The study on management of acid soils by using organic fertilizer on organic herbal
roselle product was conducted at farmer’s field, Banlam sub-district, Wihandaeng district,
Saraburi province, during October 2008 – September 2010. Soils were classified as Hin Kong
soil series, soil group no.16. The objectives of the research were to study effect of various
soil conditioners with organic fertilizer on soil chemical properties change, yields of roselle
and economic return. The experimental design was randomized complete block with 3
replications. The treatments included 1) control 2) farmers pratice 3) cow dung at rate of 2
tons per rai 4) compost at rate of 2 tons per rai 5) marl at rate of 500 kilogram per rai in
combination with cow dung at rate of 2 tons per rai 6) marl at rate of 500 kilogram per rai in
combination with compost at rate of 2 tons per rai 7) dolomitic limestone at rate of 500
kilogram per rai in combination with cow dung at rate of 2 tons per rai 8) dolomitic limestone
at rate of 500 kilogram per rai in combination with compost at rate of 2 tons per rai. The
results showed that soil pH increased when compare to before experiment. The treatments of
dolomitic limestone in combination with cow dung and dolomitic limestone in combination
with compost showed highest soil pH of 6.5. The highest organic matter and available
potassium content were observed in treatment applied cow dung, which were 2.71% and 150
milligram per kilogram, respectively. The highest available phosphorus and magnesium
content were observed in treatment applied with dolomitic limestone with compost, which
were 19 and 169 milligram per kilogram, respectively. The calcium content was highest in
treatment applied with marl 500 with cow dung, which was 1,625 milligram per kilogram.
The effect of lime and organic fertilizer on roselle yields was found. Application of marl in
combination with cow dung gave highest average roselle yield of 1,519 kilogram per rai.
While for control treatment showed the lowest average yield of 612 kilogram per rai. The
economic analysis showed that the application of marl in combination with cow dung
obtained the highest economic return of 8,490 baht per rai.