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Heavy metal pollution is a widespread problem and strongly affects human health through the food chain. In this study, the overall pollution situation and source apportionment of heavy metals in soil (Hg, Cd, As, Pb, Ni, Zn, Cu and Cr) were evaluated using various methods including geo-accumulation index (I geo), potential ecological risk index (RI) and positive matrix factorization combined with Geographical Information System (GIS) to quantify and identify the possible sources to these heavy metals in soils. The results of I geo showed that this farmland top soil moderate contaminated by Hg, other selected elements with noncontamination level. And the average RI in the top soil was 259.89, indicating a moderate ecological risk, of which Hg and Cd attributed 88.87% of the RI. The results of the PMF model showed that the relative contributions of heavy metals due to atmospheric depositions (18.70%), sewage irrigations (21.17%), soil parent materials (19.11%), industrial and residential coal combustions (17.43%) and agricultural and lithogenic sources (23.59%), respectively. Of these elements, Pb and Cd were came from atmospheric deposition. Cr was attributed to sewage irrigations. As was mainly derived from the soil parent materials. Hg originated from industrial and residential coal combustions, and most of the Cu, Zn and Ni, except for Pb, were predominantly derived from agricultural and lithogenic sources. These results are important in considering management plans to control the aggravation of heavy metal pollution and ultimately to protect soil resources in this region. In addition, this study enhances the understanding of heavy metal contamination occurrence in agroecosystem that helps predicting and limiting the potential of heavy metal exposure to people and ecosystem.

and then grew the four crops in conspecific and heterospecific soils to examine intra-and inter-specific PSFs. ResultsWe found that crop species, nitrogen and water treatments created differential effects on soil bacteria and fungi diversity and community composition. Wheat grew better in conspecific-conditioned soil than in heterospecific-conditioned soil, whereas maize and soybean performed better in heterospecific-conditioned soils regardless of water and nitrogen treatments. The PSFs of rapeseed depended on the water and nitrogen treatments. The dissimilarity of both soil bacterial and fungal communities showed a consistently positive correlation with the feedback effect for wheat, while it negatively correlated for maize, rapeseed and soybean. Path analysis showed that soil abiotic, bacterial and fungal legacies all impacted the corresponding crop growth. Conclusions We show that via selecting crop species and by changing management practices we can create positive legacies that can enhance the growth

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Phytate-phosphorus (P) in food and feed is not efficiently utilized by humans and non-ruminant livestock, potentially contributing to high losses of P to the environment. Crops with high P-acquisition efficiency can access soil P effectively. It remains elusive whether crop genotypes with high P-acquisition efficiency can also have low seed phytate concentrations. A core collection of 256 soybean [Glycine max (L.) Merr.] genotypes from China with diverse genetic background were grown in the same environment and seeds were sampled to screen for seed phytate-P concentration. Some of these genotypes were also grown in a low-P soil in the glasshouse to measure root morphological and physiological traits related to P acquisition. Large genotypic variation was found in seed phytate-P concentration (0.69–5.49 mg P g–1 dry weight), total root length, root surface area, rhizosheath carboxylates, and acid phosphatase activity in rhizosheath soil. Geographically, seed phytate-P concentration was the highest for the genotypes from Hainan Province, whereas it was the lowest for the genotypes from Inner Mongolia. Seed phytate-P concentration showed no correlation with any desirable root traits associated with enhanced P acquisition. Two genotypes (Siliyuan and Diliuhuangdou-2) with both low phytate concentrations and highly desirable P-acquisition traits were identified. This is the first study to show that some soybean genotypes have extremely low seed phytate concentrations, combined with important root traits for efficient P acquisition, offering material for breeding genotypes with low seed phytate-P concentrations.

Land degradation and desertification are the great concern of arid and semiarid areas. In Euphrates poplar forest, there exists large number of bare spots which have been considered as representative of desertification. In this study, Unmanned Aerial Vehicle (UAV) technology was used to determine the spatial distribution and extract the bare spots area and morphological characteristics of Populus euphratica stands. Besides, the physical and chemical properties between soils inside and outside of these spots were compared. We found that: (1) the UAV method could be reliably used to extract the area of bare spots and the morphological characteristics of Populus euphratica stands;(2) with Pearson correlation coefficients of 0.673 and 0.894, there were a strong correlation relationship between bare spots area and canopy area in both measured and estimated data rather than other morphological characteristics;(3) electrical conductivity, pH, soil water content, total nitrogen, total phosphorus and soil organic matter has great differences between soils inside and outside of bare spots. These results not only could contribute to further understanding of spatial distribution of bare spots, but also helps to the sustainable management of Populus euphratica forest in arid regions.