Harvesting more grain zinc of wheat for human health.

Increasing grain zinc (Zn) concentration of cereals for minimizing Zn malnutrition in two billion people represents an important global humanitarian challenge. Grain Zn in field-grown wheat at the global scale ranges from 20.4 to 30.5 mg kg-1, showing a solid gap to the biofortification target for human health (40 mg kg-1). Through a group of field experiments, we found that the low grain Zn was not closely linked to historical replacements of varieties during the Green Revolution, but greatly aggravated by phosphorus (P) overuse or insufficient nitrogen (N) application. We also conducted a total of 320-pair plots field experiments and found an average increase of 10.5 mg kg-1 by foliar Zn application. We conclude that an integrated strategy, including not only Zn-responsive genotypes, but of a similar importance, Zn application and field N and P management, are required to harvest more grain Zn and meanwhile ensure better yield in wheat-dominant areas.

[Remediation of Cd/Ni Contaminated Soil by Biochar and Oxalic Acid Activated Phosphate Rock].

Taking soil contaminated with a combination of Cd and Ni as the research objective, biochar, and oxalic acid activated phosphate rock (APR) were applied both together and separately for the remediation of this contaminated soil. The effects of different ratios of amendments on the remediation of Cd and Ni heavy metals in the soil and on inorganic nitrogen and microbial biomass nitrogen (MBN) in the soil were compared. The results show that an increasing amount of biochar and APR, increases the soil pH gradually and acid-extractable Cd and Ni are gradually transformed into reducible, oxidable and residual Cd and Ni, resulting in a reduction in Cd and Ni bioavailability. After 40 days incubation, the acid extractable Ni decreased by 37.04% with a 14.8% increase in residual Ni, and acid extractable Cd decreased 40.28% with a 35.20% increase in residual Cd with the amendment of C50P3 (Applying 50 g·kg-1 biochar and 3 g·kg-1 APR) when compared to C0P0 treatment (Applying nothing). Furthermore, the MBN content for C50P0 (Applying 50 g·kg-1 biochar only) and C0P3 (Applying 3 g·kg-1 APR only) increased by 1.5 and 1 times, respectively, while the content of ammonium nitrogen decreased by 12.5% and 6.4%, respectively and the content of nitrate nitrogen decreased by 11.6% and 10.2%, respectively. This comparison shows that the combined effect of the application of biochar and APR is superior to each respective separate treatment. A mixture of 50 g·kg-1 of biochar and 3g·kg-1 of APR (C50P3) demonstrates the best effect on the remediation of the Cd and Ni in soil. Furthermore, the application of amendments promoted the transformation of inorganic nitrogen into organic nitrogen.

[Assessment of groundwater vulnerability to nitrate in He'nan Province of China based on principal component regression].

According to the hydrological and morphological characteristics, He'nan Province was divided into mountainous region and plain region. The level of rich water, infiltration modulus of precipitation, fertilization level per unit area, proportions of vegetable planting area, and soil texture were selected as the common indices, and the slope and groundwater depth were selected as specific indices to assess the groundwater vulnerability to nitrate. Principal component regression analysis was adopted to determine the index weights, and the spatial distribution of groundwater vulnerability to nitrate in He'nan Province was assessed with ArcGIS 9.2. In the Province, the groundwater vulnerability to nitrate was mainly at low and medium level, and the region with this vulnerability level accounted for 68.4% of the total. The high vulnerability region accounted for 19.8%, and the extremely high vulnerability region occupied 11.8%. The main factors affecting the groundwater vulnerability to nitrate in plain region were soil texture, fertilization level, and infiltration modulus of precipitation, while those in mountainous region were fertilization level, soil texture, and slope. This study provided a theoretical basis for reasonable fertilization and agricultural environment management.

[Soil nutrient distribution and its relations with topography in Huangshui River drainage basin].

By using GIS and geostatistic techniques, this paper studied the spatial distribution patterns of soil nutrients and their relationships with topographic factors in Huangshui River drainage basin, a water source of Danjiangkou Reservoir. In the study area, the soil total nitrogen, total phosphorus, and organic matter varied spatially at medium level, with the variation coefficients being 51%, 66%, and 85%, respectively, whereas the soil available phosphorus displayed a strong spatial variation, with the variation coefficient reached 161%. The soil total nitrogen and organic matter exhibited a spatially positive autocorrelation, while the soil total and available phosphorus presented a spatially weak autocorrelation. Altitude was one of the main topographic factors affecting the spatial distribution patterns of the soil nutrients, having significant effects on the spatial distribution of total nitrogen, total phosphorus, and organic matter. Slope and profile curvature also had significant effects on the spatial distribution of the soil total nitrogen and organic matter. Based on these, the regression prediction models of topographic factors and soil nutrient spatial distribution were established, and the digital mappings of the soil nutrients were made, which provided data support for the precise management of soil resources in the study area.