SPATIAL VARIABILITY IN SOIL NUTRIENT STATUS AND SOIL FERTILITY MAPPING USING GEOSPATIAL TECHNIQUES IN KURNOOL DIVISION OF ANDHRA PRADESH
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Date
2019
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ACHARYA N G RANGA AGRICULTURAL UNIVERSITY, GUNTUR
Abstract
A study was undertaken to assess the relation between soil available nutrient content and spectral indices, soil fertility status, delineation of spatial variability of soil fertility status in order to prepare soil available nutrient maps, identification of constraints and suggest fertilizer recommendations and nutrient management options for improved productivity in different crops grown in the study area of Kurnool revenue division in Kurnool district of Andhra Pradesh state using remote sensing and GIS techniques.
Georeferenced soil samples were collected in two season’s viz., rabi 201617 and 2017-18 from the study area using GPS receiver. The soil samples were analysed for various soil fertility parameters by adopting standard procedures.
Soil analysis of the study area during 2016-17 and 2017-18 indicated that the soils are neutral to strongly alkaline in reaction with low electrical conductivity. The organic carbon was low to medium in range. The soils were low to medium in available nitrogen, low to high in available phosphorus and medium to high in available potassium. The available secondary and micro nutrients viz., Ca, Mg, S and Mn were sufficient whereas Zn, Fe and Cu are deficient to sufficient in range. Spatial variability of soil properties was studied and maps were generated based on the data generated using geo-statistics. In the present study, the variability was observed in the availability of all the nutrients except calcium, magnesium and manganese. The spatial variability was high with phosphorus followed by sulphur, zinc, iron, nitrogen, potassium and copper.
A significant and positive correlation was observed between NDVI and available nitrogen only during 2017-18 whereas both organic carbon and
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available nitrogen had significant and positive correlation with NDVI during 2016-17 in bengalgram. A significant and positive correlation was observed between the NDVI and organic carbon and available nitrogen in cotton crop during 2016-17. However, no significant correlation was observed between NDVI and organic carbon or available nitrogen during 2017-18 under cotton cropping.
The main soil constraints faced by farmers were low soil fertility followed by inadequate organic matter in the soil. The main production constraints noticed were lack of knowledge on soil testing and soil test based fertilizer application followed by inadequate knowledge on basal application of phosphorous fertilizers, split application of nitrogen fertilizers, poor availability of improved variety and lack of adoption of optimum seed rate. The socio-economic related constraints faced by farmers were high cost on labour and inputs. The other constraints during the survey were lack of training facilities, knowledge about latest production technologies, lack of knowledge club/group/union etc.,
The spatial variability maps were generated and delineated into different zones for N, P and K. The site specific fertilizer recommendations for cotton and bengalgram for both years viz., 2016-17 and 2017-18 in Kurnool division were developed utilizing the thematic maps of spatial variability of N, P and K status.
It can be summarized that remote sensing and GIS technologies are highly reliable in generating natural resource database to integrate and assess their potential on spatial basis. The use of geostatistics enabled the assessment of heterogeneous nature of fertility variations. Integration of GIS with various models in the present study was highly useful in correlation studies between spectral indices and soil properties, generating the soil fertility and fertilizer recommendation maps. These studies can be extended up to village level for micro level planning and management of crop fields provided the real time availability of high spatial resolution satellite data is ready available. Further, the results provide actual estimates of fertilizer requirement for important crops of any area under study, thereby saving budget on fertilizer use at farmer’s level as well as at planner’s level.
Description
D5884
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