Evaluation on abundance or deficiency of avai－lable trace elements in soil of middle area in China and the effect of applying trace element fertilizer

The authors selected the west part of Xinxiang City,Henan Province in the north China plain as a typical region and carried out assessments of the abundanca or deficiency of the trace ele- ments(B,Mn,Mo,Zn,Cu,Fe)in soil.It can be seen from results that more than 80% of the farmland is deficiency of zinc(<1.0ppm),40% of molybdenum(0.15ppm),38% of boron(0.5ppm),29% of manganese(100ppm)and 13% of iron(7.0ppm)and that the content of available trace ele- ments in soil are related to the topography closely.Next the proper application of trace elements on grain crops is presented.

Distribution characteristics of available trace elements in soil from a reclaimed land in a mining area of north Shaanxi,China

Through field and laboratory tests we studied the temporal and spatial variation in the soil content of four available trace elements:copper(Cu),iron(Fe),manganese(Mn)and zinc(Zn),to analyze their distribution characteristics in reclaimed mining land under different reclamation conditions.The available trace elements content varied considerably with different land reclamation patterns.Extended reclamation time was helpful for the recovery of the available trace element content in the soil,and after more than eight years of soil reclamation,the content of available trace elements was closer to or greater than that in soil under natural conditions.Various treatment measures significantly influenced the content and distribution of available trace elements in the soil,and reasonable artificial treatments,including covering the soil and growing shrubs and herbaceous plants,increased the content of available trace elements.

Responses of soil microbial communities to manure and biochar in wheat cultivation of a rice-wheat rotation agroecosystem in East China

Soil contamination in agroecosystems remains a global environmental problem. Biochar has been suggested as an organic amendment to alleviate soil pollution, sequester carbon(C), and improve soil fertility. However, information on how bacterial and fungal communities in acidic bulk and rhizosphere soils respond to swine manure and its biochar is still lacking. In this study, biochar and swine manure were applied at two rates of 1.5 and 3 t ha-1in a rice-wheat rotation field to assess how soil characteristics, especially p H and chemical element availability, correlate to compositional variations of bacteria and fungi in bulk and rhizosphere soils. Our results showed that high rates of biochar and manure promoted the bacterial richness in bulk and rhizosphere soils by increasing soil pH and reducing soil arsenic(As) and copper(Cu) availability. Compared with soil As and Cu availability, soil p H had opposite effects on beta diversity of both the bacterial and fungal communities. Specifically, biochar and swine manure applications stimulated the bacterial classes Gemmatimonadetes, Deltaproteobacteria, and Gammaproteobacteria by increasing soil pH and decreasing soil available chemical elements. Opposite trends were observed in fungal communities responding to biochar and manure. For example, biochar restrained the fungal class Eurotiomycetes by decreasing soil As and Cu availability, but manure inhibited Leotiomycetes mainly because of an increase in soil pH and a decrease in soil dissolved organic C. These suggest that both bacterial and fungal communities respond significantly to biochar and manure amendments in both bulk and rhizosphere soils, possibly because of their sensitive adaptation to variations in soil environmental factors, such as pH level and chemical element availability.

Characteristics of biomass ashes from different materials and their ameliorative effects on acid soils

The chemical characteristics,element contents,mineral compositions,and the ameliorative effects on acid soils of five biomass ashes from different materials were analyzed. The chemical properties of the ashes varied depending on the source biomass material. An increase in the concrete shuttering contents in the biomass materials led to higher alkalinity,and higher Ca and Mg levels in biomass ashes,which made them particularly good at ameliorating effects on soil acidity. However,heavy metal contents,such as Cr,Cu,and Zn in the ashes,were relatively high. The incorporation of all ashes increased soil p H,exchangeable base cations,and available phosphorus,but decreased soil exchangeable acidity. The application of the ashes from biomass materials with a high concrete shuttering content increased the soil available heavy metal contents. Therefore,the biomass ashes from wood and crop residues with low concrete contents were the better acid soil amendments.