According to the traditional farming experience, the soil after years of farming is generally called cooked soil or cooked soil. According to the literature, in the loess hilly region of China, the thickness of mature soil layer is set at 30cm, so the original cultivated land soil is often stripped and preserved during land consolidation, and then covered on the surface after the land is formed. No matter in-situ cultivated soil or foreign cultivated soil is used as topsoil matrix, this method is time-consuming and costly. Whether loess with wide distribution and large thickness can be used as surface soil matrix material in Dayugou mining area is one of the contents of this study.

The loess in Dayugou area, known as loessial soil and Heilongtu in soil science, is composed of alluvial and aeolian deposits. Different from the general residual soil, the loess has been exposed to the surface in the process of formation, so the loess below the tillage layer should not be regarded as "raw soil" or parent material.

According to the analysis, the clay in Quaternary loess in Dayugou (

Sample pit No.2 represents the loess plateau or slope top soil in Dayugou mining area, and its total fertility and layered fertility are shown in Table 5.6 and Figure 5. 10.

Table 5.6Fertility Status of Sample Pit No.2

Fig. 5. Statistical curve of fertility of102 sample pit

No.3 sample pit profile represents the soil condition of loess slope in Dayugou mining area, and its total fertility and layered fertility are shown in Table 5.7 and Figure 5. 15438+0.

Table 5.7 Fertility Status of No.3 Sample Pit

Fig. 5. Statistical curve of fertility of113 sample pit.

No.4 sample pit is located in the farmland at the foot of loess slope. See Table 5.8 and Figure 5. 12 for soil fertility.

1 sample pit is located in the artificial reclamation land under the coal gangue in the industrial square. See Table 5.9 and Figure 5.438+03 for soil fertility.

Table 5.8 Fertility Status of Sample Pit No.4

Fig. 5. Statistical curve of fertility of sample pit124

Compared with the soil fertility grading index of loess cultivated land in China, Dayugou loess is equivalent to the third type of cultivated land soil (belonging to the seventh type of cultivated land soil in China). According to the cropping system of three crops a year or two, even if the subsoil below 1m is used as farming soil, the annual output can reach 300 ~ 400 kg/mu as long as the field management is strengthened.

Table 5.9 Fertility Status of Sample Pit 1

Fig. 5. 13 sample pit 1 fertility statistical curve

It can be considered that the loess in Dayugou mining area is a good covering material.

See Table 5. 10 for routine ion test results of soil samples in each pit.

Table 5. Routine Ion Test Data of10 Soil Samples

sequential

Note: The number before the number indicates the sample pit number, and the number after the number indicates the soil layer number sorted from top to bottom. For example, 2-5 represents the fifth soil sample of pit 2.