Publication
Effect of the topography in within-field variability and detection of the moment in the growing season when the within-field variability appears
| Summary: | For long, farmers and agronomists have known that their fields do not produce the same in all areas. However, the factors affecting yield do not always behave in the same way from year to year. As such, this dissertation will try to identify and understand the main factors driving within-field variability in an irrigated maize to answer the following questions: 1) Can topography explain the spatial variability of yield in irrigated maize? 2) When does the variability within-field appear in the growing season? To answer these questions, we used data from a farm located in Azinhaga, Portugal, near the Tagus River, where the fields are very flat, and most soils are fluvisoils. Contrary to what is written in the literature, in this work there was no robust evidence supporting that the distribution of water with-in field caused variability in production. These results are explained by the fact that the soils of the farm under study are fertile, well-drained, and the irrigation management is done efficiently, and small retention basins are dug between the rows, avoiding surface runoff. The effect of topography on yield variation was higher when the elevation increased, leading to the conclusion that in other locations, where the field is steeper, the distribution of water in the field is an essential factor in explaining with-in field variability. This study also concluded that there is great variability in the field right after the emergence, but that it quickly disappears, not affecting yield. On the other hand, most of the variability that affects yield arises between the v6 stage and tasseling. After this moment, there is some variability, but it no longer affects the final yield. This variability is to some extent linked to the distribution of water in the field |
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| Main Authors: | Coimbra, Simão Torres |
| Subject: | maize intra-field variability irrigation topography remote sensing |
| Year: | 2019 |
| Country: | Portugal |
| Document type: | master thesis |
| Access type: | open access |
| Associated institution: | Universidade de Lisboa |
| Language: | English |
| Origin: | Repositório da Universidade de Lisboa |
| Summary: | For long, farmers and agronomists have known that their fields do not produce the same in all areas. However, the factors affecting yield do not always behave in the same way from year to year. As such, this dissertation will try to identify and understand the main factors driving within-field variability in an irrigated maize to answer the following questions: 1) Can topography explain the spatial variability of yield in irrigated maize? 2) When does the variability within-field appear in the growing season? To answer these questions, we used data from a farm located in Azinhaga, Portugal, near the Tagus River, where the fields are very flat, and most soils are fluvisoils. Contrary to what is written in the literature, in this work there was no robust evidence supporting that the distribution of water with-in field caused variability in production. These results are explained by the fact that the soils of the farm under study are fertile, well-drained, and the irrigation management is done efficiently, and small retention basins are dug between the rows, avoiding surface runoff. The effect of topography on yield variation was higher when the elevation increased, leading to the conclusion that in other locations, where the field is steeper, the distribution of water in the field is an essential factor in explaining with-in field variability. This study also concluded that there is great variability in the field right after the emergence, but that it quickly disappears, not affecting yield. On the other hand, most of the variability that affects yield arises between the v6 stage and tasseling. After this moment, there is some variability, but it no longer affects the final yield. This variability is to some extent linked to the distribution of water in the field |
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Funded activities
No funded projects found.