Soil Phosphorus Characteristics Analysis Of Chinese Fir Plantation In Different Soil Forming Rock

Phosphorus in the soil is one of the basic elements needed for plant growth and metabolism,it is also a limiting factor for plant growth,phosphorus in soil can be divided into inorganic and organic phosphorus.Cunninghamia lanceolata is is an important timber tree species in southern China,but the continuous growth of artificial fir also leads to the continuous decline of productivity,one of the main reasons is due to insufficient supply of available phosphorus in the soil.The contents distribution and change of phosphorus in forest soil were mainly determined by the nature of soil and the maturity of vegetation.In southern China,granite and siltstone as a typical soil parent material,not only can affect the soil nutrient composition,but also directly determines the production efficiency of Chinese fir plantation.Therefore,it is important to study the characteristics of phosphorus in different soils of different mother rocks,which will be of great significance to improve the productivity of Chinese fir and reduce the scientific management measures.In this paper we chooses two kinds of parent soils,such as granite and siltstone,which are mainly distributed in the different developmental stages of Xinkou teaching forest farm in Sanyuan Town,Sanming City,Fujian Province,China.The differences of total phosphorus and available phosphorus contents in different soils of Cunninghamia lanceolata plantations were analyzed,and the determination of phosphorus.The difference of phosphorus forms was analyzed by nuclear magnetic resonance(NMR)technique from the point of view of bonding type,and the different forms of phosphorus were studied deeply.The correlation analysis between different forms of phosphorus and other nutrients,reveal the difference of soil phosphorus composition in different mother rock soils,explain the different nutrient differences of different age of different parent rock,and discuss the influence of different development stages on soil phosphorus in Chinese fir plantations in order to reveal the soil phosphorus availability at different age and to provide theoretical basis for solving the problem of productivity decline caused by multi-generation plantation of plantation in order to achieve the purpose of rational operation of artificial fir forest.The results were as following:(1)The content of total P in the soil of Chinese fir plantation at different developmental stages decreased with the increase of soil depth.The soil total phosphorus content in the soils of the same age siltystonewas lower than that of the granites,the soil layers of mature forest siltstone are significantly higher than those of granite soil.The contents of total phosphorus in the same parent rock were:mature forest>young forest>middle age forest.(2)The content of available phosphorus in Chinese fir plantations at different developmental stages decreased with the increase of soil depth in vertical distribution,the content of available phosphorus in the soil at each age of siltstone was significantly lower than that of granite.The available phosphorus content of the two parent rocks is higher than that of the siltstone in the same age of the same age,the content of available P in the same age was the same as that of young forest>middle age forest>mature forest.(3)The contents of inorganic phosphorus in the development of soil were as follows:middle aged forest>mature forest>young forest.In the granite soil,the content of inorganic phosphorus was as follows:Mature forest>middle age forest>young forest.Different forms of inorganic phosphorus to O-P accounted for the highest proportion of the total excess of inorganic phosphorus 60%;and the lowest content of Al-P,the proportion of inorganic phosphorus in the total 5.5%.(4)There was no significant difference in the contents of organophosphorus in the soils of the two parent rocks,except the active organic phosphorus content in the same parent rock,the organic phosphorus content in the three forms was as follows:middle age forest>mature forest>young forest.The contents of organic phosphorus in four different forms of soils were as follows:medium active organic phosphorus>active organic phosphorus>medium stable organic phosphorus>high stable organic phosphorus.(5)The 31P-NMR experimental results showed that orthophosphate,pyrophosphate and monophosphate were detected in the sandstone soil.The contents showed as orthophosphate>orthophosphate monoester>pyrophosphate,while the granite soil of the young and mature forests in addition to the above three forms of phosphorus,but also detected phosphate.The contents of orthophosphate and orthophosphoric acid in the first layer of siltystone were significantly higher than those in granite,the soil pyrophosphate content in the granite soil was 6%higher than that in the siltstone soil.The soil layers of the siltystone mature forest were significantly higher than those in the granite soil.The content of orthophosphate monoester in mature soil was significantly higher than that in young forest.The content of orthophosphoric acid was young>mature forest>middle age forest,which was significantly different,the content of pyrophosphate in mature forest and mature forest was significantly higher than that in young forest and increased with the depth of soil.In the granite soil,and the mature forest was significantly higher than that of the young forest.The content of monophosphate monoester in young forest was significantly higher than that in mature forest.(6)The contents of C,N,C/N,total phosphorus,available phosphorus,Al-P content,Fe-P content,active organic phosphorus,medium active organophosphate,medium stable organic phosphorus and other nutrients,with the distribution of the characteristics of the surface,the content decreased with the increase of soil layer.(7)The correlation analysis showed that the contents of total phosphorus in soils of two different Chinese fir plantations were positively correlated with C,N,C/N ratio,Al-P,Fe-P,O-P and three organic phosphorus,and negatively correlated with total potassium and Ca-P in the soil.The content of available P was positively correlated with C,CN ratio,indicating that the organic matter in soil was the main source of available phosphorus,and the available phosphorus was positively correlated with Al-P,indicating that Al-P is a potential source of available phosphorus in soil and that of available phosphorus is negatively correlated with total potassium and phosphorus except Al-P.