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China's croplands have experienced drastic changes in management practices, such as fertilization, tillage, and residue treatments, since the 1980s. There is an ongoing debate about the impact of these changes on soil organic carbon (SOC) and its implications. Here we report results from an extensive study that provided direct evidence of cropland SOC sequestration in China. Based on the soil sampling locations recorded by the Second National Soil Survey of China in 1980, we collected 4,060 soil samples in 2011 from 58 counties that represent the typical cropping systems across China. Our results showed that across the country, the average SOC stock in the topsoil (0-20 cm) increased from 28.6 Mg C ha in 1980 to 32.9 Mg C ha in 2011, representing a net increase of 140 kg C ha year However, the SOC change differed among the major agricultural regions: SOC increased in all major agronomic regions except in Northeast China. The SOC sequestration was largely attributed to increased organic inputs driven by economics and policy: while higher root biomass resulting from enhanced crop productivity by chemical fertilizers predominated before 2000, higher residue inputs following the large-scale implementation of crop straw/stover return policy took over thereafter. The SOC change was negatively related to N inputs in East China, suggesting that the excessive N inputs, plus the shallowness of plow layers, may constrain the future C sequestration in Chinese croplands. Our results indicate that cropland SOC sequestration can be achieved through effectively manipulating economic and policy incentives to farmers.

Soils maps of China have been generated at different scales from ground surveys and laboratory analyses. A comprehensive effort coordinated by the Office for the Second National Soil Survey of China resulted in a series of soil maps covering the extent of the country at a scale of 1:1,000,000. The map series is now being converted from its current paper form to a digital format. The 1:1,000,000 digital soil map of China will consist of three parts: soil mapping unit boundaries, soil attributes, and the “reference system for Chinese soils.”The spatial data is based on the soil genetic classification of China, consisting of 12 orders, 61 great groups, 235 subgroups, and 909 families. The 1:1,000,000 soil maps are delineated based on the soil family definitions. The sampled soil attributes included physical, chemical, and fertility properties measured for 2473 soil species (series) (known as TuZhong in Chinese). The reference system for Chinese soils will use the attribute data for each soil species (series) to cross reference soil names in three classification systems, namely, Soil Genetic Classification of China, U.S. soil taxonomy, and the FAO World Reference Base for Soil Resources (WRB). The cross‐reference system will be constructed in a relational database so that any Chinese or international scientists can access equivalent names for a soil in any of the three systems.

The first efficient asymmetric total syntheses of xestodecalactones B and C have been accomplished in 10 steps with an overall yield of 22 and 20.2%, respectively. The key steps involve the utility of Evans oxazolidinone-mediated syn-aldol condensations to establish the C-9 configuration and the macrolide ring formation by intramolecular acylation. The absolute configurations of xestodecalactones B and C have been determined via these syntheses.