杉木中龄林施肥效应与效益研究

Effect of Fertilization on Growth of Middle-aged China-fir

对中亚热带黄红壤上中等立地条件下杉木中龄林的需肥规律、不同施肥配比对杉木径级分布的影响进行了研究，并比较了不同施肥配比的经济效益．结果表明：氮肥肥效最显著，单施N200kg／hm2，可增加蓄积量40．9m3／hm2；磷肥肥效较明显．单施P2O5400kg／hm2，可增加蓄积量31．0m3／hm2；而单施钾肥肥效不明显．P，K肥单施效应明显低于N，NP，PK和NPK肥，尤以处理N2P2K，即每hm2施200kgN，200kgP2O5，200kgK2O为最优，可增加蓄积49．1m3／hm2．以经济效益而论，较好施肥方案为N1（即施肥量为100kgN／hm2），N2（200kgN／hm2），N1p1（100kgN／hm2．100kgP2O5／hm2），N1K（100kgN／hm2，200kgK2O／hm2）和P1K（100kgP2O5／hm2，200kgK2O／hm2），其内部收益率达15％以上．沟施与撤施肥效差异不大．合理的施肥方案可提高杉木大、中径材比例．

This paper makes a general study of the fertilizing law of middle-aged China-fir forests planted on yellow-red soil in central subtropical zone,of the effects of fertilization with differert recipes on the distribution of China-fir diameter-class,and of the economic benefits obtained by applying fertilizers with different recipes. The results are as follows. The effect of applying nitrogen fertilizer by 20a kg/hm2 is obvious, and the tree stock area has increased by 40. 9 m3/hm2. The effect of applying P,O, by 400 kg/hm2 is obvious too,and the wood stock volume has increased by 31. 0 m3/hm2. The effect of applying potash fertilizer alone is not obvious. The effect of applying potash fertilizer alone or phosphate fertilizer alone is less obvious than that of applying N,NP,PK,and NPK fertilizers.In particular, the applying of N2P2K (N200 kg, P2O2 200 km, K2O 200 kg per hectare) results in a best effect, and the wood stock volume has increased by 49. 1 m3/hm2. The recipes with better economic benefits are N1 (N100 kg/hm2 ), N, (N200 kg/hm2 ), N1P1(N100 kg/hm2, P2O5100 kg/hm2 ),N1K (N100 kg/hm'2 K2O200 kg/hm2 ) and P1K(P2O5100 kg/hm2, K2O200 kg/hm2). The optimum recipes inter rates of return are over 15%. No significant differences have been found between the ditch-fertilization method and the castfertilization method. Rational fertilization plans can enhance the percentage of large and middle diameter trees.