Distribution characteristics of soil nutrients in Jiudian Gorge resettlement area in Gansu Province

Aiming at solving problems concerning soil hardening,high soil salt content and low soil fertility with poor crop emergence rate in Jiudian Gorge resettlement area of Gansu Province,we investigated the distribution of soil nutrients in order to provide a scientific reference for local soil management.In the area,we collected 56 topsoil samples of 0-30 cm depth by grid sampling at 500 m intervals with GPS,and analyzed their organic matter content,total nitrogen,alkaline nitrogen,total phosphorus,available phosphorus,total potassium,available potassium,total salt content and pH.Then,we evaluated the enrichment and deficiency of soil nutrients with Surfer 8.0 software based on the standard of nutrient classification in the second national soil survey.The results showed that organic matter content,total nitrogen,alkaline nitrogen,total phosphorus,available phosphorus,total potassium,available potassium,total salt and pH were with 3.58-13.7 g·kg^-1,0.29-0.79 g·kg^-1,40.6-165 mg·kg^-1,0.01-0.42 g·kg^-1,0.02-6.0 mg·kg^-1,14.3-23.6 g·kg^-1,62-659 mg·kg^-1,2.0-9.9 g·kg^-1 and 7.20-8.74,respectively.The alkaline nitrogen and total potassium distributed in normal fashion patterns.Soil organic matter,total nitrogen total phosphorus,available phosphorus,available potassium and salt were with positive kewness distribution (right deviation),and the pH was with negative skewness distribution (left deviation).The CV of pH was less than 10%,indicating weak variation; while the CV of other indicators was with 10%-100%,indicating intermediate variability.According to the statistical data for this study area,92.9% of the area was lack of soil organic matter,98.2% of the area was short of total nitrogen and total phosphorus,28.6% of the area was short of total potassium,19.6% of the area was lack of alkaline nitrogen,82.1% of the area was severely short of available phosphorus,11.6% of the area was lack of available potassium,and 96.4% of the area was with moderate salinization.This study would guide the soil fertility improvement of Jiudian Gorge resettlement area.