The effect of cutting interval on foliage yield
and chemical composition of Tropical Kudzu
(Pueraria phaseoloides)
cultivated as cover-crop in rubber plantation
Nguyen Van Hiep, Hans Wiktorsson* and Ngo
Van Man
Facultry
of Animal Science and Veterinary Medicine,
Nong Lam
University, Ho Chi Minh City, Vietnam
* Department
of Animal Nutrition and Management, Swedish
University of Agricultural Sciences,
PO Box 7024, S-750 07 Uppsala, Sweden
Abstract
An experiment was
carried out with Tropical Kudzu, which was cover crop for rubber at second year,
to evaluate effect of cutting interval on yield and chemical composition of
foliage. Four cutting intervals of Kudzu
foliage: 40, 50, 60 and 70 days were arranged in a randomized completely block
design (RCBD) with 4 replicates in 12 m2 of one experimental plot.
The
present study showed decreasing leaf proportion, CP content and increasing DM
and ADF content with increasing length of cutting interval. The leaf proportion
and CP content ranged from 58.63 to 48.97% and 22.11 to 19.65%, respectively.
The DM and ADF content ascended from 21.8 to 26.17% and from 38.01 to 39.94%,
respectively. The DM and
OM yield of Kudzu foliage were highest at 60-day cutting interval with 5.81 and
5.46 tonnes/ha/6months, respectively. The DM and OM yield at 40-day cutting
interval were significantly lower than that at 60-day cutting interval. The
fresh and CP yield of Kudzu were 21.75 – 23.13 tonnes/ha/6months and 1.08 – 1.14
tonnes/ha/6months, respectively. There were no significant differences of fresh
forage and CP yield among the cutting intervals.
To provide a balance
between quality and yield of Kudzu foliage, the optimum cutting interval was
60 days.
Key words:
chemical composition, cover-crop, cutting interval, Tropical Kudzu and yield.
Introduction
Legumes have been
considered as suitable crops in intercropping systems with perennial trees.
Legume crops are used with the aim of improving soil fertility through root
nitrogen fixation and mulching of crop residues (Ashokan et al, 1985), Binh
et al (1997) and Dung et al (2003) reported that
intercropping leguminous tree can improve soil fertility.
Tropical
Kudzu (Pueraria phaseoloides) is
a leguminous plant that appeared naturally throughout humid-tropics. It is used
as a part of a mixture or a sole cover-crop to prevent soil erosion as well as
enrich the soil of tree crop such as coconuts, oil-palm and rubber throughout
South East Asia and the Pacific islands. The most important role of Kudzu
cover-crop is the beneficial contribution to the parent tree crops through the
deposition of leaf litter and nitrogen fixation in the soil (Soong and Yap,
1976; Tajuddin et al, 1990).
The report of Dongnai Rubber Company (2005) showed that
biomass production of Kudzu in the rainy seasons was 36.7, 57.1 and 39.2 fresh
matter tonnes/ha at first, second and third years, respectively. Only one cutting
per year at the end of the rainy season has been applied in the rubber companies
in the region. The whole biomass of the cover-crops has been used as green
manure to the rubber field. There is not any demonstration in using this product
as animal feed.
Up to the present time, some of the
experiment report has been evaluated on the production potential of Kudzu
foliage for animals by pure planting or grass mixture (Nghia, 1978; Quang, 1979;
Trong, 1981; Manh et al, 2003) and none published report have focused on
the nutrition value of Kudzu foliage production cultivated as cover-crop in
perennial plant farm, which is popular in the rubber plantations in Vietnam.
The objective of the study was:
To evaluate the
effect of cutting interval on biomass yield and chemical composition of Tropical
Kudzu foliage, which has been inter-planted in the rubber plantation in the
second planting year.
Materials and methods
Location and climate
of the experimental site
The experiment was conducted from July 2006 to January 2007
at the Long Thanh rubber plantation, Dongnai province, Vietnam. It is about 70
km Northeast of Ho Chi Minh city. The weather conditions at the experimental
site are characterized by a tropical monsoon climate with two seasons, rainy and
dry. The rainy season lasted from April to October, with peaks in May and August
and an annual precipitation of about 1700 mm. The monthly mean temperatures
ranged form about 23.9 to 34.2 0C with minima in December and maxima
during the early rainy season (Figure 1). Air humidity varies in the range
69-83%.
Figure 1. Monthly rainfall and temperature in
the rainy season in 2006
The soil was basaltic red with the following characteristic with Kudzu
as cover crop but without frequent cutting: pHH2O = 4.6; OM % = 3.58;
Ntotal % = 0.205; P2O5 % = 0.309; K2O
% = 0.022 (Table 1).
