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Background and aims: Organic farming has been viewed as a sustainable practice that can maintain yields and improve soil quality in greenhouse vegetable production. However, little attention has been given to the leaching of dissolved organic nitrogen (DON) due to excessive application of organic manure. The objectives of this study were to compare the characteristics of dissolved inorganic nitrogen (DIN) and DON leaching under different greenhouse vegetable production systems. Methods: A 2-year lysimeter field experiment was conducted with three different farming systems in North China, i.e. conventional (CON, 70% chemical fertilizer +30% organic manure), integrated (INT, 50% chemical fertilizer +50% organic manure) and organic (ORG, 100% organic manure). Results: The results indicated that vegetable yields under the ORG system were normally larger than the CON or INT. The amount of water drainage and dissolved total N (DTN, DIN + DON) leaching differed during two cropping seasons, with spring and summer seasons giving greater leaching than autumn and winter seasons. The total DIN leaching throughout four seasons of vegetable production under ORG was 176 kg N ha−1, which was much lower than that of CON (327 kg N ha−1) and INT (269 kg N ha−1). The DTN leaching under ORG (485 kg N ha−1) was also less than that of CON (528 kg N ha−1) and INT (521 kg N ha−1). However, the total DON leaching under the ORG was 309 kg N ha−1, far higher than the amounts for CON (202 kg N ha−1) and INT (252 kg N ha−1). The average DON leaching ratio (DON/DTN) under the ORG system was 63.7%, which was also much higher than that of the CON (38%) and INT (48%) systems. The increase in the proportion of organic manure in fertilizer types and over-irrigation were the main reasons for the increase in DTN leaching. Structural equation modeling analysis showed that the soil bulk density, saturated hydraulic conductivity and saturated soil water content were the most important factors influencing the DTN leaching. Conclusions: While the ORG system has many advantages, irrigation and fertilizer scheduling should be optimized under the ORG system in order to minimize DON leaching. [ABSTRACT FROM AUTHOR]

Groundwater pesticide safety management is essential for providing consistently safe water for humans, but such management is limited globally. In this study, we developed an accurate and convenient exposure assessment method for the safety management of pesticides in groundwater by conducting a lysimeter experiment to evaluate the leaching of 11 pesticides into groundwater. During the experimental period, flutoalanil and oxadiazon had the highest cumulative leaching amounts, 603.7 and 83.5 ng, respectively. Comparative analysis of existing groundwater exposure prediction indices, including the GUS, LEACH, modified LEACH, Hornsby index, and GLI showed no correlations with the measured data (p > 0.05). To enhance the accuracy of the assessment method, we used lysimeter data and principal component analysis to determine the main factors affecting groundwater leaching, and developed the "pesticide groundwater leaching scoring system" (PLS). The soil and water half-life, which had the greatest positive impact on groundwater leaching, was set as a 10-point indicator, whereas log P was set as a 1-point indicator. In contrast, solubility in water was determined as a 5-point indicator, and organic carbon partition coefficient and vapor pressure were determined as 2.5-point indicators owing to their negative relationship. The correlation coefficient was 0.670, indicating a significant correlation with the lysimeter data (p < 0.05). Using our scoring system, we ranked 376 pesticides. As an exposure assessment method developed using actual data, the PLS is expected to be applicable to groundwater safety management. [ABSTRACT FROM AUTHOR]

Soil–hydrophysical research substantiating the mathematical models of water movement, taking into account the soil heterogeneity, due to the vertical change in texture, is considered. The vertical movement of water on large-size lysimeters of the Federal Scientific Center of Agroecology of the Russian Academy of Sciences (Volgograd) was studied. The influence of statistical heterogeneity of hydrophysical parameters of lysimeter substrates was studied on models of water transfer dynamics and formation of gravitational runoff developed in the HYDRUS-1D software package. The change in texture along the vertical profile of the lysimeters and the related variability of the main hydrophysical characteristic or water retention curve (WRC) were taken into account. The textural heterogeneity of the substrates was estimated by the scaling method, according to the scale factors of the WRC parameters, assuming a normal probability distribution of the logarithms of the pore space capillary radii between soil particles. The effect of texture on water holding capacity, boundary and initial conditions, intensity of gravitational runoff and cumulative accumulation of water were studied. [ABSTRACT FROM AUTHOR]

The ALTEO company produces approximately 300,000 tons per year of bauxite residue after alumina extraction, which is washed and dried in a press filter to produce Bauxaline®. In this study, different ways for recovering and reusing this residue were explored, namely transformation into a vegetated soil, use in acid mine drainage depollution, and application in sulfide-mine tailings remediation. The Bauxaline® was therefore transformed into modified bauxite residue (MBR), resulting in reduced alkalinity, salinity, and sodicity. To counterbalance the net acid generation potential of two sulfidic mine tailings with 1 mol H+ kg−1 (1.5% sulfide) and 3.3 mol H+ kg−1 (5.3% sulfide), respectively, various treatments were applied. These treatments included the addition of 10% MBR or 10% MBR plus limestone, or by limestone only, within 40-l lysimeters. Six lysimeters were monitored over a 5-year period to assess the long-term emissions from treated materials. Vegetation was tested under various conditions, and its impact on emission was evaluated. The emissions of mine tailings treated with MBR and limestone were very low. The mine tailings with limestone showed intermittent peaks of emission, probably due to the coating of calcite grain by ferric oxide, hindering contact with percolating water. Vegetation successfully grew in the treated tailings. This study demonstrated that the alkalinity of limestone can temporarily immobilize elements in sulfidic mine tailings, with a reduction factor of emissions of 300 and 40 for the two mine tailings, respectively. For long-term immobilization, the alkalinity provided by both limestone and MBR and the Al and Fe oxides of MBR are more effective and necessary for long-term immobilization, with a reduction factor of 300 and 900, respectively. [ABSTRACT FROM AUTHOR]

Deep fertilization has been tested widely for nitrogen (N) use efficiency but there is little evidence of its impact on N leaching and the interplay between climate factors and crop N use. In this study, we tested the effect of three fertilizer N placements on leaching, crop growth, and greenhouse gas (GHG) emissions in a lysimeter experiment over three consecutive years with spring-sown cereals (S1, S2, and S3). Leaching was additionally monitored in an 11-month fallow period (F1) preceding S1 and a 15-month fallow period (F2) following S3. In addition to a control with no N fertilizer (Control), 100 kg N ha−1 year−1 of ammonium nitrate was placed at 0.2 m (Deep), 0.07 m (Shallow), or halved between 0.07 m and 0.2 m (Mixed). Deep reduced leachate amount in each cropping period, with significant reductions (p < 0.05) in the drought year (S2) and cumulatively for S1-S3. Overall, Deep reduced leaching by 22, 25 and 34% compared to Shallow, Mixed and Control, respectively. Deep and Mixed reduced N leaching across S1-S3 compared with Shallow, but Deep further reduced N loads by 15% compared to Mixed and was significantly lowest (p < 0.05) among the fertilized treatments in S1 and S2. In S3, Deep increased grain yields by 28 and 22% compared to Shallow and Mixed, respectively, while nearly doubling the agronomic efficiency of N (AEN) and the recovery efficiency of N (REN). Deep N placement is a promising mitigation practice that should be further investigated. [ABSTRACT FROM AUTHOR]

This study aimed to accurately estimate daily wheat evapotranspiration using two remote sensing algorithms, Surface Energy Balance System (SEBS) and Surface Energy Balance Algorithm for Land (SEBAL), in central Khuzestan province during 2019–2020. The results of two algorithms were compared with lysimeter (as a direct method), FAO-Penman–Monteith (FAO-PM), two temperature-based methods (Hargreaves-Samani and Blaney-Criddle), two radiation-based methods (Priestley–Taylor and Doorenbos–Pruitt), and two mass transfer-based methods (Mahringer and World Meteorology Organization) (as indirect methods). Coefficient of Determination (R2), Root-Mean-Square Error (RMSE), Percentage of Bias (PBIAS), Mean Bias Error, Mean Absolute Percentage Error, and Nash–Sutcliffe indicators used for comparing the results. According to the results, both SEBAL and SEBS algorithms showed the highest compatibility with lysimeter data (R2 = 0.92 and 0.96, RMSE = 2.15 and 1.53 mm/day, respectively). Comparing both algorithms with the FAO-PM method, resulted in RMSE and R2 of 2.42 mm/day and 0.87 for SEBS and 3.14 mm/day and 0.79 for SEBAL. The Hargreaves-Samani method (R2 = 0.72, RMSE = 16.4 mm/day) and (R2 = 0.8, RMSE = 10.4 mm/day) among temperature-based methods, Doorenbos–Pruitt (R2 = 0.71, RMSE = 3.33 mm/day) and (R2 = 0.79, RMSE = 2.63 mm/day) among radiation-based methods, and the Mahringer method (R2 = 0.6, RMSE = 6.8 mm/day mm/day) and (R2 = 0.68, RMSE = 5.51 mm/day) among mass transfer-based methods yielded better estimations than SEBAL and SEBS algorithms, respectively. Owing to the high accuracy of SEBAL and SEBS algorithms, in estimating the amount of evapotranspiration in the study area and close to the actual values in the field, using energy balance algorithms is recommended in Khuzestan province. [ABSTRACT FROM AUTHOR]

Groundwater is a significant source of plant water use since groundwater consumption of plants reduces the volume of surface irrigation water. In this study, groundwater table effect on hard red spring wheat (Triticum aestivum L.) growth and yield parameters were investigated using a lysimeter technique in a controlled environment. Three different groundwater table depths including 30, 60, and 90 cm and a control treatment with surface irrigation were tested. The results showed that water consumption in the 90 cm water table depth was 11% and 31% lower than the water consumption in the 60 and 30 cm water table depths, respectively. Consequently, the groundwater table depth increased, and crop water consumption decreased. Similarly, with the increasing water table depth from 30 to 90 cm in the lysimeter, the crop water use efficiency and crop yield increased by 79% and 71%, respectively. The 90 cm water table produced the highest crop yield, above-ground biomass, and kernel quality compared to 30 and 60 cm water table depths. Quality analysis of the wheat kernels indicated that the kernels from the 90 cm depth had relatively higher starch content, pasting properties, and gluten proteins compared to the kernels from other water table depths. [ABSTRACT FROM AUTHOR]

The present study investigates the performance of six pre-existing models to estimate the capillary rise from a shallow groundwater table using data from the lysimeters experiment. Essential parameters for estimating capillary rise were observed for nine crop species, i.e., Wheat, Indian mustard, Potato, Maize, Sorghum, Guar, Pea, Spinach, and Tomato. Based on a comparative evaluation, Modified Averianov Formula showed better agreement between the observed and estimated capillary rise than other evaluated models. However, its performance was not satisfactory. An empirical model comprising soil-crop-climatic variables for estimating the capillary rise is proposed using experimental data on nine crop species. Further, the performance of the proposed model was compared with pre-existing models and the observed capillary rise for three crop species, i.e., Wheat, Maize, and Pea. The values of R2, NSE, and MBE ranged between 0.82 to 0.85, 0.80 to 0.83, and −0.07 to 0.11, respectively for Wheat, Maize, and Pea, indicating good agreement between observed and the proposed model estimated values. [ABSTRACT FROM AUTHOR]

Crop coefficients are important to determine crop evapotranspiration (ETc), seasonal crop water requirement, and irrigation water depth. Similarities between the curve of crop coefficient and remote sensing-based vegetation indices of a crop during its growth period suggested the possibility of modeling crop coefficient (Kc) as a function of vegetation indices. In this study, high-resolution multispectral (MS) images of a rice crop acquired using a quadcopter unmanned aerial vehicle (UAV) were processed to generate Kc maps. Lysimeter experiments were conducted for estimating daily ETc of rice using the water balance concept for conventionally irrigated paddy during kharif (monsoon) 2018/2019, rabi 2018/2019 (non-monsoon), and kharif (monsoon) 2019/2020 seasons. The average lysimeter-based crop coefficients for all three seasons were observed to be 1.04, 1.24, 1.36, and 1.18 for initial, crop development, reproductive, and late growth stages of the rice crop season, respectively. The mean Kc was significantly different for the growth stage, but it was not significantly different for the season. Among the eight vegetation indices tested, the ratio vegetation index (RVI) and normalized difference red edge (NDRE) were found to be correlated well with the lysimeter-based Kc for the kharif 2019/2020 season. The developed linear regression equations (RVI vs. Kc; NDRE vs. Kc) were tested using kharif 2018/2019 and rabi 2018/2019 seasons and found acceptable levels of different performance indices. These regression models will be helpful in generating Kc maps and estimating irrigation water requirement of paddy crop (MTU 1010 variety) in the sub-humid subtropical region. [ABSTRACT FROM AUTHOR]

One of the most challenging parameters to estimate in leachate generation quantification is the percolation rate through a landfill cover. Since leachate generation is critical to operators, particularly when discussing walk-away aftercare conditionalities, this topic is still relevant. The best method for estimating the percolation rate of a cover involves placement of a lysimeter below or within the landfill cover to collect the percolating water. Previous work has focused on optimizing the height of the sidewalls of lysimeters to minimize the interference of its presence on the flow regime within the cover. Using numerical modeling, this paper examines the influences of climate, lysimeter geometry, and location, on the effectiveness of lysimeters. Robustness tests were proposed to assess the extent to which lysimeters altered the flow regime. The results show that lysimeter effectiveness depends on the relationship between its wall height, width, and depth within the profile. The lysimeters that passed all three performance robustness tests were considered reliable. Percolation measurement efficacies were found to be high when the height of the lysimeter, H, tended towards the height calculated using a simplified methodology based on steady-state calculations, Hlinear. For example, in the case of the cover soil tested and the Canadian climate, lysimeters whose H = Hlinear would not know any loss of performed for width to height (W/H) ratios greater than 3, no matter the depth it is placed. And it would lose only 5% in percolation efficacy for W/H = 2. In other words, a 3-m wide lysimeter would fit the bill in Canada. In the case of the Floridian climate, even when H = Hlinear, W/H ratios greater than 4 would be required for lysimeters placed nearer to the surface. When placed deeper, lysimeters with H > Hlinear perform better. [ABSTRACT FROM AUTHOR]

This study investigated manure loads in outdoor paddocks for laying hens and the capacity of two phosphorus (P) retaining materials for reducing leaching from manure in areas with high hen density. Inventories on two commercial farms during 2 years (2017 and 2018) of the impact of hens (groups of 3000 hens) on vegetation, as a proxy for land use by hens, showed that 16–21% of outdoor area in grassland paddocks and 22–39% of area in a forest paddock were used by the hens. Sand and limestone were tested as P retention materials in areas with high manure load in a field study during the outdoor season for laying hens (May 1 to October 31 in 2018). The materials were placed on the ground (0.2 m deep bed, 3.3 m wide) outside the pop-hole in paddocks with 76 hens. The average numbers of hens outdoors were recorded at 9 am and 3 pm daily. There was no significant difference between the materials concerning distribution of hens, and they seemed not to prefer any material more than the other. When cylinders containing the spent materials were exposed to simulated rainfalls in a laboratory study, the P concentrations in drainage water were high for all materials, including a control with gravel (58–136 mg PO4-P L−1 and 130–197 mg total-P L−1). On average, 14% of manure P retained in the sand and limestone materials was leached after 100 mm of simulated rainfall. Thus, these materials may act as physical filters for P in manure, but to reduce the risk of P losses to waters during the following winter, they need to be removed from the paddocks and preferably used as potential P fertilizers on arable land. [ABSTRACT FROM AUTHOR]

Background and aims: High and stable plant productivity is a major aim in agricultural research. Silicon fertilization improves yields of various crops under stress. Nonetheless, broad application of silicon is inhibited by the lack of a mechanism explaining this effect. Experimental System: To study the role of silicon in soil-grown plants under drought, we utilized a sorghum (Sorghum bicolor) mutant plant lacking the key silicon root channel – Low silicon 1 (SbLsi1). The sblsi1 mutant plants absorb 1/15 of the silicon absorbed by wild type plants, making them a suitable tool to examine silicon physiology in soil and under field conditions. Results: In mutant plants grown in pots, significant reductions in momentary and accumulated whole plant transpiration, photosynthesis rate, and stomatal conductance were found only under water stress. Root structure, root hydraulic conductance, and stomatal density were similar between wild type and sblsi1 plants. Similar leaf water contents between the genotypes suggested that the water uptake was balanced with transpiration. Conclusions: The similarity between the genotypes under benign conditions are in accordance with minor to no effects of silicon fertilization in non-stressed plants, and support the minor pleiotropic effects of the mutation. Early stomatal closure in the mutant plants under drought stress caused the reduced transpiration. Thise early response suggests that silicon may delay the onset of drought physiology by either reduced stress signaling or reaction. [ABSTRACT FROM AUTHOR]

Irrigated paddy rice needs new strategies and tools to improve water use efficiency and productivity by applying just enough to sustain production with huge savings on irrigation water. In this regard, an experiment was conducted in Tainan, Xuejia district where lowland paddy rice was grown under the SRI using two different irrigation methods (rill irrigation and sprinkler hose). This was conducted over a period of two years (2019 and 2020) to obtain an optimized irrigation method with high water-saving benefits and increased yields. In the first-year, rill irrigation was used with varying rill depths of 10, 20 and 25 cm (as T10, T20 and T25 treatments) under SRI, and the depth of 10 cm was found to be the most optimum, attaining a yield of 1500 kg/ha. T10 had also the highest water productivity of 0.7 kg/m3. In the second year, a sprinkler hose was used for irrigation with varying irrigation volumes of 0.3, 0.2, 0.1 m3 (as T3, T2 and T1 treatments) and the traditional SRI method as the control. All plots were irrigated at a moisture stress of 25 kPa. The 0.3 m3 treatment was effective in producing the highest yield of 950 kg/ha with a water productivity of 0.21 kg/m3. The results showed that the yield and the water productivity were 63% and 30% higher under rill irrigation, respectively, favouring the adoption of rill irrigation. Generally, lowland paddy rice performed better in the dry season for both methods applied due to high prevalence of diseases in the wet season. In conclusion, any modifications of water applied to paddy should be made during the crucial stages of grain filling to improve the fertility rate otherwise optimum yields will not be realised. [ABSTRACT FROM AUTHOR]

The increasing use of antibacterial silver nanomaterials (AgNM) in consumer products leads to their release into sewers. High amounts of AgNM become retained in sewage sludge, which causes their accumulation in agricultural soils when sewage sludge is applied as fertilizer. This increase in AgNM arouses concerns about toxicity to soil organisms and transfer within trophic levels. Long-term field studies simulating the sewage sludge pathway to soils are sparse, and the effects of a second sewage sludge application are unknown. In this perennial field lysimeter study, a twofold application of AgNM (NM-300K, 2 + 3 mg AgNM/kg dry matter soil (DMS)) and a onefold application of silver nitrate (AgNO3, 2 mg Ag/kg DMS) by sewage sludge to the uppermost 20 cm of the soil (Cambisol) were applied. The response of microorganisms to the applications was determined by measuring the inhibition of ammonium-oxidizing bacteria (AOB). Silver concentration in soil, leachates, and crops were measured after acid digestion by inductively coupled plasma mass spectrometry (ICP-MS). Almost no vertical Ag translocation to deeper soil layers and negligible Ag release to leachates suggest that soil is a large sink for AgNM and AgNO3. For AgNM, an increase in toxicity to AOB was shown after the second sewage sludge application. The application of AgNO3 resulted in long-term toxicity comparable to the toxicity of AgNM. Low root uptake from both AgNM- and AgNO3-spiked lysimeters to crops indicates their incomplete immobilization, which is why food chain uptake cannot completely be excluded. However, the root-shoot barrier for wheat (9.8 → 0.1 mg/kg) and skin body barrier for sugar beets (1.0 → 0.2 mg/kg) will further reduce the accumulation within trophic levels. Moreover, the applied AgNM concentration was above the predicted environmental concentration, which is why the root uptake might be negligible in agricultural practice. Highlights: In a perennial field study, most of the applied AgNM and AgNO3 remained immobile in soil. The release of Ag to the leachates was very low (<176 ng/L). Low, continuous, species-specific transfer of AgNM and AgNO3 from soil to wheat and sugar beet. Constant and comparable inhibition of AOB by AgNM and AgNO3. Second sewage sludge application (AgNM) after four years leads to increased toxicity. [ABSTRACT FROM AUTHOR]

Crop coefficient (Kc) represents the actual crop growth of the crop. It plays an important role in estimating water requirements at the different growth stages of the crop. However, FAO 56 Penman–Monteith Kc method does not account for spatial heterogeneity and uncertainty for regional climatic conditions significantly. Therefore, this study aims to develop the relation between Kc and normalized difference vegetation index (NDVI) using a linear regression and back calculations. These relationships were adjusted to local conditions using information from survey data obtained during Rabi season (2014–2015). The NDVI–Kc model (r2 = 0.86) has developed using NDVI–Kc from a fine resolution Landsat 8 remote sensing data. NDVI–Kc regression equation was utilized for generating crop coefficient for different month of season. The Vegetation Index-based AET estimated was evaluated with lysimeter data for different crop growth stage across the season. The results have shown that NDVI–Kc estimated AET has been better correlated with NDVI–Kc remote sensing model. Thus, the output of this research can help to calculate actual water demand in a command area and be helpful in allocating water from less demand area toward more demand area. [ABSTRACT FROM AUTHOR]

The objectives of this study are to test the penetration depth and determine the soil content in hydrocarbons' components BTEX, PAHs, and TPH, after vertical movement of crude oil through undisturbed soils of different textures, and to assess their risk. The experiment simulates the fate of oil spills in the cold season. Three soil types were investigated: a sandy-textured eutric Arenosol, AR-eu; a loamy-textured haplic chernozem, CH-ha; and a clayey-textured, swell-shrink, Luvic Chernic Phaeozem, PH-ch-lv. Undisturbed small-scale lysimeters, 0.3 m in diameter and 1 m in length, were used. Crude oil was first applied and then water. TPH, BTEX, and PAH retention in the soils depends on soil texture. PH-ch-lv soil stored most of them in the upper horizons. TPH, BTEX, and PAH were found in different amounts as percentage from the applied ones, TPH as 48% (PH-ch-lv), and > 76% in the other two soils. BTEX was stored as 1.6% from the applied in PH-ch-lv, 5.1–5.1% in CH-ha and AR-eu soils, while PAH ranged from 15.1% in AR-eu soil to 24.8% in PH-ch-lv and 31% in CH-ha. Though subject to volatilization, chemical transformation, and bioremediation, TPH, BTEX, and PAH stored in soils present a health risk if they reach the groundwater. PH-ch-lv appears to be the most resilient soil to oil pollution. The results concern different soil textures and might be used in various countries. Future experimentation should focus on soil behavior in relation to crops, water, and certain crude oil types. [ABSTRACT FROM AUTHOR]

In many watersheds, nitrogen (N)-fixing alder (Alnus spp.) provides key nutrient subsidies to terrestrial and aquatic ecosystems. The importance of these subsidies may increase as alder cover expands under climate warming at high latitudes. We assessed how landscape features and meteorological conditions affect aquatic N and phosphorus (P) availability and stoichiometry in 26 streams across natural gradients of alder cover in southwestern Alaska over the spring and summer, covering 4 years. Analyses of resin lysimeter samples from select watersheds showed that annually, soils under alder leached almost three times more N, and two times more P than under non-alder vegetation. Stream NO3− concentrations displayed a non-linear relationship with alder cover; NO3− was low where alder cover was < 30%, but increased markedly where alder cover was > 30%. Watershed elevation was inversely related to alder cover, stream NO3− concentrations, and stream NO3− yields. Dissolved and particulate stream P were unrelated to alder cover, watershed elevation or discharge, highlighting decoupling of controls on P between terrestrial and aquatic ecosystems. Snowmelt-associated nutrient pulses and hydrology likely resulted in greater stream N and P in the spring, compared to the summer. However, weather parameters only impacted stream N via their interaction with alder. Stream DIN:TP increased with alder cover and decreased with elevation, suggesting that alder intensified P-limitation. Hence, aquatic P-limitation may become increasingly pronounced as climate-induced alder expansion continues. These results demonstrate that the elevational gradient in watershed alder cover determined spatial patterns in stream N availability and nutrient limitation. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effects of different irrigation strategies, planting methods and various nitrogen application rates on water and solutes transport under the root zone. Furthermore, Hydrus-1D model was used to simulate the drainage water and soil nutrient (N, K) leaching by the drainage water in the experimental treatments. Results indicated that variable alternate furrow irrigation (VAFI) decreased drainage water by a mean value of 30% compared with that obtained in full irrigation (OFI); whereas, precipitation played a significant role in increasing drainage water. About 60% and 80% of drainage water occurred due to rainfall in the full irrigation strategy in the first and second year, respectively, and most of the drainage water in VAFI strategy occurred due to precipitation as 90% for both years. Additionally, precipitation during the low growth stages of winter wheat (fall and winter) had noticeable influence on solute transport. On average, 75%, and 65% of leached nitrate, and potassium, respectively, occurred due to rainfall in OFI method; however, about 85% of leached nitrate, and potassium in VAFI strategy occurred due to rainfall events. Application of 150 kg N ha−1 decreased about 40% nitrate leaching below the root zone in comparison with that obtained in 300 kg N ha−1 without significant difference in crop yield. Hydrus-1D model reasonably simulated solute transport especially nitrate and potassium. Therefore, Hydrus-1D could be a successful tool for predicting N, and K transport and making proper management decisions to improving environmental problems. [ABSTRACT FROM AUTHOR]

Evapotrantaspiration is a crucial part of the hydrological cycle but few ground observatories for the Tibetan Plateau exist. In this study, we present lysimeter measurements from the growing season during seven years at a remote field location on the Tibetan Plateau. The measurements show rates between 2.5 and 3 mm·d−1 during the warmer months from June to August, dropping to 2 to 2.5 mm·d−1 in September. This results in a total volume of evapotranspiration of approximately 300 mm·yr−1 for the months from June to September. The inter-daily variability is however large, and comparison to meteorological variables suggest that this is largely driven by radiation and humidity. Data for a single season from a nearby flux tower allows us to compare the two common measurement methods for evapotranspiration in the field, showing an overall good agreement between the approaches. We also tested commonly applied models used to estimate evapotranspiration rates, namely the FAO-Penman-Monteith (PM) and the Priestly-Taylor (PT) model, which both make use of radiation data as well as the simpler Hargreaves-Samani (HS) and Rohwer (R) models which only need air temperature and wind speed as input. The most data intensive model (PM) has the lowest root mean square error (RMSE) (1.36 mm·d−1) and the mean bias error (MBE) (−0.05 mm·d−1) and reproduces the daily variability generally well. The much simpler HS model performs slightly worse (1.38 and 0.35 mm-d−1), but fails to reproduce the variability, due to its lack of information of local radiation and humidity data. Our results are in line with large scale estimates of evapotranspiration for the cold and arid region, provide a first long time series of in-situ measurements from a high elevation site and suggest that both the PM and HS models are appropriate when no direct measurements are available. [ABSTRACT FROM AUTHOR]

Knowledge of the long-term leaching behavior of potentially harmful substances is crucial for the assessment of the environmental compatibility of reusing municipal solid-waste incineration bottom ash (MSWI BA) in construction, i.e., as a road base layer. BA fractions obtained from wet-processing aiming at the improvement of environmental quality were used to investigate the mobility of relevant substances. Eluates from laboratory-scaled leaching procedures (column percolation and lysimeters) were analyzed to learn about the long-term release of substances. Unsaturated conditions and artificial rainwater (AR) were used in the lysimeter tests to simulate field conditions. In addition, batch test eluates were generated at usual liquid-to-solid ratios (L/S) for compliance testing purposes. A variety of cations and anions was measured in the eluates. The wet treatment reduces the leaching of chloride and particularly sulfate by more than 60%. The release of typical contaminants for the treated MSWI BA such as the heavy metals Cu and Cr was well below 1% in the conducted leaching tests. An increase in the Sb concentration observed in the lysimeter experiments starting at L/S 0.75 L/kg and in the column experiment at L/S 4 L/kg is assumed to be related to decreasing concentrations of Ca and thus to the dissolution of sparingly soluble calcium antimonate. The same leaching mechanism applies with V, but the concentration levels observed are less critical regarding relevant limit values. However, on the long term the behavior of Sb could be problematic for the application of MSWI BA in construction. [ABSTRACT FROM AUTHOR]

With regards to European waste catalog, automotive shredder residues (ASR) can be classified both as a hazardous or non-hazardous waste according to its hazardous properties (H1–H14). It is thus important to carry out an adequate chemical-physical characterization to identify the presence and concentration of those substances able to give, to this extremely heterogeneous material, the hazardousness character of. The issue of waste characterization, to identify the proper site for appropriate waste disposal, is based, according to the relevant laws, to the use of leaching tests. The analysis of the potential effects of landfilled waste in laboratory, however, run into several difficulties in reproducing phenomena depending both on the characteristics of small, heterogeneous quantity of waste and on the local boundary conditions. These difficulties are much more significant as the waste is heterogeneous at the small scale of the laboratory. This is one of the main problems often leading to scattered results even when starting from the same waste parcel. Present research aimed to overcome the above-mentioned difficulties deriving from waste heterogeneity and was based on a lysimetric simulation. Experimentation with lysimeter has shown it effectiveness in the comparison between leachate from the lysimeter and an ASR landfill leachate, from which similar distribution of metal mass ratios, close values for both BOD5 and COD, as well as the absence in both the fluids of organochlorinated compounds, emerge. [ABSTRACT FROM AUTHOR]

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The size and chemical composition of leachates migrating into the aquifer are dependent on the parameters of the waste and the storage conditions. Lysimeter studies allow us to determine the size and chemical composition of leachates as well as the leachate water balance. Lysimeter studies were conducted on a 230-L municipal waste sample for 6 months. During the tests, the specific electrolyte conductivity, pH, Eh, and temperature, as well as the chemical composition, microbiological analysis, and profiling of physiological population level using EcoPlate™ microarrays were measured in collected leachate samples. During the entire experiment, the amounts of inflow and outflow from lysimeters were measured. To assess the existence of significant differences in the chemical component concentrations in leachates, use of Principal Component Analysis was taken into account. The maximum EC value from leachate from the lysimeter was 33 mS/cm. High concentrations of ammonium ion (up to approx. 1400 mg dm−3), chlorides (up to approx. 6800 mg dm−3), and iron (up to approx. 31 mg dm−3) were observed in the effluents. The number of enterococci in May reached 53,000 cells/100 ml. By contrast, the number of these microorganisms was about 15,000 and 16,000 CFU/100 ml in January and April, respectively. Community-level physiological profiling indicates that the activity and functional diversity of microorganisms were higher in the leachate samples obtained in winter compared to effluents collected from lysimeters in spring. [ABSTRACT FROM AUTHOR]

Grasslands are thought to be more vulnerable than many other ecosystems to climate change since their soils are characterized by high organic carbon contents and warming in montane regions is twice the global average rate. Despite these expected vulnerabilities, little is known about how climate change and management influence dissolved organic carbon (DOC) losses from montane grasslands and how relevant these losses are compared to other ecosystem carbon fluxes. In this study, 36 large (1 m2, 140 cm height) grassland lysimeters were filled with undisturbed soil monoliths and operated at three different sites located along an elevational gradient from 860 to 600 m a.s.l. From 2012 to 2014, changes in soil DOC concentrations and DOC leaching losses were quantified under different climate, soil and management (intensive vs. extensive; i.e., differing in the frequency of cutting and manuring events) conditions. The annual DOC leaching losses ranged between 6.6 and 27.5 kg C ha−1 year−1, which was only a minor (< 3%) component of the net ecosystem carbon exchange. DOC leaching losses were not affected by management intensity but were positively correlated with soil organic carbon in the top soil. Climate warming (~ + 2 °C) significantly increased DOC leaching rates for intensive (+ 43%) and extensive management (+ 58%), but only if simultaneous reductions in leachate were moderate. The DOC concentrations in soil water significantly decreased with soil depth. In 10, 30 and 50 cm DOC concentration were positively correlated with aboveground biomass production, indicating that plants play a crucial role in topsoil DOC dynamics. However, this relationship did not occur for DOC in soil water collected at 140 cm, suggesting that adsorption and degradation processes in the subsoil ultimately determine the dynamics of DOC losses below the rooting zone. [ABSTRACT FROM AUTHOR]

Evapotranspiration from paddy fields under alternate wetting and drying (AWD) irrigation was measured using lysimeters (ETL) and eddy covariance (ETec) during the late 2016 and early 2017 rice seasons. Four energy balance closing methods were explored, and discrepancy of ETL and ETec (with or without adjustment) in different growth stages and wet/dry conditions were examined. The results indicated that both energy balance non-closure and wet/dry conditions of the field affect the discrepancy of ETL and ETec. Energy balance was suggested to be closed each half hour by 'residual-LE closure' method only at daytime, and nighttime flux stayed unchanged, while a careful data control and interpolation should be noted for nighttime flux. In the meantime, wet-to-dry patterns of AWD irrigation can affect the discrepancy between ETec and ETL. In wet periods, ETec with suitable adjustment method was well matched with the ETL. However, ETL was underestimated in dry periods due to lower water content in the lysimeter. Finally, net radiation (Rn), vapor pressure deficit (VPD), air temperature (Ta), soil and water temperature (Ts and Tw), and wind speed (u) were selected to conduct path analysis on ETL and ETec (with adjustment) for both wet and dry conditions. The direct dependencies of each meteorological factor on ETL and ETec were similar under wet conditions; however, under dry conditions, VPD and Rn are the respective main controls for ETL and ETec. Moreover, ETL is more sensitive to Ta and Tw under wet conditions. [ABSTRACT FROM AUTHOR]

Purpose: Recent research suggests that Swedish organic arable soils have been under-recognized as a potential source of phosphorus (P) loading to water bodies. The aim of this study was to compare P losses through leaching from organic and high-fertility mineral soils. In addition, the effectiveness of a magnesium-salt-coated biochar applied below the topsoil as a mitigation strategy for reducing P losses was evaluated. Materials and methods: Phosphorus leaching was measured from four medium- to high-P arable soils, two Typic Haplosaprists (organic 1 and 2), a Typic Hapludalf (sand), and an unclassified loam textured soil (loam), in a 17-month field study utilizing 90-cm-long lysimeters. A magnesium-salt-coated biochar was produced and characterized using X-ray powder diffraction (XPD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and X-ray adsorption (XANES) spectroscopy, and its phosphate adsorption capacity was determined at laboratory scale. It was also applied as a 3-cm layer, 27 cm below the soil surface of the same lysimeters and examined as a mitigation measure to reduce P leaching. Results and discussion: Total-P loads from the 17-month, unamended lysimeters were in the order of organic 2 (1.2 kg ha−1) > organic 1 (1.0 kg ha−1) > sand (0.3 kg ha−1) > loam (0.2 kg ha−1). Macropore flow, humic matter competition for sorption sites, and fewer sorption sites likely caused higher P losses from the organic soils. Analysis by XRD and SEM revealed magnesium was primarily deposited as periclase (MgO) on the biochar surface but hydrated to brucite (Mg(OH)2) in water. The Langmuir maximum adsorption capacity (Qmax) of the coated biochar was 65.4 mg P g−1. Lysimeters produced mixed results, with a 74% (P < 0.05), 51% (NS), and 30% (NS) reduction in phosphate-P from the organic 1, organic 2, and sand, respectively, while P leaching increased by 230% (NS) from the loam. Conclusions: The findings of this study indicate that P leached from organic arable soils can be greater than from mineral soils, and therefore, these organic soils require further investigation into reducing their P losses. Metal-enriched biochar, applied as an adsorptive layer below the topsoil, has the potential to reduce P losses from medium- to high-P organic soils but appear to be less useful in mineral soils. [ABSTRACT FROM AUTHOR]

An equation of the balance of chemicals is proposed which makes it possible to estimate the changes in their quantity in the soil under a growing stand. When determining the sources of chemicals for forest soils, the measured data of their contents in atmospheric precipitation and estimated inputs of dieback are used. Sinks of elements are calculated from lysimetric data and their accumulation is determined for phytomass increase. Due to the insufficient study of element migration during transpiration, the influence of this process on the balance is evaluated for two options: with and without taking possible losses of chemicals as a result of biogenic evaporation into account. Growth increment and dieback phytomass are estimated differentially for the soil cover and the stand. We have documented the species-averaged contents of certain chemicals accumulating by growing phytomass and returning with dieback in pine and spruce stands and their soil covers. The accumulation of elements in soil cover rises due to precipitation falling through the forest canopy. The greatest increase is obtained in the input of potassium and calcium. Their contribution is the highest in the precipitation flux of all studied chemicals in the soil cover. However, the precipitation of potassium is comparable to its uptake by phytomass. Dieback is the dominant source of silicon, nitrogen, and total phosphorus for the forest soils. The balance model shows that the mature and old-growth stands support the accumulation of nutritional elements in the soils. Losses of silicon might be compensated by its soil storage. [ABSTRACT FROM AUTHOR]

The time required for deep percolating water to reach the water table can be considerable in areas with a thick vadose zone. Sustainable groundwater management, therefore, has to consider the spatial and temporal dynamics of groundwater recharge. The key parameters that control the lag time have been widely examined in soil physics using small-scale lysimeters and modeling studies. However, only a small number of studies have analyzed how deep-percolation rates affect groundwater recharge dynamics over large spatial scales. This study examined how the parameters influencing lag time affect groundwater recharge in a semi-arid catchment under irrigation (in northeastern Iran) using a numerical modeling approach. Flow simulations were performed by the MODFLOW-NWT code with the Vadose-Zone Flow (UZF) Package. Calibration of the groundwater model was based on data from 48 observation wells. Flow simulations showed that lag times vary from 1 to more than 100 months. A sensitivity analysis demonstrated that during drought conditions, the lag time was highly sensitive to the rate of deep percolation. The study illustrated two critical points: (1) the importance of providing estimates of the lag time as a basis for sustainable groundwater management, and (2) lag time not only depends on factors such as soil hydraulic conductivity or vadose zone depth but also depends on the deep-percolation rates and the antecedent soil-moisture condition. Therefore, estimates of the lag time have to be associated with specific percolation rates, in addition to depth to groundwater and soil properties. [ABSTRACT FROM AUTHOR]

Purpose: Dissolved organic matter (DOM), a heterogeneous mixture of low concentrations of organic matter draining from soils, plays a significant role in soil C cycling and in nutrient and pollutant transport. DOM from undisturbed soil profiles has rarely been studied. Hydrophobic acids (Ho) and hydrophilic acids (Hi), the major components of DOM, were recovered, using XAD-8 and XAD-4 resins in series, from waters draining in winter and in spring periods from well-drained and poorly drained Irish grassland soil profiles in lysimeters.Materials and methods: Waters were collected from 45 soil undisturbed lysimeters at the Teagasc Research Centre, Johnstown Castle, Wexford, Ireland. Four Irish representative soils had been collected as undisturbed 1.0-m-deep monoliths, transported to the experiment site and arranged randomly in an experimental facility. Water collections were carried out in winter and spring periods. The DOM was isolated and fractionated using an XAD-8 and XAD-4 resins in-tandem procedure, and hydrophobic acids (Ho) and hydrophilic acids (Hi) were isolated.Results and discussion: The amounts of DOM recovered in the winter period were much greater than those in the spring period, and the soil types had only minor influences on the DOM concentrations recovered. The Ho and Hi fraction contents ranged from 62 to 90 and 10 to 28%, respectively, of the total DOM content extracted. The Hi acids were most enriched in 13C, and considered to reflect greater microbial inputs. The neutral sugar (NS) contents for the Ho and Hi fractions were in the range of 15 to 52 μg mg−1, with the Hi fraction most enriched. The amino acids (AAs) for the Ho and Hi fractions varied from 0.6 to 2.4%, and the total AAs and NS of the Ho acids were well correlated. The DOM fractions from the drainage waters contained much less AAs and NS than the corresponding fractions in the parent soils. The solid- and liquid-state NMR data indicated organic structures with low aromaticity, significant amounts of carbohydrate and with lesser amounts of peptide structures, and with long-chain methylene (CH2)n and methine (-CH-) groups.Conclusions: The application of a variety of wet chemistry and of spectroscopy procedures has given a more in-depth awareness of the compositions of the DOM in the drainage waters from four different soils in 1.0-m-deep lysimeter arrangements. Based on wet chemistry analyses, and FTIR and liquid- and solid-state NMR spectrometry, it is clear that there are some differences between the compositions of the DOM fractions recovered. Alkyl functionalities dominated the structures. These included significant amounts or O-alkyl (predominantly carbohydrate), and with lesser (and variable amounts in the different fractions) aromatic structures (to which aromatic amino acid components were considered to be significant contributors), and with no evidence for lignin-derived structures The results suggest that, during residence in the soil solution, microbiological processes transform the SOM components released into products that are greatly different from their materials of origin in the SOM. [ABSTRACT FROM AUTHOR]

Accurate methods to determine irrigation requirements are necessary for the efficient use of water in agriculture. We conducted measurements of transpiration (T) of one almond tree placed in a large weighing lysimeter and instrumented with sap-flow probes for three seasons (2014-2016; 6-9 years after transplanting). We also conducted independent T estimations by the water balance method in four plots. Transpiration was related to reference evapotranspiration (ETo) to obtain the coefficient of transpiration (KT = T/ETo). Average mid-season KT of the lysimeter tree was 0.55, 0.68 and 0.91 in 2014, 2015, and 2016, respectively, and maximum ground cover (GC) was 55, 59 and 55% for the same years. These KT values standardized by GC were supported by the independent estimations of KT/GC obtained in the plots using the water balance, except in 2016, when a very high KT value was observed in the lysimeter tree. There were significant fluctuations in daily KT during mid-season, which we found to be related to wind speed. Furthermore, the exceptionally high KT/GC relationship of 2016 was apparently related to the very high crop load in the lysimeter of that year (75% more than the 2 other normal years). Hourly bulk canopy conductance values were derived from lysimeter T records to confirm the high transpiration rates prior to harvest during 2016. From the KT values measured here, we propose that the mid-season KT of fully mature almond orchards, with a GC of 75%, should be around—between 0.9 and 1.05. An estimation of evaporation from soil, which is dependent on the method of irrigation, needs to be added to obtain the net water requirements. [ABSTRACT FROM AUTHOR]

Primary tropical rainforests are generally considered to be relatively nitrogen (N) rich, with characteristically large hydrologic and gaseous losses of inorganic N. However, emerging evidence suggests that some tropical ecosystems can exhibit tight N cycling, with low biologically available losses. In this study, we combined isotopic data with a well-characterized watershed N mass balance to close the N budget and characterize gaseous N losses at the ecosystem scale in a lowland tropical rainforest on the Osa Peninsula in southwestern Costa Rica. We measured δ15N and δ18O of nitrate (NO3−) in precipitation, surface, shallow and deep soil lysimeters and stream water biweekly for 1 year. Enrichment of both isotopes indicates that denitrification occurs predominantly as NO3− moves from surface soil down to 15 cm depth or laterally to stream water, with little further processing in deeper soil. Two different isotopic modeling approaches suggested that the gaseous fraction comprises 14 or 32% of total N loss (2.7 or 7.5 kg N ha−1 y−1), though estimates are sensitive to selection of isotopic fractionation values. Gas loss estimates using the mass balance approach (3.2 kg N ha−1 y−1) fall within this range and include N2O losses of 0.9 kg N ha−1 y−1. Overall, gaseous and soluble hydrologic N losses comprise a modest proportion (~ 25%) of the total N inputs to this ecosystem. By contrast, relatively large, episodic hydrologic losses of non-biologically available particulate N balance the majority of N inputs and may contribute to maintaining conservative N cycling in this lowland tropical forest. Similar patterns of N cycling may occur in other tropical forests with similar state factor combinations—high rainfall, steep topography, relatively fertile soils—such as the western arc of the Amazon Basin and much of IndoMalaysia, but this hypothesis remains untested. [ABSTRACT FROM AUTHOR]

World recent concerns about the shortage of water resources and contamination of groundwater supplies have motivated scientists seeking for more efficient techniques in irrigation and fertilization of farms while taking the advantage of models. The objective of this study is to address how water and nitrogen (N) dynamics are affected by efficient management strategies and to evaluate the application of HYDRUS-1D model in these conditions. In terms of using management policies, different irrigation strategies, planting methods, and different N fertilization rates applied on safflower (Carthamus tinctorius L.) in volumetric field lysimeters. The irrigation regimes were ordinary furrow irrigation (OFI) and variable alternate furrow irrigation (VAFI) as a partial root drying (PRD) technique. The planting methods were on-ridge planting (P1) and in-furrow planting (P2) methods. The fertilizer levels were 0 (N0), 100 (N1), and 200 (N2) kg ha−1 of urea as 0, 46, and 92 kg N ha−1. Results showed that VAFI regime and in-furrow planting method favorably reduced the amount of drainage water below safflower root zone in comparison with the ordinary methods. Furthermore, VAFI regime satisfactorily decreased the seasonal nitrate (NO3-N) leaching below the root zone, whereas differences between the leached NO3-N in in-furrow and on-ridge planting methods were not significant. Moreover, VAFI regime did not show any negative effects on total N uptake in safflower seed and straw, whereas in-furrow planting accumulated higher N in comparison with the on-ridge planting method. In addition, safflower nitrogen (N) uptake was responsive to application of nitrogen, although the rate of increase in N accumulation was not significant between the application rates of 46 and 92 kg N ha−1. The soil nitrate concentration decreased during the growing season indicating that safflower root system has a great ability in absorption of NO3-N from soil N supplies. HYDRUS-1D model favorably predicted the drainage water, nitrate concentration of drainage water, crop N uptake, and residual soil NO3-N concentration for safflower field. Therefore, it can be an applicable model for prediction of water and nitrogen dynamics, despite of two-dimensional flow conditions in furrow irrigation. It was concluded that VAFI strategy and in-furrow planting method are suitable alternatives helping farmers produce food while conserving water and preserving the environment. [ABSTRACT FROM AUTHOR]

Aims: Rice is often cultivated in drought-prone regions causing growth inhibition. Therefore, we investigated whether close mixed planting of rice with pearl millet would mitigate these effects.Methods: We used pot and lysimeter to evaluate whether close mixed planting with pearl millet is more effective than single-stand planting in suppressing the growth inhibition of rice (NERICA4) under drought.Results: Close mixed planting only slightly alleviated the growth inhibition of rice under drought in the pot experiment and the first year lysimeter experiment, but mitigated this in the second year lysimeter experiment due to the lower levels of competition. Deuterated water applied from the bottom of the pot and lysimeter was present at a higher concentration in the xylem sap of rice under close mixed planting than under single-stand planting, and this tendency was enhanced by drought. Partitioning of the available water between the two crops was also observed under close mixed planting, with the rice and pearl millet depending on water from the soil surface and deep soil, respectively.Conclusions: Close mixed planting with pearl millet effectively mitigates the growth inhibition of rice under drought due to the increased access to deep water and the partitioning of available water between the two crops. [ABSTRACT FROM AUTHOR]

This study aimed to demonstrate the impact of phosphorus (P) mineral fertilization on topsoil P content and P leaching. We evaluated 83 datasets from 25 years from lysimeter experiments involving different cropping systems (winter crop, summer crop and autumn tillage, harvested grass) or unfertilized fallow, four types of soil texture, and three levels of applied mineral P fertilizer. A positive monotonic and significant correlation was indicated between P in the topsoil determined by the double lactate method ( P ) and the yearly flow-weight total (TP) concentrations in leachates with Spearman rank correlations r ( r > 0.183) and probability ( p) < 0.05. The present German recommended rates of P mineral fertilization are proposed insufficient to protect fresh and marine waters from undesired P pollution and eutrophication. A long-term reduction of excess soil P is urgent along with other measures to mitigate high P inputs to surface and ground waters. [ABSTRACT FROM AUTHOR]

Despite the wide use of trace metals in various technologies, such as chemical industries and electronic equipment, insufficient information is available on their behavior in the environment. We investigated changes in chemical forms and vertical distribution during the migration processes of trace metals, whose usage is currently increasing rapidly, such as Ag, In, Sn, Sb, and Bi, in soil contaminated with the equivalent of 50-100 times the background concentrations of these metals using an indoor control type monolith lysimeter filled with Andosol during an 8-year monitoring period. The vertical distribution of the total elemental concentrations, the mobile fractions (exchangeable, carbonate-bound, and metal-organic complex-bound) in soils, and the total elemental concentrations in soil solutions were analyzed to study trace metal migration in soil. Except for In, most of the added metals were retained in the uppermost (0-2 cm) soil layer, even after 8 years. However, In markedly migrated downward and accumulated at a depth of approximately 15 cm after 8 years. Furthermore, 10.0 ± 2.9 μg L of In was detected in soil solution at a depth of 17.5 cm. The mobility of In was probably caused by the acidity of the soil, because the pH of the soil between 0 and 15-cm depth was 5 and below, and soluble hydro-oxides, such as In(OH)aq and In(OH), might be produced at this pH. Consequently, the remarkable mobility of In occurred in Andosol, which strongly retains various trace metals. The proportions of the mobile fractions observed in this study indicated that the mobility of the five metals in Andosol occurred in the order In > Bi ≥ Sb ≥ Sn > Ag. [ABSTRACT FROM AUTHOR]

Sealing layers made of two alkaline paper mill by-products, fly ash and green liquor dregs, were placed on top of 50-year-old sulfide-containing tailings as a full-scale remediation approach. The performance and effectiveness of the sealing layers with high water content for an oxygen barrier and low hydraulic conductivity for a sealing layer in preventing the formation of acid rock drainage were evaluated 5 years after the remediation. The leaching behavior of the covered tailings was studied using batch leaching tests (L/S ratio 10 L/kg). The leaching results revealed that, in general, the dregs- and ash-covered tailings released relatively lower concentrations of many elements contained in acid rock drainage compared to those from the uncovered tailings. A change in the chemical composition and mineralogical state of the tailings was observed for the tailings beneath the covers. The increase in pH caused by the alkaline materials promoted metal precipitation. Geochemical modeling using PHREEQC confirmed most of the geochemical changes of the covered tailings. Both the ash and dregs showed potential to function as sealing materials in terms of their geochemical properties. However, mobilization of Zn and Ni from the lower part of the dregs-covered tailings was observed. The same phenomenon was observed for the lower part of the ash-covered tailings. Ash showed advantages over dregs as a cover material; based on geochemical studies, the ash immobilized more elements than the dregs did. Lysimeters were installed below the sealing layers, and infiltrating water chemistry and hydrology were studied to monitor the amount and quality of the leachate percolating through. [ABSTRACT FROM AUTHOR]

Background and aims: Nitrogen balances are useful tools to increase our understanding of soil N processes and the efficiency of plants in taking up animal urine-N. This study aimed to investigate the effect of forage type on the fate of autumn-applied urine-N (700 kg N ha). Methods: In a 17-month lysimeter study the recoveries of N in herbage, leachate, nitrous oxide, and soil + roots (at the end of the trial) were determined for three forage types: perennial ryegrass-white clover (RGWC, Lolium perenne L. -Trifolium repens L.), Italian ryegrass (Italian RG, Lolium multiflorum Lam.), and lucerne ( Medicago sativa L.) under simulated autumn grazing. Results: We recovered 81.5-85.5% of the N applied in the urine. Italian RG had the greatest amount of urine-N recovered in the herbage (49.5%) and the least recovered in leachate (16.8%) making it the most efficient of the three forages for utilizing urine-N. For RGWC, herbage and leachate recoveries were 40.1% and 23.7% , respectively. Lucerne was the least efficient with recoveries of N in herbage and leachate equaling 18.4% and 52.5%, respectively. Conclusions: This study demonstrates that Italian ryegrass could offer benefits in reducing urine-N leaching losses through its ability to take up more urine-N over winter. [ABSTRACT FROM AUTHOR]

Sewage sludge is repeatedly applied as fertilizer on farmland due to its high nutrient content. This may lead to a significant increase of silver nanomaterials (AgNM) in soil over years. Therefore, our aim was to investigate the ecotoxicity and fate of AgNM under environmentally relevant conditions in outdoor lysimeters over 25 months. Two AgNM concentrations (1.7 and 8.0 mg/kg dry matter soil) were applied via sewage sludge into soil. In subsamples of the soil, incubated under laboratory conditions for 180 days, the comparability of outdoor and laboratory results regarding ecotoxicity was determined. The results from our long term lysimeter experiments show no detectable horizontal displacement in combination with very low remobilization to the percolate water. Thus, indicate that the sludge applied AgNM remains nearly immobile in the pathway between soils and leachate. However, Ag uptake to the roots of wheat and canola suggests that the chemical conditions in the rhizosphere induce AgNM remobilization from the incorporated sewage sludge even after two harvesting cycles. At the higher AgNM concentration a steady inhibition of the soil microflora was observed over 25 month in the lysimeter study, while there was no effect at the lower AgNM concentration. The results of the laboratory experiment reflect the findings of the lysimeter study and indicate that a risk assessment for AgNM based on data from laboratory tests is acceptable. [ABSTRACT FROM AUTHOR]

This study aimed to quantify the water balance components at a grassland and a forest site representative of the Atlantic Forest biome in southern Brazil using drainage lysimeters. Since it was not possible to place mature trees on the forest lysimeter, it was planted with young trees and understory vegetation. Data from this lysimeter and computations with the water balance and the Penman-Monteith equation were then used to assess the values of the water balance components for the mature forest. Total precipitation during the study period was 2308 mm. In the forest environment, 46% thereof was intercepted by the canopy from where it later evaporated. Hence, much less rain reached the ground than under grassland. Runoff from both sites was <1% of precipitation and therefore not a significant factor in the water balance. Cumulative drainage amounted to 1136 mm from grassland: from the mature forest, it was estimated to be 389 mm. There were two reasons for this low value under forest: Interception prevented a lot of water from reaching the ground, and the actual evapotranspiration from the mature forest was much higher than from grassland (1231 mm compared to 1964 mm). [ABSTRACT FROM AUTHOR]

Background and aims: Irrigated olives are increasingly exposed to conditions of high salinity. Salt tolerance of olives is commonly attributed to ion exclusion. Our objective was to advance understanding of salt stress response of olive roots. Methods: Nine levels of root zone salinity originating from either irrigation water salinity or leaching level were applied to bearing olive cv. Barnea trees grown in large weighing-drainage lysimeters. Minirhizotrons were used to measure count, diameter, length and age (color) of roots while analysis of sampled roots and leaves quantified ion uptake and accumulation. Results: Increased exposure to salinity caused reduction in number and length of roots and increased root turnover. The most drastic effects occurred at the first level of salt gradient. Concentration of Na and Cl was 5-10 times greater in root compared to leaf tissue. The K/Na ratio decreased tenfold as root zone salinity increased in both roots and leaves. Conclusions: Restricted ion transport from roots protected aerial tissue from ion toxicity, but at a high cost as root growth decreased and mortality rate increased. We suggest that the ionic component of salt stress is a prevailing force restricting root growth, life span and development in olives. [ABSTRACT FROM AUTHOR]

The assessment of polluted areas and municipal solid waste (MSW) sites using non-destructive geophysical methods is timely and much needed in the field of environmental monitoring and management. The objectives of this study are (i) to evaluate the ground-penetrating radar (GPR) wave responses as a result of different electrical conductivity (EC) in groundwater and (ii) to conduct MSW stratification using a controlled lysimeter and modeling approach. A GPR wave simulation was carried out using GprMax2D software, and the field test was done on two lysimeters that were filled with sand (Lysimeter-1) and MSW (Lysimeter-2). A Pulse EKKO-Pro GPR system with 200- and 500-MHz center frequency antennae was used to collect GPR field data. Amplitudes of GPR-reflected waves (sub-surface reflectors and water table) were studied under different EC levels injected to the water table. Modeling results revealed that the signal strength of the reflected wave decreases with increasing EC levels and the disappearance of the subsurface reflection and wave amplitude reaching zero at higher EC levels (when EC >0.28 S/m). Further, when the EC level was high, the plume thickness did not have a significant effect on the amplitude of the reflected wave. However, it was also found that reflected signal strength decreases with increasing plume thickness at a given EC level. 2D GPR profile images under wet conditions showed stratification of the waste layers and relative thickness, but it was difficult to resolve the waste layers under dry conditions. These results show that the GPR as a non-destructive method with a relatively larger sample volume can be used to identify highly polluted areas with inorganic contaminants in groundwater and waste stratification. The current methods of MSW dumpsite investigation are tedious, destructive, time consuming, costly, and provide only point-scale measurements. However, further research is needed to verify the results under heterogeneous aquifer conditions and complex dumpsite conditions. [ABSTRACT FROM AUTHOR]

A common irrigation strategy is to replenish the soil water reservoir according to evapotranspiration (ET). However, the ET from plants under deficit irrigation is not well explored and is normally assumed to be a constant fraction of their respective well-watered condition. In the current experiment, we hypothesized that the ratio between the ET of well-watered (WW) and water deficit (WD) grapevines is not constant but depends on the reference ET (ET). The hypothesis was tested using lysimeters over two consecutive seasons to measure the ET of WD grapevines ( Vitis vinifera L.) that were irrigated at 35 % of a second set of lysimeters with WW vines. The WD treatment started at veraison and resulted in a quick depletion of the soil water reservoir; thereafter a relatively stable soil water content ( θ) and crop coefficient (K) were measured. The ET of the WD vines was 20-75 % lower than that of the WW vines, depending on the reference evapotranspiration (ET). Under high ET, the difference between the treatments was much larger than under low ET. The dynamic ratio between the ET of the treatments demonstrates the difficulty in predicting the ET of WD plants and suggests that irrigation according to a constant fraction from a WW plant might result in either excessive or insufficient irrigation amounts. The high correlation between instantaneous stomatal conductance ( g ) measurements and K emphasizes the advantage of utilizing g to improve current irrigation models. [ABSTRACT FROM AUTHOR]

Time regularities of litter fall input are revealed in the investigation of phytocenoses under conditions of stationary soil lysimeters. These regularities correlate well with the dynamics typical of phytocenoses of the Botanical Garden of Moscow State University. The data on litter fall input obtained by sampling with the use of stationary litter fall traps and by the approach of collection of the total year litter fall are highly comparable. The total amount of organic substance and ash elements received with litter fall corresponds to the data given for natural ecosystems. It may be concluded that the functioning of modern phytocenoses under conditions of very restricted volume and area of soil lysimeters is normal. [ABSTRACT FROM AUTHOR]

The use of overhead trellis systems for the production of dry-on-vine (DOV) raisins and table grapes in California is expanding. Studies were conducted from 2006 to 2009 using Thompson Seedless grapevines grown in a weighing lysimeter trained to an overhead arbor trellis and farmed as DOV raisins for the first two years and for use as table grapes thereafter. Maximum canopy coverage for the two lysimeter vines across years was in excess of 80 %. Seasonal (15 March-31 October) evapotranspiration for the lysimeter vines (ET) was 952 mm in 2007 (farmed as DOV raisins) and 943 and 952 mm (when farmed as table grapes). The maximum crop coefficient ( K ) across all 4 years ranged from 1.3 to 1.4. These maximum values were similar to those estimated using the relationship where K is a function of the amount of shaded area measured beneath the canopy at solar noon ( K = 0.017 × percent shaded area). Covering the lysimeter's soil surface with plastic (and then removing it) numerous times during the 2009 growing season (1 June-14 September) reduced ET from an average of 6.4 to 5.6 mm day and the K from 1.07 to 0.93. A seasonal basal K ( K ) was calculated for grapevines using an overhead trellis system with a 13 % reduction in the K across the growing season. [ABSTRACT FROM AUTHOR]

The aim of TERENO (TERrestrial ENvironmental Observatories) is to collect long-term observation data on the hydrosphere, biosphere, pedosphere, lower atmosphere and anthroposphere along multiple spatial and temporal gradients in climate sensitive regions across Germany. The lysimeter-network SOILCan was installed as a part of TERENO between March and December 2010 within the four observatories. It represents a long-term large-scale experiment to study the effects of climate and management changes in terrestrial ecosystems, with particular focus on the impact of these changes on water, energy and matter fluxes into groundwater and atmosphere. SOILCan primarily focuses on soil hydrology, the carbon and nutrient cycle and plant species diversity. Time series measurements of states and fluxes at high spatial and temporal resolution in the soil and biosphere are combined with remote sensing information for the development and calibration of process-based models simulating impacts of climate change in soil processes at field to regional scale. Within the framework of SOILCan, 132 fully automated lysimeter systems were installed at 14 highly equipped experimental field sites across the four TERENO observatories. Relevant state variables of grassland and arable ecosystems are monitored characterizing climate, hydrology and matter fluxes into the atmosphere and within the hydrosphere as well as plant species diversity. Lysimeters are either being operated at or near their original sampling location or were transferred within or between the four TERENO observatories thereby using temperature and rainfall gradients to mimic future climatic conditions (space for time), which allow measuring impacts of climate change on terrestrial ecosystems. The lysimeters are cultivated as grassland (intensive, extensive and non-used) or arable land, the latter with a standardized crop rotation of winter wheat-winter barley-winter rye-oat. This publication describes the general design of the SOILCan experiment including a comprehensive description of the pedological characteristics of the different sites and presents a few exemplary results from the first years of operation. [ABSTRACT FROM AUTHOR]

The objective of this research was to determine the process of atrazine transport compared to bromide and δO transport in sands near Denver. Three 1.5 × 2 × 1.5-m plots were installed and allowed to equilibrate for 2 years before research initiation and were instrumented with 1.5 × 2-m zero-tension pan lysimeters installed at 1.5-m depths. Additionally, each plot was instrumented with suction lysimeters, tensiometers, time domain reflectometry (TDR) moisture probes, and thermocouples (to measure soil temperature) at 15-cm depth increments. All plots were enclosed with a raised frame (of 8-cm height) to prevent surface runoff. During the 2-year period before research began, all suction and pan lysimeters were purged monthly and were sampled for fluids immediately prior to atrazine and KBr application to obtain background concentrations. Atrazine illustrated little movement until after a significant rainfall event, which peaked concentrations at depths of about 90 to 135 cm. Both Br and δO moved rapidly through the soil, probably owing to soil porosity and anion exclusion for Br. Concentrations of atrazine exceeding 5.0 μL were observed with depth (90 to 150 cm) after several months. It appears that significant rainfall events were a key factor in the movement of atrazine in the sand, which allowed the chemicals to move to greater depths and thus avoid generally found biodegradation processes. [ABSTRACT FROM AUTHOR]

Natural abundance nitrate (NO) isotopes represent a powerful tool for assessing denitrification, yet the scale and context dependence of relationships between isotopes and denitrification have received little attention, especially in surface soils. We measured the NO isotope compositions in soil extractions and lysimeter water from a semi-arid meadow and lawn during snowmelt, along with the denitrification potential, bulk O, and a proxy for anaerobic microsites. Denitrification potential varied by three orders of magnitude and the slope of δO/δN in soil-extracted NO from all samples measured 1.04 ± 0.12 ( R = 0.64, p < 0.0001), consistent with fractionation from denitrification. However, δN of extracted NO was often lower than bulk soil δN (by up to 24 ‰), indicative of fractionation during nitrification that was partially overprinted by denitrification. Mean NO isotopes in lysimeter water differed from soil extractions by up to 19 ‰ in δO and 12 ‰ in δN, indicating distinct biogeochemical processing in relatively mobile water versus soil microsites. This implies that NO isotopes in streams, which are predominantly fed by mobile water, do not fully reflect terrestrial soil N cycling. Relationships between potential denitrification and δN of extracted NO showed a strong threshold effect culminating in a null relationship at high denitrification rates. Our observations of (1) competing fractionation from nitrification and denitrification in redox-heterogeneous surface soils, (2) large NO isotopic differences between relatively immobile and mobile water pools, (3) and the spatial dependence of δO/δN relationships suggest caution in using NO isotopes to infer site or watershed-scale patterns in denitrification. [ABSTRACT FROM AUTHOR]

Phosphorus (P) fertilisers have long been applied to sandy soils in south-western Australia to enhance agricultural production. However, significant P leaching is experienced which decreases P availability to crops. The aim of this study was to determine if biochar could be used as a soil amendment to decrease P leaching and increase P uptake by wheat plants. A lysimeter study was designed where two types of biochar, derived either from chicken manure (CM) or wheat chaff (WC) at 0, 1 and 2 % ( w/ w) and three P fertiliser rates at 0, 25 and 50 kg/ha, were applied to a loamy sand soil where wheat ( Triticum aestivum L. var. Wyalkatchem) was grown under glasshouse conditions. Leaching events were conducted over a period of 8 weeks at two weekly intervals. Leachate volume was less in the biochar-amended soil compared to non-amended soil. Biochar increased plant shoot P uptake but also P leaching, which was attributed to P derived from both the applied fertiliser and the biochar. Biochar also increased available P and microbial biomass P in soil, although the extent of increase with WC biochar was less pronounced than for that with CM biochar. Biochar application increased mycorrhizal colonisation in wheat roots which was higher (up to 70 %) at the P application rate of 25 kg/ha but declined with P application rate of 50 kg/ha (to 35 %). Increase in soil pH and mycorrhizal colonisation from biochar application might be contributing to the increase in plant P uptake and shoot growth. However, biochar was not a mitigation strategy to decrease P leaching on these sandy soils. [ABSTRACT FROM AUTHOR]

The soil formation on noncalcareous loam under different phytocenoses in soil lysimeters (Soil Experimental Station of Moscow State University) for 49 years has led to a decrease in acidity and an increase in the content of organic matter, microelements, and heavy metals in the surface soil layer. The rate of microbial CO emission and the microbial biomass content reached the maximum values under the mixed forest stand followed by the broad-leaved forest, then spruce forests, perennial grasses, and fallow. The minimum values of these parameters were characteristic of the black fallow. The percentage of C in the organic carbon content of the soils under the broad-leaved forest was 2.7; in the mixed forest, spruce forest, fallow, and black fallow, it was 1.9, 1.2, 0.9, and 3.3, respectively. The maximum accumulation of heavy metals was recorded in the litter and at the depth of 2-15 cm. The Zn content in the soils under the woody vegetation was 18-20 times higher than in the parent mantle loam; in the soils under perennial grasses and in the plots without plants, it was 14-16 and 5 times higher, respectively. The biogenic accumulation and aerial dust transfer of heavy metals are responsible for the differences in their accumulation between the soils of the model phytocenoses and soils without vegetation. The content of elements in the dust exceeded that in the parent loam by 200-300 times for Zn, 20-40 for lead, 6-60 for nickel, and 20-30 times for strontium and barium. The composition and amount of dust determined the trends in these elements of accumulation in the soils. [ABSTRACT FROM AUTHOR]

The standardized form of the well-known FAO Penman-Monteith equation, published by the Environmental and Water Resources Institute of the American Society of Civil Engineers (ASCE-EWRI), is recommended as a standard procedure for calculating reference evapotranspiration ( ET) and subsequently plant water requirements. Applied and validated under different climatic conditions it generally achieved good results compared to other methods. However, several studies documented deviations between measured and calculated reference evapotranspiration depending on environmental and weather conditions. Therefore, it seems generally advisable to evaluate the model under local environmental conditions. In this study, reference evapotranspiration was determined at a subhumid site in northeastern Austria from 2005 to 2010 using a large weighing lysimeter ( ET). The measured data were compared with ET calculations. Daily values differed slightly during a year, at which ET was generally overestimated at small values, whereas it was rather underestimated when ET was large, which is supported also by other studies. In our case, advection of sensible heat proved to have an impact, but it could not explain the differences exclusively. Obviously, there were also other influences, such as seasonal varying surface resistance or albedo. Generally, the ASCE-EWRI equation for daily time steps performed best at average weather conditions. The outcomes should help to correctly interpret ET data in the region and in similar environments and improve knowledge on the dynamics of influencing factors causing deviations. [ABSTRACT FROM AUTHOR]