The Soil Compaction Special Features In Reclaimed Area And Improving Results By Using Mushroom

The major mines of Yanzhou Coal Mining Group locate in Zoucheng City, Jining, Shandong Province. Since 1950s, there has been 5653hm2 (8.48×104 acres) of subsided land, which caused the environmental damage. From 1980s on, the city began to strengthen the management of mining subsidence and gradually improved the ecological environment. However, because of the coal production is growing, subsidence land increases at the speed of 200hm2/year. Mining collapse and reclamation seriously disturbed the soil, resulting in great changes of reclaimed soil quality. Soil compaction is the most critical factor to judge the quality level and success of reclamation. The study selected the reclaimed soil in Zoucheng City as the object, analyzed compaction characteristics during five years of reclamation, and revealed compaction variation of reclaimed soil. Meanwhile, through the evaluation for the physical and chemical properties and synthetic quality of reclaimed soil, the quality variation of reclaimed soil was verified. Mushroom was applied to improve the reclaimed soil quality.The analysis shows:the soil compactness of land surface in block 2 and 9 which interference by human in much smaller than undamaged block (413.40kpa), which is disadvantage to crop growth; remaining reclaimed land compactness is much larger than block 1. Reclamation time have affect to the soil compaction, the longer the reclamation, the smaller the soil compaction.In soil vertical profile, as the depth increases, soil compaction increased. Different filling materials have some influence to soil compaction, Gangue can help to improve soil compaction than coal fly ash,the compaction of block 8 is big in the whole body, which seriously affecting crop growth. In the soil layers 1-4, the compation of block 9 is less than block 3,which due to human factors and the impact of root crops. At the same time which tell that crops have larger impact in soil compation than trees;but as the depth increases, block 9 have biger compation than block 3. The compaction of surface soil in block which was just finished mushroom is small,due to cementation of organic matter in mushrooms, and with longer time by using mushroom, the compaction of soil surface gradually increased, which is better to crop growth. Block 6 which was just using mushroom have the same change trend with the block which was cultivated land after reclamation. However, the compaction of all plots reach the maximum in level 4-5, then have litter change. Soil compaction have interconnect withsoil physical, chemical and biological properties, the biological characteristics of soil and soil compaction have the biggest correlation, the largest significance level P is 0, the correlation coefficient with the fungi reached-0.73599; soil compaction and soil clay content have the minimum correlation coefficient which reach-0.02889, significance level P is 0.83573.The application of mushroom took some effects on the physical and chemical properties, microbial quantity and soil quality of reclaimed soil.The compaction degree of surface soil was low (438.30kpa) when mushroom waste was just used, A few days later, compaction degree of surface soil gradually increased (826.80kpa). Different approaches caused compaction difference in the second and third layers of the vertical profile. In the undamaged plot and cultivated land after reclamation, the compaction decreased to the minimum-68.90kpa, and then increased. Plot 6 with mushroom application and the cultivated plot after reclamation had the similar compaction status. The highest compaction value (1378.00kpa) occurred in the plot with long-time use of mushroom, and then decreased or stayed unchanged. However, all the plots had the maximum compaction value in the fourth and fifth layers, little compaction change took place below the two layers. Whenever the mushroom waste was applied, surface soil bulk density was higher than that of undamaged land. The application in 2004 and 2005 was the example. Mushroom waste can maintenance water very well; soil moisture content with the application of mushroom gradually increased, much higher than that in the plots without mushroom. In the vertical profiles, due to the mixture of mushroom and soil, the resistance of water infiltration to the underground increased, which gave high water content and help soil maintenance water. The plot with mushroom application owned a larger clay fraction than the undamaged land, and the highest content appeared in plot 5 (14.40%). The surface soil of block 7 contained the maximum amount of silt particles (94.06%), which gradually decreased, but still higher than the plot 3 without mushrooms. It showed that the application of mushroom could improve soil permeability, good for farming.Mushroom scrap application increased the content of organic matter in the surface soil, which was still lower than that of undamaged soil. Later, soil organic matter content fell lower; with the increase of soil depth, it became less. The content of available N was high-27.33mg/kg, but later it decreased. In the second and third layer of vertical profiles, the available N content with mushroom increased, but decreased with soil depth. However, the plot without mushroom (land block 1) had a higher decreasing speed with soil depth. The influence of mushroom scrap application was significant on soil available phosphorus content. Without application of mushroom scrap, the content in the surface soil was very low (0.98mg/kg), seriously hindering crop growth. The time of mushroom scrap use related little to the content of available phosphorus, and there was little difference of available P content in the vertical profile between with and without mushroom scrap. Mushroom scrap's application is great for increasing soil available K content, but later, it reduced a lot. For example, the content of surface soil in block 4 (in 2005; mushroom application) was only 40 mg/kg. The surface reclaimed soil had great alkalinity (pH>8.3). By applying mushroom scrap, the alkalinity could be effectively improved. In the vertical profile, plots of 4,5,6,7 had stable pH value and with the time passed, alkalinity was reduced by using mushroom scrap. From plot 5, pH value fell down to 7.92 with 3-year use of mushroom scrap (since 2004). The conductivity of land after mushroom scrap disposal decreased over time, but increased with soil depth; the peak occurred in the 5th layer.With the increase of soil depth, the number of microbes decreased; generally, the surface had the biggest number. Plot 7, with 1-year mushroom scrap application, had more bacteria, fungi and actinomycetes, the number was namely 324 * 105,103 * 103 and 26 * 104, significantly higher than the plot without mushroom (83 * 105,56 * 103 and 12 * 104), less than plot 9-the reclaimed land for cultivation (1520 * 105,240 * 103 and 57 * 104), higher than the undamaged plot (293 * 105,80 * 103 and 29 * 104). Mushroom scrap application impacted on different soil microbes, the number bacteria and fungi increased more significantly than actinomycetes.The comprehensive quality of reclaimed soil was obviously different after using mushroom. scrap Because of human cultivation and fertilization, cultivated soil after reclamation owned high comprehensive quality, with average index of 0.52-0.54. The index of surface soil got to 0.64 and 0.73, much higher than other soils. Due to little human measurements, the quality of reclaimed soil for planting trees was low, with the average of 0.40. The effects of mushroom scrap mainly focused on the top soil other than subsoil. The time of its influence was mainly the first 2 years after application, later with the decomposition of mushroom scrap, soil quality index tended to the value without mushroom scrap. The quality of top soil was higher than that of subsoil, especially in application of mushroom scrap, soil quality reached a peak at about 15cm-depth. Cultivated soil after reclamation had great soil quality variance, with the coefficient of 24.74%. Mushroom scrap application could reduce this kind of variation, particularly with the longer-time use; the variance coefficient fell down to 3.59% after 3-year application.