甘肃九甸峡移民区土壤养分分布特征

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

针对甘肃省九甸峡移民区新垦耕地土壤板结、盐碱含量高、土壤肥力低及种植作物出苗率差等问题,本研究以九甸峡移民区开垦400 hm 2土地为研究对象,采用GPS定位,网格采样法,以500 m为间隔,采集了56个耕层(0~30 cm)土样,对其土壤有机质、全氮、碱解氮、全磷、速效磷、全钾、速效钾、盐分及pH等进行了测定,应用Surfer8.0软件对其克里格插值,以全国第二次土壤普查技术规程规定的养分分级标准为依据,对其养分丰缺进行评价。结果表明:九甸峡移民区土壤有机质含量变化在3.58~13.7 g·kg^-1之间,全氮含量变化在0.29~0.79 g·kg^-1之间,碱解氮含量变化在40.6~165 mg·kg^-1之间,全磷含量变化在0.01~0.42 g·kg^-1之间,速效磷含量变化在0.02~6.0 mg·kg^-1之间,全钾含量变化在14.3~23.6 g·kg^-1之间,速效钾含量变化在62.0~659 mg·kg^-1之间,土壤盐分含量变化在2.0~19.9 g·kg^-1之间,pH值变化在7.20~8.74之间。土壤碱解氮和全钾接近正态分布,有机质、全氮、全磷、速效磷、速效钾及盐分是正偏(不对称,右偏),且具有比正态分布曲线更尖峭的峰态,而pH呈现负偏(左偏)。从变异系数来看,除pH的变异系数小于10%,属于弱变异之外,其余各指标均属中等变异(10%<CV<100%)。该区92.9%的土壤有机质处于较缺的范畴,98.2%的土壤全氮、全磷处于较缺和极缺的范畴,28.6%的土壤全钾处于缺的范畴,19.6%的土壤碱解氮较缺,82.1%的土壤速效磷处于极缺的范畴,11.6%的土壤速效钾处于缺的范畴,中度以上盐渍化土壤占96.4%。这一研究结果为移民区土壤培肥和改良提供一定的科学依据。

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.