Evaluation of productivity of some sub-surface layers of soil profile

The influence of four non-surf ace soil profile layers(AB, Ab, Bk, Bg)on the growth of crop root system and nutrient adsorption were studied by using Chinese cabbage (Jinglu 2)cultivated in pots with 3 different fertilizer treatments: no fertilization, urea treatment, and diammonium orthophosphate treatment. The results indicate that no apparent difference among the treatments in seedling emergence is observed. The dry matter accumulation is increased with the addition of urea and diammonium orthophosphate, but the latter is much more effective. Root-shoot ratio is the lowest in the diammonium orthophosphate treatment; the plant nitrogen content is increased with the addition of urea or diammonium orthophosphate. Plant phosphorus content is increased apparently in diammonium orthophosphate treatment. The experimental results suggest that sub-surface soil layers show no impedient effect on crop growth, and the supplement of nitrogen and phosp horus as well as proper tillage and irrigation would help to improve the product ivity of sub-surface soil.