SOIL RESOURCE INVENTORY AND NUTRIENT MAPPING IN NANDYAL DIVISION OF ANDHRA PRADESH USING RS AND GIS
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Date
2014
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ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY
Abstract
A study was undertaken to assess the soil fertility status, delineate the spatial variability of soil fertility status in order to suggest fertilizer recommendation maps, customized fertilizer formulation, crop suitability analysis and soil quality assessment of Nandyal revenue division in Kurnool district of Andhra Pradesh state using remote sensing and GIS techniques.
Georeferenced samples were collected from the study area following spatially balanced sampling technique. The soil samples were analysed for various soil fertility parameters by adopting standard procedures.
Ground truth analysis indicated that soils of the study area are moderately to highly alkaline and with low EC ranges. The Available nitrogen, phosphorus, potassium and sulphur content showed much variation with high coefficient of variation. Soils vary across fields and within the fields. Hence to prove this fact, studies were done at village level taking Thimmapuram village of Mahanandi Mandal where much variability was observed. The data revealed that CV was high for phosphorus content (45%), all other nutrients also observed high values of CV confirming the existence of spatial variability within field.
It can be inferred that when average content of micronutrients is analysed, soils exhibit sufficient status of micronutrients but the coefficient of variation for available Fe, Cu, Zn and Mn is 13, 24, 26 and 21 per cent respectively. The larger CV depicts that within a village there is much variation in the micronutrient status, proving that soil fertility is not homogeneous.
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Spatial variability of soil properties was studied and maps were generated using geo-statistics. In the present study the variability is observed in case of all the nutrients under study with more variation in sulphur followed by phosphorus, iron, nitrogen, zinc, manganese, potassium and copper.
Soil Quality Index (SQI) was computed using the Geometric mean of the five quality indicators and SQI maps were generated using GIS, through which the percentage area in each mandal under different soil quality type is assessed. Soil quality index maps show that 89.96, 60.91 and 70.68 per cent areas are having high soil quality, whereas 3.02, 24.70 and 20.64 per cent areas of Mahanandi, Nandyal and Panyam, respectively are having low soil quality type, where farmers should be careful in selecting land use management and cropping patterns.
The soil site suitability maps for rice, sorghum, cotton and bengal gram delineate the areas in to suitable and not suitable which could be utilized for selecting the proper cropping pattern at local level.
Site specific fertilizer recommendations for rice in Nandyal division and for rice and banana in Thimmapuram are made utilizing the thematic maps of spatial variability of N, P and K status. It shows that nitrogen and potassium are being excessively applied whereas in case of phosphorus, in some parcels, less application of nutrient is observed. The study on the economics of STCR based fertilization for paddy in Nandyal division shows that the difference in blanket recommendations of N, P and K from that of the site specific fertilizer recommendations of nutrients saves ` 782 lakh for N, ` 1531 lakh for P and ` 850 lakh for K for paddy growing farmers if SSNM is followed.
Customized fertilizer formulations are prepared for paddy crop in different fertility zones. Recommended doses of N-P-K are calculated for each fertility zone and later customized fertilizer formulation is designed only for basal application as nitrogen is applied in three equal split doses for paddy crop and entire dose of P and K are applied basally. Hence, customized fertilizers are specific to each zone and each stage of the crop thereby increasing fertilizer use efficiency and reducing input costs.
In conclusion, it can be summarized that application of remote sensing, GIS and GPS have opened a new era in generating natural resource database to integrate and assess their potential on spatial basis. Integration of GIS with various models in the present study was highly useful in generating the soil suitability assessment, fertilizer recommendation maps, soil quality assessment and preparation of customized fertilizer formulations. These studies can be made up to village level for micro level management of crop fields which help in attaining sustainability by catering the actual requirement of soil and crop within spatially variable fields. Further, the results provide actual estimates of fertilizer requirement for the study area for the important crops grown, thereby saving budget on nutrients at both planning and farmers level.
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