Abstract:

Effects of fertilizer application of P and PK on soil properties and foliar nutrients of young stands of loblolly pine(Pinus taeda) and slash pine (P.elliottii) were studied during 1991~1995 on the site of red earth derived from phyllite in the hilly land of Jingdezhen City of Jiangxi Province. The results showed that: (1)Rapidly available P content of soil increased while organic matter and other nutrients decreased in the soil of both stands after the fertilization of P and PK; P application could facilitate the mineralization of organic matter and the absorption of N. (2) P and PK application could increase the numbers of bacteria, fungi and cellulose-decomposing bacteria but reduce actinomyces in the soil of slash pine and stimulate aerobic nitrogen-fixing bacteria and phosphobacteria at the early stage of fertilization while inhibit at the later stage. (3) P and PK application could also improve activities of soil urease and catalase, and inhibit soil phosphatase at the early phase of fertilization but release its activity at the latter phase; sucrase activity could be improved by P application while inhibited by PK. (4) P and PK application could significantly increase Ca and Mg after two years from fertilization but reduce N content in the needle of slash pine, and there was no significant effect on P and K content in the needles.

Key words: Slash pine, Loblolly pine, Fertilization, Soil property, Foliar nutrient