In arid and semi-arid regions, desertification threatens crop production because it reduces the soil’s capacity to retain water and soil nutrients. At two fertilizer levels (90 kg N hm⁻² and 45 kg P hm⁻² and 270 kg N hm⁻² and 135 kg P hm⁻²), the effects of soft rock (sand: soft rocks = 3:1) and biochar (4500 kg hm⁻²) applications on soil moisture, soil nutrients, and millet (Setaria italica L.) photosynthesis, yield, and its agronomic traits (biomass, thousand kernel weight, harvest index) were investigated in a field experiment in the Mu Us Sandy Land of China in 2018–2019. The addition of biochar and soft rock singly increased soil water content, alkali-hydrolyzed nitrogen (AN), total nitrogen (TN) and phosphorus (TP), and organic matter content significantly, suggesting that their application may increase the nutrient and water holding capacity of soil. Application of biochar and soft rock singly increased the net photosynthesis rate of millet flag leaf, at the flowering stage, from 15.97% to 56.26%. Biochar and soft rock application increased the yield range (2109.0 kg hm⁻² to 5024.7 kg hm⁻²) from 5.26% to 54.60% under the same fertilizer level. Correlation analyses showed grain yield was significantly correlated with photosynthesis rate at the flowering stage, which was significantly correlated with soil AN at flowering, soil TP at flowering and harvest, and soil TN at flowering. These results indicated that the application of biochar and soft rock singly could increase soil fertilizer holding capacity to improve the photosynthesis rate at flowering, and, therefore, lead to improvements in crop yield.

Foxtail millet is an important crop in Northwest China; however, the mechanism responsible for regulating root adjustment, including water uptake, sugar transport, or metabolism, in foxtail millet remains unclear. Two millet cultivars (the drought-resistant Yugu1 [YG] and the drought-sensitive An04 [An]) were used to detect physiological, molecular, and agronomic traits under two different soil water conditions. Water use efficiency increased by 18.4% and 63.2% under drought stress in An and YG, respectively. Under drought stress, YG and An root exudation (RE) decreased by 66.7% and 89.0%, the photosynthesis rate decreased by 34.3% and 61.8%, and the grain yield decreased by 40.6% and 62.6%, respectively. An contained a high ratio of soluble sugar to starch, whereas YG remained consistent. RNA-seq data showed a lower expression of beta-amylase 2 in YG than in An. The expression levels of three SWEET genes involved in sugar transport and four plasma membrane intrinsic protein (PIP) genes were higher in YG than in An, allocating more photosynthetic sugar to the roots to prevent a significant elevation in the ratio of soluble sugar to starch. The high expression levels of SiPIPs also enhanced root water transport capacity. Based on the above-mentioned adaptations, millet maintains high RE, stomatal conductance, and net photosynthetic rate in drought stress conditions.

To cope with the growing population, there is a growing demand for more land to be rendered cultivable. A complex soil created by applying soft rocks into sandy soil can be cultivated. However, the strong water-retaining ability and extreme poverty in nutrients of this complex soil has a negative effect on plant growth. To solve this problem, a complex of microbes and bacterial manure (BM) was added to the complex soil. The soil column culture test was used to detect the influence of BM application on soil bulk-density and infiltration parameters, and a pot experiment was conducted to evaluate its effect on the physical and chemical properties of soil, and ryegrass growth. The addition of 0.15% of BM to the complex soil decreased soil bulk-density, and increased the wetting front migration distance and soil hydraulic conductivity. The BM application also increased soil enzyme activities, which increased the available nitrogen and phosphorus content. As a result, BM increased the ryegrass root and shoot biomass. Overall, this study indicates that BM could be used as an eco-friendly sandy soil conditioner for improving the quality of complex soils, thereby, sustaining agricultural production in arid and semi-arid regions.

Vegetation restoration enhances soil erosion resistance by enhancing soil aggregates, but the function of these aggregates and their relationship with soil nutrients and microbes remain unclear. In this study, two land cover types that induce different aggregate ratios were selected to determine the soil aggregate ratio, aggregate ability, nutrients, and microbes. The results showed that high vegetation cover induced a higher macroaggregate ratio and soil water content; stronger soil shear strength; higher mean weight and geometric mean diameters; and lower soil bulk density. Macroaggregates had a lower soil organic matter (SOM) content compared with small macroaggregates. The aggregates and SOM influenced soil microbial diversity, especially microbial species and functions, and the large and small macroaggregate soils contained more microbes involved in SOM degradation, which accelerated the degradation and induced macroaggregate fragmentation. Total phosphorus (TP) had a direct impact on macroaggregates, and TP and macroaggregates showed the same correlation with the main microbial abundance. Taken together, we conclude that in the environment studied, SOM influenced soil microbes and the microbial function in SOM degradation affecting soil aggregates. TP contributed more to soil aggregate variations, especially in large macroaggregate formation.

The Grain for Green Project is one of the important projects implemented by the Chinese government to control soil erosion on the Loess Plateau, and its successful implementation has brought remarkable ecological benefits to relevant regions in China. The land use change is the most intuitive representation. Meanwhile, the soil erosion and soil nutrient distribution has also been influenced to produce significant changes. In this research, the characteristics of soil erosion and nutrient loss characteristics of soils from different land utilization types including apple, shrub, forest, grass and gully land, and their relationship were quantitative evaluated with 137Cs tracer technique in a typical watershed, which is located in Yan'an city of northern Shaanxi province in China. Results showed that soil erosion was observed in the all-land use types but shrub land, however, the degree of soil erosion was slight (the maximum value of soil erosion rate for 151.27 t/km²•a). The soil erosion of forest was significant differences with apple, shrub and gully but not with grassland. As will as there were significant differences in among shrub, apple orchard and gully. The soil nutrient loss, soil nutrient status and soil erosion degree showed a very similar pattern of spatial variation, with the difference that the correlation coefficients were different. In addition, there was highly significantly positive correlation between three indicators. However, Soil total nitrogen, total phosphorus, organic matter, N/P and C/P significantly affected the total nitrogen loss, total phosphorus loss and organic matter loss, but C/N ratio and nutrient loss were not significant. Soil nutrient loss in small watershed was more closely related to the soil carbon and nitrogen and soil erosion. The basic contents of different nutrients affected their nutrients loss laws, by and large, soil erosion affected soil nutrient loss and results in differences in nutrient distribution in the small watershed.