[Comprehensive evaluation of soil quality of different land use types on the northeastern margin of the Qinghai-Tibet Plateau, China].

Soil quality evaluation is an important prerequisite for the rational soil resource utilization. We collected soil samples from forest (=9), grassland (=18) and cropland (=38) in Tianzhu County, Gansu Province, which is located on the northeastern edge of the Qinghai-Tibet Plateau. Soil quality was evaluated based on thirteen soil physical and chemical indicators, including soil bulk density, field capacity, and organic matter.

[Distribution of soil organic carbon, total nitrogen, total phosphorus and water stable aggregates of cropland with different soil textures on the Loess Plateau, Northwest China].

In this study, combined with field investigation and laboratory analyses, we assessed the distribution of soil organic carbon, nitrogen, phosphorous contents and their stoichiometric ratios, and the distribution of soil water stable aggregates along a soil texture gradient in the cropland of the Loess Plateau to understand the effect of soil texture and the regulation of soil aggregates on soil fertility in cropland. The results showed that, with the change from fine soils to coarse soils along the texture gradient (loam clay→ clay loam→ sandy loam), the contents of macroaggregates, organic carbon, nitrogen, phosphorous and their stoichiometric ratios decreased, while pH value and microaggregates content showed an opposite changing pattern. The contents of macroaggregates, organic carbon, nitrogen, phosphorous, and C/P and N/P were significantly increased, but pH value and microaggregates content were significantly decreased with increasing the soil clay content.

[Stem biomass estimation models for dominant shrubs on the northern Loess Plateau of China].

A total of 200 stems of Caragana korshinskii and 210 stems of Salix psammophila were collected in the late August of 2015 in the Liudaogou catchment of Shenmu County, Shaanxi Pro-vince, China. Basal diameter (D), length (H), water content (W), fresh mass (W) and dry mass (W) were measured for each stem of the two species. Exponential and allometric equations were used to establish relationship models relating stem biomass to its morphological parameters.

[Effects of different re-vegetation patterns on soil organic carbon and total nitrogen in the wind-water erosion crisscross region, China].

This study was conducted to analyze the responses of soil organic carbon (SOC) and total nitrogen (TN) to three typical re-vegetation patterns, i.e., grassland, alfalfa land and peashrub land on the Loess Plateau of China, and also to assess the dynamics of SOC and TN with re-vegetation age.

[Nitrate leaching characteristics of wheat-corn rotation farmland in Guanzhong area of Shaanxi].

By using in situ leaching device, a field experiment was conducted to study the effects of nitrogen fertilization rate and straw mulching on the nitrate leaching at 90 cm soil depth, nitrate accumulation in soil profile (0-100 cm), crop yield, and nitrogen balance of wheat-corn rotation farmland in Guanzhong area of Shaanxi. Six treatments were installed, i. e.