant A1B1. During the period of full ripeness of the grain, soil compaction occurred in all tillage options. Its minimum compaction (1.34 t/cubic m), compared with the control (winter plowing), was noted with a combination of winter plowing and spring deep loosening. The minimum values of the water consumption coefficient and irrigation water loss were obtained in the A2B3 variant, and their numerical values were 851.7 and 703.6 cubic m/t, respectively. Conclusions. It was found that winter plowing to a depth of 0.25–0.27 m in combination with spring deep loosening to a depth of 0.40 m, in comparison with traditional winter plowing in one step, provides a decrease in soil density in a layer of 0.0–0.4 m by 0.10 (after sowing) and 0.12 t/cubic m (during the period of full ripeness of grain), which contributes to the yield increase to 6.95 t/ha and a reduction in irrigation water loss by 112.4 cubic m for the formation of 1 ton of grain.

Purpose: to study the features of irrigation regimes and their impact on the yield of sweet pepper based on the analysis of scientific sources of information. Discussion. Sweet pepper is a moisture-loving crop. For its normal growth and development, optimal soil moisture is required. Plants experience a special need for moisture when planting seedlings, flowering, as well as during fruit set and formation. Since sweet pepper crops are located in southern regions with a moisture deficit, irrigation acts as a guarantor of obtaining the planned yield of this crop. The main elements of the irrigation regime are irrigation, irrigation norms, the number of irrigations, the timing of their implementation to maintain a given level of soil moisture during crop cultivation. Modern irrigation regimes for sweet pepper have been developed both for conditions of full provision of water resources and for conditions of their deficiency. Under conditions of full water supply, maximum productivity and product quality indicators, more efficient use of irrigation water are ensured by drip irrigation mode with maintaining the pre-irrigation moisture threshold of the calculated soil layer at least 70–80 % of the lowest moisture capacity during the growing season. In differentiated irrigation regimes, higher values of pre-irrigation soil moisture thresholds are maintained in the first half of the growing season, when it is necessary to create favorable conditions for the rooting of seedlings, growth and development of plants. However, during this period the size of the calculated soil layer is reduced. By the stage of technical ripeness and until the end of fruit harvesting, soil moisture thresholds are reduced to 70–75 % of the lowest moisture capacity, but the moistened layer is increased. Conclusions. Optimal irrigation regimes make it possible to maintain the vital processes of plants and obtain the planned productivity even in dry conditions. The combination of irrigation modes with other elements of the technological process (mulching, fertilizing, etc.) increases the productivity of sweet pepper by 15–20 %.

Purpose: to determine and scientifically substantiate the optimal combinations of regimes for regulating soil moisture by irrigation and the use of biological plant protecting agents at various stages of their growth and development, ensuring the minimization of anthropogenic impact on the environment. Materials and methods. The studies were conducted in 2021–2022 on the experimental site of the All-Russian Research Institute of Irrigated Agriculture near the village Vodny, Sovetsky district of Volgograd, in plantings of the Gulliver potato variety in a two-factor field experiment. Factor A: A₁ – the moisture content of the soil layer 0.4 m deep throughout the entire potato growing season was maintained at a level not lower than 70 % of the minimum moisture capacity; A₂ – the same, only at 80 % of the minimum moisture capacity. Factor B: B₁ – biological system of potato plant protection; B₂ – integrated protection system; B₃ – chemical protection system (control). The experiment was carried out on light chestnut, heavy loamy, low-humic, non-saline soils. In terms of precipitation, the years of research are characterized as: 2021 – average wet, 2022 – average. Results. In the first option of the irrigation regime, the irrigation rate of 2720 and 3060 cubic m/ha was provided with eight and nine irrigations. The second irrigation regime was maintained with almost twice as many irrigations – up to 15–17, but at the same time the watering rate decreased to 230 cubic m/ha, and the irrigation rate increased to 3450–3910 cubic m/ha. In the option of the moisture regime of 80 % of the minimum moisture capacity in a horizon of 0.4 m, in conjunction with a plant protection system based on the use of biological preparations, the largest green matter of 385 g/plant, which is 98 g/plant more control one was obtained. The maximum mass of tubers in the nest was also obtained in this combinable option; it was 660 g/plant, which is 30 % higher than the option with chemical protection. Conclusions: on low-fertility light chestnut soils of the Lower Volga region, potatoes are best cultivated at a moisture regime in which humidity does not fall below 80 % of the minimum moisture capacity in a soil horizon of 0.4 m, in conjunction with a plant protection system based on the use of biological preparations, which provides favorable conditions for obtaining a tuber yield of 32.4 t/ha.

Longer term monitoring of soil water content at a catchment scale is a key to understanding its dynamics, which can assist stakeholders in decision making processes, such as land use change or irrigation programs. Soil water monitoring in agriculturally dominated catchments can help in developing soil water retention measurements, for assessment of land use change, or adaptation of specific land management systems to climate change. The present study was carried out in the Pannonian region (Upper-Balaton, Hungary) on Cambisols and Calcisols between 2015 and 2021. Soil water content (SWC) dynamics were investigated under different land use types (vineyard, grassland, and forest) at three depths (15, 40, and 70 cm). The meteorological data show a continuous decrease in cumulative precipitation over time during the study with an average of 26% decrease observed between 2016 and 2020, while average air temperatures were similar for all the studied years. Corresponding to the lower precipitation amounts, a clear decrease in the average SWC was observed at all the land use sites, with 13.4%, 37.7%, and 29.3% lower average SWC for the grassland, forest, and vineyard sites, respectively, from 2016 to 2020 (measured at the 15 cm depth of the soil). Significant differences in SWC were observed between the annual and seasonal numbers within a given land use (p < 0.05). The lowest average SWC was observed at the grassland (11.7%) and the highest at the vineyard (28.3%). The data showed an increasing average soil temperature, with an average 6.3% higher value in 2020 compared to 2016. The grassland showed the highest (11.3 °C) and the forest soil the lowest (9.7 °C) average soil temperatures during the monitoring period. The grassland had the highest number of days with the SWC below the wilting point, while the forest had the highest number of days with the SWC optimal for the plants.

Aim of study: Detecting possible small-scale soil effects on height growth of single trees in monospecific stands of three important tree species (Abies alba, Fagus sylvatica, and Picea abies). Area of study: 37 mature stands along an ecological gradient in Southern Germany from the cold and wet “optimal niche zone” to warmer and drier niche zones, including gravelly soils with poor water supply. Material and methods: Measurement of achieved height and age of 15 to 20 sample trees per stand. Estimation of the available water capacity of the soil (AWC) in close proximity to sample trees based on soil texture following the German soil survey guidelines. Examining height growth depending on niche zone and AWC. Main results: On sites (stand level) with the lowest water regime, height growth increased significantly with AWC of microsites. The estimated effect on height growth over the whole range of AWC values was almost 8 m at those sites. In contrast, the effect was negative on optimal sites. For intermediate and marginal sites, the effect was positive, albeit not significant for marginal sites. Research highlights: To our knowledge this is the first study about small-scale effects of AWC on height growth of single trees in temperate European forests. Small-scale soil variability should be considered in future scientific studies and practical evaluation, involving single tree performance at stands with low water regime. This seems particularly important in genetic environmental associations studies and in the process of selecting trees for breeding purposes in such stands.

Agricultural production in the Weibei rainfed highland, Northwest China, is challenged by severe drought and water shortages. While the land use pattern has shifted gradually from crop production to orchard farming in Weibei, little is known about the influence of fruit industry development on regional water resources and the rationality of planting orchards. Here, we characterized soil water depletion patterns in rainfed orchards and farmlands to evaluate the occurrence of soil desiccation under land use conversion from farmlands to orchards in Weibei. Soil moisture dynamics were monitored in the 0–150 cm soil profiles of different aged Red Fuji apple orchards (young: 7 years, mature: 13 years, old: 22 years) and long-term cultivated winter wheat fields. We measured soil moisture content by oven-drying method in the middle of each month during the growing season of apple trees (March–September 2019). The over-depletion and depletion of soil water were analyzed to evaluate water stress and differential water depletion by distinct vegetation, respectively. The soil desiccation index was used to determine the occurrence of dry soil layers. Water stress was only observed at the 0–70-cm soil depths in the old orchards (mid-June) and farmlands (mid-May–mid-July). Water depletion took place at deeper depths for longer periods in the older orchards than in the younger orchards. Soil desiccation was absent in the young orchards, with mild desiccation at the 0–80-cm soil depths in the mature and old orchards in mid-June. The desiccation intensity was mild at the 0–60-cm soil depths in mid-April–mid-May, intense at the 0–150-cm soil depths in mid-June, and moderate at the 20–150-cm soil depths in mid-July. Results of this study demonstrate the mitigation of water stress and soil desiccation following conversion from wheat fields to apple orchards, which verifies the rationality of planting orchards in the rainfed highland area. Our findings provide strong support for developing a novel model of agro-industrial development, ecological construction, and sustainable economy in the vast arid and semi-arid areas of Northwest China.

According to the Hungarian Soil Information and Monitoring System's (HSIMS) database a group estimation method was developed to predict the mean soil hydrophysical properties. The estimation efficiency of the worked out prediction procedures was controlled on a test database, and on a dataset of a study area. It can be established that the water retention and the hydraulic conductivity of soils are sufficiently predictable from the category data of soil maps. The 10-digit map codes of the PWW mapping method were created by different estimation methods, and as a result the PWW map was drawn. However, it is not always possible to estimate the necessary soil hydrophysical properties from the available map information for preparing the PWW map. Sometimes the knowledge gained from the field reports is needed as well. Further studies are planned for integrating these morphological information into our estimations. The present work was supported by the National Scientific Research Fund (OTKA) under grant No. T048302. [ABSTRACT FROM AUTHOR]

It is established that at the beginning of the 21st century due to significant exploitation of land resources of Ukraine, there was a violation of ecological balance in natural agroecosystems, intensified erosion and other degradation processes in soil, which now reached the highest level in the world. Due to the reduction in the use of organic fertilizers, the use of mineral fertilizers and pesticides has exceeded the permissible limits, which has led to pollution of soils, the environment and agricultural products with harmful chemicals. Currently, the use of physiological and genetic characteristics of crops belonging to different biological groups plays an important role in agrarian production in Ukraine. Along with the productive use of the genetic potential of crops, the use of modern innovative technologies, in particular the elements of biologization in organic farming, is of great importance. These include the systematic use of scientifically sound crop rotations, the use of optimal rates of organic and mineral fertilizers, green manure, post-harvest crops, biohumus, and minimize tillage. With increasing aridity of the climate, they adapt to new climatic conditions due to the accumulation and preservation of moisture, which is an effective measure in regulating soil water regime in the arid Southern Steppe of Ukraine. It was found that among the elements of biologization, the maximum use of natural mass of surface and root crop residues and by-products of crops -- cereal straw, tops and stalks of corn and sunflower, root crop buds and green manure -- is effective. Along with increasing the production of competitive agricultural products of better quality, their use ensures the efficient use of land resources, preservation and reproduction of soil fertility, improving the ecological state of the environment. It is determined that the use of plant residues actualizes the use of modern biodestructors, which are adapted to different soil and climatic conditions of Ukraine and technologies for cultivation crops. Of great importance in the production of corn for grain is the use of effective biodestructors of stubble Ecostern and Cellulad. Such studies are gaining relevance in the arid Southern Steppe of Ukraine, especially in climate change. [ABSTRACT FROM AUTHOR]

Tile drainage belongs to one of the most important meliorative measures in the Czech Republic. It has been hypothesised that it may improve some soil properties which are influenced by the groundwater and their water regime. In the case of meadows, the used management method may also influence the soil properties. In this study, different physical soil properties (particle and bulk density, total soil porosity, maximum capillary water capacity, minimum air capacity, water retention capacity and saturated water content, volumetric water content and matric potential) at depths of 15, 35 or 40 and 60 cm in differently managed meadows (drained versus undrained) located near the village of Železná in the Czech Republic (mildly cold, humid climatic region) were investigated. The drained meadow is used mainly for grazing (extensively) and the undrained meadow is mown twice a year. In addition, the actual evapotranspiration was estimated for the 2018 vegetation season. The selected physical soil properties were significantly (P < 0.05) different between the experimental meadows, especially at depths of 0-28 versus 0-35 cm (particle and bulk density, total soil porosity, maximum capillary water capacity, water retention capacity and saturated water content) and 28-49 versus 35-45 cm (particle density, water retention capacity and saturated water content). In the case of all the studied soil depths, the volumetric water content and matric potential were significantly (P < 0.05) different between the experimental meadows in the years 2016-2019. The actual evapotranspiration was also significantly different (P < 0.05) between the meadows. The obtained differences in the measured soil properties and estimated actual evapotranspiration were probably influenced by the used tile drainage and also by the type of management of the meadow. It is necessary to obtain more research findings with respect to different types of management in the case of drained meadows and also undrained meadows to understand the role of both treatments (tile drainage, management).

Periods of soil water stress have been recurrent in the Cerrado region and have become a growing concern for Brazilian tropical pasture areas. Thus, the search for forage grasses more tolerant to water stress has intensified recently in order to promote more sustainable livestock. In a greenhouse experiment, the degree of water stress tolerance of nine tropical forage grass cultivars was studied under different soil water regimes. The investigation followed a 9 × 3 factorial design in four randomized blocks. Nine cultivars from five species of perennial forage grasses were tested: Urochloa brizantha ('BRS Piatã', 'Marandu', and 'Xaraés'), Panicum maximum ('Aruana', 'Mombaça', and 'Tanzânia'), Pennisetum glaucum ('ADR 300'), Urochloa ruziziensis ('Comum'), and Paspalum atratum ('Pojuca'). These cultivars were grown in pots under three soil water regimes (high soil water regime—HSW (non-stressful condition), middle soil water regime—MSW (moderate water stress), and low soil water regime—LSW (severe water stress)). Plants were exposed to soil water stress for 25 days during the tillering and stalk elongation phases. Twelve tolerance indices, including tolerance index (TOL), mean production (MP), yield stability index (YSI), drought resistance index (DI), stress tolerance index (STI), geometric mean production (GMP), yield index (YI), modified stress tolerance (k1STI and k2STI), stress susceptibility percentage index (SSPI), abiotic tolerance index (ATI), and harmonic mean (HM), were calculated based on shoot biomass production under non-stressful (YP) and stressful (YS) conditions. Soil water stress decreased leaf area, plant height, tillering capacity, root volume, and shoot and root dry matter production in most cultivars, with varying degrees of reduction among tropical forage grasses. Based on shoot biomass production under controlled greenhouse conditions, the most water-stress-tolerant cultivars were P. maximum cv. Mombaça and cv. Tanzânia under the MSW regime and P. maximum cv. Aruana and cv. Mombaça under the LSW regime. P. maximum cv. Mombaça has greater adaptability and stability of shoot biomass production when grown under greenhouse conditions and subjected to soil water stress. Therefore, this forage grass should be tested under field conditions to confirm its forage production potential for cultivation in tropical regions with the occurrence of water stress. The MP, DI, STI, GMP, YI, k2STI, and HM tolerance indices were the most suitable for identifying forage grass cultivars with greater water stress tolerance and a high potential for shoot biomass production under LSW regime. [ABSTRACT FROM AUTHOR]

Available water resources for agricultural irrigation have decreased worldwide in recent decades, prompting advances in water saving methods. In this study, soil water regime and water balance in a transplanted rice field with reduced irrigation (multiple shallow depth irrigations) in the Taihu Lake Basin of East China were observed and then evaluated using Hydrus-1D model during two consecutive growing seasons. During the 2008 season, irrigation water accounted for 48% of the total water input (TWI, 94.6 cm), but only 20% of TWI (120.4 cm) during the 2009 season. Due to heavy rainfalls during the wet 2009 season, surface runoff accounted for about 6.4% of the TWI, whereas during the much drier 2008 season with higher controlled irrigation inputs, no surface runoff occurred. Simulated evapotranspiration during the 2008 and 2009 seasons accounted for 67.4% and 54.9% of TWIs, respectively. Measured and simulated results indicate that water percolation (approximately 32.5% and 37.6% of TWIs during the 2008 and 2009 seasons, respectively) was the main path of water losses from the transplanted rice fields, suggesting that long and high standing water during the 2009 season increased water percolation. Water productivities evaluated from total irrigations and TWIs were 2.08 and 0.99 kg.m-3 during the 2008 season and 3.85 and 0.77 kg.m-3 during the 2009 season, respectively, and were 1.47 and 1.40 kg.m-3, respectively, when evaluated from modeled evapotranspiration fluxes. The cultivation method with multiple shallow depth irrigation efficiently used rainfall water and reduced the losses due to water percolation and surface runoff by stabilizing rice yields.

Accurate estimation of the hydrological features in the unsaturated zone is mandatory for the effective planning of irrigation strategies. Irrigation scheduling depends on crop and soil type as well as climatic characteristics and is usually empirically conducted. This paper simulates the water flow in order to model the soil water balance in three agricultural fields (maize, cotton, alfalfa) located in the River Strymonas basin using the HYDRUS-1D model. The model is fed with meteorological data, soil data and soil moisture measurements. After the calibration, through HYDRUS-1D's inverse solution, model results were used to evaluate the irrigation activities applied in the pilot application fields in terms of irrigation dose, irrigation interval and soil moisture variation for the cultivation period. In addition, in order to measure the efficiency of the irrigation method evaluated in this work, water productivities for all three fields were compared with productivities yielded from similar applications and experiments as well as precision irrigation experiments found around the world at similar climates with the one at Nigrita. [ABSTRACT FROM AUTHOR]

Taro (Colocasia esculenta L. Schott) is an important food staple in developing countries in Africa, West Indies, the Pacific region, and Southeast Asia. Because taro can be grown in almost all tropical regions of the world, it will play a crucial role in food security. The use of organic mulches, which contribute to soil water management, weed control, and fertilization simultaneously, shows promise as an eco-friendly approach in agronomy. In the present study, a field experiment including two cropping seasons (I and II) was conducted to evaluate the effects of water regimes with organic mulching on the taro growth and corm nutritive values. In results, compared with that under the upland regime, taro cultivation under the flooding regime had a higher level of soil fertility and better weed control. The flooding regime promoted more the taro plant growth and further enhanced the yields of the harvested corms; also, sugarcane bagasse and rice husk would be the superior mulch to obtain better corm attributes. By contrast, cultivation under the upland regime enhanced the nutritive values of taro corm more than did that under the flooding regime. Regardless of the upland or flooded regime, mulching treatments with rice husk could enrich taro corm nutrition more than could those with sugarcane bagasse and peanut hull. Also, the effects of water regime and mulching on taro plant growth and corm attributes would be varied with the rainfalls during the period of vegetative growth.

Main conclusion: Drought alone and drought plus warming will change the nutrient requirements and biomass distributions of Stylosanthes capitata, while warming will be advantageous only under well-watered condition for the next decades. Climate change effects on natural and managed ecosystems are difficult to predict due to its multi-factor nature. However, most studies that investigate the impacts of climate change factors on plants, such as warming or drought, were conducted under one single stress and controlled environments. In this study, we evaluated the effects of elevated temperature (+ 2 °C) (T) under different conditions of soil water availability (W) to understand the interactive effects of both factors on leaf, stem, and inflorescence macro and micronutrients concentration and biomass allocation of a tropical forage species, Stylosanthes capitata Vogel under field conditions. Temperature control was performed by a temperature free-air controlled enhancement (T-FACE) system. We observed that warming changed nutrient concentrations and plant growth depending on soil moisture levels, but the responses were specific for each plant organ. In general, we found that warming under well-watered conditions greatly improved nutrient concentration and biomass production, whilst the opposite effect was observed under non-irrigated and non-warmed conditions. However, under warmed and non-irrigated conditions, leaf biomass and leaf nutrient concentration were greatly reduced when compared to non-warmed and irrigated plants. Our findings suggest that warming (2 °C above ambient temperature) and drought, as well as both combined stresses, will change the nutrient requirements and biomass distributions between plant aerial organs of S. capitata in tropical ecosystems, which may impact animal feeding in the future. [ABSTRACT FROM AUTHOR]

Soil hydrology has deep Russian roots, which are primarily related to the theory of soil hydrological constants and their practical application. These constants have been used to assess the hydrological soil conditions in stationary observations, for which attempts to arrange regular hydrological observations in the landscape faced impracticable complexity of work and calculations and provided unreliable quantitative predictions. At present, there are new opportunities for experimental research, digital analysis, and prediction of hydrological indicators of soils in the landscape. A new quantitative approach to the use of digital technologies for monitoring soil water and temperature in the soils of agricultural landscapes, their dynamics, and their probabilistic calculations has been developed. Based on the soil map, it is proposed to create an information and measurement system with the studied thermal and hydrophysical characteristics of soils using mathematical models to calculate the dynamics of moisture and temperature for given periods and conditions of different availability of heat and precipitation, which allows us to quantify the availability of moisture reserves in the soils of the agricultural landscape. This system of observations, assessment, and forecast includes the use of modern technologies for determining soil water content and temperature, the adaptation of predictive physically based models for calculating the dynamics of moisture reserves depending on the availability of precipitation and conditions at the lower boundary of soil profiles. The paper deals with the hydrological analysis of soils by the example of the agricultural landscape of the Zelenograd station of the Dokuchaev Soil Science Institute in the village of El'digino, Pushkino district, Moscow oblast. [ABSTRACT FROM AUTHOR]

Background: Ectomycorrhizal (ECM) symbiosis is a fundamental driver in forest ecosystems. Studies of effects of fertilizer treatment on ECM fungal community structure were predominantly based on large, single additions of nitrogen. Studies involving chronic additions of nitrogen in combination with different gradients of water regime are much less common. Aim: To investigate effects of water regime and nitrogen addition on the structure and diversity of ECM community, and identify main factors leading to changes in ECM community of Picea asperata. Methods: The structure and diversity of the ECM community were assessed by Illumina high throughput sequencing analysis of the internal transcribed spacer (ITS) region of rDNA extracted from ECM root tips, after 5 years of different gradients of water regimes [40% (W1), 50% (W2), 60% (W3), 80% (W4) and 100% (W5) of field capacity, respectively] and nitrogen additions [0 (N0), 20 (N1), 40 (N2) g N m–2 y–1 by adding ammonium nitrate (NH4NO3) solution]. Results: ECM community structure was altered by water and nitrogen treatments. Clearer separations were found under water treatment than under nitrogen treatment. ECM community species richness of N1 was significantly higher than that of N2 under W5 treatment and was significantly influenced by the interaction of water and nitrogen. However, the diversity and evenness of the ECM community were unaffected. Soil water content (SWC), nitrogen availability and their interaction, soil available phosphorus, and pH (which were induced by treatments) significantly explained the variation in ECM community structure among different treatments. Conclusion: ECM species are more sensitive to changes in SWC than changes in nitrogen addition. Nitrogen and water treatments influenced the structure of the ECM community mainly through altering the relative abundances of exploration types and specific genera. Our findings can enhance understanding of the implications of nitrogen addition and water regime on soil processes in ECM‐dominated coniferous forests under global changes. [ABSTRACT FROM AUTHOR]

Periods of soil water stress have been recurrent in the Cerrado region and have become a growing concern for Brazilian tropical pasture areas. Thus, the search for forage grasses more tolerant to water stress has intensified recently in order to promote more sustainable livestock. In a greenhouse experiment, the degree of water stress tolerance of nine tropical forage grass cultivars was studied under different soil water regimes. The investigation followed a 9 × 3 factorial design in four randomized blocks. Nine cultivars from five species of perennial forage grasses were tested: Urochloa brizantha (‘BRS Piatã’, ‘Marandu’, and ‘Xaraés’), Panicum maximum (‘Aruana’, ‘Mombaça’, and ‘Tanzânia’), Pennisetum glaucum (‘ADR 300’), Urochloa ruziziensis (‘Comum’), and Paspalum atratum (‘Pojuca’). These cultivars were grown in pots under three soil water regimes (high soil water regime—HSW (non-stressful condition), middle soil water regime—MSW (moderate water stress), and low soil water regime—LSW (severe water stress)). Plants were exposed to soil water stress for 25 days during the tillering and stalk elongation phases. Twelve tolerance indices, including tolerance index (TOL), mean production (MP), yield stability index (YSI), drought resistance index (DI), stress tolerance index (STI), geometric mean production (GMP), yield index (YI), modified stress tolerance (k1STI and k2STI), stress susceptibility percentage index (SSPI), abiotic tolerance index (ATI), and harmonic mean (HM), were calculated based on shoot biomass production under non-stressful (YP) and stressful (YS) conditions. Soil water stress decreased leaf area, plant height, tillering capacity, root volume, and shoot and root dry matter production in most cultivars, with varying degrees of reduction among tropical forage grasses. Based on shoot biomass production under controlled greenhouse conditions, the most water-stress-tolerant cultivars were P. maximum cv. Mombaça and cv. Tanzânia under the MSW regime and P. maximum cv. Aruana and cv. Mombaça under the LSW regime. P. maximum cv. Mombaça has greater adaptability and stability of shoot biomass production when grown under greenhouse conditions and subjected to soil water stress. Therefore, this forage grass should be tested under field conditions to confirm its forage production potential for cultivation in tropical regions with the occurrence of water stress. The MP, DI, STI, GMP, YI, k2STI, and HM tolerance indices were the most suitable for identifying forage grass cultivars with greater water stress tolerance and a high potential for shoot biomass production under LSW regime.

Taro (Colocasia esculenta L. Schott) is an important food staple in developing countries in Africa, West Indies, the Pacific region, and Southeast Asia. Because taro can be grown in almost all tropical regions of the world, it will play a crucial role in food security. The use of organic mulches, which contribute to soil water management, weed control, and fertilization simultaneously, shows promise as an eco-friendly approach in agronomy. In the present study, a field experiment including two cropping seasons (I and II) was conducted to evaluate the effects of water regimes with organic mulching on the taro growth and corm nutritive values. In results, compared with that under the upland regime, taro cultivation under the flooding regime had a higher level of soil fertility and better weed control. The flooding regime promoted more the taro plant growth and further enhanced the yields of the harvested corms; also, sugarcane bagasse and rice husk would be the superior mulch to obtain better corm attributes. By contrast, cultivation under the upland regime enhanced the nutritive values of taro corm more than did that under the flooding regime. Regardless of the upland or flooded regime, mulching treatments with rice husk could enrich taro corm nutrition more than could those with sugarcane bagasse and peanut hull. Also, the effects of water regime and mulching on taro plant growth and corm attributes would be varied with the rainfalls during the period of vegetative growth. [ABSTRACT FROM AUTHOR]

Wetlands are increasingly exposed to human activities, resulting in degradation. As the wetland degrades, it loses functionality. In South Africa, wetlands can play an important water-regulating role. This study aims to establish the ecological condition of a historically utilised wetland on the Lions River floodplain in the uMngeni catchment, to provide a guide for the planning and implementation of rehabilitation interventions. A comprehensive assessment of the wetland's structure was undertaken in 2014, using vegetation and soil parameters, mapped and compared with changes in landuse on the wetland from historical aerial photographs. The study concluded that the wetland's ecological condition had declined, as a result of historical cultivation and commercial forestry. The wetland vegetation present is still generally aligned with the prevailing hydro-edaphic gradient and soil water regime; however, some areas of the wetland showed a mismatch in the soil water indicators and vegetation wetness indicators (the level of wetness based on vegetation being higher than that showed by the soil), suggesting localised drying out. A moderately high abundance of ruderal indigenous and invasive alien species in 61% of the wetland, particularly the drier areas of the wetland, contributed to the altered ecological condition. [ABSTRACT FROM AUTHOR]

Dill (Anethum graveolens L.) is a one-year herbaceous, spicy plant, which has aromatic smell and taste. One of its important ingredients is essential oil. The experiment showing the effect of irrigation on essential oil and biomass yield of dill was conducted in rainy 2016 and dry 2017 in two variants: control (without irrigation) and variant with irrigation. Favourable water balance of the soil was provided by applying drop-by-drop irrigation method. The average yield of fresh biomass was 8,252 kg ha-1 (10,194 kg ha-1 under irrigation and 6,310 kg ha-1 in control). Under irrigation, the yield of biomass was higher than the control variant by 78.59% in 2017 and 47.41% in 2016. Under irrigation, essential oil content and yield were higher than the control by 10.73% and 95.97% in 2017, respectively, and 3.93% and 54.06% in 2016, respectively.

Perennial ryegrass (Lolium perenne) is widely cultivated around the world for turf and forage. However, the plant is highly susceptible to disease and is sensitive to drought. The present study aims to determine the effect of the fungal endophyte Epichloë festucae var. lolii of perennial ryegrass on the combined stresses of drought and disease caused by Bipolaris sorokiniana in the greenhouse. In the experiment, plants infected (E+) or not infected (E−) with the fungal endophyte were inoculated with Bipolaris sorokiniana and put under different soil water regimes (30%, 50%, and 70%). The control treatment consisted of E+ and E− plants not inoculated with B. sorokiniana. Plant growth, phosphorus (P) uptake, photosynthetic parameters, and other physiological indices were evaluated two weeks after pathogen infection. The fungal endophyte in E+ plants increased P uptake, plant growth, and photosynthetic parameters but decreased the malondialdehyde concentration, proline content, and disease incidence of perennial ryegrass (p < 0.05). E+ plants had the lowest disease incidence at 70% soil water (p < 0.05). The study demonstrates that the fungal endophyte E. festucae var. lolii is beneficial for plant growth and stress tolerance in perennial ryegrass exposed to the combined stresses of drought and B. sorokiniana.

This paper is aimed to assess the impact of climate change on water regime of wetland in the area of Poiplie Ramsar site. To simulate the climate change the CGCM3.1 global model (SRES A2 pessimistic scenario and SRES B1 optimistic scenario) and KNMI and MPI regional models were selected as the most appropriate. For the 20-year reference period the years 1977–1996 was chosen, which is within the evaluation compared with the 20-year time horizons 2020, 2050 and 2080. Simulation of soil water regime was carried out using the GLOBAL model. Within the soil water regime evaluation actual evapotranspiration was evaluated in this paper. Actual evapotranspiration has in the future in the studied area also increasing course over the reference period, while the SRES A2 pessimistic scenario expected the increase of 24%, KNMI regional model the increase of 21% and SRES B1 optimistic scenario and MPI regional model the increase of 19%. The development of actual evapotranspiration is derived from the predicted increase in air temperature and pre- cipitation. On the base of these results the ongoing climate change does not cause dramatic changes in Poiplie Ramsar site, thereby this unique wetland ecosystem should be preserved in the future.

A modern model of optimal control of the water regime of the soil in conditions of irrigation, the use of which allows to assess the need for sequential vegetation watering, the probable date of the next watering, to make the graphics of watering and develop water use plan for the short, medium and long terms is suggested. The proposed model provides the possibility of determining the current status of soil moisture in two ways: by computational method or by hardware measurement system in contrast to the known solutions. A feature of the proposed model is the using of different calculation methods to determine the evapotranspiration during the forecast and retrospective calculations. Increasing the accuracy of forecast and retrospective calculation of evapotranspiration is achieved through the use of multi-parameter models with the introduction of the actual meteorological findings of the past period (the computational unit “retrospective”) and simple one-parameter models that may determine the total water consumption of crops using forecast meteorological data, which can be highly uncertain and with probabilistic nature. [ABSTRACT FROM AUTHOR]

Spoljar A., Kisic I., Peremin Volf, T., Kamenjak D., Kaucic D.: Influence of climate change on soil water regime in Koprivnica-Krizevci County. Ekológia (Bratislava), Vol. 33, No. 2, p. 178-187, 2014.

In the years 2008–2012, the infiltration capacity was monitored in the different sites, viz. on the arable land and permanent grassland. In the permanent grassland site the soil was characterised as Leptic Cambisol, loamy sand with the depth of the top layer 0.20 m while on the arable land, it was classified as Eutric Cambisol, sandy loam with the maximum depth of the topsoil humus horizon 0. 40 m. Experimental variants with different doses of incorporated compost were as follows: Variant 1 –without compost incorporation, Variant 2 – compost incorporated in the dose of 80 t.ha−1, Variant 3 – compost incorporated in the dose of 150 t.ha−1. It was found out within the study period that the application of the higher compost doses showed a positive effect on infiltration rate in both localities. In Variant 3, the highest values of the water infiltration were recorded. It can be concluded that the highest dose of compost (150 t.ha−1) improved and accelerated both the infiltration and water holding capacity of soil for a longer period. With the exception of the year 2009, increased values of water infiltration were recorded on experimental plots with arable land than with permanent grassland. It was found also that after five years have not been marked differences between variants. It follows that the regular supply of organic matter is necessary, preferably after three years.

The relationships between biocrusts and shrubs in semiarid areas, are of great importance, however, not yet sufficiently investigated. It is unknown whether or not biocrusts will decrease soil moisture and result in the degradation of artificially planted shrubs in semiarid climates. In a semiarid watershed on the Loess Plateau of China, we selected 18 sampling sites in artificial shrublands and measured at each the soil moisture from 0 to 200 cm depth under bare land, moss-dominated biocrusts, artificially planted Artemisia ordosica , A. ordosica with biocrusts, and dead A. ordosica with biocrusts. We also estimated the water-holding capacity and infiltrability of the soil with and without biocrusts. The A. ordosica with biocrusts had 24.4% lower biomass and 18.9% lower leaf area index than those without biocrusts, suggesting negative effects of biocrusts on these shrubs. Moreover, the biocrusts underneath A. ordosica decreased soil moisture 14.8% on average (2.6% vs. 3.1%; p < 0.01) due to their significant higher water-holding capacity (≥ 21.6%) and lower infiltrability (50.4%), compared to the area without biocrusts. Most importantly, the area with biocrusts and dead A. ordosica had similar soil moisture to the area with biocrusts and live A. ordosica , suggesting that the decreased soil moisture under the biocrusts persists after the death of A. ordosica . Our results suggest that biocrusts reduce soil water resources available to the artificially planted shrubs, thus increasing the risks of shrub mortality and further land degradation. The high coverage of moss-dominated biocrusts appears to be a dominant factor in soil moisture variations in artificial shrublands under semiarid climates, making the soil water balance more vulnerable in this region. [ABSTRACT FROM AUTHOR]

Available water resources for agricultural irrigation have decreased worldwide in recent decades, prompting advances in water saving methods. In this study, soil water regime and water balance in a transplanted rice field with reduced irrigation (multiple shallow depth irrigations) in the Taihu Lake Basin of East China were observed and then evaluated using Hydrus-1D model during two consecutive growing seasons. During the 2008 season, irrigation water accounted for 48% of the total water input (TWI, 94.6 cm), but only 20% of TWI (120.4 cm) during the 2009 season. Due to heavy rainfalls during the wet 2009 season, surface runoff accounted for about 6.4% of the TWI, whereas during the much drier 2008 season with higher controlled irrigation inputs, no surface runoff occurred. Simulated evapotranspiration during the 2008 and 2009 seasons accounted for 67.4% and 54.9% of TWIs, respectively. Measured and simulated results indicate that water percolation (approximately 32.5% and 37.6% of TWIs during the 2008 and 2009 seasons, respectively) was the main path of water losses from the transplanted rice fields, suggesting that long and high standing water during the 2009 season increased water percolation. Water productivities evaluated from total irrigations and TWIs were 2.08 and 0.99 kg·m-3 during the 2008 season and 3.85 and 0.77 kg·m-3 during the 2009 season, respectively, and were 1.47 and 1.40 kg·m-3, respectively, when evaluated from modeled evapotranspiration fluxes. The cultivation method with multiple shallow depth irrigation efficiently used rainfall water and reduced the losses due to water percolation and surface runoff by stabilizing rice yields. [ABSTRACT FROM AUTHOR]

• Soil moisture was manipulated by infiltration at distances from a gully sidewall. • The saturated soil domain was closer to the ground and sidewall under higher infiltration. • Cracks appeared at the upper position of the sidewall after snow melting under higher infiltration. • The slumped soil was greater in spring and less in summer under higher infiltration. • Prewinter soil water affected soil slumping via the freezing and cracking positions. Gully erosion is one of the most destructive land degradation processes. Soil slumping along cracks on a gully sidewall is a crucial process of gully development, yet the factors controlling the dynamics and amount of slumped soil remain unclear. It was hypothesized that soil slumping along the cracks in summer might be affected by the prewinter soil water regime, as it determines the depth of freezing-induced fissures within the soil profile, which affects the depth and dynamics of the cracks on the gully sidewall. To test this hypothesis, the soil water regime was manipulated by infiltrating 250 mm of water into the plots placed with one edge 10, 30 and 50 cm away from a gully sidewall before winter. This plot layout eventually resulted in four treatments with different amounts of infiltrated water. The isolines of near-saturation soil water contents appeared closer to the ground and the sidewall under the higher infiltration treatments before and after winter. Soil freezing started from the topsoil on 14 Nov. 2017 and penetrated the 1-m soil profile within 24 days. Soil thawing started from both the topsoil and subsoils (1 m depth) on 13 Apr. 2018 and ended on 24 Apr. 2018. The cracks that appeared on the sidewalls in Apr. had similar lengths and widths at the depths with a near-saturation soil water content (between 25 and 45 g kg−1). The cracks appeared at deeper position on gully sidewall under lower infiltration treatments. The soil mass slumped from the sidewall was greater in Apr. and less from Jul. to Aug. under higher infiltration treatments. The annual total of slumped soil mass was the lowest in the low infiltration treatment, where the near-saturation isolines were the deepest. These findings suggested that the prewinter soil water regime along the slope controlled the depth of freezing within the soil profile. The freezing depth determined the depth and time of soil cracking and slumping on the gully sidewalls the following year. Our study implies that gully development through soil slumping depends on pre-winter slope hydrology, which should be considered in modeling and controlling gully development. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the impact of different vegetation on the distribution of rainfall (due to throughfall and stemflow), water regime, and Al and SO4 2- leaching from forest soils. The water flow and Al and SO4 2- transport were modeled using HYDRUS-1D. The study was performed at two elevation transects on the Paličník and Smědava Mountain in Jizera mountains. Podzols and Cambisols were prevailing soil units in this area. It was shown that the effect of the precipitation redistribution on water regime was considerable in the beech forest, while it was almost negligible in the spruce forest. Redistribution of precipitation under trees caused runoff (in one case), increased water discharge through the soil profile bottom, reduction of water storage in the soil, and thus reduction of root water uptake. Simulated Al leaching from the soil profile was determined mainly by the initial Al content in the soil profile bottom. Leaching of SO4 2- was mainly determined by its initial content in the soil and to a lesser extent by redistributed precipitation and SO4 2- deposition.

The settlements situated on broad flat floodplains of rivers are threatened by floods during increased water flows in the rivers. The floodplain of the Dyje river situated in the area between the Nové Mlýny water reservoir and Břeclav has been protected from former annual floods since the 70s of the last century due to the water-management measures. The realised measures including the construction of the new floodway protect the town of Břeclav as well. A long-term research into the soil water regime of the floodplain forest is underway in the region. The results obtained document its historical evolution and current status. Only in the early April of 2006 (i.e. after 34 years), an unexpected "flash flood" occurred again due to a specific climatic situation. The combination of the high snow cover in higher parts of the basin and a rapid warming up caused an intensive runoff. The so-called dry polder (floodplain forests, meadows and fields) above Břeclav protected the town and its infrastructure from potential catastrophic consequences.

Biological soil crusts (BSCs) have been recognized as a vital influence factor to desert terrestrial ecosystems under semiarid climate. However, their effects on soil moisture and temperature, which play very important roles in many ecological and hydrological processes, have not yet been well understood. To provide more insight into this issue, we conducted a five-year monitoring experiment for moisture (0–150 cm) and temperature (0–30 cm) of soil with or without moss-dominated BSCs in a semiarid ecosystem on the Loess Plateau of China. The results showed that: (1) the BSCs significantly increased soil moisture by up to 7.6% at 5 cm depth, and significantly decreased soil moisture by up to 3.1%, 6.1%, and 8.1% at 15, 30, and 50 cm depths, respectively; while they had nearly no influence on soil moisture at 70–150 cm depths; (2) the BSCs significantly decreased soil temperature by up to 11.8, 7.5, 5.4, and 3.2 °C at 0, 5, 15, 30 cm depths, respectively, under wet and hot conditions in summer; whereas they significantly increased soil temperature by up to 8.0, 3.7, 2.9, and 1.9 °C, respectively, under dry and cold conditions in winter; and (3) the effects of the BSCs on soil moisture and temperature were significantly correlated with each other, and both of them were significantly driven by solar radiation and precipitation. We concluded that soil moisture and temperature regimes were significantly changed by moss-dominated BSCs in semiarid ecosystems, however, their effects mostly depended on seasons and soil depths. [ABSTRACT FROM AUTHOR]

This paper presents an approach to downscaling of climate models based on a combination of Generalised-additive-models and geostatistics. The paper aims at increasing the usefulness of Climate Models by creating data sets with a spatio-temporal resolution appropriate for applications of environmental models at the management scale. Simulations of climate change available from global and regional climate models require downscaling and bias correction for hydrological or ecological applications. The paper assess the effectiveness of the approach applied to monthly means of temperature and rainfall, to predict soil wetness conditions. The main focus was on reconstructing the spatial structure of the landscape. The climate model data were firstly downscaled using a geo-statistical approach combining generalised additive models (GAMs) with kriging, making use of the covariates to reproduce the spatial pattern. The downscaled climate model data were corrected for bias using interpolated meteorological ground station data (1961–1999). In general the downscaling approach provided lower RMSE and closer reproduction of the variogram structure. The use of the bias corrected downscaled data improved the results of the model used to predict soil wetness, increasing the validation metrics. The approach is completely implemented in open-source software, in particular GRASS-GIS and R. [ABSTRACT FROM AUTHOR]

Basic elements of agrotechnical complexes for potato cultivation, which provide regulation of the light, nutrition, and water regimes, as well as the phytosanitary condition of potato crops, have been developed with the view of plants' adaptability to the irrigation conditions of the Ural steppe to obtain different levels of planned yields. The nature of water consumption by potatoes in ontogenesis typical for the regional conditions is determined. According to the results of the multifactor analysis conducted, the impact of the study factors on change in potato yields is determined. [ABSTRACT FROM AUTHOR]

Integrating micro-flood irrigation with in-field rainwater harvesting (IRWH) was proposed and experiments were conducted in the 2007–2008 production season at Parady's Experimental Farm of the University of the Free State, South Africa. Three water regimes, dryland (DL), supplemental (SPI), and full irrigation (FI), were tested with 1, 2, and 3 m runoff strip width (RSW) to determine their effects on soil water balance components for the integrated IRWH. Four blocks with nine subplots were prepared for the 3 × 3 split plot factorial experimental design. Plots were 30 m long with a standard 1 m width. Site specific data were used to estimate rainfall-runoff and deep drainage functions. Soil water content (SWC) was measured with a Neutron water meter. Evapo-transpiration (ET) was partitioned into evaporation and transpiration using a β parameter. Deep drainage was the least significantly affected. Rainfalls not less than 24 mm had significantly higher gains on change in SWC for the 2 m and 3 m RSW. During dry spells these RSWs had significantly higher SWC deficit. For the vegetative and reproductive growth stages evaporation from the 3 m RSW constituted not less than 60% of ET compared to less than 40% from 1 m RSW. The 1 m RSW had significantly higher ET and T, irrespective of water regime with the highest values from irrigation treatments. The 1 m RSW can, therefore, be used with either FI or SPI to optimize soil water balance for the integrated IRWH water management. [ABSTRACT FROM AUTHOR]

Morphology (ancient) and chemistry (recent) were used as indicators of hydrological response and used to construct a conceptual hydrological response model with new insights into hydropedological interpretations of easily accessible soil data. Soil chemistry is hypothesised to be equilibrated with the recent water regime. Profiles of three soil types on the soilscape with descriptions, analyses, long-term soil water content and water tension data are discussed and 15 auger observations with descriptions and MIR data are used to develop a conceptual response model. Morphology was able to identify the primary response of soils. The deep interflow Cambisol on the midslope has a vertical flowpath through the first subsoil, indicated by the red apedal morphology, which combines with interflow in the second subsoil, indicated by stagnic colour patterns. The responsive Gleysol on the footslope is a storage mechanism, indicating permanently saturated conditions. The responsive Luvisol at the toeslope has interflow in the Albic horizon while the subsoils act as a storage mechanism. pH and base saturation were used to indicate leaching (flowpath), ferrolysis (fluctuating watertable), acid weathering and accumulation (water saturation). Iron and Mn were used as indicators of reducing conditions to infer the duration of saturation. Soil response was verified by water contents and tension data. Pedological processes were correlated to horizons and hydrological response. Chemistry was more sensitive to water regime change than soil morphology. Therefore soil chemistry was successfully used in designing a conceptual hydrological response model and improved identification of hydrological processes. [ABSTRACT FROM AUTHOR]

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Aims: Soil respiration in forest plantations can be greatly affected by management practices such as irrigation. In northwest China, soil water is usually a limiting factor for the development of forest plantations. This study aims to examine the effects of irrigation intensity on soil respiration from three poplar clone plantations in this arid area. Methods: The experiment included three poplar clones subjected to three irrigation intensities (without, low and high). Soil respiration was measured using a Li-6400-09 chamber during the growing season in 2007. Results: Mean soil respiration rates were 2.92, 4.74 and 3.49 μmol m s for control, low and high irrigation treatments, respectively. Soil respiration decreased once soil water content was below a lower (14.8 %) or above an upper (26.2 %) threshold. When soil water content ranged from 14.8 % to 26.2 %, soil respiration increased and correlated with soil temperature. Fine root also played a role in the significant differences in soil CO efflux among the three treatments. Furthermore, the three poplar hybrid clones responded differently to irrigation regarding fine root production and soil CO efflux. Conclusions: Irrigation intensity had a strong impact on soil respiration of the three poplar clone plantations, which was mainly because fine root biomass and microbial activities were greatly influenced by soil water conditions. Our results suggest that irrigation management is a main factor controlling soil carbon dynamics in forest plantation in arid regions. [ABSTRACT FROM AUTHOR]

During the vegetation season, the water storage in the soil aeration zone is influenced by meteorological phenomena and by the vegetated cover. If the groundwater table is in contact with the soil profile, its contribution to water storage must be considered. This impact can be either monitored directly or the mathematical model of the soil moisture regime can be used to simulate it. We present the results of monitoring soil water content in the aeration zone of the East Slovakian Lowland. The main problem is the evaluation of the soil water storage in seasons and in years in the soil profile. Until now, classification systems of the soil water regime evaluation have been mainly based upon climatological factors and soil morphology where the classification has been realized on the basis of indirect indicators. Here, a new classification system based upon quantified data sets is introduced and applied for the measured data. The system considers the degree of accessibility of soil water to plants, including the excess of soil water related to the duration for those characteristic periods. The time span is hierarchically arranged to differentiate between the dominant water storage periods and short-term fluctuations. The lowest taxonomic units characterize the vertical fluxes over time periods. The system allows the comparison of soil water regime taxons over several years and under different types of vegetative cover, or due to various types of land use. We monitored soil water content on two localities, one with a deep ground water level, one with a shallow ground water level. The profile with a shallow ground water level keeps a more uniform taxons and subtaxons of soil water regime due to the crop variation than the profile with a deep ground water level.

Aims: An incubation study was conducted to investigate how changes in soil water content affect labile phosphorus and carbon pools, mineralisation patterns and microbial community composition. Methods: Two soils from different climatic histories were subjected to four long-term (15 weeks) soil water regimes (constant field capacity (m); 3 dry-rewet (DRW) cycles evenly spaced (intermittent, int); 3 DRW cycles with a shorter interval after a long dry period (false break, fb); constantly air-dry (d)) (incubation period 1). In the subsequent incubation period 2, a set of cores from each treatment were subjected to one DRW cycle (air-dry for 7 day; field capacity for 14 day) or maintained at field capacity. Results: Long-term soil water regime altered soil respiration with the largest CO pulse occurring in soil with the longest dry period. However, changing the distribution of the 3 DRW events within incubation period 1 (int/fb) did not alter cumulative CO. In addition, DRW during incubation period 2 did not affect cumulative CO in either treatment (m, int, fb, d) (except for Hamilton int). Our results show that carbon and phosphorus availability and the size and community composition of the microbial biomass were largely unaffected by fluctuating soil water content. Conclusions: Changes in soil water content altered respiration, phosphatase activity and microbial C:P ratio and indicate physiological and/or functional changes in the microbial community. However, it appeared that these would have little impact on plant P availability. [ABSTRACT FROM AUTHOR]

The temporal patterns of growth and nutrient accumulation into shoots of coexisting species were studied at two neighbouring areas contrasting with respect to long-term water availability, in an upland herbaceous grassland. Plant growth limiting nutrients were nitrogen (N) in the wet area, and N and phosphorus (P) in the dry area. A series of seven harvests allowed assessment of temporal patterns of peaks for dry matter, N, P and potassium (K) accumulation into shoots and their respective rates of accumulation. Additionally, 'pairwise species' proportion similarities' and 'pairwise species' overlaps' were estimated from shoot biomass data. The peaks of N and P accumulation preceded those of K and dry matter accumulation. Similar trends were evident for the respective rates of accumulation. Compared to the dry area, in the wet area there was a prolonged growing period that increased the inter-species temporal variability in the rates of nutrient accumulation. Abundance of species was correlated (negatively) to species N and P concentrations only in the dry area. It is argued that the significant negative correlation between abundance and either N or P concentrations in the dry area was indicative of intensified inter-species competition resulting from declined temporal complementarity. [ABSTRACT FROM AUTHOR]

The lower boundary maintained throughout leaching experiments in column and lysimeter studies influences the transport behavior of solutes. In this study we wanted to determine the effects of different flux regimes and soil organic matter treatments on reactive (pesticide) and non-reactive (bromide) solute movement in lysimeters. Four large soil monoliths, collected from the same experimental site but differing in the organic carbon content by an added manure layer, were subjected to two consecutive leaching tests. Unsaturated steady-state flow with a unit hydraulic gradient was established in Test 1 by applying a constant negative pressure at the base of the lysimeter while during Test 2 atmospheric pressure was maintained (zero-tension). Although less herbicide (isoproturon) was leached from the soil with added manure, the flux regime, as controlled by the lower boundary, dominated the adsorption and the degradation coefficients. The lower moisture content of Test 1 enhanced isoproturon binding, whilst chemical degradation was more effective under the increased but non-uniform soil water content of Test 2. This study demonstrates how solute leaching studies using zero-tension lysimeters do not represent unsaturated in-field processes; the physicochemical processes occurring in unsaturated field soils are only adequately reflected in leaching tests when a constant negative soil water pressure head is maintained throughout the soil sample. [ABSTRACT FROM AUTHOR]

The global warming may induce intensive changes in soil water regime. In this article, we analyse tendencies of changes in the soil water content in Lithuania for the period from 2001 to 2090. Results of the work are based on the calculations of soil water regime and its change in the 0-1000 mm layer. The analysis was based on the water balance method. To forecast the climate, the general circulation models HadCM3 and Echam5 with appropriates emission scenarios A1B and B1 were employed. To characterize the meteorological situation in Lithuania, we used information of 16 meteorological stations. The hydrological situation was characterized by 18 various catchments. The information was analysed using the Thorntwaite-Mather (TM) and WatBal hydrological models. When in the analysis results of the climate change scenario HadCM3-A1B, were applied using the TM model estimated that soil water in 2001-2090 would decrease. In comparison with 1971-2000, soil water content reduction in May-August in 2001-2030 will total 18%, in 2031-2060 24% and in 2061-2090 31.5%. Very intensive changes were predicted in West Lithuania. The main reason for soil water reduction (according to WatBal model) is increase of evaporation in the 21st century. The soil water forecast by TM hydrological models applying results of the climate scenario Echam5-B1 established a less significant water decrease. The maximum soil water depression was found for 2001-2030 (14-19%) and 2061-2090 (12-16%). The main reason that determined these soil water forecast results is more abundant precipitation in the scenario Echam5-B1. The highest desiccation will occur in the surface layer of soil on a light texture ground (both HadCM3-A1B and Echam5-B1 climate scenarios). [ABSTRACT FROM AUTHOR]