Effect of Gully Land Reclamation on Soil Organic Matter and Carbon Contents

[Objectives]This study was conducted to investigate the effects of Yan an gully land reclamation project on farmland soil organic matter and carbon contents.[Methods]Through indirect sampling and random sampling methods,soil samples were collected from six areas of Baota District,Ansai District,and Zichang County in Yan an City,before and after gully land reclamation,and the organic matter and soil organic carbon contained in them were determined.[Results]Through sampling experiments,we initially analyzed the changes of the above components in the land consolidation areas after different years and the reasons for the changes:①after the Yan an gully land reclamation project was implemented,the soil organic matter and carbon contents increased;②directing at the improvement of soil organic matter and carbon content different years after the consolidation,the improvement ranked as 5 a>2 a>1 a;and③correlation analysis showed that there was a significant positive correlation between soil organic matter and carbon contents.[Conclusions]This study provides scientific decision-making and theoretical basis for the construction of high-standard farmland in gully areas and the implementation and promotion of gully land reclamation projects.

Site Pollution Remediation and Its Technology

This paper summarized the connotation of contaminated site remediation,the differences between contaminated site and brownfield,the differences between contaminated site and soil pollution and land pollution,clarified the relationship between the concepts,and introduced the remediation technology of contaminated site.

Soil Physical Properties of Different Land Use Types in Loess Hilly Region

[Objectives]To explore the impact of land use changes on physical properties of soil in loess hilly region.[Methods]The methods of field sampling and indoor analysis were adopted.Farmland in a small watershed in the middle of the Loess Plateau,grassland that had been abandoned for 7 years,grassland that had been abandoned for 30 years,jujube orchard and ditch were sampled,and the particle composition(clay,silt and sand)and moisture changes of the soil in the top 0-100 cm were studied.[Results]In the small watershed,the top 0-100 cm of the soil was composed of 14%clay,70%silt and 16%sand.The contents of clay,silt and sand in the grassland that had been abandoned for 30 years varied greatly,while varied little in the land of other use types.The soil moisture content of grassland that had been abandoned for 30 years,jujube orchard,grassland that had been abandoned for 7 years,farmland and ditch increased with the increase of depth,with means of 10.29%,11.66%,10.08%,11.43%and 11.34%,respectively.[Conclusions]This study provides a theoretical basis for the growth of crops of different land use types in the loess hilly region.

Distribution Characteristics of Soil Total Nitrogen in Low-efficiency Forest Land in the Northern Windy Desert Area of Jingbian County

[Objectives]The paper was to investigate the distribution characteristics of soil total nitrogen in low-efficiency forest land in the northern windy desert area of Jingbian County.[Methods]The distribution of soil total nitrogen in the 0-40 cm soil layer of 5 towns in the northern windy desert area of Jingbian County was studied through field sampling and laboratory detection.[Results]The average soil total nitrogen contents of Hongdunjie Town,Haizetan Town,Huanghaojie Town,Ningtiaoliang Town,Dongkeng Town and windy desert area in the 0-20 cm soil layer were 0.259,0.224,0.242,0.248,0.431 and 0.275 g/kg,respectively.The soil total nitrogen content in Dongkeng Town was higher than those in other towns,while there was little difference among other regions.The average total nitrogen contents in the 20-40 cm soil layer were 0.239,0.285,0.113,0.262,0.349 and 0.241 g/kg,respectively.The soil total nitrogen content in Huanghaojie Town was slightly lower than those in other towns,while that in Dongkeng town was higher.The variation coefficient of soil total nitrogen content in the survey area was greater than 30%,and there was great difference in spatial distribution.With the increase of soil depth,there was little change in soil total nitrogen content,namely the soil total nitrogen contents in 5 towns and windy desert area were not statistically different in the 0-40 cm soil layer.According to the nutrient grading standard of the second national soil survey,the soil total nitrogen content in the survey area was in the deficiency grade.[Conclusions]The research will provide a scientific guidance for the healthy and sustainable development of vegetation in arid regions.

Changes in N,P and K Contents in Eum-orthic Anthrosols at Different Moisture Contents

[Objectives]This study aimed to provide a basis for the management of nitrogen,phosphorus and potassium nutrients in eum-orthic anthrosols and the fertilization of crops.[Methods]Using the indoor culture method,the contents of total nitrogen,available phosphorus and available potassium in eum-orthic anthrosols under three different moisture conditions:long-term drying,long-term logging and alternate drying and logging were analyzed and compared.[Results]The total nitrogen content was higher under the moisture condition of long-term drying.The minimum(0.60 g/kg)appeared on day 30,and the maximum(0.74 g/kg)appeared on day 120,increased by 8.8%compared with the minimum.The available phosphorus content was also higher under the moisture condition of long-term drying.The minimum(16.9 mg/kg)appeared on day 60,and the maximum(22.5 mg/kg)appeared on day 120,increased by 33.1%compared to the minimum.The available potassium content showed a downward trend under long-term logging,and was higher than those under the other two moisture conditions.The maximum(150 mg/kg)appeared on day 30,and the minimum(136 mg/kg)appeared on days 75 and 90,reduced by 9.3%compared with the maximum.[Conclusions]Water plays a positive role in activating nutrients.Different nutrients have different responses to different moisture conditions.

Application of Big Data in the Remediation of Contaminated Sites

China has large population but little land.Such objective conditions determine that it is required to adhere to the policy path of"cherishing,rationally utilizing land and practically protecting cultivated land".Due to the relatively immature technology in the early stage of resource development in China,extensive utilization of resources leads to serious pollution,and the situation of the restoration of contaminated sites is severe.After nearly 20 years of a large number of pollution,land restoration there have been a lot of achievements in research and practice,but in the era of big data development,prevention and cure of soil pollution in China,there are a number of problems in the development of science and technology,this paper put forward the corresponding recommendations and opinions for the existing problems,in order to provide decision support for using big data to repair contaminated sites.

Experience in Remediation of Contaminated Sites at Home and Abroad

The selection of remediation technology for contaminated site is a key link of the remediation project.It determines the success or failure of the site remediation.The complexity of the types of contaminants in the site determines the diversity of remediation technologies.The experience of many countries in the world shows that the use of scientific and technological means and advanced technology can more effectively carry out the work of soil protection and pollution prevention and control,and achieve obvious results.