Significant loss of soil inorganic carbon at the continental scale.

Widespread soil acidification due to atmospheric acid deposition and agricultural fertilization may greatly accelerate soil carbonate dissolution and CO release. However, to date, few studies have addressed these processes. Here, we use meta-analysis and nationwide-survey datasets to investigate changes in soil inorganic carbon (SIC) stocks in China.

[Reduction of Soil Cadmium Activity and Rice Cadmium Content by 4-year-consecutive Application of Organic Fertilizer].

Because commercial organic fertilizers may contain cadmium (Cd) and may cause the dual effect of "inhibition" and "activation" on Cd availability in paddy soil with organic fertilizer input, the reduction of rice Cd following organic fertilizer application is still uncertain. Herewith, typical purple mud paddy fields were selected in the eastern Hunan Province. The effect of commercial organic fertilizer input on Cd reduction of double-rice paddy ecosystem was monitored for four consecutive years.

[Ecological Stoichiometry of Carbon, Nitrogen, and Phosphorus in Subtropical Paddy Soils].

This study aims to understand the existence of stable soil organic carbon (C), nitrogen (N), and phosphorus (P) ratios in paddy soil. Based on a field soil survey database, the ecological stoichiometry of the C:N:P ratio of 110 subtropical paddy soil profiles and 587 genetic horizons were analyzed at a regional scale. Relevant analysis and redundancy analysis (RDA) are used to study the relationships between C:N:P ratios and soil-environmental factors (topography, parent materials, soil genetic horizons, soil groups, soil physical, and chemical properties).

Effect of biochar from peanut shell on speciation and availability of lead and zinc in an acidic paddy soil.

Biochar has been used to reduce the mobility and availability of heavy metals in contaminated paddy soils. A pot experiment was carried out to analyze the effects of peanut shell biochar (PBC) on the speciation and phytoavailability of Pb and Zn in contaminated acidic paddy soil using rice (Oryza sativa L.) as an indicator plant.

Foliar application of Zn can reduce Cd concentrations in rice (Oryza sativa L.) under field conditions.

Cadmium (Cd) pollution in rice and its transfer to food chain are cause of global concern. Application of zinc (Zn) can reduce Cd uptake by plants, as both these metals are generally antagonistic in soil-plant systems. In a field experiment on Cd-contaminated acid soil, we investigated the effectiveness of foliar application of Zn in minimizing Cd accumulation and its effect on the content of mineral nutrient elements in rice.

Effect of peanut shell and wheat straw biochar on the availability of Cd and Pb in a soil-rice (Oryza sativa L.) system.

Soil amendments, such as biochar, have been used to enhance the immobilization of heavy metals in contaminated soil. A pot experiment was conducted to immobilize the available cadmium (Cd) and lead (Pb) in soil using peanut shell biochar (PBC) and wheat straw biochar (WBC), and to observe the accumulation of these heavy metals in rice (Oryza sativa L.).

[Change characteristics of rice yield and soil organic matter and nitrogen contents under various long-term fertilization regimes].

A long-term (1982-2010) field experiment was conducted in the Red Soil Experiment Station of Chinese Academy of Agricultural Sciences in Qiyang County of Hunan Province, South-central China to investigate the dynamic changes of rice yield and soil organic matter (OM) and nitrogen contents under different fertilization treatments. The treatments included NPK, NPKM (M: manure), NPM, NKM, PKM, M, and CK. Fertilization increased the soil OM, total N, and alkaline-hydrolysable N contents and the rice yield.

[Profile of soil microbial biomass carbon in different types of subtropical paddy soils].

The soil microbial biomass carbon (C(mic)), one of the most active components of soil organic carbon (C(org)), is an effective indicator of soil quality. In the present study, five subtropical paddy soils developed from different parent materials were selected, and the distribution of C(mic) through the profiles was studied, as well as the relationship of C(mic) with C(org) and soil nutrients. The results showed that the contents of C(org) and C(mic) decreased markedly with increasing soil depth, ranging from 2.

[Influence of soil iron oxide on VNIR diffuse reflectance spectroscopy].

The influences of iron oxide on soil reflectance, soil line parameter, organic matter spectral characterization and the shape of soil reflectance spectra were studied in the present paper with thirteen samples in several soil types, which covered a range of iron oxide content obtained from various combination of original and iron-removing samples. The results highlight that (1) a decrease on 350-570 nm and an increase on 570-2 500 nm were showed in the reflectance spectra with increasing iron oxide content. However, there was no significant correlation between iron oxide and spectral reflectance quantitatively; (2) iron oxide content had a negative linear correlation with soil line slope and a positive linear correlation with intercept, both were significant, which illustrated the feasibility of iron oxide prediction using soil line parameter; (3) the spectral characteristics of soil organic matter could be covered by iron oxide on 622-851 nm; (4) iron oxide in soil had influence on the shape of reflectance spectra after continuum removal and calculating statistical F and spectral angle.

[Quantifying rice (Oryza sativa L.) photo-assimilated carbon input into soil organic carbon pools following continuous 14C labeling].

The microcosm experiment was carried out to quantify the input and distribution of photo-assimilated C into soil C pools by using a 14C continuous labeling technique. Destructive samplings of rice (Oryza sativa) were conducted after labeling for 80 days. The allocation of 14C-labeled photosynthates in plants and soil C pools such as dissolved organic C (DOC) and microbial biomass C (MBC) in rice-planted soil were examined over the 14C labeling span.

[Content of soil heavy metals and characteristics of environmental quality in tea plantations of Changsha Baili Tea Zone].

The distributing and changing characteristics and content of soil heavy metals was studied using methods of field survey and sampling, indoor analysis, and pollution index were used to investigate the soil environmental quality in the tea plantations of Changsha Baili Tea Zone. The results showed that the content of soil total Pb, Hg, Cd, Cr, As, Ni basically was in the soil background value, their averages were 42.7, 0.