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

soil surface is usually started to mulching during the period from November or December to March of next year
to increase soil temperature and keep soil moisture in the winter season. The data showed the ground
temperature could raise 4-5 after mulched with organic materials (Fang et al. 1994). During the mulching
process, rice straw was firstly mulched to a height of 10-15 cm from the surface and then rice bran was filled
onto another height of 10-15 cm. The total rice straw and bran used in one time commonly reached 40 and 55 t
hm -2 . In the next year, the undecomposed rice bran layer was removed in March or April while the rice straw
almost decomposed or mixed into soils. In the next mulching time, the removed rice bran was mixed with new
to be used. The fertilizer applications were used for three times, i.e. mid-May, mid-September and the time
before the mulching, respectively. The fertilizer application rate was about 2.25 t hm -2 (N:P:K=16:16:16) and
urea 1.125 t hm -2 , sometimes manures with equal nutrient used as well. The use of organic material mulching
technique began from the 5th year after the bamboo transplanting.
Soil Sampling
During the bamboo plot selecting, similar soil position, landform, initial soil fertility and soil basic
physiochemical properties before bamboo plantation were considered. The selected planting time was 1 5 10
and 15 years, respectively. After 10 years, the bamboo stand became to showing degradation in the field. The
rice field was chosen as the control because the bamboo planted on soils shifted from the paddy soils. Each
replicate of plot selecting was located at one farmer’s field to keep the same original condition of soils from the
influence of field management. The area of each selected bamboo plot is larger than 100 m 2 . Due to the shallow
root depth of Lei bamboo, the soil profile was separated into 5 layers as 0-5, 5-10, 10-15, 15-20 and 20-25 cm,
respectively. Before the collection, litters and mulching materials on the soil surface were removed. We selected
three sites for sampling and there replicates were done on the each bamboo plot and paddy plot. Fresh soil
samples were air-dried and ground to pass through 2 mm sieve. In order to test the hypothesis of Al toxicity with
low pH to Lei bamboo, roots of bamboo were also collected in each plot.
Soil Analysis
Soil basic physicochemical properties, including soil pH, organic matter, nitrogen, cation exchangeable capacity
(CEC), were analyzed. Soil pH was determined by electrode method. Soil organic matter was measured with
K2Cr2O7 oxidation and FeSO4 titration. CEC was extracted by 1 M NH4Cl and K, Na, Ca and Mg were
determined by the atom adsorption system (AAs). Because Al may be one factor influencing bamboo growth in
red soil with low soil pH, various Al forms were also measured. These Al forms included exchangeable Al,
dissociated Al, amorphous Al, organic bound Al and total Al. The exchangeable Al was extracted by 0.1M KCl
(James et al. 1983), dissociated Al (Ald, dithionate), amorphous Al (Alo, oxalate) and organic bound Al (Alp,
pyrophosphate) were determined by the method proposed (Odes 1963; McMeague and Day 1966). Bamboo
roots were digested with HClO4+HF and Al content was measured by AAs.
VIII World Bamboo Congress Proceedings Vol 4-59