Poor soil structure and nutrients, excessive exchangeable Na⁺, high pH as well as low enzyme activities are common in the solonetz, and significantly restrict corn (Zea mays L.) production. Cattle manure application combined with deep tillage is an important management practice that can affect soil physico-chemical properties and enzyme activities as well as corn yield in the solonetz. Field experiments were carried out in a randomized complete block design comprising four treatments: Corn with conventional tillage was used as a control, and corn with manure application combined with deep tillage as well as film mulching and aluminium sulfate were used as the experimental treatments, respectively. The relationship between corn yield and measured soil properties was determined using stepwise regression analysis. Manure application combined with deep tillage management was more effective than conventional tillage for increasing corn yield and for improving soil properties in the solonetz. The highest corn yield was obtained in the treatments with manure application+deep tillage+plastic film mulching (11 472 and 12 228 kg ha^–1), and increased by 38 and 43% comparing with the control treatment (8 343 and 8 552 kg ha^–1) both in the 2013 and 2014 experiments, respectively. Using factor analysis, three factors were obtained, which represented soil fertility status, soil saline-alkaline properties and soil structural properties both in the 2013 and 2014 experiments, respectively. Manure and deep tillage management resulted in two distinct groups of soil properties: (1) soils with manure application combined with deep tillage and (2) soils with conventional tillage. Stepwise regression analysis showed that corn yield was significantly and positively correlated to urease and available P, as well as negatively correlated to pH, electrical conductivity (EC), exchange sodium percentage (ESP), and bulk density (ρ_b). We concluded that ρb was dominant factor for corn yield on the basis of discriminant coefficient. Manure application combined with deep tillage management resulted in an increase in corn yield mainly owing to improved soil structural properties, followed by decreased soil saline-alkaline obstacle as well as increased urease activity and available P. This result is likely that the improvement in soil organic matter (SOM) from manure application greatly and positively contributed to better soil physico-chemical properties and enzyme activities, especially decrease in ρ_b. Suggestion for corn production should be improvement in soil structural properties firstly. This could cause decrease in ρ_b that key factor which limited the corn production in the solonetz.

Carbon and nitrogen are the most important elements in the terrestrial ecosystem. Studying carbon and nitrogen distributions in plant and soil is important for our understanding of the ecosystem dynamics and carbon cycle on arid lands. A study was conducted in a typical arid area, the Yanqi Basin, Northwest China. Carbon and nitrogen distributions in plant tissues and soil profiles were determined at 21 sites with typical native plants and crops. Our results indicated that carbon content was similar between crops and native plants, and the average carbon contents in aboveground (42.4%) and belowground (42.8%) tissues were almost the same. Average nitrogen contents in crops were nearly the same (~0.7%) in aboveground and belowground tissues whereas mean nitrogen content was approximately 100% higher in aboveground (2.2%) than in belowground (1.2%) tissues for native species. Soil organic carbon (SOC) and total nitrogen (TN) in cropland (9.4 and 0.9 g kg-1) were significantly higher than those in native land (6.2 and 0.7 g kg-1). Multiple regression analyses indicated that carbon content in belowground tissue and nitrogen content in aboveground tissue were key factors connecting plant and soil in native land. However, there was no significant relationship for carbon or nitrogen between soil and crop, which might reflect human disturbance, such as plowing and applications of various organic materials.