Abstract
The study investigates the suitability of time series Sentinel-2 NDVI-derived maps for the subfield detection of a sunflower crop cultivated in an organic farming system. The aim was to understand the spatio-temporal behaviour of subfield areas identified by the K-means algorithm from NDVI maps obtained from satellite images and the ground yield data variability to increase the efficiency of delimiting management zones in an organic farming system. Experiments were conducted on a surface of 29 ha. NDVI time series derived from Sentinel-2 images and k-means algorithm for rapidly delineating the sunflower subfield areas were used. The crop achene yields in the whole field ranged from 1.3 to 3.77 t ha −1 with a significant within-field spatial variability. The cluster analysis of hand-sampled data showed three subfields with achene yield mean values of 3.54 t ha −1 (cluster 1), 2.98 t ha −1 (cluster 2), and 2.07 t ha −1 (Cluster 3). In the cluster analysis of NDVI data, the k-means algorithm has early delineated the subfield crop spatial and temporal yield variability. The best period for identifying subfield areas starts from the inflorescences development stage to the development of the fruit stage. Analyzing the NDVI subfield areas and yield data, it was found that cluster 1 covers an area of 42.4% of the total surface and 50% of the total achene yield; cluster 2 covers 35% of both surface and yield. Instead, the surface of cluster 3 covers 22.2% of the total surface with 15% of achene yield. K-means algorithm derived from Sentinel-2 NDVI images delineates the sunflower subfield areas. Sentinel-2 images and k-means algorithms can improve an efficient assessment of subfield areas in sunflower crops. Identifying subfield areas can lead to site-specific long-term agronomic actions for improving the sustainable intensification of agriculture in the organic farming system.
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Claims 10
Claim · model-written summary
Sunflower achene yield ranged from 1.3 to 3.77 t ha −1 with significant within-field variability.
- Taxon
- sunflower crop
Helianthus annuust0 - Outcome
- achene yieldse0
- Value
- 1.3 to 3.77 t ha −1e0
- Setting
- whole fielde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sunflower crop”
e0“The crop achene yields in the whole field ranged from 1.3 to 3.77 t ha −1 with a significant within-field spatial variability.”
Claim · model-written summary
Hand-sampled cluster 1 had mean achene yield of 3.54 t ha −1.
- Taxon
- sunflower cropHelianthus annuust0
- Outcome
- achene yield mean valuese0
- Value
- 3.54 t ha −1e0
- Setting
- cluster 1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sunflower crop”
e0“The cluster analysis of hand-sampled data showed three subfields with achene yield mean values of 3.54 t ha −1 (cluster 1), 2.98 t ha −1 (cluster 2), and 2.07 t ha −1 (Cluster 3).”
Claim · model-written summary
Hand-sampled cluster 2 had mean achene yield of 2.98 t ha −1.
- Taxon
- sunflower cropHelianthus annuust0
- Outcome
- achene yield mean valuese0
- Value
- 2.98 t ha −1e0
- Setting
- cluster 2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sunflower crop”
e0“The cluster analysis of hand-sampled data showed three subfields with achene yield mean values of 3.54 t ha −1 (cluster 1), 2.98 t ha −1 (cluster 2), and 2.07 t ha −1 (Cluster 3).”
Claim · model-written summary
Hand-sampled cluster 3 had mean achene yield of 2.07 t ha −1.
- Taxon
- sunflower cropHelianthus annuust0
- Outcome
- achene yield mean valuese0
- Value
- 2.07 t ha −1e0
- Setting
- Cluster 3e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sunflower crop”
e0“The cluster analysis of hand-sampled data showed three subfields with achene yield mean values of 3.54 t ha −1 (cluster 1), 2.98 t ha −1 (cluster 2), and 2.07 t ha −1 (Cluster 3).”
Claim · model-written summary
NDVI K-means delineated sunflower subfield yield variability early.
- Taxon
- sunflower cropHelianthus annuust0
- Outcome
- subfield crop spatial and temporal yield variabilitye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sunflower crop”
e0“the k-means algorithm has early delineated the subfield crop spatial and temporal yield variability.”
Claim · model-written summary
The best subfield identification period ran from inflorescence development to fruit development.
- Taxon
- sunflower cropHelianthus annuust0
- Outcome
- identifying subfield arease0
- Qualifier
- from the inflorescences development stage to the development of the fruit stagee0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sunflower crop”
e0“The best period for identifying subfield areas starts from the inflorescences development stage to the development of the fruit stage.”
Claim · model-written summary
Cluster 1 covered 42.4% of area and 50% of achene yield.
- Taxon
- sunflower cropHelianthus annuust0
- Outcome
- total surface and 50% of the total achene yielde0
- Value
- 42.4%e0
- Setting
- cluster 1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sunflower crop”
e0“cluster 1 covers an area of 42.4% of the total surface and 50% of the total achene yield”
Claim · model-written summary
Cluster 2 covered 35% of both surface and yield.
- Taxon
- sunflower cropHelianthus annuust0
- Outcome
- surface and yielde0
- Value
- 35%e0
- Setting
- cluster 2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sunflower crop”
e0“cluster 2 covers 35% of both surface and yield.”
Claim · model-written summary
Cluster 3 covered 22.2% of area and 15% of achene yield.
- Taxon
- sunflower cropHelianthus annuust0
- Outcome
- total surface with 15% of achene yielde0
- Value
- 22.2%e0
- Setting
- cluster 3e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sunflower crop”
e0“the surface of cluster 3 covers 22.2% of the total surface with 15% of achene yield.”
Claim · model-written summary
Sentinel-2 NDVI K-means delineated sunflower subfield areas.
- Taxon
- sunflowerHelianthus annuuse0
- Outcome
- sunflower subfield arease0
Not reportedComparatorValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“sunflower crop”
e0“K-means algorithm derived from Sentinel-2 NDVI images delineates the sunflower subfield areas.”