Knowledge Map of Soil Nutrient Migration Analysis Based on WOS (Web of Science) Database

It is important to understand the research trends and hotspots of global soil nutrient migration and control. Based on the core collection of WOS (Web of Science), citespace knowledge map analysis tool was used to analyze the number of publications, cooperation networks, disciplines, research hotspots and frontier trends on nutrient migration in soil. The results showed that: the number of publications on the study of soil nutrient migration showed a good growth from 1990 to 2021. 173 countries had cooperative relationships. The number of articles published in the United States and China was significantly higher than that in other countries, while Chinese Academy of Sciences was the institution with the largest number of publications. It was a comprehensive system that permeates with agriculture, environmental science, botany and other disciplines. The research of nutrient migration in soil mainly focused on the measures of microbial community in different land types to promote nutrient transformation, improve soil fertility and reduce nutrient loss. In the future, the research trends will be the management measures of soil nutrient loss, the relationship between the change of soil nutrient and plant community diversity, and the remediation of agricultural contaminated soil. Through the above analysis, there was an overall understanding of soil nutrient migration. The research on nutrient migration may continue to increase in the future. It is suggested that Chinese research institutions, teams and universities need to strengthen international cooperation, and speed up their integration with the international community.

Effects of Different Nitrogen Fertilizer Treatments on Soil Enzymatic Activities in Mulberry Gardens

[ Objective] The present experiment was undertaken to investigate the effects of different nitrogen fertilizer application levels on soil enzymatic activities in mulberry gardens, thus providing reference for rational application of nitrogen fertilizer and production of high-quality mulberry leaves. [Method] Field experiments were conducted with three different nitrogen fertilizer application levels： N, （ 120.75 kg/hm2 ）, N2 （ 172.5 kg/hm2 ）, and N3 （207 kg/hm2 ）. Activities of catalase, urease, acid phosphatase and invertase in soil applied with different amount of nitrogen fertilizer were determined to analyze the correlation between soil enzymatic activities and mulberry leaf yield. [ Result] Activities of urease and invertase in soil were improved with the increasing application level of nitrogen fertil- izer; activities of catalase and acid phosphatase reached the highest in treatment N2. Activities of invertase and urease in soil exhibited significant positive correla- tions; activities of invertase and phosphatase exhibited significant positive correlations; extremely significant positive correlations were found between mulberry leaf yield and activities of urease, phosphatase and invertase in soil. [ Conclusion] Rationally applying nitrogen fertilizer can improve activities of invertase, phosphatase and urease in mulberry gardens ; activities of urease and invertase in soil can be used as indicators to evaluate soil properties in mulberry gardens.

Effects of Different Nitrogen Levels on Growth and Nitrogen Utilization of Sugarcane

[Objectives]To systematically study the effects of different nitrogen levels on the growth and nitrogen utilization of sugarcane in Guangxi.[Methods]Through field experiment and indoor analysis,different nitrogen application levels were set up to determine soil nitrogen content and sugarcane nitrogen content.The effects of different nitrogen levels on sugarcane yield,agronomic characters and nitrogen utilization were studied.[Results]The effect of nitrogen application rate on sugarcane yield showed a quadratic curve,and nitrogen application could significantly increase sugarcane yield,and the sugarcane yield reached the maximum when the nitrogen application rate reached 714 kg/ha.[Conclusions]With the increase of nitrogen application rate,sugarcane yield increased,but when it exceeded a certain range,the sugarcane yield decreased significantly.

Nutritional Elements Related to Leaf Blight of Pearl Plum in Longtan Town

[Objectives]This study was conducted to investigate the correlation between leaf blight of pearl plum and nutrient elements from the perspective of plant nutrition.[Methods]Branch and leaf samples of pearl plum plants infected by or free of leaf blight and the corresponding 0-30 cm cultivated soil were collected,and statistical analysis was conducted according to the changes in nutrient contents and the incidence of leaf blight,so as to look for nutrients in pearl plum plants associated with leaf blight,as well as soil constraint factors.[Results]Phosphorus,iron and manganese in nutrients may be related to leaf blight,and the factors affecting leaf blight may be the ratios of P/Fe and P/Mn in leaves.[Conclusions]This study provides a basis for further research on the relationship between phosphorus,iron and manganese on the effect of leaf blight in pearl plum trees.

Survey and Study of Soil Nutrients of Sugarcane Field in Southern Guangxi

To survey and analyze soil nutrients of sugarcane field in southern Guangxi and provide basic data for reasonable land use and scientific fertilization,combining GIS technology,a total of 498 samples of topsoil of typical soil types in southern Guangxi sugarcane planting areas were collected and soil nutrients were measured. Survey results indicate that the p H value of 95% soil in southern Guangxi is lower than 6. 5;acid soil is major soil type of sugarcane planting areas in southern Guangxi; the organic matter content is 6. 03- 44. 58 g / kg; alkali-hydrolyzable N is 14. 0- 175. 0 mg / kg; available P is 1. 7- 95. 0 mg / kg; available K is 11. 0- 358. 0 mg / kg; the content of most nutrients remains at medium level,and there is still a large gap with high-yield soil condition. In various trace elements,the average content of B is 0. 24 mg / kg,- 98% soil lacks B; the average content of available Mg is 62. 34 mg / kg and 69. 08% soil lacks Mg; the average content of active Ca is 592.68 mg / kg and the active Ca is relatively low in 54. 84% soil; the average content of available Zn is 0. 93 mg / kg,and 19. 08% soil lacks Zn;the average content of available Cu is 0. 65 mg / kg,and 7. 02% soil lacks Cu. It is concluded that the overall soil fertility of sugarcane planting areas in southern Guangxi is not high,the organic matter is relatively low,the content of rapidly available N,P and K is at medium or low level,the content of Fe and Mn is high,and the available Cu and available Zn of most soil remain at medium level.