Following the modern-day urbanization and industrialization, heavy metal contamination has become a prime concern for today’s society. Starting from the agricultural soil in our food basket these heavy metals and metalloids, like - Cr, Mn, Co, Ni, Cu, Zn, Cd, Sn, Hg,Pb and others, showing significant toxic impacts. The intensification of agricultural land-use and changes in farming practices along with technological advancement has led to heavy metal pollution in soil. Metals/ metalloids concentrations in the soil are increasing at alarming rate due to modern day agricultural practices as these could not be degraded and affect plant growth, food safety and soil microflora. The biological and geological reorganization of heavy metal depends chiefly on green plants and their metabolism. Metal toxicity has direct effects and importance to flora that forms the integral component of ecosystem. Altered biochemical, physiological and metabolic processes are found in plants growing in regions of high metal pollution. However, metals like Cu, Mn, Co, Zn and Cr are required in trace amounts by plants for their metabolic activities. The present review aims to catalogue major published works related to heavy metal contamination in modern day agriculture, and draw a possible road map towards future research in this domain.

Glyphosate [N-(phosphonomethyl)-glycine] is a broad-spectrum, non-selective, post-emergence herbicide that is widely used in agricultural. We studied, in vitro, changes in the microbial activity of typical Hapludult and Hapludox Brazilian soils, with and without applied glyphosate. Glyphosate was applied at a rate of 2.16 mg glyphosate kg(-1) of soil and microbial activity was measured by soil respiration (evolution of CO(2)) and fluorescein diacetate (FDA) hydrolysis over a period of 32 days. We found an increase of 10-15% in the CO(2) evolved and a 9-19% increase in FDA hydrolyses in the presence of glyphosate compared with the same type of soil which had never received glyphosate. Soil which had been exposed to glyphosate for several years had the strongest response in microbial activity. Most probable number (MPN) counts showed that after 32 days incubation the number of actinomycetes and fungi had increased while the number of bacteria showed a slight reduction. After the incubation period, high pressure liquid chromatography (HPLC) detected the glyphosate metabolite aminomethyl phosphonic acid (AMPA), indicating glyphosate degradation by soil microorganisms.

Land‐use change is one of the most important anthropogenic environmental change drivers affecting the biodiversity and functioning of ecosystems. However, there is limited knowledge of the consequences for soil processes in many regions around the globe. The Brazilian semi‐arid ecosystem known as Caatinga has experienced the transformation from native forest into agricultural land, with heretofore unknown effects on soil processes and microbial properties. The aim of this study was to evaluate the impact of five land‐use changes (to maize and cowpea cropland, grape orchard, and cut and grazed pasture) on total organic C (TOC) and total N (TN) stocks and soil microbial properties of Ultisol from Caatinga. Soil samples (0–10 and 10–20 cm depth) were collected during the wet and dry periods. Split–split plot analysis of variance was used to test the effects of land use, soil depth, season and the interaction between land‐use and soil depth on soil microbial properties, TOC and TN stocks. Land‐use effects were more pronounced in the top soil layer than in the lower layer, while the pattern was less consistent in soil microbial properties. Land conversion from native forest to cropland may cause C losses from the soil, but conversion to pastures may even increase the potential of soils to function as C sinks. Grazed pastures showed not only high C and N stocks but also the highest soil microbial biomass and lowest respiratory quotients, all indications for elevated soil C sequestration. Thus, grazed pastures may represent a land‐use form with high ecosystem multifunctionality in Caatinga. Copyright © 2014 John Wiley & Sons, Ltd.