scholarly journals Rhizobium-Legume Symbiosis and Nitrogen Fixation under Severe Conditions and in an Arid Climate

1999 ◽  
Vol 63 (4) ◽  
pp. 968-989 ◽  
Author(s):  
Hamdi Hussein Zahran
Keyword(s):  
Heavy Metals ◽  
Agricultural Soils ◽  
Nutrient Deficiency ◽  
Arid Lands ◽  
Stress Factors ◽  
Future Research ◽  
Stress Effects ◽  
Legume Symbiosis ◽  
Important Direction ◽  
Synthetic Fertilizers

SUMMARY Biological N2 fixation represents the major source of N input in agricultural soils including those in arid regions. The major N2-fixing systems are the symbiotic systems, which can play a significant role in improving the fertility and productivity of low-N soils. The Rhizobium-legume symbioses have received most attention and have been examined extensively. The behavior of some N2-fixing systems under severe environmental conditions such as salt stress, drought stress, acidity, alkalinity, nutrient deficiency, fertilizers, heavy metals, and pesticides is reviewed. These major stress factors suppress the growth and symbiotic characteristics of most rhizobia; however, several strains, distributed among various species of rhizobia, are tolerant to stress effects. Some strains of rhizobia form effective (N2-fixing) symbioses with their host legumes under salt, heat, and acid stresses, and can sometimes do so under the effect of heavy metals. Reclamation and improvement of the fertility of arid lands by application of organic (manure and sewage sludge) and inorganic (synthetic) fertilizers are expensive and can be a source of pollution. The Rhizobium-legume (herb or tree) symbiosis is suggested to be the ideal solution to the improvement of soil fertility and the rehabilitation of arid lands and is an important direction for future research.

Bacteria in agricultural soils: Diversity, role and future perspectives

2003 ◽  
Vol 83 (Special Issue) ◽  
pp. 303-309 ◽  
Author(s):  
E. Topp
Keyword(s):  
Soil Bacteria ◽  
Crop Production ◽  
Agricultural Soils ◽  
Future Research ◽  
Functional Biodiversity ◽  
Microbial Biodiversity ◽  
Soil Microbial ◽  
Pesticide Biodegradation ◽  
Important Object ◽  
Bacterial Biodiversity

Bacteria in soil are very diverse, very numerous, and functionally important, and have historically been an important object of research by Canadian microbiologists. Only a small fraction of bacteria in soils are amenable to culturing in the laboratory, limiting the ability to study these organisms. Canadian scientists have contributed to the development and implementation of both nucleic acidbased and chemical biomarker-based methods now widely used for assessing soil microbial biodiversity without the need for isolation and cultivation. Pesticide degradation, and the cycling of nitrogen in soils are used here to illustrate the significance of bacterial biodiversity to soil functions relevant to human and environmental health, and crop production . There remains much to be discovered about the genetic and functional biodiversity of soil bacteria, and much to be gained from this knowledge. A number of recommendations are made for future research in soil bacteriology. Key words: Soil quality, bacteria, microbial biodiversity, pesticide biodegradation, nitrogen cycling.

Vertical Distribution and Mobility of Heavy Metals in Agricultural Soils along Jishui River Affected by Mining in Jiangxi Province, China

2014 ◽  
Vol 42 (10) ◽  
pp. 1450-1456 ◽  
Author(s):  
Guannan Liu ◽  
Wei Xue ◽  
Li Tao ◽  
Xinhui Liu ◽  
Jing Hou ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Vertical Distribution ◽  
Agricultural Soils ◽  
Jiangxi Province

scholarly journals Assessment of heavy metals in soils of a vineyard region with the use of principal component analysis

2009 ◽  
Vol 66 (3) ◽  
pp. 361-367 ◽  
Author(s):  
Gustavo Souza Valladares ◽  
Otávio Antônio de Camargo ◽  
José Ruy Porto de Carvalho ◽  
Alessandra Maria Cia Silva
Keyword(s):  
Heavy Metals ◽  
Principal Component Analysis ◽  
Agricultural Soils ◽  
Principal Component ◽  
Component Analysis ◽  
Soil Samples ◽  
Metal Concentrations ◽  
Zn Content ◽  
Heavy Metals In Soils ◽  
Cu And Zn

Agricultural management with chemicals may contaminate the soil with heavy metals. The objective of this study was to apply Principal Component Analysis and geoprocessing techniques to identify the origin of the metals Cu, Fe, Mn, Zn, Ni, Pb, Cr and Cd as potential contaminants of agricultural soils. The study was developed in an area of vineyard cultivation in the State of São Paulo, Brazil. Soil samples were collected and GPS located under different uses and coverings. The metal concentrations in the soils were determined using the DTPA method. The Cu and Zn content was considered high in most of the samples, and was larger in the areas cultivated with vineyards that had been under the application of fungicides for several decades. The concentrations of Cu and Zn were correlated. The geoprocessing techniques and the Principal Component Analysis confirmed the enrichment of the soil with Cu and Zn because of the use and management of the vineyards with chemicals in the preceding decades.

scholarly journals Arsenic and heavy metal concentrations in agricultural soils in South Savo province

2002 ◽  
Vol 11 (4) ◽  
pp. 285-300 ◽  
Author(s):  
V. MÄNTYLAHTI ◽  
P. LAAKSO
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Agricultural Soils ◽  
Mineral Soil ◽  
Soil Samples ◽  
Potential Hazard ◽  
Metal Concentrations ◽  
Limit Values ◽  
Heavy Metal Concentrations ◽  
Target Values

Increasing concentrations of arsenic and heavy metals in agricultural soils are becoming a growing problem in industrialized countries. These harmful elements represent the basis of a range of problems in the food chain, and are a potential hazard for animal and human health. It is therefore important to gauge their absolute and relative concentrations in soils that are used for crop production. In this study the arsenic and heavy metal concentrations in 274 mineral soil samples and 38 organogenic soil samples taken from South Savo province in 2000 were determined using the aqua regia extraction technique. The soil samples were collected from 23 farms.The elements analyzed were arsenic, cadmium, chromium, copper, mercury, nickel, lead and zinc. The median concentrations in the mineral soils were:As 2.90 mg kg –1, Cd 0.084 mg kg –1, Cr 17.0 mg kg –1, Cu 13.0 mg kg –1, Hg 0.060 mg kg –1, Ni 5.4 mg kg –1, Pb 7.7 mg kg –1, Zn 36.5 mg kg –1. The corresponding values in the organogenic soils were:As 2.80 mg kg –1, Cd 0.265 mg kg –1, Cr 15.0 mg kg –1, Cu 29.0 mg kg –1, Hg 0.200 mg kg –1, Ni 5.9 mg kg –1, Pb 11.0 mg kg –1, Zn 25.5 mg kg –1. The results indicated that cadmium and mercury concentrations in the mineral and organogenic soils differed. Some of the arsenic, cadmium and mercury concentrations exceeded the normative values but did not exceed limit values. Most of the agricultural fields in South Savo province contained only small amounts of arsenic and heavy metals and could be classified as “Clean Soil”. A draft for the target values of arsenic and heavy metal concentrations in “Clean Soil” is presented.;

Sign in / Sign up

Export Citation Format

Share Document