Prediction of Variation of Soil Nutrient Status in Reclaimed Subsidence-damaged Farmlands by Filling with Yellow River Sediment Different in Reclamation History in Jining City
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Supported by the National Natural Science Foundation of China (No. 41771324)

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    Abstract:

    【Objective】Jining is an important energy base in China, thanks to its rich natural resources, like coal. However, decades of mining has caused land subsidence, which has become a protruding environmental problem, destructing large areas of farmlands in the region. Filling with Yellow River sediment has come up as a new method to solve the problem in recent years. The new method can not only help alleviate the hazard of sediment blocking the river course of the Yellow river, but also make full use of the endless filling materials for subsidence reclamation in the eastern plain mining area without any concern about the possibility of secondary pollution. At present, the study on subsidence reclamation using Yellow River sediment as filling is mainly focused on feasibility and cost of the technology. So far no comprehensive and systematic research has been done on reclaiming subsided farmlands with sediment diverted from the Yellow River. 【Method】 In this study, a typical tract of farmland reclaimed by filling with sediment diverted from the Yellow River in Liangshan County, Jining was selected as research object , and another tract of unaffected farmland was cited as CK, both following the same tillage procedure. For years observatory data were collected and analyzed for construction of a regression equation for relationships of various soil nutrient indices and reclamation history, or number of years the reclaimed farmland had been cultivated, and further for variation of soil fertility with reclamation history. On such a basis, this study attempted to predict how long soil fertility of the reclaimed farmland will recover. 【Result】 Results show that with cultivation of the reclaimed farmland going on, soil organic matter, alkalyzable nitrogen, available phosphorus and readily available potassium all exhibited rising trends. The first three indices reached also as high as their corresponding ones in CK in the fifth year, but the last one, though on a rising trend, was only 60% of that in CK. Obviously, it takes only 5 or 6 years for the reclaimed farmland to build up as much as soil organic matter, alkalyzable nitrogen, and readily available potassium as CK has, whereas it may take as long as 15 years for the farmland to accumulate the same amount of effective phosphorus as CK has. The reclaimed farmland is relatively low in available phosphorus, and productivity, and has to be cultivated for quite a long time before it gets recovered in soil fertility. The problem can be solved through modification of the irrigation pattern, rationalization of the cropping system and adoption of split application of P fertilizer, that is, “More frequent application, each at a limited rate” to ensure crop growth and build-up of soil fertility. With cultivation of the reclaimed farmland going on and on, soil organic matter, alkalyzable nitrogen and available potassium in the soil will build up to the same level as in CK. So they are not the limiting factors of the agricultural production in the reclaimed land. But great attention should be paid to building up of soil nutrients in the process of reclamation. 【Conclusion】Therefore, the paper recommends building up and regulating soil nutrients, and reducing nutrient loss, through increasing application of organic manure, planting green manure crops, returning straw to soil, and regulating hydrothermal conditions, etc. to improve soil quality and ensure crop quality. Once the problem of diverting Yellow River water with sediment through a long distance is successfully solved, the technology of reclaiming of subsided farmlands by filling with Yellow River sediment can be popularized for application in coal mining areas alongside the Yellow River in the future.

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LI Junying, LI Xinju, WU Kening, SONG Wen, ZHANG Xiaodan. Prediction of Variation of Soil Nutrient Status in Reclaimed Subsidence-damaged Farmlands by Filling with Yellow River Sediment Different in Reclamation History in Jining City[J]. Acta Pedologica Sinica,2018,55(6):1358-1366.

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History
  • Received:January 09,2018
  • Revised:July 26,2018
  • Adopted:August 15,2018
  • Online: August 27,2018
  • Published: