| Taking a typical karst and non-karst mountain area, Maocun in Guilin as an example, the author discussed the pH value, the organic matter, the total contents of elements(N, P, K, Ca, Mg, Cu, Fe, Zn, Mn) and the five species contents including exchange species, carbonate bound species, Fe-Mn oxide bound species, organic bound species and remain species in woodland, bush and tilled land at the depth of 0-20 cm and 20-40 cm respectively. The main results were listed as follows:1. The contents of soil organic matter and nitrogen in surface layer were higher remarkably than that in bottom layer. And the contents of soil organic matter and nitrogen in karst area were higher than that in non-karst area, the highest contents of organic matter presented in woodland of karst area, and reached to 5.24%. It may caused by stable calcium humus which was formed in the processes of combination, agglomeration between soluble carbonate and soil humus, which was favourable for accumulating the soil organic matter.2. No remarkable variation was found in phosphorus contents in different depth of soil. The highest contents of total phosphorus presented in the soil of bottom layer and reached to 0.171% in karst area, 0.134% in non-karst area. Whereas the contents of available phosphorus was less than 0.1%, that is why the phosphate fertilizer have to be used in the most of farm land.3. The contents of available potassium account for a very small part of total potassium. Moreover the available potassium contents were not always high in soil with higher total potassium contents.4. No matter where the soil was in surface layer or bottom layer, the contents of calcium and magnesium in karst area soil was much higher than that in the non-karst area. The contents of total calcium in karst area were 2.845mg/g-5.5785mg/g, four times higher than that in non-karst area. And the exchange species contents of calcium was up to 70% of total; furthermore magnesium in karst soil existed mainly in form of carbonate bound species and remain species, the content of this two species was up to 80% of total, but the content of exchange species which can be directly absorbed by plant was below 2% of total, and also below 4%, the mean value of exchange species of magnesium in soil of southern China. It means that the scarcity of magnesium could happen in southern karst area. Accordingly, it is very important to transfer bound species to exchange species using some reasonable measures, thus improving magnesium usage in plant.5. In the study area, soil mineral elements(Cu,Fe and Zn) existed mainly in form of remain species. The highest contents of remain species could be over 98% of its total, but the contents of available mineral elements which could be directly used by plant was only about 1.0%; manganese in soil mostly was from oxide and oxysalt, and the colloid-protecting effect of organic matter and biological processes played an important role in transferring, enrichment, depositing of manganese. So the manganese in soil existed as Fe-Mn oxide bound species, around 70% of its total. Contents of total Manganese in surface layer (0-20cm) in karst area were 1173.498ug/g-2200.985ug/g, 1.9 times higher than that in the non-karst area. It also was higher than whole China soil average content of manganese, 580mg/kg (layer A).6. The result showed that there are 34 pairs'positive correlations among pH value, organic matter, total contents of nutrient elements in karst area, about 61% of total relativity, in which 5 paris(organic matter and total nitrogen, potassium and calcium, potassium and manganese, copper and iron) have significant positive correlation, it was proved that the synergistic effect was the dominant interaction between the nutrient elements in the karst area. But among 55 pair of nutrient elements in the non-karst area, 30 pairs presented negative correlation, in which 3 pairs (potassium and calcium, pH value and manganese, manganese and iron) have significant negative correlation. This indicated that antagonistic effect was the main interaction between nutrient elements in non-karst area.7. In study area, both in karst area and non-karst area, the soil pH value, the organic matter and the contents of exchange bound species and the soil pH value, the organic matte and the contents of carbonate bound species of various nutrient elements have positive correlation, the correlation account for 75%, 64% respectively in the karst area, and they are slightly higher than that in non-karst area, 61%, 54% respectively.8. In karst area: the soil pH value, the organic matter and the contents of Fe-Mn oxide bound species of various nutrient elements mainly have negative correlation, accounting for 54%; whereas in non-karst area, the positive and negative correlation are 50% to 50% respectively. Adversely, the correlation between the soil pH value, the organic matter and the contents of remain species were 50% to 50% respectively in karst area. And most of correlations are positive in non-karst area, accounting for 57%.9. In karst area, correlation between soil pH value, organic matter and the contents of organic bound species of various nutrient elements were mainly positive, accounting for 79%. Adversely they were mainly negative in non-karst. Although interaction between the soil pH value, the organic matter and the contents of various nutrient elements were mainly synergistic effect in the karst area, and antagonistic effect in the non-karst area, the exchange species, the carbonate bound species, Fe-Mn oxide bound species, the organic bound species, remain species and so on didn't not always change with the variation of total contents of elements, moreover the interaction between each species of a element also was quite different. Therefore, it was important to study the species of various nutrient elements and their relationship and transformation.
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