Tidal Soil Research Articles

Temporal Variations on Soil Salinity and Cation Displacement at Saemangeum and Yeongsangang Reclaimed Tidal Lands

Soil salinity at reclaimed tidal land in Korea is highly variable and depending on soil characteristics and weather conditions. The objective of this study was to evaluate the temporal changes on soil salinity and the relationships between soil salinity and salinity parameters in reclaimed tidal lands. Soil samples were periodically collected at 0 - 20 cm (surface) and 20 - 40 cm (subsurface) layer at Saemangeum (sandy loam) and Yeongsangang (silty loam) reclaimed tidal land. Electrical conductivity (EC) had a wide range from 0.0 to 34.3 dS·m-1 during the experimental period. The average soil EC was 6.4 and 3.4 dS·m-1 at Saemangeum and Yeongsangang reclaimed tidal land, respectively. Soluble sodium concentration had great variations and it was the most important single factor for temporal variations of soil EC regardless of soil textural properties. Calcium concentration was negatively correlated with soil EC and soluble sodium. Soil exchangeable sodium percentage (ESP) was estimated as a function of soil sodium adsorption ratio (SAR) and a linear regression model (ESP = 6.075 (SAR) + 0.677 for Saemangeum and ESP = 3.925 (SAR) + 0.421 for Yeongsangang reclaimed tidal soil) was suggested for predicting soil ESP from soil SAR. The characteristics of reclaimed tidal lands had different shares of saline and sodic properties during the experimental period. Saemangeum reclaimed tidal soil was highly characterized by sodium, but the effect of sodium on Yeongsangang soil was less pronounced. Our results indicate that persistent monitoring and modeling on soil salinity at reclaimed tidal soil is fundamental and the results can provide some useful information for deciding management plans for diverse utilization or to reduce salt damage for stable crop production at reclaimed tidal land.

Characteristics of a Reclaimed Tidal Soil for Effective Resalization at Saemangum and Youngsan-River

The total area of a reclaimed tidal soil distributed on the south-west coast is approximately 156,600 ha, and the soil contains high contents of sand and silt as well as highly saline. Most of the reclaimed tidal soils are used as a paddy due to bad permeability and high groundwater table, resulting in easy accumulation of salts on the soil surface by capillary rise. Therefore, resalinization may occur because of rise of groundwater table after desalinization. The researches related to the reclaimed tidal soil mainly focused on desalinazation while most of the researches completed were limited to yields of crop based on desalinazation. pH of old reclaimed tidal soil is neutral or less than 7 while that of newly developed reclaimed tidal soils is greater than 7, that cause N-fertilizer to be volatile as ammonia. Thus, the physical and chemical properties should be investigated to be used as an arable upland instead of a paddy soil due to change in government policy. We need to develop measures to make soils grow crops normally by identifying problems related to reclaimed tidal soils.

Understanding to Enhance Efficiency of Nitrogen Uses in a Reclaimed Tidal Soil

In most agricultural soils, ammonium (NH 4 + ) from fertilizer is quickly converted to nitrate (NO 3 - ) by the process of nitrification which is crucial to the efficiency of N fertilizers and their impact on the environment. The salinity significantly affects efficiency of N fertilizer in reclaimed tidal soil, and the soil pH may influence the conversion rate of ammonium to nitrate and ultimately affect nitrogen losses from the soil profile. Several results suggest that pH has important effects on recovery of fall-applied N in the spring if field conditions are favorable for leaching and denitrification except that effects of soil pH are not serious under unfavorable conditions for N loss by these mechanisms. Soil pH, therefore, deserves attention as an important factor in the newly reclaimed tidal soils with applying N. However, fate of N studies in a newly reclaimed tidal soils have been rarely studied, especially under the conditions of saline-sodic and high pH. Therefore, understanding the fate of nitrogen species transformed from urea treated into the reclaimed tidal soil is important for nutrient management and environmental quality. In this article, we reviewed yields of rice and fate of nitrogen with respect to the properties of reclaimed tidal soils.

Nutrient Value and Yield Response of Forage Crop Cultivated in Reclaimed Tidal Land Soil Using Anaerobic Liquid Fertilizer

Nutrient Value and Yield Response of Forage Crop Cultivated in Reclaimed Tidal Land Soil Using Anaerobic Liquid Fertilizer

Response of soil microbial respiration of tidal wetlands in the Yangtze River Estuary to increasing temperature and sea level: A simulative study

Undisturbed natural wetlands are considered carbon sequesters because of their high primary productivity and low soil microbial respiration (SMR). Tidal wetlands in Yangtze River Estuary are typical and impermanent original ecological coastal salt marshes, and their carbon sequestration functions are of great significance to the balance of carbon emissions from Shanghai. Global warming and its associated effects comprise one of the most serious environmental problems humans are currently facing. To analyze changes in the SMR of tidal wetlands in the Yangtze River Estuary in response to global warming and the associated increase in sea level, a simulation study was conducted in the laboratory. The results show that when organic input is limited, increasing temperature can lead to an initial sharp increase in SMR, but that the SMR reverts to its original level with time even becomes lower. Overall, increasing the temperature does not have a significant effect on SMR because organic input is limited under these conditions. Increasing sea level can accelerate SMR and β-glucosidase activity, but this effect is not significant. This may occur because more nutrients are input by the tide, which facilitates SMR by attenuating the disadvantage associated with the anaerobic environment caused by prolonged water logging. However, synergistic effect of increased temperature and sea level lead to an obvious acceleration in SMR and β-glucosidase activity. In tidal soil in which the soil nutrient levels are low, organic matter input is found to be the dominant factor affecting SMR and microbial activity.

Natural Ripening versus Artificial Enhancing of Silty Reclaimed Tidal Soils for Upland Cropping Tested by Profile Characterization

This study was performed to produce basic data for silty reclaimed tidal lands and to develop techniques of environmentally-friendly utilization in agricultural system. We chose the two sites in Saemangeum reclaimed tidal lands, one (Site I) has been treated with cultivating green manure and conducting the desalinization process through submergence since April, 2007 and the other (Site II) has been under natural condition without artificial treatment. In situ and ex situ physic-chemical properties were determined and comparisons were made for soil profiles examined at these two sites in April 2009. Surface soil of Site I had lower EC and higher field saturated hydraulic conductivity than those of Site II, uncultivated land. Especially, exchangeable sodium content was lowest in Site I Ap1 layer than in other layers. This is probably due to flooding desalination and green manure cultivation. Besides, Ap1 and A2 layers of soil profile in Site I showed brighter soil color and more root observation than those of Site II. This is probably due to green manure cultivation. By the large, for high cash upland crops and intensive agricultural use of silty reclaimed tidal land, site-specific soil ripening such as flooding desalination and green manure cultivation could be useful.

간척지 토양환경 조건별 토양내 질소 동태와 영향 요소

In most agricultural soils, ammonium () from fertilizer is quickly converted to nitrate () by the process of nitrification which is crucial to the efficiency of N fertilizers and their impact on the environment. However, nitrification studies have been studied extensively in agricultural soils, not in a newly reclaimed tidal soil which show saline-sodic and high pH. Therefore, understanding the fate of nitrogen species transformed from urea introduced into reclaimed tidal soil is important for nutrient management and environmental quality. This paper reviewed studies regarding to transformation and fate of nitrogen sources such as urea under the circumstances of a reclaimed tidal soils located in a western coastal area.

Properties and fate of nitrogen in a reclaimed tidal soil

In this article, we reviewed properties of reclaimed tidal soil and fate of nitrogen in its soil. The results were summarized as followings. Most of the soil derived from the fluvio-marine deposit were silly textured soils. The EC of the Saemanguem soil were ranged from 14.7 to 33.9 dS m?¹, pH was 7.7. The organic matter content was low with 1.5 g ㎏?¹. The cation exchange capacity was 7.2 c㏖ ㎏?¹ and exchangeable sodium percent was high with range 45.1 % to 56.2%. High sodium concentration caused poor drainage. The salinity significantly affects efficiency of N fertilizer in reclaimed tidal soil.

Effect of Soil Water Contents on Urea Hydrolysis and Nitrification in a Newly Reclaimed Tidal Soils

The effect of soil water content on the transformation potential of N compounds derived from hydrolysis of urea applied in a reclaimed tidal soils which was saline-sodic was observed to evaluate nitrification rates of urea. Soil samples were collected from Moonpo series at the newly reclaimed area in Saemanguem. For the transformation potential of N compounds from urea (46% N), newly reclaimed tidal soils (RS) were amended with urea at the rates of 0, 10, and 20 kg 10a -1 . With leachate obtained from the incubated RS in a leaching tube at 25°C, urea hydrolysis and nitrification were measured for a total of 30days. The cumulative amounts of NO3 - -N in each of the four soils treated with urea was linear with time of incubation. Results showed that increase in pH occurred with increasing application rate of urea and volumetric water content due to hydrolysis of urea. The total N in the RS was decreased with incubation time, indicating that rates of urea hydrolysis was influenced by soil moisture conditions. Also, the cumulative amount of nitrate in RS gradually increased with increase in time of incubation.

Characterization of Kinetics of Urea Hydrolysis in A Newly Reclaimed Tidal Soils

It is imperative to study the hydrolysis of urea in high saline-sodic condition of a newly reclaimed tidal land in order to overcome the problems associated with use of urea fertilizer. The methodology adopted in this study tried to get a convenient way of estimating rate for N transformation needed in N fate and transport studies by reviewing pH and salt contents which can affect the microbial activity which is closely related to the rate of urea hydrolysis. The hydrolysis of urea over time follows first-order kinetics and soil urease activity in reclaimed soils will be represented by Michaelis-Menten-type kinetics. However, high pH and less microorganisms may delay the hydrolysis of urea due to decrease in urease activity with increasing pH. Therefore, the rate of urea hydrolysis should adopt V max referring enzyme activity (E 0 ) accounting for urease concentration which is indicative for urea hydrolysis, especially in a high saline and sodic soils.

온실기체 (CH4, CO2, N2O)의 하구언갯벌 배출량과 배출특성연구

A closed flux chamber system was used for measuring major greenhouse gas (GHG) emission from tideland and/or wetland soils in estuarine area at Saemankum, Kunsan in southwestern Korea during from months of February to June 2006. Hourly averaged GHG soil emissions were measured two to three times a day during the ebb tide hours only. Site soils were analyzed for soil parameters (temperature, pH, total organic contents, N and C contents in soil) in the laboratory. Soil GHG fluxes were calculated based on the GHG concentration rate of change measured inside a closed chamber The analysis of GHG was conducted by using a Gas Chromatography (equipped with ECD/FID) at laboratory. Changes of daily, monthly GHGs' fluxes were examined. The relationships between the GHG emissions and soil chemical contents were also scrutinized with respect to gas production and consumption mechanism in the soil. Soil pH was pH <TEX>$7.47{\pm}0.49$</TEX> in average over the experimental period. Organic matter contents in sample soil was <TEX>$6.64{\pm}4.98\;g/kg$</TEX>, and it shows relatively lower contents than those in agricultural soils in Kunsan area. Resulting from the soil chemistry data, soil nitrogen contents seem to affect GHG emission from the tidal land surface. The tidal soil was found to be either source or sink for the major GHG during the experimental periods. The annual average of <TEX>$CH_{4}\;and\;CO_{2}$</TEX> fluxes were <TEX>$0.13{\pm}0.86\;mg\;m^{-2}h^{-1}\;and\;5.83{\pm}138.73\;mg\;m^{-2}h^{-1}$</TEX>, respectively, which will be as a source of these gases. However, <TEX>$N_{2}O$</TEX> emission showed in negative flux, and the value was <TEX>$-0.02{\pm}0.66\;mg\;m^{-2}h^{-1}$</TEX>, and it implies tidal land surface act as a sink of <TEX>$N_{2}O$</TEX>. Over the experimental period, the absolute values of gas fluxes increased with soil temperature in general. Averages of the ambient gas concentration were <TEX>$86.8{\pm}6.\;ppm$</TEX> in <TEX>$CO_{2},\;1.63{\pm}0.34\;ppm\;in\;CH_{4},\;and\;0.59{\pm}0.15\;ppm\;in\;N_{2}O$</TEX>, respectively. Generally, under the presence of gas emission from agricultural soils, decrease of gas emission will be observed as increase in ambient gas concentration. We, however, could not found significant correlation between the ambient concentrations and their emissions over the experimental period. There was no GHG compensation points existed in tide flat soil.

Natural radionuclides in tidal saltmarsh soils in South Australia—An unusual distribution?

Sediments collected from tidal saltmarsh areas in South Australia have been analysed for natural radionuclides from the uranium and thorium decay series. The concentrations observed indicate a significant enhancement of some nuclides in comparison to inland soils, consistent with the recent incorporation of uranium, thorium and actinium into the sediments. The probable source of the nuclides is sea-water. It has been experimentally established that the organic residues from the decay of vegetable matter play a major role in this process.

Sea-Water as the Primary Source of Sulphate in Tidal Swamp Soils from Sierra Leone

ONE of the main features of the chemical composition of the black glutinous muds of relatively high organic content in the Sierra Leone River Estuary is their high content of sulphide. Work carried out by the Rice Research Station at Rokupr on the Scarcies River, some 30 miles north of the Sierra Leone River estuary, suggests that the principal source of oxidizable sulphur in these estuarine soils is iron disulphide, or possibly some other polysulphide1. The presence of sulphide in marine muds has been ascribed by various authors to a number of causes. It may be produced by the way of bacterial decomposition of organic matter containing sulphur. On the other hand, it is known that certain bacteria in the presence of organic material can reduce sulphates to sulphides; this reaction probably accounts for the presence of ferrous sulphide in marine muds in many parts of the world.