Effects of a single application of four environmental materials on soil structure and properties in a coal mining area
The purpose of this study was to address the problems caused by poor surface soil structure,low water holding capacity,and nutrient depletion during land reclamation in a coal mining area.Potassium polyacrylate,black alum,biochemical humic acid,and coal-based humic acid were individually added to improve the properties of the soil,which were evaluated with a soil incubation simulation test.For the control(CK),no materials were added.This study investigated the effect of the four materials on soil parameters and determined their appropriate application rates.The results showed that potassium polyacrylate significantly reduced soil bulk density and increased porosity and field water-holding capacity;its addition at 5 g·kg-1 for 7 days reduced the soil bulk density by 14.02%and increased porosity and field water holding capacity by 28.31%and 54.32%,respectively,compared with those of the CK.Black alum application reduced the soil pH and available nutrients.When 5 g·kg-1 of black alum was added for 25 days,pH,available phosphorus,nitrogen,and potassium decreased by 0.21,30.24%,56.81%,and 9.77%,respectively,compared with those of the CK.The two kinds of humic acid affected soil bulk density,field capacity,pH,and available nutrients.The addition of 8 g·kg-1 biochemical humic acid for 25 days increased the available phosphorus and alkali-hydrolysable nitrogen by 15.18%and 55.83%,respectively,and the pH decreased by 0.38 compared with those of the CK.The addition of 5 g·kg-1 coal-based humic acid increased the available phosphorus,alkali-hydrolysable nitrogen,and available potassium by 12.38%,28.72%,and 11.47%,respectively,compared with those of CK.The results showed that the four materials improved the soil structure and water retention ability and increased the available nutrient content to different degrees.