Spatial And Temporal Changes Of Soil Quality And Sustainable Utilization In Liaocheng City

Lying in the west of Shandong, Liaocheng City, with its vast flat-bottomed land, is one of the main grain producing regions of Shandong Province. This research systematically analyses the soil quality variation in Liaocheng and probes into the variation trend, quantity and reasons, aiming to guide the actual agricultural production, improve soil quality and agricultural production environment and realize soil sustainable utilization of the region.Based on the relevant collected data of Liaocheng soil survey in 1985, this research, using the method of lattice, fixes the sample position and amount with GIS as the platform. It does the indoor physicochemical analysis after air-drying the gathered soil sample (0 - 25 cm deep) and analyzes the time change of the soil nutrient from 1985 to 2005 according to the findings of laboratory test and relevant materials. Moreover, by means of the statistical techniques on the ArcGIS platform, it analyses the space-variation trend of soil nutrient and forms a variation diagram. Last but not least, it appraises and analyzes the soil quality and the space-variation trend by means of the relative soil quality assessment and land statistics technology, and hence confirms the special change characteristic of soil quality.Analyzed from the perspective of time, the organic matter, the soil content of whole nitrogen, alkali-hydrolyzable nitrogen, rapidly available phosphorus increased in 2005 compared with that of 1985; however, the integral level was still not high; Although the first-grade proportion of rapidly available phosphorus in soil increased 11.4% from zero in 2005, the five, six-grade proportion increased more and other proportions decreased, which proves the quick-acting potassium content of soil of Liaocheng is reduced on the whole.The increase of soil organic matter owes much to the fertilizing, manuring and the application of large-scale wheat, maize harvester, which has increased straws to return the field. The increase of soil nitrogen, phosphorus content is mainly caused by the use of a large amount of nitrogen, phosphorus fertilizer; whereas the decrease of soil quick-acting K results from the long-time ignorance to the use of K fertilizer.Analyzed from the perspective of space, the organic matter and the nitrogen content of Liaocheng soil, both being low, with the former being0.972% on average and the latter only 0.071%, have little special differences. The crest value of alkali-hydrolyzable nitrogen is mainly distributed in Chiping County and Dong'er County whereas the Schwellenwert mainly in Linqing County, the north of Gaotang County and the northwest of Shenxian County.The contrast of alkali-hydrolyzable nitrogen content in Liaocheng is not big, but the overall content is relatively high: the average content of alkali-hydrolyzable nitrogen is 62.910 mg/kg, soil sample of over 60 mg/kg accounting for 46.49%, with that of Chiping County reaching more than 103 mg/kg, and the alkali-hydrolyzable nitrogen content is lowest in Linqing, north of Gaotang and the north of Shenxian County.The contents of quick-acting phosphorus and quick-acting potassium in Liaocheng soil differ greatly. The overall content of the former(15.257 mg/kg on average) is not high, with the content (reaching over 47 mg/kg)in the middle part of Dongchangfu District, the northwestern part of Guan County and the west of Yanggu county are relatively high. The minimum value is distributed in Linqing County and north of Gaotang County. The quick-acting potassium content in most of Liaocheng area is relatively low, the average being only 94.96 mg/kg, and the soil sample of above 100 mg/kg. quick-acting potassium content only accounting for 19.29%.According to the results of soil quality evaluation, the soil quality level in Liaocheng is generally not high, mainly concentrating on the middle and low-level. The samples with first- and second-grade soil quality accounts for 1.75% only, and the three - four– five-grade accounts for 21.05%, 32.46% and 42.98% respectively. The low grade soil mainly distributes in Linqing County, north of Gaotang County, northwestern Shen County and the middle part of the Guanxian County. In contrast, the relatively high grade soil distribute in the east of Chiping County, Shen County and south of Dong'er. The spatial variation of soil quality is, on one hand, related to the microtopography of Liaocheng, especially with the old reaches of the Yellow River, where the overall soil quality is quite low on account of the sandy soil texture, poor irrigation, bad crop growth. On the other hand, the implementation of family-contract responsibility system leads to the diversified soil-management measures and individual differences in such aspects as intensive cultivation and agricultural material input.In order to realize the sustainable development of the Liaocheng agriculture, the middle-and-low-yielding fields should be transformed so as to improve the soil output competence; moreover, the appropriate fertilizing should be implemented to improve soil properties, supplement the nutrient of the soil in an all-round way, and improve the soil output and fertility constantly; finally, the dynamic monitoring system of soil quality should be set up and improved, which can offer the theoretical foundation for the sustainable utilization of soil.