Soil Properties and Characteristics of Soil Aggregate in Marginal Farmlands of Oasis in the Middle of Hexi Corridor Region, Northwest China

The composition and stability of soil aggregate are closely related to soil quality, soil erosion, and agricultural sustainability. In this study, 49 soil samples at the 0-10 cm surface layer were collected from four soil types （i.e., Ari-Sandic Primosols, Calci-Orthic Aridosols, Siltigi-Otrthic Anthrosols, and Ustic Cambosols） in the marginal farmland in the oasis of the middle Hexi Corridor region and was used to determine the characteristics of soil aggregates. The composition of dry- and wet- sieved aggregates and the physical and chemical properties （including soil particle distribution, soil organic carbon （SOC）, calcium carbonate （CaCO3）, and oxides of Fe^3＋ and Al^3＋） of the selected soils were analyzed. The results show that soil particle size distribution is dominated by fine sand fraction in most of soils except Ustic Cambosols. Soil organic carbon concentration is 5.88 ± 2.52 g kg^-1 on average, ranging from 4.75 g kg^-1 in Ari-Sandic Primosols to 10.51 g kg^-1 in Ustic Cambosols. The soils have high calcium carbonate （CaCO3） concentration, ranging from 84.7 to 164.8 g kg^-1, which is increased with soil fine particle and organic carbon content. The percentage of 〉0.25 mm dry aggregates ranges from 65.2% in Ari-Sandic Primosols to 94.6% in Ustic Cambosols, and large dry blocky aggregates （〉5 mm） is dominant in all soils. The mean weight diameter of dry aggregates （DMWD） ranges from 3.2 mm to 5.5 mm. The percentage of 〉0.25 mm water-stable aggregate is from 23.8% to 45.4%. The percentage of aggregate destruction （PAD） is from 52.4% to 66.8%, which shows a weak aggregate stability. Ari-Sandic Primosols has the highest PAD. The distribution and characteristics of soil aggregates are in favor of controlling soil wind erosion. However, the stability of aggregate of all soils is weak and soils are prone to disperse and harden after irrigation. The mass of macro-aggregates and DMWD are positively significantly correlated with the contents of soil clay and silt, soil organic carbon （SOC）, CaCO3, and oxides of Fe^3＋ and Al^3＋. Soil fine silt and clay, SOC and CaCO3 are important agents of aggregation in this region, and the effect of SOC and CaCO3 on aggregate stability is more significant than that of soil silt and clay. Converting cropland to alfalfa forage land can increase SOC concentration, and in turn, enhance the formation of aggregates and stability. For the marginal farmlands in this fragile ecological area, converting cropland to alfalfa grassland or performing crop-grass rotation is an effective and basic strategy to improve soil structure and quality, to mitigate soil wind erosion, and to enhance oasis agricultural sustainability.

Estimation Study of New Cancer Cases and Deaths in Wuwei, Hexi Corridor Region, China, 2018

Population-based cancer registration data were collected to estimate the cancer incidence and mortality in Wuwei, Hexi Corridor Region, China in 2018. We used the 2011-2013 data to predict the number of new cases and deaths in 2018 and the 2003-2013 data to analyze trends in cancer incidence and mortality. The goal is to enable cancer prevention and control directions. Our results indicated that stomach cancer is the most common cancer. For all cancers combined, the incidence and mortality rates showed significantly increasing trends（＋2.63% per year; P 〈 0.05 and ＋1.9% per year; P 〈 0.05）. This study revealed a significant cancer burden among the population of this area. Cancer screening and prevention should be performed after an epidemiological study of the cause of the cancer is completed.