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The easy fixation of phosphorus fertilizer in soil is a main reason for the low utilization rate of phosphorus fertilizer. In order to study the effects of fertilization frequency on availability of phosphorus fertilizer, three cinnamon soils with different Olsen-P levels (19.4, 24.2, 49.7 mg·kg-1) were collected in the long-term fertilization test based on Shouyang County, Jinzhong City Shanxi Province, and the same amount of phosphorus fertilizer (potassium dihydrogen phosphate) was added to the soil with different Olsen-P levels by once and 3 times, respectively. The soil with Olsen-P was incubated under constant temperature condition for 90 d, soil Olsen-P content was measured by 11 sampling intervals, and the phosphorus forms in soil were measured at the end of incubation. The effects of fertilization frequency on soil Olsen-P content, phosphorus fixation rate and phosphorus forms were analyzed, and characteristics on availability of phosphorus fertilizer under different fertilization times were clarified. The results showed that after 90 d of fertilization, the soil Olsen-P contents under 3 times of application increased significantly compared with that of once of application, and the increase rates at 3 Olsen-P levels were 21.0%, 13.5% and 9.4%, respectively. However, the phosphorus fixation rate decreased significantly, which were 8.0%, 6.8% and 10.5% at 3 Olsen-P levels, respectively. The Michaelis-Menten equation betterly fitted the process of soil phosphorus fixation. The maximum phosphorus fixation rate of once application was greater than that of 3 times application, but the time to reach 50% of the maximum phosphorus fixation rate was shorter than that of 3 times application. The phosphorus fixation rate decreased with the increase of Olsen-P levers under once application. Phosphorus fixation rate in high Olsen-P (49.7 mg·kg-1) soil was significantly reduced by 10.8%~ 12.4% compared with low Olsen-P (19.4~24.2 mg·kg-1) soil under 3 times application.When compared with once application, the content of labile P in soil increased by 6.8%~12.1%, and the content of non labile P decreased by 8.4% under 3 times application. This study showed that the 3 times application of phosphorus fertilizer could significantly improve the availability of soil phosphorus and reduce the fixation rate of phosphorus fertilizer; the higher soil Olsen-P content was, the smaller the proportion of phosphorus fertilizer was invalidated in soil; the 3 times application of phosphorus fertilizer could increase soil Olsen-P content, decrease phosphorus fixation rate and increase the content of labile P. These results had important directive significance to improve the utilization rate of phosphorus fertilizer, and provided theoretical basis for efficient and scientific application of phosphorus fertilizer. [ABSTRACT FROM AUTHOR]

In order to explore the effects of long-term application of cattle manure on soil antibiotic resistome, five fertilization treatments were selected from the long-term location experiment in the cinnamon soil of Shouyang, Shanxi Province, i.e., CK (No fertilization), N2 P1M1(N: 120 kg·hm-2, P: 37.5 kg·hm-2 ; Cow dung: 22 500 kg· hm-2 ), N4 P2M2(N: 240 kg·hm-2 ; P: 75 kg·hm-2 ; Cow dung: 45 000 kg·hm-2 ), N3 P2M3(N: 180 kg·hm-2 ; P: 75 kg·hm-2 ; Cow dung: 67 500 kg·hm-2 ) and N0 P0M6(Cow dung: 135 000 kg·hm-2 ). Soil samples of surface layer (0 -20 cm) at the middle growth stage of maize were collected. A total of 384 antibiotics resistance genes (ARGs), mobile genetic elements and related taxonomic genes in soil were detected by high-throughput quantitative realtime polymerase chain reaction (HT-qPCR), and their diversity and correlation with soil physical and chemical factors were analyzed. The results showed that with the increase of cow manure application amount, the diversity of ARGs related genes increased gradually. There were 64 shared ARGs related gene subtypes in the five treatments, and 21 specific ARGs related gene subtypes in treatment N0 P0M6, which was significantly higher than other treatments. The highest abundance of ARGs related gene subtypes in all treatments were AAC(6' )- Im, ANT(4' )- Ia, aadA5, AAC(3)- Viaand copA. The highest abundance of ARGs types in all treatments were aminoglycoside, multi- drug, tetracycline, fluoroquinolone and macrolide-lincosamide-streptogramin B (MLSB). The β-diversity of ARGs related gene subtypes was significantly different among different treatments. Redundancy analysis showed that pH, total nitrogen and organic matter were the most important environmental factors affecting the difference of ARGs between different treatments. In conclusion, although the returning livestock and poultry manure to the field can improve soil fertility and promote crop growth, it can also cause the dispersal of ARGs in the soil ecosystem. Therefore, in the future of agricultural production, environmental and ecological benefits should be taken into comprehensive consideration to strengthen the harmless treatment of manure, so as to control the environmental risk of ARGs. [ABSTRACT FROM AUTHOR]

A ten years location experiment of various kinds straw return to field and deep fertilization in autumn was conducted in Shouyang dryland experimental area of Shanxi Province to study their effect on the growth and yield of dryland corn, the use efficency of soil water and fertilizer, and the changes of soil fertility. The results showed that this kind of experimental method could better solve the contradiction of deep fertilization with maintaining soil moisture and keeping a full stand of seedlings in spring, and the competition of water and fertilizer between the degradation of crop remains and the seedlings. What is more, the abundant resources of crop remains were used more sufficiently, the activity of soil microorganisms was more active, and soil fertility was obviously improved, which was proved by the complete and strong seedlings and developed roots, the photosynthesis and transpiration rates were enhanced, the water use efficiency (WUE) was increased by 3.26 - 3.51 kg x hm(-2) x mm(-1), and the accumulated water consumption was decreased by 8.1 - 264.5 mm. During plant growth period, the utilization rate of fertilizer N and P could increase 3.9% - 13.9% and 3.0% - 9.1%, respectively, and the use efficiency of water and fertilizer was higher. The ten years accumulated yield increased 12.10 - 17.27 t x hm(-2), a rise of 25.6% - 36.5%, and in the meantime, higher soil fertility and productivity were maintained.