How much irrigation would increase maize production in Brazil? a crop modelling approach

• Autor(a) principal: Antolin, Luís Alberto Silva
• Data de Publicação: 2022
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/11/11152/tde-03012023-152902/
• topic: Zea mays; Zea mays; Crop modelling; Irrigação; Irrigation; Modelagem de culturas; Produtividade potencial; Yield potential

Acknowledged as one of the main crops with a major social and economic importance for most human communities worldwide, maize (Zea mays) production sustainability, i.e., without dangerously depleting agricultural natural resources, is evaluated as concern in a foreseen future where world population will surpass 9 billion people by 2050. In face of such scenarios, Brazil stands itself both by the higher potential of agriculture expansion and also to be amongst the largest maize cropland areas on Earth. Additionally, initiatives such as the Global Yield Gap Atlas (GYGA) have conducted studies in more than 50 countries, evaluating how much crop production yields could increase without occupying new areas and efficiently using the available resources. Within the scope of the GYGA project, this study aims to evaluate the current yield gap of maize production in Brazil, and additionally understand whether irrigation will significantly help on closing this gap. Several field experiments were caried in at least 3 maize producing regions of Brazil, with rigorous control of fertilization, pest, weed and diseases, in order to obtain data to calibrate a crop model and deliver reliable information about the full potential of production across different environments. For defining which locations will represent the whole country yield potential (Yp) through simulations, was followed the protocol described by the GYGA project to define weather stations that represent different Homogeneous Climate Zones (CZ) and the buffer areas that are covered. Moreover, an additional protocol was followed in order to determine a different set of locations that can be used to carry irrigation studies for increasing maize production. Estimates has shown that in average, actual maize yields (Ya) in Brazil are 55.4% below the Yp, although an increase on crop production by the same amount could be reached by irrigating 50% of current cropland areas. Government estimations has pointed that irrigated areas will be increased by near 30% of the areas that are cropped nowadays, which will aid the maize production to barely surpass current values. Our findings showed that it is possible to increase irrigation levels in order to reach full potential of maize crops without compromising the available water resources. However, is still required public efforts to maximize the efficient utilization of water resources by crops, such as investments on scientific programs of genetic adaptation for drought and social assistance to aid farmers on implementing irrigated areas in a sustainable way. The trade-off between increasing production and expanding irrigated areas, must planned to do not affect poor regions where water scarcity already limits the potentiality of agriculture and be focused on locations where resources are fully available to close the current gap of maize production in Brazil. Results from this study should provide reliable data for decision-makers and new public policies, as such governmental programs aiming to plan the expansion of irrigated areas.