Effects Of Extensive Application Of Iron Tailings On Soil Properties And Crop Growth In Chaoyang City

Low grade iron tailings after grinding processing, resulting in a large number of tailings, because of its fine particle, also known as tailings Chaoyang city is abundant in iron tailings. The long-term large-scale iron tailings mining and production, lead to the substantial accumulation of iron backfilling, take up the cultivated land and forest land. Chaoyang city is located in the mountainous and hilly areas of Western Liaoning, the area proportion of slope agriculture is bigger, the middle-and-low-yielding fields is numerous, with thin soil layer.In this paper, sample analysis, column leaching tests, pot experiment and demonstration field test methods are used, in order to study the effect on soil and crops growth of applying a large number of iron tailings in middle-and-low-yielding fields. After harvest and growth period, the physical and chemical characteristics of soil samples and crop growth condition are analyzed respectively, and explore a lot of applied effect of iron tailings on the environment.The analysis of soil and tailings samples show that there is lack of nutrients, phosphorus deficiency,less nitrogen and potassium medium. However, iron tailings in the heavy metal content well below the soil environmental quality standards (1995). And tailings rich in iron (Fe content in the sample 6.1%), and some other useful elements, a large number of applying in the middle-and-low-yielding fields soil can promote crop growth, and improve the grain quality. Research indicates:The soil density increased with the quantity of iron tailings using, and in pot experiment the porosity of the soil is the largest of applied for 25% iron tailings. Corn is 53.98%, millet is 54.11%, compared with 0%(CK), respectively 1.24% and 1.08% upgrade. The porosity of the soil decreases significantly with the increment of iron tailings imposed When applied more than 35%.The conductivity of corn potting is between201μS/m-329μS/m, millet potting is between 184μS/m—290μS/m. Demonstration field experiment showed that administration of 5cm and 7cm iron tailings thickness have good Compared with the control group, water storage and water retention capacity improved significantly, while decreased soil bulk density and improved the soil porosity, beneficial to the growth of crop root system.Applying a large number of iron tailings adjusted cohesive soil texture and regulate soil nutrient content. Compared with the control group, the demonstration field of corn and millet effective Phosphorus increased by 29.71% and 47.06%; Available Potassium increased by 2.90% and 4.83% within the effective arable layer. And potted corn and millet, the highest available phosphorus increased by 28.82% and 29.50%, rapidly-available potassium increased by 2.57% and 2.57%.But the soil Nitrogen has gradually decreases with the amount of iron tailings applied increased.The CEC of soil is between 24.749mol/kg-30.854mol/kg, applied for 0%,5%,10% the CEC is biggest. A large number of iron tailings applied also increased the soil of iron, manganese, copper, zinc and other trace elements.Compared with the control group, crop conditions imposed iron tailings good yield improved significantly. Demonstration plots yield monitor millet yield 70.9%, corn yield 39.6%. And in Stems and leaves the Nitrogen is higher than 74.48% of potted corn, is higher than 40.42% of potted millet; the Phosphorus is higher than 70.45% of potted corn, is higher than 73.29% of potted millet; the potassium is higher than 43.73% of potted corn, is higher than 45.28% of potted mille. The content of heavy metals in grain of demonstration field was lower than the<the national standard for food safety-food contamination limits>(GB 2762-2012)Column leaching test showed that a large number of iron tailings is applied to the surface water environment has little effect, but an increase in surface soil salinity, pH increased, in terms of heavy metal content in soil had no significant difference from the ontrol group. In leaching solution, the highest value of Fe content is 0.117mg kg-1, Cu is 0.008 mg kg-1; Zn is 0.111 mg kg-1; Pb is:0.009mg kg-1. According to< surface water environmental quality standards, determine the GB3838-2002>, lower heavy metal content in leachate, with secondary agricultural water standardsThese results indicate that a large number of iron tailings is applied to improve the local low-yielding fields significantly. Iron tailing can improve the physical and chemical properties of the soil and decreased soil viscosity, the right of iron tailings application ratio can reduce soil bulk density, increase soil porosity, and promote the mineralization of organic matter and soil nutrient transformation and utilization According to the local production condition, a large number of iron tailings can complement the trace elements in the soil, and do not cause the pollution of soil and surface water. In terms of local,5cm is the best choice, and also can increase the crop yield and quality. There are broad prospects of application of iron tailings to the middle-and-low-yielding fields backfilling way of recycling use.