Nutrient accumulation and fertilizer potential of terrace section soils in loess areas

In Weibei dry-land and Guanzhong Plain, farmers usually collect the surface soil of terrace section (≤ 5 cm) and use it as fertilizer. Sampling was carried out in Chengcheng County, Tongchuan County, Baishui County, Fuping County, Mei County. Sampling points were selected in the study area to surface soil of terrace section (about 2 years, about 6 years, and more than 10 years), at different soil depths (1 cm, 3 cm, 5 cm), different orientation (shady side, sunny side) and at different heights (0.2 m, 0.8 m, 1.0 m from the ground).The results show: (1) Available potassium, ammonium nitrogen and total nitrogen were easily enriched in the surface soil of terrace, which can be used as a good soil fertilizer to supplement potassium and nitrogen fertilizer. (2) Only nitrogen, phosphorus and potassium elements necessary for plant growth were studied. The rational application of medium and trace element fertilizers and bio-organic fertilizers had become an important symbol of intensive economic utilization of agriculture. In the next step, attention should be paid to the changes of trace element and microbial activity in the terraced surface soil. Further, the activity state of soil fertilizer process carried out by nutrients, organisms and microorganisms in terraced surface soil was fully revealed.3) Human factors can promote the activation of surface soil nutrients and accelerate the formation of natural fertilizers. In local management of terraced soil, farmers should implement engineering slope protection to maintain the stability of terraced slopes. Construction of water conservancy measures such as intercepting ditches and cisterns can be used for keeping the soil moderate moisture. Adopt biological measures, plant climbing crops, implement vegetation cover, reduce erosion, improve soil aggregate structure and water retention capacity. In this way, the accumulation rate of nutrients in terraced topsoil will be accelerated, and the wide application of natural fertilizer in land regulation and soil ripening will be realized.