Spatial variability and site specific fertility management of six soil parameters viz. soil pH, soil organic carbon, available nitrogen, available phosphorus, available potassium and available sulphur were undertaken using both classical statistics and geostatistical analysis for the intensively cultivated research farm of Indian Agricultural Research Institute, New Delhi that represents agroecological sub-region of north Punjab plain, Ganga Yamuna Doab and Rajasthan upland under hot semi-arid eco-subregion. The soil properties exhibited variability with highest variation observed in available sulphur (72.7 %) whereas the lowest variation was in pH (7.3 %). Bivariate correlation coefficient analysis showed highly significant (P \ 0.01 %) relationship within six attributes of the soil, except between the available sulphur and pH. The exponential model for pH, available phosphorus and available potassium were the best fitted semi-variogram models while that of soil organic carbon, available nitrogen and available sulphur was spherical model. The nugget and sill ratio indicated moderate spatial dependency for all soil properties within the farm. Ordinary kriging was used for interpolation of soil attributes in non-sampled areas. It was observed that use of geostatistical method on a small scale could accurately generate the spatial variability map of soil nutrients in alluvial soils. Based on the study recommended level of fertilization except sodic soil patches where reclamation measures are needed for sustainable crop productivity are advocated.
Present irrational crop and nutrient management practices have raised several concerns of high merit. The concerns include low factor productivity or nutrient use efficiency (NUE), declining crop productivity, farmer’s profitability, impaired soil health and ecological contamination. Site-specific nutrient management (SSNM), after considering indigenous nutrient supplying capacity of soil using plant and soil analysis, can feed the crop in synchrony with its nutrient requirement in different physiological growth stages. Besides, several modern geospatial techniques viz. remote sensing techniques, geographic information system (GIS), global positioning system (GPS), proximal sensing; information and communication technologies (ICTs) including decision support system, smartphone apps and web services can also assist in diagnosis of soil and crop nutrient status, fertilizer recommendation and its dissemination to users. Optical and thermal remote sensing can effectively detect crop stress including nitrogen (N) deficiency through several vegetation indices especially normalized difference vegetation index (NDVI). GIS techniques with spatial data acquired by GPS, can create spatial variability map and management zone (MZ) for precise farm operations including variable rate fertilization. Proximal crop sensors viz. chlorophyll meter and Green Seeker can also recognize crop nitrogen status and promote fertilizer N use efficiency by synchronizing fertilizer N supply with crop requirement. Even proximal soil sensing using electromagnetic radiation and contact electrode can estimate soil properties like soil pH, electrical conductivity, major and micronutrient content. Several decision support systems such as QUEFTS based model, crop manager, nutrient expert® and smartphone apps like ‘crop doctor’ can suggest for precise application of agro-inputs to rural youths and farmers. Yield monitoring and mapping tool can generate historical GIS database for spatial variability of crop yield under farmers’ crop management practices and assessment of nutrient uptake. Variable rate machinery based on variability map and sensor technologies can also be used for fertilization under different management zones. Therefore, SSNM technologies can enhance NUE; improve and sustain crop productivity, profitability; avoid nutrient wastage; maintain good soil health and environmental safety.
The paper deals with the structure, function, and fisheries resources of Bhagar lake, South Bihar, one of the oxbow lakes in Dumraon (un-reported and un-described), from February 2018 to January 2020 under the state non plan research project. This lake is spread from Nauki par (Chakki) to Nainijore (Brahampur), Dumraon, (Buxar) with a large size wetland in dimension of 20 km length & 1 km width. Bhagar oxbow lake is U shaped, hydrological closed lentic type meander of the Ganga river, it is fed by the monsoon runoff and ingress of flood water from the river Dharmawati. The water depth of lake ranges between 1.5 to 3 meters in summer and depth 4 to 6 meters during the Monsoon months. Water temperature ranged from 16°C (January) to 30°C (August) whereas the pH value of lake water was found within 7.0 to 7.8. In aspect of biological properties of the lake, it was highly infested with submerged vegetation with dominancy of Hydrilla cillata and floating aquatic weeds (water hyacinth) such as Eichhormia crassipes with approximately 30 percent area coverage. This lake is rich sources of fishes with identified forty four species with example of annual fishes like Mystus spp., Puntius spp., Channa spp., Carps spp., small Macrobrachium spp. and several seasonal fishes, providing livelihood support to more than sixty five household, socio-cultural importance. It also gives protection to many wild mammals like Blackbucks (Antelope cervicapra), swamp deer (Rucervus duvaucelii) and Nilgai (Boselaphus tragocamelus) during summer time. This lake is also wintering ground of the migratory birds such as Heron and Crane.
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