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Crop yield stability and soil mineral nitrogen (Nmin) have rarely been evaluated from a long-term perspective in the extremely arid cropland regions of China. Therefore, a nationwide experiment aimed to optimize fertilizer application and increase productivity and nitrogen use efficiency in gray desert soils was initiated in 1990. Eight combinations of chemical fertilizers (CK, N, NK, NP, and NPK), straw return (NPKS), and manure amendments (NPKM and NPKM+) were tested for 24 years on spring wheat, winter wheat, and maize. The results displayed that the yield of three crops from balanced fertilizer treatments (NPK, NPKS, NPKM, and NPKM+) did not differ significantly after 24 years; however, reliable yield stability due to lower coefficient of variation (CV) and higher nitrogen harvest index (NHI) were recorded for manure amendment treatments. Compared to NPKM, NHI was lower for the NPKM+ treatment, but crop yield and stability did not improve, suggesting that the appropriate choice for manure amendment is important for guaranteeing food security in extremely arid regions. Balanced fertilizer treatments resulted in lower Nmin residual in the 300 cm soil profile, compared to unbalanced fertilizer treatments. The NPKS treatment gave the lowest value. In the 0–100 cm soil profile, Nmin was higher in NPKM than in the NPK treatment, suggesting that straw or manure amendment can effectively maintain Nmin in the topsoil undercurrent cropland management in arid areas. The NPKM treatment had the highest crop nitrogen recovery rate and the lowest nitrogen losses, further illustrating that manure amendment has higher N retention potential. Overall, although Nmin residues are relatively high in these regions, balanced fertilizer treatments, especially NPKM and NPKS, are the optimum strategies in extremely arid regions. [ABSTRACT FROM AUTHOR]

Phosphorus (P) fertilizer is generally applied to enhance the soil P pool and meet crop demand, but most of the added P is absorbed by soil. This study aimed to explore the importance of P fractions and adsorption–desorption characteristics on the demand for P fertilizer to determine the optimum P fertilizer amount for a cotton field under mulched drip irrigation in Xinjiang, China. A 4-year experiment (2016–2019) was conducted in a cotton field to evaluate the effects of five P fertilizer addition levels (0, 75, 150, 300, and 450 kg P2O5 ha−1 year−1) on inorganic P fractions and P adsorption–desorption properties at different soil depths and explore the effects of soil properties on P adsorption. The 4-year continuous P fertilization enhanced the inorganic P content and altered the proportions of various P forms. A large proportion of P accumulated in soil was transformed into Ca8-P, followed by Ca2-P, mainly in the surface layer. The accumulation and transformation of P in fertilized soil reduced P adsorption and enhanced P desorption. Soils with higher P application levels had higher inorganic P accumulation with lower adsorption and higher desorption. The total P and Olsen-P in a 0- to 5-cm soil layer; Ca8-P and calcium carbonate (CaCO3) in a 5- to 10-cm soil layer; Olsen-P, Ca10-P, clay, and cation exchange capacity in a 10- to 20-cm soil layer; and Olsen-P in a 20- to 40-cm soil layer significantly affected the P adsorption–desorption (p < 0.05). The application rate of 75–150 kg P2O5 ha−1 year−1 produced lower inorganic P accumulation, favorable adsorption–desorption properties, and high cotton yield, and thus could be considered the optimal P fertilizer application level.

There are abundant oil resources in Xinjiang, and the exploitation of oil resources could easily pollute the soil. In this paper, the impact of oil pollution on permeability of the gray desert soil affected by freeze-thaw cycles under a dry and cold climate of Karamay region in Xinjiang was studied. First, varying-head infiltration tests were conducted on soil samples with different water contents and pollution intensity without exposing to freeze-thaw cycles. The variability of permeability were analyzed employing the scanning results of the polluted soil samples by an electron microscope. Then several freezing and thawing cycle tests were implemented on the samples. The test results shown that the soil permeability was optiomal and the permeability coefficient was highest when the crude oil pollution intensity was 0.61% and the water content was 15.53%. With the water content in soil samples being the same, the soil permeability coefficient increased in the beginning and then decreased as the pollution intensity increased. When the pollution intensity ranging from 0.5% to 1.75%, the freezing and thawing condition could be the leading factor affecting the soil permeability. However, when the oil content was within the range of 1.81% – 2.41%, the freezing and thawing condition could not be the leading factor affecting the soil permeability. The results provided in this study could serve as a relevant basis for the remediation of soil pollution in oil production plants in arid areas of Western China. [ABSTRACT FROM AUTHOR]

This work investigated the irradiation behavior of gray desert soil holding simulated An4+ waste under an irradiation of 1.5 MeV Xe20+ to fluences from 1 × 1012 to 1 × 1015 ions cm− 2. The results indicated that the structure has no obvious change due to irradiation fluences and waste load. The normalized leaching rate of Ce after 28 days of the MCC-1 test is in the order of 1 × 10− 5 g cm− 2 d− 1 before and after irradiation. This work identifies gray desert soil, which has good radiation resistance, as a potential matrix for solidification tetravalent actinides. [ABSTRACT FROM AUTHOR]

Physical fractionation technique was used to analyze the content, distribution, and temporal evolution of organic carbon associated with particle size fractions of grey desert soil under long term (1990-2007) fertilization. Compared with no fertilization, a combined application of manure and chemical fertilizers increased the organic carbon associated with particle-size fractions significantly, with the highest increment (0.34 g·kg-1·a-1) in sand. Fallowing also increased the organic carbon associated with clay and silt significantly. Straw return to cropland only maintained the organic carbon content in different particle size fractions, while long-term application of chemical fertilizers was not beneficial to the organic carbon increase in particle size fractions. Coarse silt and coarse clay had the highest distribution rates of organic carbon (27.9% and 27.1%, respectively), being the important fractions in sequestrating organic carbon. When manure was applied with chemical fertilizers, the organic carbon in sand was significantly increased by 119.4%, while that in fine silt and coarse clay was significantly decreased by 40.3% and 37.9%, respectively, which resulted in the increase in the ratio of particulate organic carbon content (WPOC) to mineral associated organic carbon content (WMOC), and improved soil carbon property. Long term application of manure combined with chemical fertilizers was the best mode to increase the organic carbon content in particle size fractions and improve the fertility of grey desert soil. [ABSTRACT FROM AUTHOR]