SUPPLEMENTARY INCOME CROPS IN RUBBER PLANTATIONS: SUSTAINABLE OPTIONS FOR FARMERS BAN SADET SUB-DISTRICT, KHAIN SA DISTRICT, SURAT THANI PROVINCE

Abstract

The objective of this research was to analyze the patterns of supplementary income crops in rubber plantations and to study the costs and returns of these supplementary crops grown by farmers in Ban Sadet Sub-district, Khian Sa District, Surat Thani Province. This quantitative research used a sample group of 66 farmers registered with the Rubber Authority of Thailand, Khian Sa Branch, selected through purposive sampling. The research instrument was a questionnaire, with data analysis using percentage and mean values in a descriptive analysis approach. The research findings revealed that regarding supplementary crop patterns in rubber plantations, most farmers had experience growing rubber trees of the RRIM 600 and RRIT 251 varieties on their own land with SPK 4-01 land rights documents. The plantations were typically on flat clay soil, using water sources from rivers, canals, and natural water sources. The most popular supplementary crops were coffee and melinjo (Gnetum gnemon). The costs and returns of supplementary crops in rubber plantations were: 1) Robusta coffee has a total cost of 3,223.88 baht per rai per year, with an average yield of 79 kilograms per rai, sold at 110 baht per kilogram, generating a net return of 5,466.12 baht per rai per year or 69.19 baht per kilogram, and 2) Melinjo has a total cost of 3,760.08 baht per rai per year, with an average yield of 162 kilograms per rai, sold at 80 baht per kilogram, generating a net return of 9,199.92 baht per rai per year or 56.73 baht per kilogram. Regarding cost structure, for both Robusta coffee and melinjo, variable costs constituted the main proportion of total costs, with labor costs being the most significant component.