Abstract
Understanding the spatial spreading patterns of plant-available sulphur (S) (AS) and plant-available micronutrients (available zinc (AZn), available iron (AFe), available copper (ACu), available manganese (AMn) and available boron (AB)) in soils, especially in coastal agricultural soils subjected to various natural and anthropogenic activities, is vital for sustainable crop production by adopting site-specific nutrient management (SSNM) strategies. We studied the spatial distribution patterns of AS, AZn, AFe, ACu, AMn, and AB in cultivated soils of coastal districts of India using geostatistical approaches. Altogether 39,097 soil samples from surface (0 to 15 cm depth) layers were gathered from farm lands of 68 coastal districts. The analysis of soil samples was carried out for soil pH, electrical conductivity (EC), soil organic carbon (SOC) and AS, AZn, AFe, ACu, AMn, and AB. Soil pH, EC and SOC varied from 3.70 to 9.90, 0.01 to 7.45 dS m-1 and 0.02 to 3.74%, respectively. The concentrations of AS, AZn, AFe, ACu, AMn, and AB varied widely in the study area with their corresponding mean values were 37.4±29.4, 1.50±1.53, 27.9±35.1, 2.14±1.74, 16.9±18.4 and 1.34±1.52 mg kg-1, respectively. The coefficient of variation values of analyzed soil parameters varied from 14.6 to 126%. The concentrations of AS, AZn, AFe, ACu, AMn, and AB were negatively and significantly correlated with soil pH and positively and significantly correlated with SOC. The geostatistical analysis indicated stable, Gaussian and exponential best-fit semivariogram models with moderate to strong spatial dependence for available nutrients. The generated spatial spreading maps revealed different distribution patterns for AS, AZn, AFe, ACu, AMn, and AB. There were variations in spatial spreading patterns of AS, AZn, AFe, ACu, AMn, and AB in east- and west-coastal area. About 62, 35, 12, 0.4, 23 and 45% of the study area had deficiency of AS, AZn, AFe, ACu, AMn, and AB, respectively. The spatial spreading maps will be highly useful for SSNM in the cultivated coastal soils of the country. This study could also be used as a base for assessing spatial spreading patterns of soil parameters in cultivated coastal areas of other parts of the world.
Highlights
Earth has 620,000 km of coast line [1]
Around 1⁄4 of the total population of the world resides in the coastal area and they predominantly depend upon agriculture and allied activities for livelihood [2]
The variations of soil pH, electrical conductivity (EC) and soil organic carbon (SOC) the study area is ascribed to the effects of the soil types, prevailing climatic conditions, and adoption of different crop-management practices
Summary
Around 1⁄4 of the total population of the world resides in the coastal area (within a distance of 100 km from the coast line) and they predominantly depend upon agriculture and allied activities for livelihood [2]. India has approximately 7,500 km of coastline along Arabian sea and Bay of Bengal [3] Both the coastal area and agriculture is very often adversely affected mainly by changes in salinity, tidal process, water stress, water logging and different anthropogenic activities. This leads to land degradation due to several reasons including soil nutrients deficiencies and reduced agricultural productivity [4, 5]. Efficient management of soil nutrients in coastal area is needed for higher agricultural productivity and better livelihood of the coastal population [6]
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