Factors Affecting Rice Production in Northeastern Thailand: The Relationship between Soil Salinity and Vegetative Cover

Abstract

Saline soil is typically found in lower elevation terrain which is also used for rice cultivation. Deforestation in recharge areas can accelerate soil salinity due to increased capillary action. This study examined the relationship between saline soil distribution and vegetative cover at Nong Due Village, Khon Kaen, Thailand. It also identified some social factors and farm management practices which affected rice production in saline paddies. A field survey was conducted in April, 2012 to determine soil property analysis, combined with a questionnaire on rice production, farm management, and farmer’s household socioeconomic conditions. In total, 34 paddy fields were surveyed with 68 soil samples collected from non-saline and saline plots. Elevations of the sampled plots were 146-178 m with electrical conductivity (ECe) 0.19-16.58 dS/m. Soil salinity did not show a significant correlation from the sampled paddies to the closest vegetation, but high salinity did occur in lower elevations and farther away from the nearest forest. Forty household representatives answered the questionnaire, of which 34 had encountered some problems with soil salinity (average 0.89 ha/household). Average rice yields from saline paddies were 1.9 tons/ha, lower than those from non-saline paddies (mean difference -113.39 kg/ha). Rice production costs associated with soil salinity were estimated 10,770 Baht/ha, of which the highest amount was spent on crop maintenance. In contrast, costs from non- saline farming systems were 9,791 Baht/ha (39.75% also spent on farm maintenance). Household income and labor did not show a significant correlation with farm management practices. Fertilizer application is dependent on the availability of on-farm resources and word-of-mouth. Farmers often use cattle manure, compost and green manure to reduce soil salinity. Moreover, farmers raised the height of paddy borders, so that more rainwater could be stored, thus ensuring that the rice paddies were continuously submerged.