WBC-VIII-Vol.4 – Resources – Forestry, Plantations and ... - BambuSC

Results and Discussion
Effects of Bamboo Plantation on Soil Properties
As shown in Table 1, soil pH value decreased with increasing planting time. After the bamboo planted 15 years
soil pH dropped to 3.85 that was almost 2 units lower than that of the paddy soil. Such a result indicated that
bamboo plantation accelerated the soil acidification when using this intensive management model. Soil
acidification is a naturally occurring phenomenon and is usually the result of long-term additions of protons to
the upper layers of the soil profile that effectively results in the displacement of exchangeable bases and their
subsequent leaching. However, accelerated acidification of soils associated with export of alkali through product
removal, or movement of cations associated with nitrate leaching, has brought into question the long-term
sustainability of crop and forage production systems (Helyar 1976). In this study, the accelerated acidification in
a short term exerted an important impact on bamboo sustainable production. When using the organic material
mulching technique, bamboo soils simultaneously received nitrogen fertilizer with a rate of ca. 800 kg N hm -2
annually that accordingly made a direct impact on the soil acidification. Due to acid release in the
decomposition, the mulched organic material also had an impact on soil acidification but no evidence was
obtained up-to-now in the bamboo plantation.
Soil organic matter content increased greatly from 31.0 to 79.2 g kg -1 after 15 years (Table 1). Obviously, the
increase of soil C and N (from 2.02 to 4.61 g kg -1 ) was closely related to the input of fertilizer and organic
matter. During the first 5 years, soil organic matter and nitrogen contents were slightly lower than those in the
control of paddy soils. In the process of paddy field shifted to upland, easily decomposable organic matter
decomposed rapidly due to a better oxidation condition. After the rice straw and bran mulching (from the 5 th
year), soil organic matter and nitrogen increased with increasing planting time. Usually in the intensive managed
moso-bamboo, soil organic matter decreased gradually with planting time (Xu et al. 2003). Because there was
no organic matter input to the moso-bamboo only chemical fertilizer applied, soil organic matter oxidized and
decomposed rapidly without extra input.
Soil total phosphorus content increased significantly from 0.500 to 2.005 g kg -1 with increasing planting time.
Since the source of P was derived from the fertilizer application and the movement of P in soils was difficulty
especially under the acid soil because P can be bound closely with Fe and Al minerals. Meantime, the bamboo
soils were shifted from paddy soils where nutrients are not easily leached through runoff due to a plat landform
with ridges. The accumulation of P reached such a high level that may result in bamboo blooming earlier and
bamboo degradation. We found some blooming bamboo culms in the field, but the number was few. However,
compared with soil P, soil total potassium showed no difference in various blocks (Table 1). This indicated that
applied K was balance to the bamboo growth if no significant K leached.
Soil available P and K increased greatly after the bamboo planted for 15 years. Especially, the available P
increased from 7.14 mg kg -1 in the paddy soil to 475.6 mg kg -1 in the bamboo soil of 15 years. The overloaded
soil P exerted a great risk to the surface water environment. Available K content increased but the total K
content showed no increase even with high fertilizer input, indicating large K leached from the bamboo field.
VIII World Bamboo Congress Proceedings Vol 4-60