Rejuvenation of Coastal Sandy Soils through Organics

The coastal zone represents the transition from terrestrial to marine influences and vice versa. They are predominated by sandy soil texture, and have low agricultural productivity due to their properties and are vulnerable to erosion. Effective maintenance of soil organic matter is found to be a pre-requisite to ensure soil health and crop productivity. Therefore, organics based rejuvenation methods for coastal sandy soils need to be developed. A pot culture experiment was done at Kochuveli, Industrial area, in the coastal belt of Thiruvananthapuram district, Kerala, with Amaranthus (variety: Arun) as test crop. The experiment was conducted in a completely randomized design (CRD) with 12 treatments and 3 replications. In the study, effect of different organic manures such as FYM, coirpith compost, vermicompost, city compost, biochar and thermochemical organic fertilizer (TOF), with and without lime on plant growth and yield, soil organic carbon and nutrient dynamics in the southern coastal sandy soils were studied. Soil management using organic manures had considerable impact on the growth and yield characteristics of the crop. Also the analyses of post-harvest soil for nutrient parameters showed that the highest value for organic carbon, nitrogen and potassium were recorded in soil treated with lime+TOF, while the highest value for available phosphorous was recorded in treatment lime+vermicompost. The study showed that soil test based lime application and basal application of TOF @ 25 t ha-1, top dressing with fresh cow dung slurry @ 1kg per 10 litres, along with 272.7 kg rock phosphate and 122.5 kg potassium sulphate ha-1 was the best treatment to improve the soil quality, growth and yield of amaranthus in coastal sandy soils in Thiruvananthapuram district.