[Economical nitrogen application rate of winter wheat under rice-wheat rotation in the Yangtze River basin of China].

To promote the rational application of nitrogen fertilizer for winter wheat under rice-wheat rotation in the Yangtze River Basin, we examined the effects of nitrogen application rates (0, 120, 210, 300 kg·hm, expressed as N, N, N, and N respectively) on soil nitrate content, nitrogen balance of soil-plant system and yield. The results showed that soil nitrate content increased with increasing nitrogen application rates. Under different nitrogen application treatments, all the nitrate was significantly transfered to the 60 cm soil layer till jointing stage.

[Characteristics of uptake, residual and loss of nitrogen fertilizer in winter wheat after rice stubble].

To promote the rational application of nitrogen fertilizer in winter wheat after rice stubble, the effects of nitrogen application rate (0, 150, 225, 300 kg·hm, expressed as N, N, N, N) on nitrogen recovery, residue, loss and grain yield were examined using field N tracer technology. The results showed that with the increases of application rate, nitrogen accumulation from different sources significantly increased while nitrogen recovery significantly decreased. The accumulation of basal nitrogen in plants reached the peak during overwintering stage to jointing stage, while the accumulation of topdressing nitrogen peaked between jointing to flowering stage.

[Heavy Metal Contents in Animal Manure in China and the Related Soil Accumulation Risks].

The environmental risks posed by heavy metals (HMs) in animal manure are increasing because of the use of trace metals as additives in feedstuffs. Manure samples were collected, and published literature was reviewed in this study to systematically analyze the HMs content in animal manure and compare the results to different sources of animal manures. Results show that the distribution of HMs content in animal manure was skewed.

Application of magnesium modified corn biochar for phosphorus removal and recovery from swine wastewater.

The recycling of lost phosphorus (P) is important in sustainable development. In line with this objective, biochar adsorption is a promising method of P recovery. Therefore, our study investigates the efficiency and selectivity of magnesium modified corn biochar (Mg/biochar) in relation to P adsorption.

[Application of ICP-mS and AFS to detecting heavy metals in phosphorus fertilizers].

In order to investigate heavy metals in phosphorus fertilizers in China, 159 samples of phosphorus fertilizers including imported fertilizers and domestic fertilizers were collected from fertilizer markets, and the contents of heavy metals were determined by ICP-MS and AFS after microwave digestion. The results showed that the phosphorous fertilizers contained certain amount of heavy metals, and there was great variability in the contents of heavy metals. The mean contents of Cd, Cu, Zn, Cr, Pb, Ni, As and Hg were 0.

Greenhouse gas emissions from a wheat-maize double cropping system with different nitrogen fertilization regimes.

Here, we report on a two-years field experiment aimed at the quantification of the emissions of nitrous oxide (N2O) and methane (CH4) from the dominant wheat-maize double cropping system in North China Plain. The experiment had 6 different fertilization strategies, including a control treatment, recommended fertilization, with and without straw and manure applications, and nitrification inhibitor and slow release urea. Application of N fertilizer slightly decreased CH4 uptake by soil.

Application of rhizosphere interaction of hyperaccumulator Noccaea caerulescens to remediate cadmium-contaminated agricultural soil.

There is an urgent requirement for selecting appropriate technologies to solve food safety problems due to soil contamination. In this study, the hyperaccumulator Noccaea caerulescens and a high Cd accumulator pakchoi cultivar (Brassica rapa L. spp.

[Uptake and translocation of selenate or selenite by wheat and rice seedlings].

Solution culture experiments were carried out to study the uptake and translocation of selenate (Na2SeO4) or selenite (Na2SeO3) by wheat and rice seedlings. When supplied with Na2SeO4 in nutrient solution, the concentrations of selenium (Se) in normal shoots and roots of rice were 30.3 mg x kg(-1) and 39.

[Effect of the soil bulk density on the root morphology and cadmium uptake by Thlaspi caerulescens grown on Cd-contaminated soil].

A pot experiment was conducted using a soil contaminated with 2.12 mg x kg(-1) Cd to study the effect of the variety of the soil bulk density on the Zn/Cd uptake by the hyperaccumulator Thlaspi caerulescens and the removal of Cd and Zn from the soil. The contaminated soil received 0, 0.

[Optimal operating condition of ICP-aES for determination of soil nutrients extracted by Mehlich 3 through solution simulation].

As a key process of fertilization with soil test, the determination of soil effective nutrients has received great attention in recent years. Based on a series of standard solution mixtures, which simulate the soil nutrients extracted by Mehlich 3 (M3) reagent, the optimal operating condition of ICP-AES was explored in a systematic way. The results show that the 20 key nutrient elements (P, K, Ca, Mg, Na, Fe, Mn, Cu, Zn, Cd, Cr, Pb, Ni, Al, B, Mo, S, Si, Se, and As) in the solutions can be determined correctly and proficiently when ICP-AES is set at 0.

[Content determination of different species of Pb, As, and Cd in the municipal sewage sludge of Beijing with ICP-MS].

Heavy metals in municipal sewage sludge can limit the utilization of sludge resources, due to their recalcitrant characteristics and harmful effects. Here, ICP-MS was used to determine the total and special content of Pb, As and Cd in the sewage sludge from G and Q Wastewater Treatment Plants, Beijing. The air-dried samples were dissolved in HNO3-HClO4 before the total content determination, or, sequentially extracted with BCR three-step method before special content determination for the heavy metals.

Accumulation of cadmium in the edible parts of six vegetable species grown in Cd-contaminated soils.

Species difference in Cd accumulation is important for selection of agronomic technologies aimed at producing low-Cd vegetables. Six vegetable species (Chinese leek, pakchoi, carrot, radish, tomato and cucumber) were grown in pot and field experiments to study the accumulation of Cd under different conditions. In the field trial (Cd 2.

[Nutrient management strategy of paddy rice-upland crop rotation system].

Paddy rice-upland crop rotation system is a major cropping system in China, and practiced widely along the Yangtze River basin. A unique feature of this system is the annual conversion of soil from aerobic to anaerobic and then back to aerobic condition, which can result in the changes of soil physical, chemical, and biological prosperities among seasons, making a special agroecosystem. The major challenges faced by this system include declining or stagnating productivity, increasing shortage of irrigation water, improper management of nutrients, low efficiency of resource utilization, and environmental pollution.

Cadmium accumulation in the edible parts of different cultivars of radish, Raphanus sativus L., and carrot, Daucus carota var. sativa, grown in a Cd-contaminated soil.

Cadmium accumulation among 12 cultivars of radish (Raphanus sativus) and 10 cultivars of carrot (Daucus carota var. sativa) was studied in a Cd-contaminated soil. The Cd concentration in the edible parts of radish and carrot ranged from 0.

Does cadmium play a physiological role in the hyperaccumulator Thlaspi caerulescens?

The southern French (Ganges) ecotype of Thlaspi caerulescens J & C Presl is able to hyperaccumulate several thousand mg Cd kg(-1) shoot dry weight without suffering from phytotoxicity. We investigated the effect of Cd on growth and the activity of carbonic anhydrase (CA), a typical Zn-requiring enzyme, of T. caerulescens in soil and hydroponic experiments.