关键词: 速生丰产林, 土壤肥力定位观测, 土壤速效养分, 施肥

Abstract:

A comprehensive analysis was made on the 5 year' s successive monitoring findings from the 34 fixed soil fertility monitoring sites of newly established high-yield timber plantations of 10 main species, such as Larix kaempferi, Populus tomentosa, Populus × euramericana, Cunninghamia lanceolata, Pinus massoniana, Pinus taeda, Pinus elliottii, Pinus caribaea, Eucalyptus globulus and Eucalyptus urophylla, for the National Afforestation Project, financed by the World Bank, which distributed in 13 provinces or autonomous regions in China.The analysis results showed the following conclusions :(1) The soil fertility indexes vary in different scale and tendency after plantation establishment.In general, the soil available nutrients, such as the content of available N, P and K in the soil changes significantly while others, such as pH and the content of organic matter and total Netc.change little over years after plantation establishment, that is to say, the afforestation has greater impacts on the soil available nutrients of plantation land.(2) For the plantations or Eucalyptus, Pinus or Cunninghamia lanceolata grown at relatively poor sites, the content of soil available N, P, K decreased over years after plantation establishment, of w hich the content of soil available Phad most significant reduction w ith average annual decrease of 30 %, while for the plantations of Larix kaempferi, Populus as well as Pinus and Cunninghamia lanceolata grown at relatively good sites, the content of soil available N, P, K had no significant reduction or even a little increase over years after plantation establishment.According to the change pattern of soil available nutrients of the plantation land over years after plantation establishment, the plantation land can be divided into two types.One is called "soil available nutrient decreasing type" (or SAND type), i.e., the content of soil available nutrients will decrease significantly over years after plantation establishment.The other one is called "soil available nutrient stable type" (or SANS type), i.e.the content of soil available nutrient has almost no change or little increase over years after plantation establishment.(3) For the plantation land of SAND type, the content of the decreased available nutrient elements in the soil could be raised in a larger scale by application of fertilizers, while for the plantation land of SANS type, the content of the available nutrient could still be raised but in a sm aller scale.(4) The content of available N, P and K in the soil of the plantations bland with fertilization increase more or less, but the content of available P in the soil has the most significant response to the application of P fertilizer, because there is the largest decrease in rate over years after plantation establishment when without fertilization, comparing to the content of available N and K in the soil.Therefore, the fertilization should be strengthened for the plantation land w ith SAND type, so that the content of soil available nutrients can be significantly improved and the fertilization can be more effective.

Key words: High-yielding timber plantation, Long-term soil fertility monitoring, Soil available nutrients, Fertilization