Mukhtar Abubakar

Mr. Mukhtar Abubakar


Research Focus & Metrics

Academic Career Length

8Years (2019-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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5 May 2023 in Remote Sensing
Verified
Journal Article
Open access
PDF file
MAMukhtar Abubakar
Mukhtar Abubakar
ACAndré Chanzy
André Chanzy
FFFabrice Flamain
Fabrice Flamain
GPGuillaume Pouget
Guillaume Pouget
DCDominique Courault
Dominique Courault
This study aimed to propose an accurate and cost-effective analytical approach for the delineation of fruit trees in orchards, vineyards, and olive groves in Southern France, considering two locations. A classification based on phenology metrics (PM) derived from the Sentinel-2 time series was developed to perform the classification. The PM were computed by fitting a double logistic model on temporal profiles of vegetation indices to delineate orchard and vineyard classes. The generated PM were introduced into a random forest (RF) algorithm for classification. The method was tested on different vegetation indices, with the best results obtained with the leaf area index. To delineate the olive class, the temporal features of the green chlorophyll vegetation index were found to be the most appropriate. Obtained overall accuracies ranged from 89–96% and a Kappa of 0.86–0.95 (2016–2021), respectively. These accuracies are much better than applying the RF algorithm to the LAI time series, which led to a Kappa ranging between 0.3 and 0.52 and demonstrates the interest in using phenological traits rather than the raw time series of the remote sensing data. The method can be well reproduced from one year to another. This is an interesting feature to reduce the burden of collecting ground-truth information. If the method is generic, it needs to be calibrated in given areas as soon as a phenology shift is expected.

25 June 2022 in Remote Sensing
Verified
Journal Article
Open access
PDF file
MAMukhtar Abubakar
Mukhtar Abubakar
ACAndré Chanzy
André Chanzy
GPGuillaume Pouget
Guillaume Pouget
FFFabrice Flamain
Fabrice Flamain
DCDominique Courault
Dominique Courault
Conventional methods of crop mapping need ground truth information to train the classifier. Thanks to the frequent acquisition allowed by recent satellite missions (Sentinel 2), we can identify temporal patterns that depend on both phenology and crop management. Some of these patterns are specific to a given crop and thus can be used to map it. Thus, we can substitute ground truth information used in conventional methods with agronomic knowledge. This approach was applied to identify irrigated permanent grasslands (IPG) in the Crau area (Southern France), which play a crucial role in groundwater recharge. The grassland is managed by making three mows during the May–October period, which leads to a specific temporal pattern of leaf area index (LAI). The mowing detection algorithm was designed using the temporal LAI signal derived from Sentinel 2 observations. The algorithm includes some filtering to remove noise in the signal that might lead to false mowing detection. A pixel is considered a grassland if the number of detected mows is greater than 1. A data set covering five years (2016–2020) was used. The detection mowing number was conducted at the pixel level, and then the results were aggregated at the plot level. An evaluation data set including 780 plots was used to assess the performances of the classification. We obtained a Kappa index ranging between 0.94 and 0.99 according to the year. These results were better than other supervised classification methods that include training data sets. The analysis of land-use changes shows that misclassified plots concern grasslands managed less intensively with strong intra-parcel heterogeneity due to irrigation defects or year-round grazing. Time series analysis, therefore, allows us to understand different management practices. Real land-use change in use can be observed, but long time series are needed to confirm the change and remove ambiguities with heterogeneous grasslands.

2 October 2023 in OENO One
Verified
Journal Article
Open access
PDF file
MAMukhtar Abubakar
Mukhtar Abubakar
ACAndré Chanzy
André Chanzy
FFFabrice Flamain
Fabrice Flamain
DCDominique Courault
Dominique Courault
Accurate data on crop canopy are among the prerequisites for hydrological modelling, environmental assessment, and irrigation management. In this regard, our study concentrated on an in-depth analysis of optical satellite data of Sentinel-2 (S2) time series of the leaf area index (LAI) to characterise canopy development and inter-row management of grapevine fields. Field visits were conducted in the Ouveze-Ventoux area, South Eastern France, for two years (2021 and 2022) to monitor phenology, canopy development, and inter-row management of eleven selected grapevine fields. Regarding the S2-LAI data, the annual dynamic of a typical grapevine canopy leaf area was similar to a double logistic curve. Therefore, an analytic model was adopted to represent the grapevine canopy contribution to the S2-LAI. Part of the parameters of the analytic model were calibrated from the actual grapevine canopy dynamics timing observation from the field visits, while the others were inferred at the field level from the S2-LAI time series. The background signal was generated by directly subtracting the simulated canopy from the S2 LAI time series. Rainfall data were examined to see the possible explanations behind variations in the inter-row grass development. From the background signals, we could group the inter-row management into three classes: grassed, partially grassed, and tilled, which corroborated our findings on the field. To consider the possibility of avoiding field visits, the model was recalibrated on a grapevine field with a clear canopy signal and applied to two fields with different inter-row management. The result showed slight differences among the inter-row signals, which did not prevent the identification of inter-row management, thus indicating that field visits might not be mandatory.

1 January 2019 in Agricultural Research Journal
Verified
Journal Article
Closed access
PDF file
MAMukhtar Abubakar
Mukhtar Abubakar
ZZZebedee Musa Zega
Zebedee Musa Zega
OJOlumuyiwa James Jayeoba
Olumuyiwa James Jayeoba
Three pedons were exposed, one in each three soil units (DD1, DD2 and DD3) and soil samples were collected from different soil horizons. Soils in pedons DD1 and DD2 were deep (100–115 cm) while DD3 was shallow (48 cm), surface soil color ranged from dark brown (7.5YR 5/2 dry, 7.5YR 2.5/0 moist) in DD1, dark brown (7.5YR 5/8 dry, 10YR 5/2 moist) in DD2 and yellowish brown (10YR 6/3 dry, 10YR 4/4 moist) in DD3. Soil textural classes ranged from sandy loam to sandy clay loam and bulk densities were high (1.54–1.94 g cm−3). Soil reaction was strongly acid to moderately acid (pH 5.50–6.98), organic carbon contents were moderate (14.6–18.7gkg−1), total nitrogen (TN) medium (21–40 g kg−1), CEC moderate (6.26–9.26 cmol kg−1). Soils of three pedons had high base saturation (88.1–94.6%); moderate in Ca and Mg contents, low in K and Na content (0.16–0.19 cmol kg−1). Soils were classified as Typic Haplusterts, Typic Plinthaqualfs and Typic Plinthustalfs according to USDA classification and as Haplic Vertisols (Eutric), Plinthic Acrisols (Eutric, oxyaquic) and Haplic Plinthosols (Eutric) according to World Reference Base for Soil Resource (WRB).

20 May 2022 in Preprints.org
Verified
Preprint
Open access
PDF file
MAMukhtar Abubakar
Mukhtar Abubakar
ACAndré Chanzy
André Chanzy
GPGuillaume Pouget
Guillaume Pouget
FFFabrice Flamain
Fabrice Flamain
DCDominique Courault
Dominique Courault
Conventional methods of crop mapping need ground truth information to train the classifier. Thanks to the frequent acquisition allowed by recent satellite missions (Sentinel 2), we can identify temporal patterns that depend on both phenology and crop management. Some of these patterns are specific to a given crop and thus can be used to map it. Thus, we can substitute ground truth information used in conventional methods with agronomic knowledge. This approach was applied to identify irrigated permanent grasslands (IPG) in the Crau area (Southern France) which play a crucial role in groundwater recharge. The grassland is managed by making three mows during the May-October period which leads to a specific temporal pattern of leaf area index (LAI). The mowing detection algorithm was designed using the temporal LAI signal derived from Sentinel 2 observations. The algorithm includes some filtering to remove noise in the signal that might lead to false mowing detection. A pixel is considered a grassland if the number of detected mows is greater than 1. A data set covering five years (2016-2020) was used. The detection mowing number was done at the pixel level and then results are aggregated at the plot level. A validation data set including 780 plots was used to assess the performances of the classification. We obtained a Kappa index ranging between 0.94-0.99 according to the year. These results were better than other supervised classification methods that include training data sets. The analysis of land-use changes shows that misclassified plots concern grasslands managed less intensively with strong intra-parcel heterogeneity due to irrigation defects or year-round grazing. Time series analysis, therefore, allows us to understand different management practices. Real land-use change in use can be observed, but long time series are needed to confirm the change and remove ambiguities with heterogeneous grasslands.

1 January 2020 in Agricultural Research Journal
Verified
Journal Article
Closed access
PDF file
MAMukhtar Abubakar
Mukhtar Abubakar
MDM U Dawaki
M U Dawaki
VOV B Ogbe
V B Ogbe
Study was conducted along the banks of three rivers (Salanta, Kofar Ruwa and Jakara) in Kano metropolis, Nigeria. Three profiles were exposed along the bank of each river and four soil samples were collected at 30 cm depth interval up to 120 cm depth. The algorithm (one profile function) displayed soil organic carbon (SOC) content decreased down the profile depth across all the rivers. However, soils of river Kofar Ruwa and Jakara had higher SOC content (11.15 and 13.00 g kg1, respectively) due to presence of municipal and domestic sewages compared with river Salanta (5.68 gkg−1) which was dominated by industrial effluents.