Large Lysimeters Research Articles

Quantifying the impacts of varying groundwater table depths on cotton evapotranspiration, yield, water use efficiency, and root zone salinity using lysimeters

Determining the evapotranspiration (ET) of cotton as a water-intensive crop is crucial for effective irrigation planning and water management, especially in regions like Sindh province, Pakistan, where shallow groundwater table depths (WTDs) are prevalent. Despite the importance of cotton, a major cash crop in Sindh, previous studies on ET were conducted decades ago and may no longer be reliable due to ongoing climate change and the introduction of new crop varieties. Thus, we quantified cotton ET across two cropping seasons and at various WTDs (0.45, 0.60, 0.75, 1.50, 2.25, and 2.75 m). The experimental study was based on the data procured from 12 mini lysimeters and 12 large lysimeters for two years (2018 and 2019) and at two soil series. The findings revealed that cotton ET ranged from 1332 to 1437, 1114–1202, 988–1075, 781–821, 690–733, and 637–683 mm at WTDs of 0.45, 0.60, 0.75, 1.50, 2.25, and 2.75 m, respectively. WTDs from 0.45 to 0.75 m fulfilled 94–96 % of cotton ET through groundwater (GW) contribution in Sultanpur soil (silt loam) and 93–97 % in Miani soil (silty clay loam). At 1.50–2.75 m WTDs, irrigation water requirements (excluding rainfall and leaching) were 63–88 % in Sultanpur soil and 67–89 % in Miani soil. The highest yield was observed at a 1.50 m WTD, while the highest water use efficiency was identified at a 2.25 m WTD. However, soil salinity increased by 60–80 %, resulting in a 40–60 % lower cotton yield at 0.45–0.75 m WTD. Therefore, periodic flushing of salts is necessary to utilize shallow WTDs effectively. Considering GW contribution to ET when allocating water for irrigation channels and devising irrigation schedules is crucial. This approach can lead to water savings, prevent land from becoming waterlogged and saline, manage the groundwater table, and reduce the need for drainage channels and labor force for their preparation.

Cadmium, zinc, and copper leaching rates determined in large monolith lysimeters

Soil mass balances are used to assess the risk of trace metals that are inadvertently applied with fertilizers into agroecosystems. The accuracy of such balances is limited by leaching rates, as they are difficult to measure. Here, we used monolith lysimeters to precisely determine Cd, Cu, and Zn leaching rates in 2021 and 2022. The large lysimeters (n = 12, 1 m diameter, 1.35 m depth) included one soil type (cambisol, weakly acidic) and distinct cropping systems with three experimental replicates. Stable isotope tracers were applied to determine the direct transfer of these trace metals from the soil surface into the seepage water. The annual leaching rates ranged from 0.04 to 0.30 for Cd, 2.65 to 11.7 for Cu, and 7.27 to 39.0 g (ha a)−1 for Zn. These leaching rates were up to four times higher in the year with several heavy rain periods compared to the dry year. Monthly resolved data revealed that distinct climatic conditions in combination with crop development have a strong impact on trace metal leaching rates. In contrast, fertilization strategy (e.g., conventional vs. organic) had a minor effect on leaching rates. Trace metal leaching rates were up to 10 times smaller than fertilizer inputs and had therefore a minor impact on soil mass balances. This was further confirmed with isotope source tracing that showed that only small fractions of Cd, Cu, and Zn were directly transferred from the soil surface to the leached seepage water within two years (< 0.07 %). A comparison with models that predict Cd leaching rates in the EU suggests that the models overestimate the Cd soil output with seepage water. Hence, monolith lysimeters can help to refine leaching models and thereby also soil mass balances that are used to assess the risk of trace metals inputs with fertilizers.

Potassium deficiency reduces grapevine transpiration through decreased leaf area and stomatal conductance

Plants require potassium (K) to support growth and regulate hydraulics. Yet, K's effects on transpiration are still speculated. We hypothesized that K deficiency would limit grapevine water uptake by limiting canopy size and stomatal conductance (gs). Hence, we constructed large (2 m3) lysimeters and recorded vine transpiration for three years (2020–2022) under three fertilization application rates (8, 20, or 58 mg K L−1 in irrigation).Maximal K availability supported transpiration up to 75 L day−1, whereas K-deficient vines transpired only 60 L day−1 in midsummer. Limited vine growth and canopy size mainly accounted for reduced transpiration under low K conditions. Hence, considering K demand in addition to supply, we compared K deficiency effects on vines bearing 20 or 50 fruit clusters and found that reduced gs further limited transpiration when yields were high. Although fruits were strong K sinks, high yields did not alter K uptake because lower vegetative growth countered the additional K demands.Potassium deficiency leads to lower transpiration and productivity. Yet, internal mineral allocation compensates for fruit K uptake and masks biochemical indices or physiological proxies for K deficiency. Thus, decision support tools should integrate mineral availability, seasonal growth, and yield projections to determine grapevine water demands.

Earthworms do not increase greenhouse gas emissions (CO2 and N2O) in an ecotron experiment simulating a three-crop rotation system

Earthworms are known to stimulate soil greenhouse gas (GHG) emissions, but the majority of previous studies have used simplified model systems or lacked continuous high-frequency measurements. To address this, we conducted a 2-year study using large lysimeters (5 m2 area and 1.5 m soil depth) in an ecotron facility, continuously measuring ecosystem-level CO2, N2O, and H2O fluxes. We investigated the impact of endogeic and anecic earthworms on GHG emissions and ecosystem water use efficiency (WUE) in a simulated agricultural setting. Although we observed transient stimulations of carbon fluxes in the presence of earthworms, cumulative fluxes over the study indicated no significant increase in CO2 emissions. Endogeic earthworms reduced N2O emissions during the wheat culture (− 44.6%), but this effect was not sustained throughout the experiment. No consistent effects on ecosystem evapotranspiration or WUE were found. Our study suggests that earthworms do not significantly contribute to GHG emissions over a two-year period in experimental conditions that mimic an agricultural setting. These findings highlight the need for realistic experiments and continuous GHG measurements.

Comparison of water-saving potential of fallow and crop change with high water-use winter-wheat – summer-maize rotation

A land fallow system (LFS) designed to adjust the winter-wheat summer-maize cropping system to fallow summer-maize was introduced in Hebei Province to alleviate groundwater depletion in the region. However, some of the water saved was lost through evaporation from bare soil and transpiration by weeds. So far, no measurement has been done in the region to address this non-productive water loss, thereby limiting the water-saving potential of the introduced LFS. Furthermore, the reduction in crop production under the summer-maize – fallow system threatens food security. The objective of this study was to determine which practice is effective to keep soil water during fallow and the exact water-saving potential of different cropping system in the region. Firstly, field experiments were conducted under various soil surface management systems — including plastic mulching (PM), straw mulching (SM), shallow tillage (ST) and weed control (WC). The effects of saving water, controlling weeds and managing nutrients were analyzed under the various surface soil management methods. The results showed that compared with the control (no soil surface management, CK), 177, 64.7, 71.0 and 25.0 mm of water was saved respectively under PM, SM, WC and ST surface soil management methods in 2019–2020. The effect of weed control decreased in the order of PM > WC > SM > ST. While PM significantly increased soil nutrient in all the treatments, the others showed slight but insignificant increases. Secondly, the precise water-use of each of the cropping systems was determined using large lysimeters. The analysis showed that compared with the wheat-maize system, 60–100 mm of water was saved under alternating wheat-soybean, wheat-millet, mung bean – fresh edible maize, spring sweet potato cropping systems. The results were key for technical guide in developing future cultivation adjustment policies.

Groundwater Depth and Nitrogen Application Amount Jointly Regulate the Water and Residual Soil Nitrate Accumulation in Agricultural Soil Profile

Despite the known influence of groundwater conditions and nitrogen application on crop growth and the soil microenvironment, less information is available on the influence of groundwater depth and nitrogen application amount on the movement and accumulation of soil water and residual nitrate in deep soil in summer maize–winter wheat rotation systems. Therefore, a large lysimeter experiment was conducted to examine how groundwater depth and nitrogen application amount influence the transport and accumulation of soil water and nitrate in the summer maize (Zea mays L.)–winter wheat (Triticum aestivum L.) rotation system. The results showed that nitrogen reduction increased soil water storage both in the summer maize and winter wheat fields. The residual soil nitrate accumulation in the entire soil profile of summer maize and winter wheat under deeper groundwater depth treatment was higher than that of shallow groundwater depth treatment. Hence, the deeper the groundwater depth, the longer the nitrate transport path, and the nitrate that would have entered the groundwater accumulates in deep soil. The residual soil nitrate accumulation in the whole soil profile of winter wheat was 76.05–130.11 kg ha−1 higher than that of summer maize. Structural equation models (SEMs) showed that the nitrogen application amount not only exhibited a directly positive effect on the residual soil nitrate accumulation but also indirectly influenced it by regulating total soil nitrogen; groundwater depth only exhibited a directly negative effect on residual soil nitrate accumulation; and soil depth had an indirect positive effect on residual soil nitrate accumulation through the regulation of soil water storage. Together, our findings prove that groundwater depth and nitrogen application amount jointly regulate the residual soil nitrate accumulation in agricultural soil rotated with winter wheat and summer maize. Therefore, in formulating a fertilization strategy for regional agricultural green development, it is necessary to consider the fertilizer application amount rate and the groundwater depth.

Phloem water isotopically different to xylem water: Potential causes and implications for ecohydrological tracing

AbstractThe stable isotopes of hydrogen and oxygen in xylem water are often used to investigate tree water sources. But this traditional approach does not acknowledge the contribution of water stored in the phloem to transpiration and how this may affect xylem water and source water interpretations. Additionally, there is a prevailing assumption that there is no isotope fractionation during tree water transport. Here, we systematically sampled xylem and phloem water at daily and subdaily resolutions in a large lysimeter planted with Salix viminalis. Stem diurnal change in phloem water storage and transpiration rates were also measured. Our results show that phloem water is significantly less enriched in heavy isotopes than xylem water. At subdaily resolution, we observed a larger isotopic difference between xylem and phloem during phloem water refilling and under periods of tree water deficit. These findings contrast with the expectation of heavy‐isotope enriched water in phloem due to downward transport of enriched leaf water isotopic signatures. Because of previous evidence of aquaporin mediated phloem and xylem water transport and higher osmotic permeability of lighter hydrogen isotopologues across aquaporins, we propose that radial water transport across the xylem–phloem boundary may drive the relative depletion of heavy isotopes in phloem and their relative enrichment in xylem.

Irrigation and grazing management affect leaching losses and soil nitrogen balance of lucerne

Intensification of agricultural management practices, including irrigation and addition of nitrogen (N) fertilizers, can lead to enhanced N leaching and loss of soil fertility. In New Zealand, expansion of the dairy industry has rapidly increased irrigated land area, particularly on shallow, stony soils of the Canterbury region that are prone to leaching, leading to degradation of surface- and ground-water quality and losses of soil N and carbon (C). In this study, we measure components of N balance for two adjacent fields of lucerne (Medicago sativa L., alfalfa) harvested for cut-and-carry feed and grazed in situ. One field was non-irrigated and one irrigated with both water and dairy effluent. Inputs from N fixation associated with the legume crop were quantified using a natural abundance isotopic approach. Drainage from the root zone and leaching were measured with 6 large lysimeters in each field. Leaching losses from non-irrigated lucerne were 7–30 kg N ha-1 y-1 with the largest losses occurring in a year with primarily grazing management. Losses from irrigated lucerne were 39–102 kg N ha-1 y-1, with the largest losses resulting from summer drainage events exacerbated by irrigation. Fixation of N was the largest input to both systems, contributing 192–257 kg N ha-1 y-1 for non-irrigated lucerne. Under irrigation, biomass production increased, but N uptake from effluent and soil stocks contributed to biomass N to a greater extent and fixation was 262–286 kg N ha-1 y-1. Management influenced N balance through inputs from animal excreta and effluent additions and exports through harvest and grazing removals. Management practices which reduce N losses from the soil are needed to minimize environmental impacts and protect soil fertility.

Artificial soils for urban greening

This study presents new data on structural and hydraulic characteristics of artificially-layered soils and their dynamics in urban environment. Full-profile soils in large lysimeters and short-profile soils at the experimental plots of Moscow University Soil Station were studied. Short-term changes and long-term evolution of soil matrix and soil hydraulic properties are discussed.

Balance Assessment of Carbon Dioxide Dynamics in the Soil of MSU Large Lysimeters

Balance Assessment of Carbon Dioxide Dynamics in the Soil of MSU Large Lysimeters

Influence of Plant Cover on Hydrothermal Conditions in Soils of Large Lysimeters of the MSU Soil Station: Results of a 60-year Experiment

Influence of Plant Cover on Hydrothermal Conditions in Soils of Large Lysimeters of the MSU Soil Station: Results of a 60-year Experiment

Features of Biogeochemical Processes of Soils in Urban Conditions Based on the Study of Ecosystems of Large Lysimeters of the Soil Stationary of MSU

Features of Biogeochemical Processes of Soils in Urban Conditions Based on the Study of Ecosystems of Large Lysimeters of the Soil Stationary of MSU

Long-Term Research on Physical Properties of Soils in the MSU Large Lysimeters: Main Results for the First 60 Years (1961–2021)

Long-Term Research on Physical Properties of Soils in the MSU Large Lysimeters: Main Results for the First 60 Years (1961–2021)

The San Dimas experimental forest: Hydrologic research in semiarid steepland terrain

AbstractThe San Dimas Experimental Forest (SDEF) is located in southern California and is representative of the chaparral shrublands of the Southwest USA. Chaparral – including genera of Ceanothus, Adenostoma, Quercus, Salvia and Arctostaphylos – is a dense, drought‐tolerant vegetation assemblage with a closed canopy 3–5 m in height. Chaparral is a fire‐prone ecosystem and wildfires have burned the SDEF about every 40 years. The SDEF was established in 1933 to quantify the water cycle in a steep, semiarid landscape. Study catchments range in size from 15 to 1160 ha and measurements of stream runoff are made in a nested weir and flume arrangement to account for the very flashy flows. Apart from native chaparral vegetation, streamflow measurements in these study watersheds have also quantified the hydrologic response of vegetation type‐conversion and fire. Innovations in hydrologic monitoring developed on the SDEF include a critical depth flume (the San Dimas flume) and tilted rain gages to better sample precipitation in mountainous terrain. Subsurface runoff and plant water relations have been measured in a large lysimeter complex. Water quality monitoring shows that stream water in the SDEF has very high levels of nitrate, derived from atmospheric deposition of chronic air pollution, that approach the Federal EPA standard of 10.0 mg L−1 for nitrate‐N. Spreadsheets of rainfall and streamflow (from 1938 to 2015) – the San Dimas Experimental Forest hydrologic database – may be found at the right‐hand side of the web page at https://www.fs.fed.us/psw/ef/san_dimas/index.shtml. Hard copy charts, tables and other records associated with the foregoing data streams are available from the USDA Forest Service, Pacific Southwest Research Station, 4955 Canyon Crest Drive, Riverside, California, 92501 USA or at pete.wohlgemuth@usda.gov.

Does actual cropland water consumption change with evaporation potential in the Lower Yellow River?

The North China Plain (NCP) is one of the most important regions for food production in China; however, the typical winter wheat–summer maize cropping system has created a continuous decline in groundwater levels, triggering serious ecological problems. Additionally, changes in the evaporation potential in the NCP have altered from decreasing to sharply increasing. Therefore, it is critical to understand the actual cropland water consumption (i.e., the actual evapotranspiration, AET) and crop water use efficiency (WUE) under this new trend. This understanding is significant for agricultural water management in the NCP. This study investigated the historical AET and WUE trends for the winter wheat–summer maize cropping system during 1992–2014. This investigation was based on a long-term AET dataset obtained using a large lysimeter from 1992 to 2014 at the Yucheng Comprehensive Experiment Station of the Chinese Academy of Sciences near the Lower Yellow River. The results showed that annual AET decreased pre-2008 and rebounded post-2008. The rebound rate of annual AET from 2008 to 2014 was more than three times the annual decrease rate of AET from 1992 to 2008. The significant increase in summer maize AET mainly contributed to the rebound of the annual AET after 2008. Following the changes in AET and crop yield, the annual WUE had evidently increased for 1992–2008 and sharply decreased from 2008 to 2014. The significant decrease in winter wheat WUE mainly contributed to the annual decrease in WUE post-2008. Climate change, agricultural management, and crop yields were observed to regulate the changes in AET and WUE. In the context of accelerating climate change and the increased frequency of extreme climatic events, strategies to improve WUE by the Lower Yellow River have been proposed, which may also be helpful in the NCP and similar regions worldwide.

Evaluation of sensitivity and setting of the MACRO 5.2. model on direct lysimeter studies of leachate

The water assembly of the MACRO model, making allowance regarding the double porosity of soils, was parameterized according to experimental laboratory data and tested according to the results of studying the water regime of sod-podzolic middle loamy soils of large lysimeters of MSU. Testing of pesticide migration models is necessary to improve forecast accuracy and justify their use. The analysis of the sensitivity, estimated from the data on the lysimetric runoff at the lower point (1.5 m) of the soil, showed that the WRC parameters are the main physical support of the models, which sets the forecast accuracy. These are the parameters that must be used to customize the model. The MACRO model has showed itself better at describing lysimetric runoff during the growing season by taking into account the fast flows along macropores and fissures that occur during periods of intense precipitation in the model than the models previously used.

Innovative method for installing soil moisture probes in a large‐scale undisturbed gravel lysimeter

AbstractAquifers of coarse gravel are an important source for drinking water; however, coarse sediments are also particularly susceptible to the rapid and long‐range transport of pollutants through the vadose zone. Therefore, understanding the flow and solute transport in unsaturated gravel material is of utmost importance for the protection of drinking water resources. Experimental investigations of flow and transport processes are dependent on suitable sensor technology, but it is a considerable challenge to install soil moisture sensors in gravelly material. In this note, we developed a novel method to install soil moisture sensors with minimal disturbance in a large lysimeter with undisturbed gravelly sedimentary material, based on drilling access cavities in frozen material. We investigated whether it is possible to obtain reliable soil moisture measurements and found that the probes measured the flow dynamics pattern well but could not quantify realistic absolute water content values.

Depression of Groundwater Table and Reduced Nitrogen Application Jointly Regulate the Bacterial Composition of nirS-Type and nirK-Type Genes in Agricultural Soil

Despite the known influence of nitrogen fertilization and groundwater conditions on soil microbial communities, the effects of their interactions on bacterial composition of denitrifier communities have been rarely quantified. Therefore, a large lysimeter experiment was conducted to examine how and to what extent groundwater table changes and reduced nitrogen application would influence the bacterial composition of nirK-type and nirS-type genes. The bacterial composition of nirK-type and nirS-type genes were compared at two levels of N input and three groundwater table levels. Our results demonstrated that depression of groundwater table, reduced nitrogen application and their interactions would lead to drastic shifts in the bacterial composition of nirS-type and nirK-type genes. Structural equation models (SEMs) indicated that depression of groundwater table and reduced nitrogen application not only directly altered the species composition of denitrifier bacterial communities, but also indirectly influenced them through regulating soil nutrient and salinity. Furthermore, the variation in soil NO3−–N and electrical conductivity caused by depression of groundwater table and reduced nitrogen application played the most important role in altering the community composition of denitrifier bacterial communities. Together, our findings provide first-hand evidence that depression of groundwater table and reduced nitrogen application jointly regulate the species composition of denitrifier bacterial communities in agricultural soil. We highlight that local environmental conditions such as groundwater table and soil attributes should be taken into account to enrich our knowledge of the impact of nitrogen fertilization on soil denitrifier bacterial communities, or even biogeochemical cycles.

Phosphorus transport in subsurface flow from a stony soil under irrigated and non-irrigated lucerne

ABSTRACT The extent of phosphorus (P) loss from soils under deep rooting crops such as lucerne is currently unknown. This study used large lysimeters (2.0 by 1.5 m) to quantify the amounts and forms of P in drainage under lucerne from two sites, a non-irrigated dairy system and an irrigated dairy system that also received farm dairy effluent (FDE). Results showed despite greater P inputs to the irrigated compared to the non-irrigated site, there was no difference in total P concentrations in drainage. There were also no differences in the forms of P lost between sites, which were dominated by particulate P (48%–52%). More P was lost from the irrigated (0.262 kg ha−1) than the non-irrigated site (0.164 kg ha−1). The larger P loss was a result of irrigation producing more drainage (42%) than observed at the non-irrigated site. The amount and forms of P lost from lucerne were similar or lower than losses reported for similar soils under grass/legume-based pasture swards amended with P fertiliser and FDE. Because P leaching was regulated by drainage volume rather than P input, management of irrigation water to reduce drainage from the root zone will likely help minimise P leaching.

Adequateness assessement of percolate and temperature model using MSU Large lysimeters

The assessement of PEARL model adequateness was carried out on the basis of temperature and percolate data obtained by means of MSU Large Lysimeters. Lysimeters are used in experimental soil science mostly for investigating water balance and substance or ions transport from observed horizons or full soil profile. PEARL 4 model, the water prediction block of which is built on the basis of classical SWAP model, uses preferential water flow describing mechanism. Systematical observation of experimental soils in MSU Large lysimeters allowed obtaining extensive data on temperature and soil moisture dynamics, as well as percolate from bottom border. Thеsе measurements are unique and can become the basis for adaptation, verification and setting of mass and energy transfer models. It was shown, that mathematical parametric model requires adjustment for reaching reliable values of percolate from bottom border, moisture and temperature profiles. It can be achieved by selection of water retention curve (WTC) approximation parameters. It was noticed that the error for all predicted parameters increases in winter period. Thereby, the use of such matter transfer models in soil are problematic for long-term prognosis. For example, due to the annual error accumulation before the spring season such models cannot be applied for estimation of the risk of ground water pollution with agrochemicals.