Coastal Saline Soil Research Articles

Response of Daylily (Hemerocallis hybridus cv. ‘Stella de oro’) to saline water irrigation in two coastal saline soils

In order to evaluate the effects of irrigation water salinity, applied by drip irrigation, on Daylily (Hemerocallis hybridus cv. ‘Stella de oro’) growth and soil salinity, a three-year experiment was conducted in coastal saline region in Caofeidian District East China during 2013–2015 in two soils (sandy loam and silt). Five water salinity treatments were used with saline water at electrical conductivity (ECiw) of 0.8, 3.1, 4.7, 6.3, and 7.8 dS/m. The original soil salinity expressed as electrical conductivity of the saturation paste extract (ECe) was 27–30dS/m in the 0–95cm depth. Results showed that drip-irrigation was effective in salt leaching. The average values of soil ECe for five treatments were 1–4 and 2–6 dS/m in 0–35cm soil profiles of sandy loam and silt soils, respectively, after 18 months with drip irrigation. In 2014–2015, the survival rates were all >93% when irrigated with saline water at <7.8dS/m for both saline soils. The survival rate and dry mass decreased by 0.63% and 17.14% for each unit of EC increase in the irrigation water in sandy loam saline soil, and the corresponding values were 0.70% and 25.63% in silt saline soil. This study implied that Daylily is a suitable plant in landscape construction of coastal saline soils using drip-irrigation at ECiw<7.8dS/m.

Response of Symphyotrichum novi-belgii and Dianthus chinensis L. to saline water irrigation in a coastal saline soil

Symphyotrichum novi-belgii and Dianthus chinensis L. perform well in landscape. However, their tolerance to salinity stress is unknown. Field experiment was conducted to evaluate the salt tolerance threshold (STI) of these two herbaceous plants cultivated in a coastal saline soil by drip-irrigation with saline water at electrical conductivity (EC) of 0.8, 3.1, 4.7, 6.3, and 7.8dS/m for three years. The original soil salinity expressed as electrical conductivity of the saturation paste extract (ECe) was an average of 27.64dS/m in the 0–95cm depth. Our results showed that drip-irrigation was effective in salt leaching. After 18 months, the average values of soil ECe for five treatments were 2.32 and 2.78dS/m in 0–35 and 0–95cm soil profile, respectively. The survival rates were >94% and >80% when irrigated with saline water at <7.8dS/m for S. novi-belgii and D. chinensis L., respectively. The survival rate and shoot dry mass decreased by 0.76% and 9.24% for each unit of EC increase in the irrigation water for S. novi-belgii, and the corresponding values were 3.01% and 8.21% for D. chinensis L. This study implied that S. novi-belgii and D. chinensis L. are suitable plants in landscape construction of coastal saline soils using drip-irrigation with suitable saline water range.

Effects of Trichoderma harzianum T83 on Suaeda salsa L. in coastal saline soil

Sustainable biotechnological techniques can transform coastal saline soil into agriculturally viable soil. In the current study, the T83 strain of Trichoderma harzianum was isolated and shown to promote growth of Suaeda salsa L., a halophytic species. We assayed the effects of T83 conidia powder and fertilizer on the physiology of S. salsa as well as the physical and biological properties of the treated soil. Compared to the control plants, the experimental S. salsa plants that received conidia powder and fertilizer exhibited increased fresh masses by 50.5% and 82.7% and increased dry masses by 67.3% and 119.3%, respectively (P<0.05). The concentrations of proline, organic acids, amino acids, soluble sugars, K+, and Ca2+ were increased in conidia powder and fertilizer treatments (P<0.05), and increased by 77.5%, 58.3%, 86.9%, 58.7%, 79.3% and 38.8% in fertilizer treatment, respectively. Both powder and fertilizer treatments significantly increased the enzyme activity of peroxidase and superoxide dismutase as well as root vigor (P<0.05) and decreased malondialdehyde concentration (P<0.05). Additionally, fertilizer treatments increased enzyme activity of phenol oxidase and catalase. Conidia powder and fertilizer treatments significantly decreased soil bulk density and soil salt concentration, while increasing soil total porosity and field water capacity (P<0.05). Powder and fertilizer significantly (P<0.05) increased the populations of total bacteria, total actinomyces, total fungi, ammonifying bacteria (AB), nitrifying bacteria (NB), phosphate-solubilizing bacteria (PHB), and potassium-solubilizing bacteria (PTB). Compared to the control, the fertilizer treatment exhibited populations of total bacteria, total actinomyces, total fungi, AB, NB, PHB, and PTB that had increased by factors of 9.2, 55.9, 6.0, 21.1, 4.0, 9.2 and 5.2, respectively. The T83 fertilizer effectively promoted the growth of S. salsa in saline soil and improved the coastal saline soil quality.

Effects of organic matter on Leymus chinensis germination, growth, and urease activity and available nitrogen in coastal saline soil

ABSTRACTThe present study was carried out to investigate the effect of three organic matters (stalk powder, microbial fertilizer, and manure) on Leymus chinensis germination, growth, and urease activity and available nitrogen (N) in coastal saline soil. The study was conducted in a completely randomized design with eight treatments: J0V0Y0, J1V0Y0, J0V1Y0, J0V0Y1, J1V1Y0, J1V0Y1, J0V1Y1, J1V1Y1. The notations were based on the quantities of each agent added to 1 kg of coastal saline soil: J0 – no straw powder, J1 – 0.2 kg straw powder, Y0 – no manure, Y1 – 0.3 kg manure, V0 – no microbial fertilizer, V1 – 0.2 L microbial fertilizer, each in quantic repeat. L. chinensis was sown as 50 seeds per pot. Results indicated that addition of organic agents exerted a significantly enhanced germination, increase in fresh weight and elevated soil urease activity. Soil available N levels were significantly positively correlated with soil urease activity and fresh weight, but not with germination rate. It is noteworthy that the halophyte L. chinensis showed improved characteristics when grown in coastal saline soil with addition of organic amendments.

Biomass production, nutrient cycling, and carbon fixation by Salicornia brachiata Roxb.: A promising halophyte for coastal saline soil rehabilitation

ABSTRACTIn order to increase our understanding of the interaction of soil-halophyte (Salicornia brachiata) relations and phytoremediation, we investigated the aboveground biomass, carbon fixation, and nutrient composition (N, P, K, Na, Ca, and Mg) of S. brachiata using six sampling sites with varying characteristics over one growing season in intertidal marshes. Simultaneously, soil characteristics and nutrient concentrations were also estimated. There was a significant variation in soil characteristics and nutrient contents spatially (except pH) as well as temporally. Nutrient contents in aboveground biomass of S. brachiata were also significantly differed spatially (except C and Cl) as well as temporally. Aboveground biomass of S. brachiata ranged from 2.51 to 6.07 t/ha at maturity and it was positively correlated with soil electrical conductivity and available Na, whereas negatively with soil pH. The K/Na ratio in plant was below one, showing tolerance to salinity. The aboveground C fixation values ranged from 0.77 to 1.93 C t/ha at all six sampling sites. This study provides new understandings into nutrient cycling—C fixation potential of highly salt-tolerant halophyte S. brachiata growing on intertidal soils of India. S. brachiata have a potential for amelioration of the salinity due to higher Na bioaccumulation factor.

Hyperspectral field estimation and remote-sensing inversion of salt content in coastal saline soils of the Yellow River Delta

This study explored hyperspectral field and satellite-based remote sensing of soil salt content. Using Kenli County in the Yellow River Delta as the study area, in situ soil field spectra and satellite-based remote-sensing images were integrated with laboratory measurements of soil sample salinity to improve remote sensing-based soil salt estimation and inversion procedures. First, the narrow-band hyperspectral reflectance field data were used to model the wide-band reflectance data from Landsat 7. Second, the bands and spectral features sensitive to soil salt content were identified through correlation analysis and band combination. Stepwise multiple linear regression was used to find a best model, which was then inverted to predict soil salt content using remote-sensing images from Landsat 7 and Landsat 8. The applicability of the model was verified by ground-checking the inversion results. The results show that the bands sensitive to soil salinity are mainly in the visible and near-infrared (NIR) regions. Combining information from these bands can eliminate some background effects and significantly improve the correlation with salinity. The best model of soil salinity is y = 1.345 − 25.898 × gSWIR1 − 245.440 × gRed × (gRed − gNIR) − 0.252 × (gRed + gNIR)/(gRed − gNIR) − 19.563 × (gRed − gSWIR1). This model has a coefficient of determination (R2) of 0.896, a verification R2 of 0.867, a relative prediction deviation (RPD) of 2.135, and a root mean square error (RMSE) of 0.264. The model fits well and is highly stable. The inversion results based on Landsat 7 and Landsat 8 images are consistent with the actual situation of soil salinity in the study area. This study provides an effective and feasible method for the estimation of soil salt content in coastal regions based on field spectral measurements and remote-sensing inversion.

黄河三角洲柽柳植株周围土壤盐分离子的分布

PDF HTML阅读 XML下载 导出引用 引用提醒 黄河三角洲柽柳植株周围土壤盐分离子的分布 DOI: 10.5846/stxb201504230839 作者: 作者单位: 中国科学院烟台海岸带研究所,烟台大学化学化工学院,烟台大学化学化工学院,中国科学院烟台海岸带研究所,烟台大学环境与材料工程学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41201293）；海洋公益性行业科研专项（201105020） Distribution of soil salt ions around Tamarix chinensis individuals in the Yellow River Delta Author: Affiliation: Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences,,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为探讨柽柳的盐分富集效应及其对不同盐分离子分布的影响，以黄河三角洲盐碱地柽柳为研究对象，分析了离植株不同距离不同土层中的盐分离子组成、含量、离子比及不同离子之间的相关性。研究结果表明：各土层阳离子中Na+含量最高，其次是Ca2+和Mg2+，K+最低，Cl-在阴离子中的含量最高，SO42-次之，HCO3-最低，而未检测到CO32-。在柽柳植株周围，尤其是表层土壤中，离植株越近盐分含量越高，显示出柽柳对盐分的富集效应，其中对不同阳离子的富集程度表现为K+ > Na+ > Mg2+ > Ca2+，而对阴离子的富集程度表现为HCO3- > Cl- > SO42-。冠层下凋落物中盐分的释放和树干径流可能是导致盐分在柽柳植株周围水平方向上存在差异的主要原因。土壤总可溶性盐含量随着土层的加深而升高。阳离子和阴离子向下迁移程度分别表现为Na+ > Mg2+ > Ca2+ > K+和Cl- > SO42-≈HCO3-，因而随土层加深而升高的Na+、Ca2+、Mg2+和Cl-，显示出底聚特征，而K+、SO42-和HCO3-含量则随着土层的加深而降低，具有表聚特征。降水淋溶、盐分离子迁移速率的差别和各土层中不同生物量根系对盐分吸收的差异可能是造成盐分在垂直方向上含量变化的主要因素。 Abstract:Spatial heterogeneity is considered a ubiquitous feature of natural ecosystems. A typical example of spatial heterogeneity in ecosystems is the formation of salt islands, which form around small shrubs and are important local and regional salt reserves that influence community structure and ecosystem function. These salt islands are formed where salts accumulate under the shrub canopy. Soil salinity has been shown to vary significantly between areas covered by shrub canopies and interspaces. To quantify the effect of halophyte plants on the salinity characteristics of salt islands in saline and alkaline soil, the native Tamarix chinensis of the Yellow River Delta (YRD) was selected as a study species, and its soil salt ion composition and content were analyzed. Differences in the cation and anion contents and ratios among distances and horizons were analyzed using an analysis of variance and multiple comparisons. A correlation analysis was also conducted, to determine the relationships among different salt ions. The results show that salt islands are mainly distributed in the surface soil. Both the cations and the anions were present in higher concentrations near T. chinensis individuals. Of the cations, Na+ was found in the highest levels of the profile, followed by Ca2+ and Mg2+ in the lower layers, and K+ in the deepest part of the profile. Anions in all soil depths both showed Cl- > SO42- > HCO3-, but CO32- was not detected. The distance from the center of the shrub to the sampling point had a significant effect on most salt ions and their ratios, with the exception of Ca2+, Mg2+, SO42-, Na+/Ca2+, Ca2+/Mg2+, and Cl-/SO42-. The soil depth had a significant effect on almost all of ions and ratios, with the exception of the Na+/K+ ratio. The interaction between distance and depth only had a significant effect on Cl- and HCO3-. Na+/K+, Ca2+/K+, Mg2+/K+, and Ca2+/Mg2+ increased in the 0-20 cm layer, while the Na+/Ca2+ and Na+/Mg2+ ratios decreased along the gradient between the canopied area and the interspace. Therefore, the cations enrichment due to the proximity of a T. chinensis individual was as follows:K+ > Na+ > Mg2+ > Ca2+. However, anions enrichment was determined to occur as follows:HCO3- > Cl- > SO42- as Cl-/SO42- decreased and Cl-/HCO3- and SO42-/HCO3- increased in the 20-40 cm soil layer, along the gradient from the shrub center to the interspace. The total soluble salt content of the soil increased with depth. However, K+, SO42-, and HCO3- concentration decreased with soil depth, indicating the presence of significant surface accumulation. The Na+/K+, Na+/Ca2+, Na+/Mg2+, Ca2+/K+, Mg2+/K+, Cl-/SO42-, and Cl-/HCO3- ratios increased and Ca2+/Mg2+ decreased significantly with increased depth; however, SO42-/HCO3- didn't change significantly with depth. Consequently, the downward migration of cations and anions was ranked as follows:Na+ > Mg2+ > Ca2+ > K+, and Cl- > SO42-≈HCO3-, respectively. The relationships among different salt ions were significant, but no significant correlation was found between SO42- and Na+ or between SO42- and Ca2+ concentration. In conclusion, the root biomass and distribution, the climatic conditions (e.g., evaporation and precipitation), the rate of salt ion migration, and the sampling time may influence the detected distribution of cations and anions in the soil. The findings of this study may serve as a reference for the elucidation of the salinization-alkalization processes at work in coastal saline soil, and in the amelioration of the soil in the Yellow River Delta. 参考文献 相似文献 引证文献

Enumeration of microbes and microbial activities in coastal saline soils of Eastern India

Enumeration of microbes and microbial activities in coastal saline soils of Eastern India

Influence of Rice Straw Incorporation on the Microbial Biomass and Activity in Coastal Saline Soils of Bangladesh

Coastal soils of Bangladesh are affected by salinity. This study investigated salinity as a stress factor on coastal soils in Bangladesh. It was also observed if incorporation of rice straw could remediate negative impacts of soil salinity (if any) on microbial activ-ity. The microbial biomass carbon ranged from 137.85 to 614.88 μg/g among the soils (n = 11). Microbial biomass carbon content and number of both cultivable bacteria and fungi decreased in the soils with higher ECes (electrical conductivity). Respiration was measured over 30 days with each soil pre incubated at 50% of water holding capacity. Basal respiration rate as well as soil organic carbon content (r = 0.88, p - 37.73 mS/cm) (12.91 - 16.89 mg CO2/g dry soil) than in the nonsaline soils (0.98 - 2.33 mS/cm) (5.79 - 6.51 mg CO2/g dry soil). Application of rice straw at 0.50%, 1.00%, 1.50% and 2.00% reduced the negative impact of soil salinity especially at higher ECes (6.63 - 37.73 mS/cm). Application of 1.00% rice straw appeared to be acceptable for successful amelioration of saline soils of the study area.

Influence of Polyacrylamide (pam) on the Soil and Water Conservation Effects of White Clover (trifolium Repens L)

In order to explore the technology of soil and water conservation in coastal saline soil area, improve the prevention and control of soil erosion, white clover (Trifolium repens L) combined with different dosage of polyacrylamide (PAM) was applied to the soil and water conservation in plot tests, and the influence of PAM on the soil and water conservation effects of white clover (Trifolium repens L) was examined. The results showed that compared to the only planting white clover, the addition of 1-5 g/m 2 PAM reduced soil erosion by 516.0-1326.3 t/(km 2 ·a), which were 29.5-75.8% of the yearly soil erosion; inhibited soil evapotranspiration by 24.3-43.4%; improved the total rain water interception by 18.0-44.1 mm; and decreased the cumulative percentage of water loss (CP) by 0.4-4.7% in the 30th day after the plants harvest. From the aspects of reduction efficiency of erosion modulus and reduction efficiency of evapotranspiration, the optimistic dosage of PAM was 1 g/m 2 . The synergy of PAM mainly focus on the early stage of white clover. In addition, PAM may still slightly prevent the water loss after the plants harvest.

A vegetation reconstruction method to plant Sedum spectabile Boreau using drip-irrigation with saline water on a coastal saline soil in region around Bohai Gulf

Soil salinity and saline groundwater are major constraints to the cultivation of crops and landscape plants in coastal regions. With the rapid industrialization and urbanization in these areas, there is an urgent need to improve the landscape to meet the increasing demand of living environments for cities and districts. The aim of this study was to propose a method to plant Sedum spectabile Boreau, a common landscape flower plant, on a very heavy coastal saline soil using drip-irrigation with saline water in region around Bohai Gulf. The salinity levels of irrigation water were 0.8, 3.1, 4.7, 6.3a, nd 7.8 dS/m, respectively. The results showed that the revegetation method, which mainly included ‘ridge planting + saline water drip-irrigation’, was effective in planting Sedum spectabile Boreau for reclaiming coastal saline silt soil. An soil matric potential (SMP) higher above −5 kPa after transplanted and −10 kPa after growing season ended, and 6 mm of irrigation water can be used as indicators for Sedum spectabile Boreau drip-irrigation scheduling with 100 % survival rate when irrigated with saline water at <7.8 dS/m in initially saline soils with a gravel–sand layer after tillage. This method is combined with comprehensive utilization of the saline water, agronomic measures, collaborative repair of the soil and plants to offer new views and theoretical support for the protection and development of saline land in coastal regions.

Effects of macro-pores on water flow in coastal subsurface drainage systems

Leaching through subsurface drainage systems has been widely adopted to ameliorate saline soils. The application of this method to remove salt from reclaimed lands in the coastal zone, however, may be impacted by macro-pores such as crab burrows, which are commonly distributed in the soils. We developed a three-dimensional model to investigate water flow in subsurface drainage systems affected by macro-pores distributed deterministically and randomly through Monte Carlo simulations. The results showed that, for subsurface drainage systems under the condition of continuous surface ponding, macro-pores increased the hydraulic head in the deep soil, which in turn reduced the hydraulic gradient between the surface and deep soil. As a consequence, water infiltration across the soil surface was inhibited. Since salt transport in the soil is dominated by advection, the flow simulation results indicated that macro-pores decreased the efficiency of salt leaching by one order of magnitude, in terms of both the elapsed time and the amount of water required to remove salt over the designed soil leaching depth (0.6 m). The reduction of the leaching efficiency was even greater in drainage systems with a layered soil stratigraphy. Sensitivity analyses demonstrated that with an increased penetration depth or density of macro-pores, the leaching efficiency decreased further. The revealed impact of macro-pores on water flow represents a significant shortcoming of the salt leaching technique when applied to coastal saline soils. Future designs of soil amelioration schemes in the coastal zone should consider and aim to minimize the bypassing effect caused by macro-pores.

Assessment of the environmental fate of cycloxaprid in flooded and anaerobic soils by radioisotopic tracing

Cycloxaprid (CYC) is a novel broad-spectrum neonicotinoid insecticide that has been developed for agricultural pest control. The fate of the 14C-labeled racemic and enantio-pure CYC isomers in flooded and anaerobic soil was investigated using radioisotope tracing techniques. After 100d of incubation, only a minor portion (<1%) of the applied CYC isomers is mineralized by each of the four tested soil types. The fraction of initially applied radioactive CYC dissipated into the bound or non-extractable residues (BR) increases with increase in the length of the incubation period, reaching up to 53.0–81.6%. The dissipation of the CYC through mineralization or formation of BR is strongly influenced by soil properties, such as humic content, pH value, and retained microbial activity. Amongst the soils studied, the fluvio-marine yellow loamy soil displayed the highest tendency to mineralize CYC while the coastal saline soil exhibited the strongest tendency to form BR. The observation that the water phase retained the large portion(>60%) of the radioactivity attributed to the total extractable residue suggested that under the experimental condition, the initially applied 14C-labeled CYC residues were readily available for leaching or offsite transport. Additionally, no enantiomer-specific behaviors are observed. The results from this study provide a framework for assessing the environmental impact resulting from the use of this pesticide.

Response of a salt-sensitive plant to processes of soil reclamation in two saline–sodic, coastal soils using drip irrigation with saline water

The aim of this study was to evaluate the impact of soil types and properties on coastal saline soil reclamation and the response of plant growth to the reclamation processes in two soils. Two very heavy coastal saline soils were reclaimed in a three-year trial using drip irrigation with saline water. Chinese roses (Rosa chinensis) were planted, and soil indexes, growth characters, ion absorption and dry matter production were determined. Our results showed that significant salt leaching occurred in both soils, and the effect during the early period of reclamation was better in sandy loam than silt soil. There were higher emergence and survival rates of plants in sandy loam soil due to the rapid reclamation process, while plant growth and dry mass were greater in silt soil due to good fertilizer and water conservation. Most roots were present in the 0–20-cm profile in both soils, but the fine root length value in silt soil was relatively high. These results indicate that water and nutrient management differed in the two soils. During soil reclamation, more attention should be paid to nutrient supply and maintaining soil moisture in sandy loam and to rapidly establishing suitable soil root-zone environments for plant emergence in silt soil.

Infiltration of meltwater from frozen saline water located on the soil can result in reclamation of a coastal saline soil

The saline soil was irrigated by the shallow groundwater of high salinity (12 g L−1) during the air temperature below −5 °C in winter, and the saline water was frozen into saline ice on the soil expeditiously. With air temperatures increasing in spring, the saline ice melted and infiltrated into soil gradually, and the saline soil may be improved by the infiltration of the meltwater. Based on this, a field experiment was conducted to evaluate changes in saline ice during melting, seasonal dynamics of soil temperature, water, salt and sodium adsorption ratios (SAR). After the meltwater infiltrated into soil in spring, the plastic mulching (FM) and non-mulching (FN) were designed, and the control treatment (CK) did not include irrigation or mulching. The results showed that the salinity of the saline ice was reduced upon melting, and the mulching of saline ice increased the soil temperature and reduced the frozen soil layers. After infiltration of meltwater, the soil salinity and SAR were both reduced significantly (p < 0.05), and the mulching of plastic film maintained the lower level of soil salinity and SAR. During the sowing season for cotton, the soil salinity and SAR were below 4 g kg−1 and 9, respectively, in FM. And higher than 65 % of emergence rates and greater than 3.4 t ha−1 seed cotton yields were obtained in this treatment, while for the FN and CK treatments, the soil salinities were both above 8 g kg−1, which leads to yields that were not obtained.

Effects of water application intensity of microsprinkler irrigation on water and salt environment and crop growth in coastal saline soils

Laboratory and field experiments were conducted to investigate the effects of water application intensity (WAI) on soil salinity management and the growth of Festuca arundinacea (festuca) under three stages of water and salt management strategies using microsprinkler irrigation in Hebei Province, North China. The soil water content (è) and salinity of homogeneous coastal saline soils were evaluated under different water application intensities in the laboratory experiment. The results indicated that the WAI of microsprinkler irrigation influenced the è, electrical conductivity (ECe) and pH of saline soils. As the WAI increased, the average values of è and ECe in the 0–40 cm profile also increased, while their average values in the 40–60 cm profile decreased. The pH value also slightly decreased as depth increased, but no significant differences were observed between the different treatments. The time periods of the water redistribution treatments had no obvious effects. Based on the results for è, ECe and pH, a smaller WAI was more desirable. The field experiment was conducted after being considered the results of the technical parameter experiment and evaporation, wind and leaching duration. The field experiment included three stages of water and salt regulation, based on three soil matric potentials (SMP), in which the SMP at a 20-cm depth below the surface was used to trigger irrigation. The results showed that the microsprinkler irrigation created an appropriate environment for festuca growth through the three stages of water and salt regulation. The low-salinity conditions that occurred at 0–10 cm depth during the first stage (–5 kPa) continued to expand through the next two stages. The average pH value was less than 8.5. The tiller number of festuca increased as SMP decreased from the first stage to the third stage. After the three stages of water and salt regulation, the highly saline soil gradually changed to a low-saline soil. Overall, based on the salt desalinization, the microsprinkler irrigation and three stages of water and salt regulation could be successfully used to cultivate plants for the reclamation of coastal saline land in North China.

Optimizing net greenhouse gas balance of a bioenergy cropping system in southeast China with urease and nitrification inhibitors

Efforts to advance our knowledge on the potential of bioenergy instead of fossil fuels in terms of mitigating climatic impact are in urgent need. No data is currently available on the use of urease and nitrification inhibitors in costal saline bioenergy cropping systems. An overall accounting of net greenhouse gas balance (NGHGB) and greenhouse gas intensity (GHGI) affected by combined effects of urease inhibitor hydroquinone (HQ) and nitrification inhibitor dicyandiamide (DCD) amendment was examined in a coastal saline Jerusalem artichoke bioenergy cropping system. The net ecosystem exchange of CO2 (NEE) was determined by the difference between soil heterotrophic respiration (RH) and net primary production (NPP) using static chamber method. Urease and nitrification inhibitors amendment increased the NPP but exerted a suppression effect on soil RH over the Jerusalem artichoke cropping system. A trade-off relationship was observed by decreasing soil N2O but stimulating soil CH4 emissions following HQ+DCD amendment. The plots combined urea with HQ+DCD application increased soil CH4 by 167% while decreased N2O by 16% as compared to with urea only in the bioenergy cropping system. On average, the fertilizer N-induced emission factor of N2O was estimated to be 0.25% across the fertilized plots. Compared with urea, the plots with urea and HQ+DCD resulted in a further decrease by 37% and 15% in estimated NGHGB and GHGI over the Jerusalem artichoke cropping system, respectively. Overall, Jerusalem artichoke production would achieve higher biomass as source of biofuels but lower climatic impacts, particularly when together with urease and nitrification inhibitors amendment in coastal saline soils.

Effects of different amendments for the reclamation of coastal saline soil on soil nutrient dynamics and electrical conductivity responses

High salinity and macronutrient deficiencies are two important limitations of coastal saline soils. The present study focused on the changes in electrical conductivity (EC), and the redistribution of water soluble carbon (C), total nitrogen (N), and absorbable phosphorus (P) during the reclamation of coastal saline soil using different amendments. Eight soil treatments were tested: cotton straw powder (J), domestic sewage sludge (W), sewage sludge+cotton residue (J+W), beach sand (S), cotton straw powder+beach sand (J+S), domestic sewage sludge+beach sand (W+S), domestic sewage sludge+cotton residue+beach sand (J+W+S), and a control treatment (CK). Triplicate soil samples for each treatment were initially treated once with underground saltwater (with or without bacterial manure). After the first month of incubation, irrigation was conducted weekly. EC measurements in different soil layers showed that sewage sludge was the best amendment for reducing soil EC, while cotton straw powder had no significant effect. Concentrations of N and C increased with soil depth, while the highest P concentration was observed in the uppermost soil. Soil amended with organic matter showed the highest P concentrations, and P availability increased with the application of all amendments except sand, which had no significant effect. The compound treatments had more positive impacts on N availability than did single amendments; however, their effects on P concentration were minimal. The results indicated that sewage sludge was the most effective amendment for reclaiming coastal saline soil and improving the availability of macronutrients.

Microbial and Enzyme Activities and Carbon Stock in Unique Coastal Acid Saline Soils of Goa

The aim of the present investigation was to study the effects of salinity under low soil pH conditions on soil microbial and enzyme activities and to quantify soil organic carbon (SOC) stocks in coastal saline soils of Goa, India. Global positioning system based replicated soil samples collected from fifteen different locations showed characteristic variations in electrical conductivity (0.09–6.29 dS m−1), soil pH (4.11–6.57), exchangeable sodium (Na) (7.40–23.2 meq 100 g−1) and exchangeable sodium percentage (48.3–85.7 %). Exchangeable Na was the most dominant cation among all the cations analyzed at all the sites. The total SOC stock of the study sites varied significantly (p < 0.05) and ranged from 4.27–24.3 Mg C ha−1. The soil microbial activity measured in terms of basal soil respiration, soil microbial biomass carbon (Cmb), Cmb as a fraction of SOC and enzyme activities related to dehydrogenase, phosphatase and urease showed a decline with increasing salinity levels. On the contrary, metabolic quotient increased with increasing salinity. The results of the study suggest that salinity under low soil pH has a depressive effect on the soil microbial and enzyme activity. Alleviation of the depressive effect of salinity on microbial activity needs to be addressed through suitable interventions and countermeasures for sustainable crop production in coastal acid saline soils of Goa.

Chinese rose (Rosa chinensis) cultivation in Bohai Bay, China, using an improved drip irrigation method to reclaim heavy coastal saline soils

This study investigated whether an improved drip irrigation method for reclaiming heavy coastal saline silt-soils could improve the growth of salt-sensitive plants threatened by soils with high salt contents and poor soil structures in Bohai Bay, China. Chinese rose (Rosa chinensis), an ornamental salt-sensitive plant, was chosen as the experiment material. The improved method used a non-saline root environment during the early stages of salt-leaching, a gravel–sand layer settled below the saline soil but above the water table and optimal soil moisture conditions. To determine the optimal soil moisture conditions, five soil matric potentials (SMPs) at 20cm depth at −5, −10, −15, −20 and −25kPa were studied. The results indicated that the mean soil electrical conductivity of the saturated paste extracts (ECe) and the sodium adsorption ratio (SAR) significantly declined in all five treatments. After three growing seasons, the highest desalinization ratios and SAR reductions reached 89% and 73%, respectively, compared with their initial values and these occurred in the roots of the seedlings exposed to the −5kPa treatment. The mean ECe and SAR values increased linearly as the SMP declined. The plant survival ratio was not affected by the SMP treatment in the first growing season, due to the non-saline root zone, but decreased significantly as the SMP threshold fell in the spring of the second year, and then remained stable in the following season. The highest survival ratio reached 97% for the −5kPa SMP treatment after three growing seasons. Stem diameter and plant height increased during three growing seasons and the largest increases occurred when the SMP was −5kPa in first year, −10kPa in second year and −20kPa in third year. The largest crown diameters were recorded in the −5kPa treatment plots in second year and −20kPa in third year. After three years of reclamation, our results showed that this improved method, which utilized a non-saline root environment during the early stages of salt-leaching, a gravel–sand layer below the saline soil and controlled the SMP threshold of −5kPa in the first year, −10kPa in second year and −20kPa in third year, can be used to reclaim coastal urban saline land for vegetation rehabilitation around Bohai Bay, China.