Sodic Land Research Articles

Rhizosphere and endophytic bacteria for induction of salt tolerance in gladiolus grown in sodic soils

Extensive development of canal irrigation system led to formation of unproductive sodic lands, which limited the cultivation of flower crop gladiolus in the basins of major rivers. The purpose of this study was to isolate native rhizospheric and endophytic bacteria from sodic environment and evaluate their growth enhancement and bio-ameloirant properties in gladiolus under sodic soils. Sixteen isolates of plant-growth-promoting rhizospheric and endophytic bacteria were isolated and screened for growth promotion potential. The promising strains were identified and evaluated for growth and production in gladiolus. The plants treated with strains CSR-G-1, CSR-B-2, and CSR-B-3 significantly produced marketable spikes and higher number of florets/spike. Also, the treated plants showed an increased activity of superoxide dismutase, phenyl alanine lyase, catalase, peroxidase, phenols, and proline than control. Further, the soil pH, total carbonates, and sodium adsorption ratio were lower in treated soils. The Na+/K+ ratio in leaves of treated plants was observed to be lower than control. In conclusion, these bio-inoculums can be used as growth enhancer and bio-ameliorant in sodic soils as an eco-friendly management strategy.

Impact of novel low cost technological interventions on expenditure pattern of landless and sub‐marginal farmers

Approximately 50% rural population is facing a major challenge of sustainable and reasonable livelihood security. In the present study, low cost‐highly profitable technologies were intervened to landless and sub‐marginal farmers for their socio‐economic upliftment. The study was conducted during 2009‐2013 in Barabanki and Raebareli districts of Uttar Pradesh, India. Base line survey in 42 villages (700 farmers) was conducted, interventions initiated in mid 2009 and later, these were expanded in 65 villages (5250 families). For pre‐intervention period, 6 months average was considered, whereas in post‐intervention period 12 months average was taken in comparing expenditure pattern. The farmers were intervened with novel technologies viz.,rural poultry production and purchase of bovine and goat, mineral based estrous induction, mastitis prevention, high yielding perennial fodder on waste land, banana as cash crop and family nutrition, lemon, guava and seasonal vegetables in courtyard, bio‐enhancer for supporting vegetables and fruit plants. Sodic or barren unused land was transplanted with guava intercropped with vegetables and banana seedlings. The expenditure on food and clothing in pre‐intervention period was costing average of 71.4% and only 28.6% monthly earning was available for other family needs, while in postintervention period, in spite of improved food, nutrition and clothing quality, the expenditure was only 23.2% of total income. In conclusion, low input technologies whenever are intervened aiming higher profitability the impact on socio‐economic status is visible within shortest time. It is a better option if governments create the infra‐structural facilities and provide support with technological innovation for rural poverty alleviation.

The Field Performance of some Accessions of Jatropha Curcas L. (Biodiesel Plant) on Degraded Sodic Land in North India

Twenty four accessions of Jatropha curcas L. (JCL) were planted on a degraded sodic land in Lucknow, India, in which growth and yield traits were measured over five years (2006–2010). There was a large variation in growth and yield among these accessions, and the average seed yield (118 g plant−1) and oil content (30%) of JCL on the sodic land were sufficiently low to make it an economically feasible venture for biofuel production. The seed:fruit, kernel:seed ratios and the 100 seed test weight were also measured. In order to make it an economically viable proposition, some preliminary screening were done to assort the superior accessions (CSMCRI-C1, NBPGR-Urlikanchan, NBPGR-Chhatrapati, and NBPGR-Hansraj), on the basis of growth and yield traits, that have attained an average height of 264.6–344.6 cm, with an 8.5- to 10-cm collar diameter, 41–57 branches per plant, a 209- to 290-cm canopy spread, a 178–246 g plant−1 seed yield, and a 27–38% oil content at five years. Though they do not correlate well between growth/yield and gas exchange parameters (photosynthetic rate, transpiration, stomatal conductance, and water use efficiency), even then these markers are useful to screen out a large number of accessions at an early stage before the yield starts or stabilizes to increase the land use efficiency. The changes in soil properties after five years of the plantations showed reduction in soil pH and electrical conductivity, with a parallel increase in organic carbon, organic nitrogen, microbial biomass, and dehydrogenase activity, indicating that JCL had a modest ability to reclaim the sodic soils.

Effect of land rehabilitation on physicochemical and microbial properties of a sodic soil

Sodic soils are widely distributed in arid and semiarid regions of the world and suffer from high values of pH, exchangeable sodium percentage (ESP), sodium adsorption ratio (SAR) and low fertility. But little is known about the effect of long term land rehabilitation on soil physicochemical and microbial properties of sodic soils. Therefore, the specific objectives of this study were (i) to evaluate the effect of long term (five decades) rehabilitation of sodic land through cropping system on soil physicochemical and microbial properties, (ii) to assess seasonal variation in soil properties of different lands and (iii) to calculate increase in soil fertility through gain percent. For this purpose, changes in soil properties (physicochemical and microbial properties) of rehabilitated sodic land (RSL) were compared with adjacent degraded sodic land (DSL) and non-sodic soil (NSS). When compared to DSL, soil pH, exchangeable sodium percentage (ESP) and sodium adsorption ratio (SAR) were significantly lower in RSL and NSS, while, soil organic carbon (SOC), available nutrients, microbial biomass (MB), microbial counts and enzyme activities (dehydrogenase, β-glucosidase, protease, alkaline phosphatase and acidic phosphatase) were significantly higher in RSL and NSS. Seasonal fluctuations in soil properties varied significantly from the annual mean and changes were not always identical for all the lands. Microbial biomass and enzyme activities were negatively correlated with soil sodicity parameters (pH, EC, ESP and SAR) except alkaline phosphatase activity. On the basis of gain %, respective decrease in soil pH, EC, ESP and SAR was 44, 78, 61 and 86% and increase in SOC, total nitrogen (Nt) MBC, fungal population, dehydrogenase and protease activities was 65, 88, 73, 65, 66 and 63%. Rehabilitation of degraded sodic land through cropping showed 79% (mean gain %) improvement in soil quality. Our findings conclude that rehabilitation of degraded sodic lands through cropping showed a considerable increase in soil fertility.

Cynodon dactylon: An efficient perennial grass to revegetate sodic lands

Sodic soils are wide-spread in semi-arid subtropical regions and characterized by high level of sodium and pH with poor physical, microbial and enzyme activities. In this study frequency (F), density (D), abundance (Ab) and important value index (IVI) of grasses naturally growing on abandoned sodic land were observed to assess sodicity tolerance ability of these grasses. The greatest IVI and visual observations showed that Cynodon dactylon (Bermuda grass) has maximum ability to grow on severely sodic lands and can be identified as an ecological tool in rehabilitation of degraded lands. Besides vegetation analysis, this further would be confirm by analysis of microbial and enzyme activities of rhizosphere soils. Therefore, we also observed the changes in microbial and enzyme activities of rhizosphere soils (RS) of C. dactylon and compared with non-rhizosphere (adjacent non-vegetated area) sodic soils (NRS) to assess its ecological suitability for reclamation of sodic soils. We collected 135 random soil samples from C. dactylon rhizosphere as well as adjacent non-rhizosphere bulk soil. Soil pH, exchangeable sodium percentage (ESP), sodium adsorption ratio (SAR), electrical conductivity (EC) and carbon nitrogen ratio (C:N) were significantly lower in rhizosphere soils in comparison to non-rhizosphere soils, while organic carbon (OC), total nitrogen (T-N), available phosphorus (P), microbial biomass carbon (MBC), soil respiration (SR), microbial quotient (Cmic:Corg), dehydrogenase, protease and alkaline phosphatase activities were significantly higher in rhizosphere soils. Decreases in soil sodicity (pH, ESP and SAR) and increases in soil nutrients, microbial biomass and enzyme activities suggest that C. dactylon can be used to restore and enhance the biological activities of abandoned sodic lands and to facilitate the further vegetation establishment.

松嫩平原微地形下土壤水盐与植物群落分布的关系

PDF HTML阅读 XML下载 导出引用 引用提醒 松嫩平原微地形下土壤水盐与植物群落分布的关系 DOI: 10.5846/stxb201306051346 作者: 作者单位: 中国科学院东北地理与农业生态研究所 长春130012,中国科学院东北地理与农业生态研究所 长春130102,中国科学院东北地理与农业生态研究所 长春130102,中国科学院东北地理与农业生态研究所 长春130102,中国科学院东北地理与农业生态研究所 长春130102 作者简介: 通讯作者: 中图分类号: S152 基金项目: 中国科学院西部行动计划重大资助项目(KZCX3-XB3-16);国家自然科学基金资助项目(41071022);国家科技支撑课题资助项目(2009BADA3B04) The correlation between soil water salinity and plant community distribution under micro-topography in Songnen Plain Author: Affiliation: Northeast Institute of Geography and Agroecology,,,, 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:以微域尺度不同盐渍化程度的盐渍土复区为研究区,利用典范对应分析方法(CCA)分析了不同水文年(丰水年、枯水年)土壤盐碱化指标、地表积水、不同土壤层含水率和相对高程与植物群落之间的关系。结果表明,在枯水年由于水分的减少和盐碱化的加重,稗草向虎尾草群落演替,虎尾草向碱蓬群落演替。而芦苇和碱茅群落相对稳定,只是由湿生向旱生转化,群落间演替较慢。在植物群落演替过程中,Na+(991 mg/kg)、CO32-(396 mg/kg)、EC(680 μs/cm),pH值(10)是稗草、芦苇向虎尾草和碱茅群落演替的驱动值。Na+(1570 mg/kg)、CO32-(576 mg/kg)、EC(879 μs/cm)是虎尾草、碱茅向碱蓬群落演替的驱动值。地表水的积水时间和积水深度是区分稗草和芦苇、虎尾草和碱茅生长分布的重要水文特征值。研究对苏打盐渍土区植被恢复和重建具有重要的意义。 Abstract:In this research, the relationship between soil salinity, sodicity, environment factors, and the plant community distribution under micro-topography were analyzed using canonical correspondence analysis method (CCA) in Songnen Plain of China. The experiment was conducted at the Da'an Sodic Land Ecological Experiment Station of the Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences. A representative saline-sodic area measuring 100×100 m was selected within the experimental station for soil sampling. The experimental area was divided into 10×10 m grid squares, and 40 grids were randomly selected as sampling points. The experiment was conducted during 1 May to 1 October for two different hydrological years (year 2005 is a wet year and year 2007 is a dry year). Soil salinity and sodicity parameters included soil ions (Na+, K+, Ca2+, Mg2+, CO32-, HCO3-, Cl- and SO42-), soil salinity content (SC), electrical conductivity (EC), sodium adsorption ratio (SAR), and pH. The environmental factors investigated were ground elevation, surface ponding time, surface ponding depth, and soil moistures at four soil layers (0-10, 10-30, 30-60, and 60-100 cm). Experiment results indicated that micro-topography has significant impacts on the spatial variations of soil water, soil salinity, and plant community distribution. Among the eight soil ions, CO32- showed the strongest correlation with the ground elevation. Soil moisture showed negative correlation with the ground elevation. The Suaeda glauca community is the highest salt-tolerant species and is distributed in the mound (highest elevation) of the local micro-topography, where the soil has the highest concentrations of CO32-, Na+, Ca2+, and Mg2+. The Echinochloa crusgalli community and Phragmite Australis community are distributed in the depression of the micro-topography, where the soil has relatively higher soil moisture and lower soil salinity. The Chloris virgata community and Puccinellia tenuiflora community are distributed in the areas between mound and depression. Results of CCA analysis also indicated that under dry condition of year 2007 the plant community succeeded from Echinochloa crusgalli community to Chloris virgata community,and from Chloris virgata community to Suaeda glauca community due to the fact of decrease in soil moisture and increase in soil salt and alkali. However, the plant community distribution (Puccinellia tenuiflora and Phragmite Australis) remained relatively stable under the dry condition. The CCA analysis and variance analysis also identified the threshold values of driving the plant community succession from Echinochloa crusgalli community, Phragmite Australis community to Chloris virgata community and Puccinellia tenuiflora community were Na+ (991 mg/kg), CO32-(396 mg/kg), EC (680 μs/cm),and pH (10). Threshold values of driving the plant community succession from Chloris virgata community,Puccinellia tenuiflora community to Suaeda glauca community were revealed by CCA analysis and variance analysis to be: Na+(1570 mg/kg), CO32-(576 mg/kg), and EC(879 μs/cm). Ponding time and ponding depth were identified by CCA analysis and variance analysis to be important hydrological characteristic values of distinguishing plant distribution between Echinochloa crusgalli community and Phragmite australis community, and plant distribution between Chloris virgata community and Puccinellia tenuiflora community. Results from this research may serve as the scientific basis for the plant restoration and saline-sodic soil reclamation in Songnen Plain of China, one of the most serious saline-affected areas in the world. 参考文献 相似文献 引证文献

Changes in physico-chemical, microbial and enzymatic activities during restoration of degraded sodic land: Ecological suitability of mixed forest over monoculture plantation

Abstract Degraded sodic lands in north India are rehabilitated under agriculture and forest sector as per national policies. Afforestation on such lands with monoculture and mixed species reclaims the soils with different efficiencies. We studied the physico-chemical and microbial properties along with enzymatic activities of degraded sodic land (control), rehabilitated sodic lands planted under Terminalia arjuna (R-TA), Prosopis juliflora (R-PJ) and mixed forest (R-MF) from two depths (0–15 and 15–30 cm). The properties of rehabilitated land uses were compared with the soils of corresponding reference (standard) land use under Tectona grandis (Ref-TG) plantation and mixed forest (Ref-MF) growing in the natural forest range of same biogeographic region to determine the status of improvement. The objective of the study was to determine efficient ecological model for the restoration of degraded sodic land. The bulk density, pH, electrical conductivity (EC) and exchangeable sodium percentage (ESP) reduced during restoration under both, pure plantations as well as mixed forest. Increase in water holding capacity (WHC), organic carbon, soil nutrients, microbial biomass (MB) [carbon, nitrogen and phosphorus], microbial counts, CO 2 flux and enzymatic activities (dehydrogenase, β-glucosidase, protease and acidic phosphatase) showed significant improvement in the soil quality of rehabilitated sites. At 0–15 cm soil depth in rehabilitated and reference land uses, in comparison to D-SL, organic carbon, nitrogen (total and available), available phosphorus, exchangeable cations (Na + , Ca ++ and Mg ++ ), MB (carbon and nitrogen) and activities of all enzymes, except alkaline phosphatase, were significantly greater, while other soil properties showed land use specific trends. The overall gain percent in physico-chemical soil properties varied from 54% under plantations to 77% under mixed forest (R-MF). Corresponding gain in microbial biomass was 21% (R-TA) and 34% (R-PJ) under plantation soils against 90% in mixed forest soil. The enzyme activities (on average) have also attained maximum gain% under R-MF (77%) followed by R‐PJ (47%) and R‐TA (35%) in decreasing order which indicates that afforestation with multiple tree species is a relatively good option for sustainable rehabilitation of sodic lands.

Ecological restoration of degraded sodic lands through afforestation and cropping

Land degradation and their restoration are emerging issues all over the world for the environmental management. In this study, degraded sodic land was rehabilitated through afforestation and cropping for 50years. We assessed physico-chemical (bulk density, water holding capacity, pH, electrical conductivity (EC), organic carbon, nitrogen, phosphorus, exchangeable cations and exchangeable sodium percent [ESP]), biological (microbial biomass-C, N, and P, quotients and counts), and biochemical (dehydrogenase, β-glucosidase, alkaline phosphatase, acidic phosphatase and protease) properties of rehabilitated forest land (R-FL) and rehabilitated crop land (R-CL) in two depths (0–15 and 15–30cm) and three seasons. The changes were compared with degraded sodic land (D-SL), control site. At 0–15cm soil depth in the R-FL and R-CL, compared to D-SL, water holding capacity, organic carbon, total nitrogen, available nitrogen, available phosphorus, exchangeable cations, ESP, microbial counts (bacteria and fungus) and biomass (C, N and P) and enzymatic activities were significantly greater, while bulk density and microbial quotient were significantly lower. Soil pH, EC, Na+, ESP and alkaline phosphatase decreased significantly, while other soil properties increased significantly in both rehabilitated lands (R-FL and R-CL). Afforestation with multiple tree species and long-term cropping system improved the soil fertility status and restored the degraded site to different levels. Furthermore, seasonal variations were land use specific and showed different trends across land use types. The study concluded that afforestation with multiple tree species induced greater changes in soil properties during restoration of degraded sodic lands in comparison to cropping system.

New Approaches to Enhance Eco-Restoration Efficiency of Degraded Sodic Lands: Critical Research Needs and Future Prospects

New Approaches to Enhance Eco-Restoration Efficiency of Degraded Sodic Lands: Critical Research Needs and Future Prospects

Biomass productivity and nutrient availability of Cynodon dactylon (L.) Pers. growing on soils of different sodicity stress

Abstract Biomass productivity and nutrient availability for Cynodon dactylon were studied in two types of soils (sandy-clay-loam, loamy-sand) of Gangetic alluvial plain, where degraded land (uncultivated sodic wasteland) was developed under cultivated system. The study was performed in three districts of Uttar Pradesh state to assess the site variations. Frequency, density, abundance and IVI increased significantly when the uncultivated sodic land was managed for crop production. Biomass of the species increased significantly from 90 ± 12 to 1349 ± 176 g m −2 with decrease in sodicity stress from 88.4 ± 2.6 to 8.0 ± 0.8 ESP of the soil. The ratio of increase in standing biomass was observed as 1:8:16 in uncultivated sodic land (USL), semi-reclaimed crop field (SCF) and non-sodic crop fields (NCF) considered as a reference site, respectively. Macronutrient concentrations in soil viz. N, K, Ca, and Mg increased from USL to SCF and NCF, whereas Na concentration decreased inversely. In the plants K concentration ranged from 0.47 to 1.8%, whereas, Ca (0.36–0.72%) and Mg (0.24–0.36) concentrations varied to lesser extent. These variations differed significantly among the soil sites. Sodium concentration decreased significantly in plant samples of semi-reclaimed site from the sodic soil site. Micronutrients in plant tissues showed a decreasing pattern from USL to NCF for Zn, Fe, and Mn, whereas, Cu increased correspondingly. Thus the low, modest, and high growth of C. dactylon corresponding to decrease in sodicity stress (ESP and pH) could be used as bio-indicator to assess the degree of reclamation.

Long‐term changes in the floristic composition and soil characteristics of reclaimed sodic land during eco‐restoration

AbstractThe study was conducted under the “Uttar Pradesh Sodic Lands Reclamation Project” to examine changes that occurred in the reclaimed sodic land in two districts of Uttar Pradesh, India. The study focuses on long‐term seasonal changes in the floral diversity and soil characteristics of the reclaimed sodic land over a period of 10 y. The changes in the floristic composition, plant density, and soil characteristics (microbial biomass carbon [MBC], pH, exchangeable‐sodium percentage (ESP), and electrical conductivity) were compared among the different study plots after different years of sodic‐land reclamation. The study plots comprised reclaimed land with rice–wheat cultivation; semireclaimed land under rice cultivation only and nonreclaimed barren sodic land. There was a significant variation in the floristic composition of the three study plots. Dominance in the floristic composition was shifted from monocotyledonous weeds in the nonreclaimed sodic land to dicotyledonous weeds in the reclaimed land after 10 y of reclamation. Among the soil characteristics, the most remarkable changes were observed in soil MBC and ESP during the course of sodic‐land reclamation. Soil MBC increased up to 480% and ESP values decreased up to 79% in the reclaimed plots with reference to the nonreclaimed plots. The soil amelioration was more pronounced in the upper layer (0–30 cm) as compared to the lower layer (below 30 cm depth). A positive significant correlation was revealed between soil MBC and floristic composition of the reclaimed plots. These changes in floristic composition and soil characteristics could be used as good indicators of the eco‐restoration of the sodic lands. The present study provides useful insights in understanding the temporal progress of eco‐restoration in the reclaimed sodic lands.

Community Structure, Diversity, Biomass and Net Production in a Rehabilitated Subtropical Forest in North India

Gangetic alluvial plain in north India constitutes significant proportions of barren sodic lands. A representative site, where afforestation was carried out during 1960s to rehabilitate the site under forest ecosystem, was selected to assess the restoration success. Three stands (S1, S2, and S3) were selected in a semi-natural subtropical forest at Banthra, Lucknow (26°45’ N, 80°53’ E) on the basis of different vegetation morphology and basal area gradient. Species composition and their growth forms were studied in overstory, understory and ground layer vegetation, in which dominants were assorted. Among the dominants few species were common in the three stands as also in different strata, which perhaps indicate their natural regeneration. Classification of individuals among the different size classes indicated ‘L’ shape distribution in which most of the individuals remained confined in younger groups. Biomass increased from the stand S1 to S3 stand in overstory, and vise versa for understory. Stand S2 consisted of predominance of ground layer biomass over the other stands. Biomass allocation in different plant components differed significantly between the overstory and understory for aerial woody components (stem and branch). Annual litter fall did not differ significantly among the stands, where as fine root biomass (up to 45 cm soil depth) decreased from S1 to S3 stands. Rainy and summer seasons contributed to two-third proportion of total annual fine root production. The state of this rehabilitated forest when compared with the degraded and reference forest of the region indicated that structural complexity, biomass and production levels have been achieved to 70% of the reference forest site even after having a different species composition.

Effect of tree plantation on composition, standing biomass and diversity of ground vegetation on sodic land of North-East region of Uttar Pradesh

The structure,composition, yield and diversity of ground vegetation under eight tree plantations on sodic wasteland were compared among each other and with an adjacent open stand. The communities were floristically distinct from each other on different stands. However, the community on open stand was relatively more similar with the communities under Eucalyptus tereticornis and Acacia catechu plantation stands than with other stands. The herbage yield was lowest on open stand and it was higher under Acacia auriculiformis and Casuarina equisetifolia plantation stands. The contribution of grasses to the total herbage yield was maximum (98%) on open stand and minimum (27%) under C. equisetifolia plantation stand. Herbage yield in the present study also indicated an inverse relationship with soil ESP and pH, thus suggesting that on improving the sodic level of the soil, the herbage yield also increased. Shannon – Wiener diversity was lower, while concentration of dominance was higher for ground vegetation on open stand than any of the plantation stand. Among the plantation stands, diversity was higher under A. catechu, E. tereticornis and Terminalia arjuna plantation stands than under other plantation stands. Diversity tended to show a positive relation with the herbage yield, whereas the relationships between diversity and soil ESP and pH were negative. Dominance-diversity curves for all the herbaceous communities fit the geometric series. Single species dominance is more pronounced in the community on open stand than the communities under tree plantation stands.

Sustainability assessment of sodic land reclamation using remote sensing and GIS

Sodicland reclamation in the Indo-Gangetic plains is being done on a large scale in the states of Uttar Pradesh, Punjab and Haryana in India. However, in certain areas, the reclamation has been reported to be unsustainable and the soils are reverting back to sodicity condition. A study was conducted in one of the reclamation sites of Etawah district for sustainability assessment of sodic land reclamation using remote sensing, Geographic Information system (GIS) and ancillary ground information. Multitemporal satellite data were used for delineation of reclaimed sodiclands and reverted sodic land. Field survey was conducted to find out the various causative factors. Groundwater level information and detailed field survey data were analysed in GIS environment. Results showed that in the reclamation site covering 3,905 ha. in 57 villages of the district, about 27 per cent of reclaimed lands were reverted to sodicity. High water table condition, improper drainage, nearness to canal (within 500 m), and hard pan in the sub-soil were found to be the reasons for unsustainability of reclamation.

Physicochemical methods for monitoring seasonal variations in Cl–, F–, and Fe++ in underground water in Unnao District in Uttar Pradesh (India)

The variations of Cl( - ), F( - ), and Fe( + + ) in the underground water during pre- and post-monsoon periods for 2003 have been examined, for two places in Unnao district, by argentrometric titration method (Sodic Land Reclamation Project Uttar Pradesh 1998) and atomic absorption spectrometry (Sodic Land Reclamation Project Uttar Pradesh 1998). The concentration of these ions falls outside the limits prescribed by the World Health Organization (WHO 1984).

Distribution analysis of salt affected soils under canal and non-canal command area in a part of Etah district, U. P., using remote sensing technique

A World Bank-aided project on sodic land reclamation in Uttar Pradesh is being executed by U.P. Bhumi Sudhar Nigam, Lucknow, and Remote Sensing Applications Centre, U.P., Lucknow has the responsibility of sodic land mapping for the execution of land reclamation programme at the cadastral level. Sodic lands are mainly concentrated in the Gangetic alluvial plains but the problem of sodicity is particularly acute in the canal-irrigated areas. A study of the distribution pattern of sodic lands in canal and noncanal command areas in a reclamation site (covering 60 villages out of which sodic lands were mapped in 51 villages) of Etah district in Uttar Pradesh, indicates that 18.39 per cent area of the canal command villages was barren sodic which was 13.41 per cent of the total geographical area of the site (15417 ha), however, 11.69 per cent area was recorded to be barren sodic in the non-canal command villages which was only 3.16 per cent of the geographical area of the site. The results of soil chemical analysis indicate that barren sodic lands of canal command area are saline-sodic with higher concentration of soluble salts (pH2 >8.5, EC2 >4 dSm−1), however, those of non-canal command area are sodic (pH2 >8.5, EC2 <4 dSm−1). The post-monsoon ground level in the canal-irrigated areas was in the critical and semicritical zone (< 3.0 mbgl) whereas it was well below the semi-critical zone in the non-canal command area, which indicates that the high ground water level is a major factor to higher the area under sodicity.

Phytoremediation of a sodic forest ecosystem: plant community response to restoration process.

The creation of a new biotope on degraded lands is the focused objective nowadays, on a global level. An attempt was made to rehabilitate sodic waste lands through the establishment of plant cover, with diverse plant communities within Banthra Research Station of the National Botanical Research Institute, Lucknow, India (80degr45min-53degr53min E and 26degr40min- 26degr45min N) for the last three decades. A rehabilitated forest ecosystem developed in this way consists in a number of herbs, shrubs and trees. Derris indica, Dalbergia sissoo, Azadirachta indica, Cassia siamea, Terminalia arjuna, Syzigium cumin were the dominant species in this rehabilitated forest, whereas Sporobolus, Desmostachya and Dactyloctenium were a common genera of grasses /forbs on a barren land. This study showed that species diversity and productivity significantly influenced the soil amelioration process. A comparison of three afforested sites with a varying degree of productivity and diversity indicated that some soil properties were influenced by diversity while others by productivity. Individual effects of diversity and productivity were classified as 42% and respectively 58%, in soil reclamation. A combined effect of both biomass productivity and species diversity contributed about 92% towards amelioration. There was an appreciable reduction in soil pH and ESP (exchangeable sodium percentage) and an increase in organic C and N contents showing that sodicity has receded in the forested soil. This experience can be tried out on similar sites of arid and semiarid regions of the world for the bioreclamation of sodic lands.

Diversity and productivity of a plantation developed on sodic wasteland

Different aspects of plant diversity and productivity were studied in a 40-yr-old rehabilitated forest developed on barren sodic land at Banthra, Lucknow, U.P. It was a dry semi-deciduous forest with both planted as well as invading species. Tree species were grouped in two strata: overstorey and understorey with 44 and 8 species, respectively. Three stands, each of about 1 ha were selected according to gross morphology, population density and different basal area of 21-39 m2 ha-1. Dominant species were established on the basis of in importance value index. Stands were compared for population size, dominance, species richness, heterogeneity and several diversity indices. On average, the forest consisted of a high equitability (0.73) and less redundancy (0.27) with a Shannon Weiner’s general diversity index of 2.45. The forest biomass has been estimated as 329 Mg ha-1 for overstorey and 5 Mg ha-1 for understorey.

Tree species diversity and dominance in a man-made forest on sodic wasteland of North India

The study was conducted with the objective of studying tree species diversity and dominance and the associated changes in soil characteristics in a man-made forest established on formerly barren sodic land at Banthra Research Station (National Botanical Research Institute, Lucknow, India) (80° 45–53′ E, 26° 40–45′N) over three decades. The results revealed that the forest has a moderate value for the tree species diversity index (H). The tree species Derris indica, Dalbergia sissoo, Azadirachta indica, Cassia siamea, Terminalia arjuna, Syzygium cumini, and Tectona grandis were found to be the major dominant species which may be considered suitable for planting on such degraded wastelands. There was a perceptible reduction in soil pH and exchangeable sodium percentage (ESP) and an increase in organic C and Ca2++Mg2+ cation contents over the past three decades, indicating that the sodicity has declined in the surface soil.

Leguminous trees for the restoration of degraded sodic wasteland in eastern Uttar Pradesh, India

AbstractThe study was carried out in sodic lands of Sultanpur District, Uttar Pradesh, India. The barren soils and the soils supporting 3‐, 6‐ and 9‐year‐old plantations of Prosopis juliflora (Swartz) D.C. and Dalbergia sissoo Roxb. Ex. D.C. plantations were examined to assess the rate and extent of changes undergone by physical and chemical properties of the soil. The study brought out that these species indicated the process of soil rehabilitation from the early stages of growth and the extent of rehabilitation increased with the age of the plantation. P. juliflora was found to be more efficient in reclaiming the soil in comparison to D. sissoo. The decline in soil pH and exchangeable sodium percentage (ESP) indicates the desodification and enrichment with organic C, N, P and K indicates improvement in nutrient status of the soil. After 9 years of planting the surface soil was completely desodified as indicated by pH (&lt;8ċ5), ESP (&lt;15) and sodium adsorption ration (&lt;15). A significant increase in organic C, exchangeable Ca2+ and Mg2+ and decrease in exchangeable Na+ reveals that the nutrient status is attaining suitable balance. The physical attributes of the soil also underwent improvement in terms of increase in porosity, water‐holding capacity, field capacity and decline in bulk density. The flocculation of dispersed soil surface and improvement in soil structure was indicated by increased infiltration rate (cm h−1) and soil permeability (cm2). Copyright © 2003 John Wiley &amp; Sons, Ltd.