Nutrient Status of Acid Sulphate Soils of Upper Kuttanad of Kerala, India

Chemical characterization of acid sulphate soils of Upper Kuttanad, Kerala was done to study its present nutrient status due to the impact of heavy flood that occurred in 2018. Extreme acidity is the major issue with this type of soil. Among the collected soil samples, 53.33 per cent of soil samples fall under very strongly acidic group (4.5 to 5) and 33.33 per cent comes under strongly acidic category (5.1 to 5.5). Lower values of EC in Upper Kuttanad indicate that this area is less affected by saltwater intrusion. More than 90 per cent of the samples were rich in organic carbon content. Among the major nutrients, 40 per cent of the soil samples recorded low available P content (<10 kgha-1). The availability of potassium, calcium, and magnesium increased with flooding. Almost all the samples collected from the acid sulphate soils of Upper Kuttanad showed high available sulphur status. It ranged from 20.20 to 3361.50 mgkg-1. The hike in micronutrient status showed the impact of flooding in these locations. The cation exchange capacity of the collected soil ranged from 5.92 to 30.64 cmol (+) kg-1 and showed a positive correlation with organic carbon (0.779***), available potassium (0.571*) and available iron (0.717*). This paper helps in understanding the present nutrient status in acid sulphate rice soils of Upper Kuttanad after the flood and adoption of suitable management practices.