| For a long time, it severely restricted the development and application of sand desert crops for the factors of lack of nutrients, easy flow, and poor water retention properties in the sand. Biochar was porous and with a high nutrient and carbon content the produced by biomass under vacuum or hypoxic conditions was a good material for improving the quality of sandy soil. By preparing different carbonization conditions Artemisia biochar, made it be simulated sand archive after proven its basic physical and chemical properties, to explore the response of physical, chemical and biological traits of sandy soil on different biochar carbon and the synergism between biochar and organic materials. It aims to provide theoretical and technical basis for the selection of high-quality biochar for improving sandy soil. The main findings are as follows:1. Carbonization process of biochar is a process that aromatic enhanced, hydrophilic and polar weakened. Biochar has developed pore, was alkaline (pH value of 8.75～10.51), containing a high amount of C (61.49～89.93%), the physical and chemical properties of biochar largely affected by carbonization temperature and carbonization time and relatively small by the heating rate. P, K, Ca, Mg, C, CEC and crude ash content in biochar increased as the carbonization temperature elevated and equally when carbonization time extended. At the same time, pH, total pore volume, mean pore diameter and specific surface area of biochar increased. In contrast, N, H, O, S content and biochar yield decreased. The total P and K, available P, K and organic C content were increased by 48.93%,31.18%,39.59%,42.18% and 28.16% respectively in biochar compared the temperature at 900℃ with at 300℃. The total N, available N content and yield were reduced by 48.29%,46.58% and 75.47% respectively at this point. When the Carbonization time was 150min comparing 5min, available P, K, Ca and Mg content were increased by 6.42%～29.17%、 5.94%～17.07%、3.56%～12.76% and 7.80%～21.48% respectively in biochar, and alkaline hydrolysis N, available S content and effective yield was decreased by 13.03%～18.37%、6.88%～61.66% and 6.68% respectively in biochar.2. Biochar and Artemisia both have moisture absorption and water retention Ability, moisture absorption rate was 4246.6～4803.3g/kg and 5340.3g/kg respectively, evaporation rate was 0.955～0.996 and 0.996 times of natural sand. The biochar under the preparation conditions of carbonization temperature of 600℃and carbonization times of 60min and heating rate of 150℃/h were good water retention material.3. The degradation rate of biochar reduced with the increased carbonization temperature, extended carbonization time and increased amount of biochar. Its half-life was approximately 2 to 11 years; witch was about 5 to 7 times of sheep manure or Artemisia powder organic materials.4. Single application of biochar or Artemisia powder for 15 months did not change the sand mechanical composition. But for the 2 treatments of sheep manure and sheep manure mixed with biochar powder, increased the percentage of sand <0.01mm grain size (an increase of 2.03%), reduced the percentage of<0.05mm grain size (reduced 2.03%) at the same time.5. Carbonization temperature and carbonization time and culture time were significantly affect the effective nutrient content,CEC and microbial C, N content of sandy soil. The nutrients, CEC, microbial C, N content, pH value, enzyme activity and microorganisms number of the sandy soil increased as the biochar application rate increased. Incubation time did not significantly affect the total nutrient content. The higher carbonization temperature and the longer carbonization time, the lower content of alkaline hydrolysis N and the higher available P, K and CEC content. The max value (occur at different culture time) luffing were -6.54%,83.33%,13.60% and 86.83% when the carbonization temperature was at 900℃ compared with300℃. The 600℃ carbonized 60min biochar helped improve sandy soil microbial C, N content. When the usage of biochar amounted to 2%, the CEC and microbial C, N content was close to the maximum (18.91cmol/kg,319.76mg/kg and 82.24mg/kg, respectively).6. Urease, catalane, inverts and alkaline phosphatase activity in sandy soil had obvious seasonal dynamics. These four enzymes, respectively, in September, April, July and July was most active. The more amount of usege, the more active (except invertase). The maximum was 0.60mg/g.d,6.20ml/g.h,10.50mg/g.d and 0.60mg/g.d respectively when the usege amount was of 4%, urease and catalase activity did not increase that obviously compared with the biochar usege amount of 2%. And significantly increased the activity of alkaline phosphatase, in contrast the activity of sucrose was inhibited.7. Biochar administration increased the number of bacteria and actinomycetes and reduced the number of fungi at the same time. The number of bacteria was of predominant in the microorganism(78.90%-96.73%). Gene sequencing showed that Microbial populations were changed.8. There was a synergistic effect when mixed use Organic materials and biochar (related to cultivation time). Especially mixed use biochar and sheep manure could make the best synergistic effect on alkaline hydrolysis N, available P, bacteria, actinomycetes, urease, cataleffect, ase and alkaline phosphatase in sandy soil. It increased by 119.78%(July),38.64%(July),33.33%(September),47.37% (September),39.06%(September),147.11%(July) and 58.65%(July) compared the cumulative effect when used them alone.In summary:Artemisia biochar played a role of improving the sandy soil. Carbonization temperature and carbonization time significantly influenced the pore structure, water retention, yield, pH value, CEC, nutrient content and coarse ash and other physical and chemical properties of Artemisia biochar. The nature and amount of biochar application and the incubation time in the sandy soil combined affect the improved results. When the carbonization temperature was at 600℃ and the carbonization time was 60min, the biochar whose structure preserved, pH value was of the medium, and had an outstanding water retention and improved activity significantly and had any other positive effects. Considering the effect of improving the sandy soil and the economy, it would get a better effect on improving the sandy soil when the application ratio of this Artemisia biochar was 2%. And when added sheep manure and other organic materials appropriately could further improved the effect. |
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