Development of spectral models for assessing soil fertility status in various agroecological sub-regions of Punjab

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dc.contributor.advisorSekhon, B.S.
dc.contributor.authorGarnaik, Saheed
dc.date.accessioned2019-10-10T04:04:29Z
dc.date.available2019-10-10T04:04:29Z
dc.date.issued2019
dc.description.abstractThe present study titled “Development of spectral models for assesing soil fertiity status in various agroecological sub-regions of Punjab” was carried out in five agroecological sub-regions, namely, Submountainous Siwalik Hills (SSH), Northeastern Undulating (NEU), Piedmont and Alluvial Plain (PAP), Central Alluvial Plain (CAP) and Southwestern Alluvial Plain (SWAP). The objectives were to develop visible-near infrared (vis-NIR) models for predicting soil properties and to examine portability of spectral models across regions. GPS based soi fertility maps were prepared by using inverse distance weighted (IDW) interpolation and classification. Highest soil organic carbon (SOC) and sand content (mean 0.77 % and 74.2 %, respectively) in 0-15cm soil were observed in SSH, whereas highest nitrogen, phosphorous and, manganese contents (mean value 104.5 kg ha-1, 40.8 kg ha-1, 7.8 ppm, respectively) were found in NEU. The largest potassium, copper and silt levels (mean 173.1 kg ha-1, 5.21 ppm, 22.4 %, respectively) were reported in PAP. The CAP represented highest calcium carbonate content (mean 1.36 %), while highest pH, electrical conductivity, iron and zinc (mean value 7.93, 0.95 dS/m, 29.5 ppm and 3.2 ppm, respectively) levels were observed in SWAP region. Spectral signatures in vis-NIR range were collected using ASD Spectroradiometer. Partial least square regression (PLSR) was emlpoyed to develop spectral models for assessing soil fertility attributes. Various model evaluation indices e.g. root mean square error (RMSE), ratio of performance to deviation (RPD) and coefficient of determination (R2) were used to evaluate predictive performance of the PLSR models. The RMSE, RPD and R2 values varied between 0.05 - 0.39, 0.32 – 1.73 and 0.05- 0.69, respectively in SSH for various soil properties. Similarly, in NEU RMSE, RPD and R2 values ranged between 0.05 – 0.39, 0.93 – 2.15 and 0.12 - 0.82, respectively. In PAP region, the RMSE, RPD and R2 values varied between 0.07-2.90, 0.32-1.6 and 0.05-0.72, respectively. CAP region showed RMSE, RPD and R2 values ranging between 0.03-0.43, 0.62-1.5 and 0.03-0.64, respectively. In case of SWAP region, RMSE, RPD and R2 values ranged between 0.03-0.73, 0.72-1.5 and 0.05-0.68, respectively. Moreover, in common model, RMSE, RPD and R2 values varied between 0.19-3.81, 0.16- 0.98 and 0.01-0.40. A comparison among models suggested about their non-portability across regions. Based upon various performance indices, the CaCO3 and sand predictions were reliable, whereas prediction of properties like SOC and Olsen-P was moderately reliable. The pH and EC, however, could not be predicted much accurately. The study suggested about exploring better statistical tools to enhance prediction performance of spectral models.en_US
dc.identifier.urihttp://krishikosh.egranth.ac.in/handle/1/5810130570
dc.keywordsModel portability, Partial least squares regression, Soil fertility maps, Spectral library, Vis-NIR spectroscopyen_US
dc.language.isoenen_US
dc.pages98en_US
dc.publisherPunjab Agricultural University, Ludhianaen_US
dc.research.problemDevelopment of spectral models for assessing soil fertility status in various agroecological sub-regions of Punjaben_US
dc.subSoil Scienceen_US
dc.themeDevelopment of spectral models for assessing soil fertility status in various agroecological sub-regions of Punjaben_US
dc.these.typeM.Scen_US
dc.titleDevelopment of spectral models for assessing soil fertility status in various agroecological sub-regions of Punjaben_US
dc.typeThesisen_US
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