Quantifying Fertilizer Application Response Variability with VHR Satellite NDVI Time Series in a Rainfed Smallholder Cropping System of Mali

Blaes, X and Chome, G and Lambert, M J and Traore, P C S and Schut, A G T and Defourny, P (2016) Quantifying Fertilizer Application Response Variability with VHR Satellite NDVI Time Series in a Rainfed Smallholder Cropping System of Mali. Remote Sensing, 8 (6). pp. 1-18. ISSN 2072-4292

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Abstract

Soil fertility in smallholder farming areas is known to vary strongly on multiple scales. This study measures the sensitivity of the recorded satellite signal to on-farm soil fertility treatments applied to five crop types, and quantifies this fertilization effect with respect to within-field variation, between-field variation and field position in the catena. Plant growth was assessed in 5–6 plots per field in 48 fields located in the Sudano-Sahelian agro-ecological zone of southeastern Mali. A unique series of Very High Resolution (VHR) satellite and Unmanned Aerial Vehicle (UAV) images were used to calculate the Normalized Difference Vegetation Index (NDVI). In this experiment, for half of the fields at least 50% of the NDVI variance within a field was due to fertilization. Moreover, the sensitivity of NDVI to fertilizer application was crop-dependent and varied through the season, with optima at the end of August for peanut and cotton and early October for sorghum and maize. The influence of fertilizer on NDVI was comparatively small at the landscape scale (up to 35% of total variation), relative to the influence of other components of variation such as field management and catena position. The NDVI response could only partially be benchmarked against a fertilization reference within the field. We conclude that comparisons of the spatial and temporal responses of NDVI, with respect to fertilization and crop management, requires a stratification of soil catena-related crop growth conditions at the landscape scale.

Item Type: Article
Divisions: Research Program : West & Central Africa
CRP: UNSPECIFIED
Uncontrolled Keywords: Precision agriculture; Fertility; UAV; Very high resolution; Digital Globe time series; Heterogeneous landscape; Unmanned Aerial Vehicle; VHR; Normalized Difference Vegetation Index
Subjects: Others > Smallholder Farmers
Others > Rainfed Agriculture
Others > GIS Techniques/Remote Sensing
Others > Cropping and Farming Systems
Others > Fertilizer Applications
Others > African Agriculture
Others > Mali
Depositing User: Mr Ramesh K
Date Deposited: 11 Apr 2017 06:42
Last Modified: 07 Sep 2017 05:05
URI: http://oar.icrisat.org/id/eprint/9948
Official URL: http://doi.org/10.3390/rs8060531
Projects: UNSPECIFIED
Funders: UNSPECIFIED
Acknowledgement: This publication was made possible (in part) by the STARS project, an integrated effort to improve our understanding of the use of remote sensing technology in monitoring smallholder farming [18]. Additional support was provided by the CCAFS Flagship 2 project on “Capacitating African Smallholders with Climate Advisories and Insurance Development”. The authors would like to acknowledge the field team members: Daouda Sanou (AMEDD), Nema Dembélé (AMEDD), Nouhoum Dembélé (AMEDD), Oumar Diabaté (AMEDD), Gilbert Dembélé (AMEDD), Birama Sissoko (AMEDD), Ousmane Dembélé (AMEDD), Bougouna Sogoba (AMEDD), and Adja R. Sangaré (ICRISAT).
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