Fertility Improvement of Sandy Soil by Vetiver Grass Mulching and Compost
Fertility Improvement of Sandy Soil by Vetiver Grass Mulching and Compost
Fertility Improvement of Sandy Soil by Vetiver Grass Mulching and Compost
ABSTRACT
To improve the productivity and fertility of Hupkapong sandy soil, fresh vetiver grass was used in
mulching and vetiver grass compost was applied in combination with chemical fertilizer. Soil fertility and
productivity were evaluated from the yields of Insee 1 super sweet corn hybrid grown on the soil, and soil
moisture determined using a neutron probe. The results indicated that super sweet corn hybrid gave a
maximum growth and yield when it was fertilized with 75-75-75 kg N-P2O5-K2O ha-1 in combination with
soil mulching of 31.25 t ha-1 of fresh vetiver grass. Reducing the application of N-chemical fertilizer and
vetiver mulching by 50% resulted in a decrease in super sweet corn hybrid yields. This decrease, however,
was not statistically significant. Mulching was found to conserve topsoil moisture and increase plant
growth and production. Soil incubated with vetiver grass or its compost released approximately the same
amount of available-N. However, fresh vetiver grass mineralized higher levels of available-P and
extractable-K than vetiver grass compost. One ton of vetiver grass yielded 1.32 kg t-1, 0.24 kg t-1 and 6.73
kg t-1 of available-N, available-P and extractable-K, respectively.
Key words : vetiver grass, fertility, sandy soil, moisture, mulching, compost
1 Department of Applied Radiation and Isotopes, Faculty of Science, Kasetsart University, Bangkok 10900,Thailand.
2 Division of Soil Science, Department of Agriculture, Bangkok 10900, Thailand.
3 Huai Sai Royal Development Study Center, Phetchaburi 76120, Thailand.
Kasetsart J. (Nat. Sci.) 34 (3) 333
superphosphate and 41 kg of potassium chloride matter, 0.77, 11.00 and 68.00 mg kg-1 available-N
(Chairoj and Na Nagara, 1999). Moreover, N content (NH4+ + NO3-), available-P and extractable-K,
of one ton of vetiver grass compost was as much as respectively. Treatments for soil improvement were
43 kg of ammonium sulfate (Office of the Royal shown in Table 1. Soil moisture contents at 10, 20,
Development Projects Board, 1998). Therefore, 30, 45, 60 and 90 cm depth levels from surface were
vetiver grass has a potential to be used as organic measured using a neutron probe at one day before
matter to increase soil fertility. The purpose of this and one after irrigation. Irrigation was applied
research was to investigate the possibility of using twice a week with 4 cm per application. Weed
vetiver grass as a soil mulch or compost to increase control was done by hoeing as necessary. There
the yield of sweet corn grown in dry, low fertility was no insecticide application since there was no
sandy soil. The amounts of available-N, available- problem with insect pest. Data were also taken on
P and extractable-K released from fresh vetiver growth and yield of Insee 1 super sweet hybrid
mulch and vetiver compost incubated with soil for corn.
different periods of time were also investigated. In addition, soil incubation experiments with
fresh vetiver grass and vetiver grass compost were
MATERIALS AND METHODS conducted, in the laboratory of the Division of Soil
Science, Department of Agriculture, Bangkok, to
From March-May 1998 and 1999, Insee 1 determine nutrient released at 0, 10, 20, 30, 40, 50,
super sweet corn hybrid was planted in a completely 60, 70, 80, and 90 days after incubation. The
randomized design (CRD) at Huai Sai Royal incubated soil was analyzed for available-N (NH4+
Development Study Center, Cha-am District, + NO3-) (Bremner, 1965), available-P (Bray and
Phetchaburi Province. The soil is classified as a Kurtz, 1945) and extractable-K (Knudsen et al.,
coarse-loamy, siliceous isohyperthermic, Ustoxic 1982).
Dystripepts (Hupkaphong series) with 0.8 % organic
Table 1 Soil improvement treatments for Insee 1 super sweet corn production at Huai Sai Royal
Development Study Center, Cha-am District, Phetchaburi in 1998 and 1999.
T1 Control M
T2 CF (full rate) 1/ CF + 1/ M
2 2
T3 CF + CP 1/ CF + CP + M
2
T4 1/ CF (half rate) + CP 1/ CF + CP + 1/ M
2 2 2
T5 CF + M 1/ CF + M
2
T6 CF + M
Figure 1 Height (cm) of super sweet corn hybrid under different soil managements in the 1998 dry season.
T1 = Control T2 = CF (full rate) T3 = CF + CP
T4 = 1/2 CF (half rate) + CP T5 = CF+ M
Where: CF = chemical fertilization at 75-75-75 kg N-P2O5-K2O ha-1
1/2 CF = chemical fertilization at 37.5 -75-75 Kg N-P2O5-K2O ha-1
M = mulching with fresh vetiver grass at 31.25 t ha-1
1/ M = mulching with fresh vetiver grass at 15.625 t ha-1
2
CP = vetiver grass compost incorporation at 37.5 kg N ha-1
Kasetsart J. (Nat. Sci.) 34 (3) 335
Figure 2 Height (cm) of super sweet corn hybrid under different soil managements in the 1999 dry season.
T1 = M T2 = 1/2 CF + M T3 = 1/2 CF + CP + M
1
T4 = /2 CF + CP + /2 M1 1
T5 = /2 CF+M T6 = CF + M
Where: CF = chemical fertilization at 75-75-75 kg N-P2O5-K2O ha-1
1/2 CF = chemical fertilization at 37.5 -75-75 Kg N-P2O5-K2O ha-1
M = mulching with fresh vetiver grass at 31.25 t ha-1
1/ M = mulching with fresh vetiver grass at 15.625 t ha-1
2
CP = vetiver grass compost incorporation at 37.5 kg N ha-1
Figure 3 Dry weight of straw, seed and cob of super sweet corn hybrid under different soil managements
in the 1998 dry season.
T1 = Control T2 = CF (full rate) T3 = CF + CP
1
T4 = /2 CF (half rate) + CP T5 = CF + M
Where: CF = chemical fertilization at 75-75-75 kg N-P2O5-K2O ha-1
1/ CF = chemical fertilization at 37.5 -75-75 Kg N-P O -K O ha-1
2 2 5 2
M = mulching with fresh vetiver grass at 31.25 t ha-1
1/2 M = mulching with fresh vetiver grass at 15.625 t ha-1
CP = vetiver grass compost incorporation at 37.5 kg N ha-1
336 Kasetsart J. (Nat. Sci.) 34 (3)
Figure 4 Dry weight of straw, seed and cob of super sweet corn hybrid under different soil managements
in the 1999 dry season.
T1 = M T2 = 1/2 CF + M T3 = 1/2 CF + CP + M
T4 = 1/2 CF + CP + 1/2 M T5 = 1/2 CF+M T6 = CF + M
Where: CF = chemical fertilization at 75-75-75 kg N-P2O5-K2O ha-1
1/2 CF = chemical fertilization at 37.5 -75-75 Kg N-P2O5-K2O ha-1
M = mulching with fresh vetiver grass at 31.25 t ha-1
1/2 M = mulching with fresh vetiver grass at 15.625 t ha-1
CP = vetiver grass compost incorporation at 37.5 kg N ha-1
Figure 5 Soil moisture percentage as affected by different soil managements under field condition one
day before (B) and one day after (A) irrigation.
T1 = Control T2 = CF (full rate) T3 = CF + CP
T4 = 1/2 CF (half rate) + CP T5 = CF + M
Where: CF = chemical fertilization at 75-75-75 kg N-P2O5-K2O ha-1
1/2 CF = chemical fertilization at 37.5 -75-75 Kg N-P2O5-K2O ha-1
M = mulching with fresh vetiver grass at 31.25 t ha-1
1/ M = mulching with fresh vetiver grass at 15.625 t ha-1
2
CP = vetiver grass compost incorporation at 37.5 kg N ha-1
Kasetsart J. (Nat. Sci.) 34 (3) 337
Figure 6 Available-N (a), available-P (b) and extractable-K (c) released at 0, 10, 20, 30, 40, 50, 60, 70,
80, 90 days after incubating soil with fresh vetiver grass leaf (FV), with vetiver compost (CV)
and control.
338 Kasetsart J. (Nat. Sci.) 34 (3)