Water and soil pollution in vineyards of central Thailand

Very intensive cultivation systems have been developed in the delta of the Chao Phraya River for about a century. The objective of the study was to determine the fate of the fertilisers and pesticides applied to vineyards grown on raised beds. Water samples were collected from the outlet of a vineyard to determine the discharge of pollutants in the canal. The accumulation of elements in the soil was investigated by analysing soil samples from different fields. Fertilisation was estimated at 670 kg N, 300 kg P, and 560 kg K year⁻¹ ha⁻¹. Insecticides and fungicides were applied every four days on average, using up to 23 different molecules. Little N and no P were discharged in the canals in solution and discharge in suspension was minor. Pesticides were detected in 36% of the water samples. The topsoil contained 1600 mg kg⁻¹ Bray II P, 936 mg kg⁻¹ exchangeable K, 170 mg kg⁻¹ total Cu, and 167 mg kg⁻¹ total Zn. Pesticides were detected in 62% of the fruits after peeling. Overuse of fertilisers did not lead to water pollution, but overuse of pesticides resulted in pollution of the water bodies and of the fruits. Most applied elements accumulated in the soil, resulting in high values of P, K, Cu, and Zn.