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Early response of second -- rotation Pinus
patula stands to nitrogen and phosphate fertilizers at Sao Hill forest plantations,
tanzania. An investigation into the effect of fertilization on second -- rotation Pinus
patula stands as an option for increasing growth and yield was initiated in April 1998 at
two sites in the Sao Hill forest plantation, Iringa region, southwest Tanzania. Six factorial
fertilizer treatments consisting of nitrogen (N) (0, 60 kg N ha -1 ) and phosphorus (P)
(0, 30, 60 kg P ha -1 ) were assigned randomly to one-year-old P. patula seedlings in April
1999. Tree heights were measured at 7, 18, 22, 30 and 42 months after out-planting.
Diameter at breast height (dbh) was measured from 22 months onwards. At 7 months,
seedlings were significantly taller at Ngwazi (0.45 + 0.03 m) than at Msiwasi (0.36 +
0.04 m). In contrast, although not significant, by 42 months trees were slightly taller at
Msiwasi (5.00 + 0.37 m) than at Ngwazi (4.87 + 0.46 m). Similarly, height increment
measured at 42 months was significantly higher at Msiwasi. Msiwasi had significantly
larger dbh trees (1.99 + 0.36 cm) than Ngwazi(1.62 + 0.0.30 cm) at 22 months, but
these differences disappeared with time. Neither the application of N nor P had any
effect on tree growth at Ngwazi. However, application of N depressed tree survival
from 96 to 89% at Msiwasi. Application of P increased diameter and height growth at
Msiwasi only. These results further stress the need for developing site-specific
recommendations based on research studies. |
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