Reduction of Chemical Application in Soybean at Farm Level I. Comparison between Two Wet Seasons Soybean Production

Abstract

The experiments were conducted in the farmer fields at Thongphaphoom district of Kanchanaburi province, Thailand in the year of 2000 and 2001. Soybean cultivar “Chakkrabhandhu no.1” were grown in the upland soil on 20 July 2000, and 20 July 2001 respectively. The harvesting dates for both
experiments were in the first week of November. Treatments composed of the combinations of chemical and non-chemical control for weed, insect
and soil fertility designed as no chemical, less chemical and moderate chemical application. The given treatments were compared with farmer practices in which various kinds of chemical at different amounts were used in soybean production. Results of two experiments conducted revealed that yield of soybean in the year 2000 was higher than in 2001 due to less weed infestation. Biophoska organic fertilizer in less chemical treatment and triple super phosphate (TSP) in moderate chemical treatment were the main cause of high yield. To grow soybean successfully in the rainy season, herbicides were still needed. In both years of 2000 and 2001, insect infestation were mild, therefore the use of neem extract from Azadirachta indica A. as insect repellant seemed enough for controlling insects in soybean fields. This study indicated that in order to grow soybean in the rainy season, herbicides are still needed to suppress weed. Growth and yield of soybean can be enhanced by using organic fertilizer or TSP.