scholarly journals Assessment of rice growth conditions in a semi-arid region of India using the Generalized Radar Vegetation Index derived from RADARSAT-2 polarimetric SAR data

2020 ◽  
Vol 237 ◽  
pp. 111561 ◽  
Author(s):  
Dipankar Mandal ◽  
Vineet Kumar ◽  
Debanshu Ratha ◽  
Juan M. Lopez-Sanchez ◽  
Avik Bhattacharya ◽  
...  
2009 ◽  
Vol 64 (5) ◽  
pp. 458-463 ◽  
Author(s):  
Wagner F. Silva ◽  
Bernardo F.T. Rudorff ◽  
Antonio R. Formaggio ◽  
Waldir R. Paradella ◽  
José C. Mura

2018 ◽  
Vol 10 (12) ◽  
pp. 1953 ◽  
Author(s):  
Safa Bousbih ◽  
Mehrez Zribi ◽  
Mohammad El Hajj ◽  
Nicolas Baghdadi ◽  
Zohra Lili-Chabaane ◽  
...  

This paper presents a technique for the mapping of soil moisture and irrigation, at the scale of agricultural fields, based on the synergistic interpretation of multi-temporal optical and Synthetic Aperture Radar (SAR) data (Sentinel-2 and Sentinel-1). The Kairouan plain, a semi-arid region in central Tunisia (North Africa), was selected as a test area for this study. Firstly, an algorithm for the direct inversion of the Water Cloud Model (WCM) was developed for the spatialization of the soil water content between 2015 and 2017. The soil moisture retrieved from these observations was first validated using ground measurements, recorded over 20 reference fields of cereal crops. A second method, based on the use of neural networks, was also used to confirm the initial validation. The results reported here show that the soil moisture products retrieved from remotely sensed data are accurate, with a Root Mean Square Error (RMSE) of less than 5% between the two moisture products. In addition, the analysis of soil moisture and Normalized Difference Vegetation Index (NDVI) products over cultivated fields, as a function of time, led to the classification of irrigated and rainfed areas on the Kairouan plain, and to the production of irrigation maps at the scale of individual fields. This classification is based on a decision tree approach, using a combination of various statistical indices of soil moisture and NDVI time series. The resulting irrigation maps were validated using reference fields within the study site. The best results were obtained with classifications based on soil moisture indices only, with an accuracy of 77%.


2021 ◽  
Vol 13 (21) ◽  
pp. 4246
Author(s):  
Zhenzong Wu ◽  
Jian Bi ◽  
Yifei Gao

The dynamics of terrestrial vegetation have changed a lot due to climate change and direct human interference. Monitoring these changes and understanding the mechanisms driving them are important for better understanding and projecting the Earth system. Here, we assessed the dynamics of vegetation in a semi-arid region of Northwest China for the years from 2000 to 2019 through satellite remote sensing using Vegetation Index (VI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS), and analyzed the interannual covariation between vegetation and three climatic factors—air temperature, precipitation, and vapor pressure deficit (VPD)—at nine meteorological stations. The main findings of this research are: (1) herbaceous land greened up much more than forests (2.85%/year vs. 1.26%/year) in this semi-arid region; (2) the magnitudes of green-up for croplands and grasslands were very similar, suggesting that agricultural practices, such as fertilization and irrigation, might have contributed little to vegetation green-up in this semi-arid region; and (3) the interannual dynamics of vegetation at high altitudes in this region correlate little with temperature, precipitation, or VPD, suggesting that factors other than temperature and moisture control the interannual vegetation dynamics there.


2019 ◽  
Vol 7 (2) ◽  
pp. 309
Author(s):  
Valéria Fernandes de Oliveira Sousa ◽  
Gisele Lopes dos Santos ◽  
Josemir Moura Maia ◽  
Carlos Henrique Salvino Gadelha Meneses ◽  
Marília Hortência Batista Silva Rodrigues ◽  
...  

It has been suggested that fatty acid balance in standard sunflower oil may be influenced by the genotype of the plant or by variation in environmental growth conditions. Therefore, this study analysed aspects of sunflower productivity and oil quality obtained from achenes of plants cultivated in a semi-arid environment, resulting from seed obtained from other regions with different edaphoclimatic characteristics. The experiment was conducted between February and May, in a Brazilian semi-arid area. At 90 days after sowing (DAS), the physiological maturation period, tissue was harvested, and the yield of plant green matter, oil and oil per hectare was evaluated. A comparative analysis of the oil content of achenes before and after planting (parental v progeny) was performed. The experiment was conducted in a randomized block design of 4 treatments (genotypes), Embrapa122, BRSG01, Helio253 and Helio250, and 4 replications, for a total of 16 experimental plots, with each plot constituting 8 plants. In this study, sunflowers were produced in the climatic conditions of the Brazilian semi-arid region with biomasses, achenes and oil contents that were different from other crop productions in the country, providing the possibility of obtaining oil with a distinct chemical composition.


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