Farmland quality monitoring point layout method based on compound control zone of monitoring index

Abstract: The purpose of this research was to explore the layout method of the quality monitoring points of cultivated land, and to solve the unreasonable problem of monitoring point space layout. In this paper, the data source of the research was from the results of farmland productivity survey and quality evaluation. The SPSS software was used to establish a histogram of the number of indicators, and whether the data were continuous and were in a normal distribution was intuitively evaluated. The continuous sample data were used to determine the level and hierarchy of the monitored control area by the variation coefficient method, and according to the error theory, combined with the area control principle, the total number of monitoring points was determined and allocated into different zones according to the monitoring control zone area. For discontinuous data, if it was determined that the variation coefficient method in the monitoring control area would result in an invalid monitoring control zone level, in order to avoid this situation, visual discretization method was used to determine the level of monitoring control. The area of concentration of the target concentration was used as the monitoring control area; the data of the monitoring points after interpolation were continuous, therefore, the intermediate value was used as the endpoint value of the interval of monitoring control zone. The compound control area based on the monitoring index was divided by the space interpolation method of Kriging. The locations of the quality monitoring points of cultivated land were based on the spatial form of the control area of the compound monitoring index. The sampling theory was used to carry out a representative analysis of the monitoring points. 1) The research puts forward farmland quality monitoring point layout method based on compound control zone of monitoring index. Compared with other methods, the method takes full account of the lower relationship of the monitoring points; with specific indicators as a logical starting point, a composite control area was formed based on monitoring indicators; the degrees of homogenization and heterogeneity of the monitoring points were consistent with the monitoring indicators, which ensured that the space layout of the monitoring points was reasonable and avoided the disadvantage of redundancy for the monitoring point positions and the corresponding monitoring indices at monitoring point positions. 2) This paper takes Keshan County as an example to apply the method of monitoring point. The original program needs 11 monitoring indicators including organic matter, barrier layer thickness, plough thickness, total nitrogen, available phosphorus, available potassium, soil bulk density, slope, surface rock outcrop, soil pH value, and irrigation guarantee rate, as well as a total of 200 monitoring points and 2 200 tests, in which 110 kg soil sample and the cost of 440 000 yuan will be consumed. But after the optimization with this method, only 7 monitoring indicators are needed, including organic matter, total nitrogen, available phosphorus, available potassium, plough thickness, barrier thickness, and soil bulk density, and during the investigation process, 30 monitoring points and 81 tests are involved, along with only 4.05 kg soil sample and 16 200 yuan which will be consumed. And the monitoring point data in the layout have a good representation for the data of farmland productivity survey and quality evaluation of cultivated land. The optimized plan shows obvious advantages in monitoring pertinence, convenience and monitoring cost, and effectively improves the quality monitoring efficiency of cultivated land. This method is feasible and has good application value. It can obtain precise and a large amount of information by means of less input, which can be used for the reference for the optimization of land quality monitoring points.