Growth response of Pinus radiata to multiple applications of nitrogen fertilizer and evaluation of the quantity of added nitrogen remaining in the forest system
Growth response of Pinus radiata to multiple applications of nitrogen fertilizer and evaluation of the quantity of added nitrogen remaining in the forest system
复制标题
辐射松对多次施氮肥的生长响应及森林系统剩余氮添加量评价
作者：
W. Neilsen;W. Pataczek;T. Lynch;R. Pyrke
在9年的时间里，922公斤公顷-1的N添加在8个应用程序的16岁的辐射P.在澳大利亚塔斯马尼亚州东北部的低降雨量地区的立场。施肥提高了目前的年生长量从8.5 m3 ha-1的未施肥地块，到31 m3 ha-1。增长与树木健康状况的改善有关。生物量的测量表明，有一个大的增加，在针保留以及针质量上的施肥树。施肥树的N浓度也较高。施肥地块含有467公斤公顷-1比未施肥地块的N。这代表了约50%的N应用。这些额外的N大部分存在于森林作物和土壤表面10 cm处。表层土壤有机碳没有增加，结果C/N比从非常高的28降低到17。尽管施氮地块获得了高生长率，但未能增加土壤有机质，并且大部分施氮地点的损失表明，这些低降雨量地点的生长不太可能得到长期改善。只有继续增加氮肥才能维持生长。
Over a period of nine years, 922 kg ha-1 of N was added in eight applications to a 16 year old P. radiata stand in a low rainfall area in north-east Tasmania, Australia. Fertilizing lifted current annual increment from 8.5 m3ha-1 for the unfertilized plots, to 31 m3ha-1. Increased growth was associated with improved health of the trees. Biomass measurements showed that there was a large increase in needle retention as well as needle mass on the fertilized trees. Concentration of N was also higher in fertilized trees. Fertilized plots contained 467 kg ha-1 more N than unfertilized plots. This represented about 50 percent of the N applied. Most of this extra N was in the forest crop and in the surface 10 cm of the soil. There was no increase in organic carbon in the surface soil with the result that the C/N ratio was reduced from a very high 28 to 17.Despite the high growth rates attained in the N fertilized plots, the failure to increase soil organic matter and the loss from the site of much of the applied N indicated that long term improvement of growth of these low rainfall sites was unlikely. Growth would only be maintained with continued N fertilizer additions.