Spatial configuration method about plow layer stripping and reusing in hilly region

Abstract: In the hilly region, how to choose the suitable plow layer to strip and configure the soil resource scientifically and rationally in the space, to achieve the purpose of controlling the implementation cost and improving the comprehensive benefit, is a scientific question that needs to be solved at present. Based on the analytic hierarchy process (AHP) method, geographic information system (GIS) technology and cost-benefit analysis, this study constructed an evaluation model of the plow layer stripping suitability with 5 indicators including earthwork, distance to the lane, topography, soil texture and organic matter. And, another evaluation model about the soil-covering priority degree was built with 8 indicators including plow layer thickness, soil thickness, distance to the lane, topography, plot size, irrigation-drainage condition, soil texture and organic matter. In order to protect the plow layer resource effectively and improve the comprehensive benefit of plow layer reusing, this study adhered to 4 basic principles for the plow layer spatial configuration, which were the maximum stripping, the priority for new farmland, the remarkable benefit and the reasonable cost. After selecting appropriate plots, a plow layer spatial configuration method based on the co-ordination of supply and demand circle was proposed, which was applied to propose a scientific framework to configure the stripped plow layer to the plots which needed plow layer soil to cover. General idea of this spatial configuration method was as follows: Firstly, use the 2 creative evaluation models to choose which plots were suitable to be stripped, and which plots were the first or the second choice for soil-covering; Secondly, according to the spatial agglomeration between the chosen soil-stripping region and the chosen soil-covering demand region, combined with the local financial investment level, set up a suitable transport distance to limit the implementation cost (within the distance range, the stripping plow layer soil was preferred to cover the plots in the first choice region for soil-covering demand); Lastly, according to certain methods and requirements, match the chosen soil-stripping region and the chosen soil-covering demand region, and form the supply-demand co-ordination circles which were relatively independent in the space. In this study, Guangze County, Fujian Province in the hilly regions was chosen to be our research area. The results showed that: the plots' area suitable to be stripped in the permit construction zone was 169.23 hm2, which contained 300 500 m3 strippable earthworks. The area of the first soil-covering region was 706.1 hm2, accounting for 5.2% in the region of soil-covering demand, which contained 700 000 m3 plow layer's earthwork. Forty-six percentage of this research area was the existing low-yielding field, which had poor quality soil, but meanwhile good infrastructure. The rest area was the supplementary farmland which had poor quality soil. The area of the second soil-covering region was 6 646.4 hm2, which accounted for 49.1% in the region of soil-covering demand, and needed 2 410 000 m3 plow layer earthwork. There was the existing middle-yielding field mainly in this region. The spatial configuration scheme including 33 supply-demand co-ordination circles was planned, with the stripped area of 169.23 hm2, the soil-covering area of 559.03 hm2, the earthwork of 300 500 m3, and the average transport distance of 4.65 km. In the definite soil-covering region, there was 57.79 hm2 for the new created farmland, accounting for 34.1% of the stripped area. There was 501.25 hm2 for the medium-and-low-yielding farmland which needed to be fattened and thickened, accounting for 37.6% of the total area of the medium-and-low-yielding farmland. The scheme's average transport distance was 4.65 km, less than the distance for suitable transportation. The spatial configuration's method proposed in this paper considered the cost and benefit. It had strong operability and high quantification, as well as a certain generalization. The developed scheme can provide a scientific basis for the study area to carry out the special planning and practice about the plow layer stripping and reusing.