The climate in Brazil has been considered one of the best for the implementation and development of many crops due to the soil conditions and nutrients, and also due to the distribution of rainfall and temperatures. However, with climate change this has been increasingly altered, which increases the risks to agricultural production in certain locations and times of the year.

It was with this in mind that the Programa Nacional de Zoneamento Agrícola de Risco Climático was created, which aims to delineate areas and times of the year with low risk for rural producers to carry out planting. Onions are the first vegetable included in the program, for all Brazilian regions.

The main idea of the program is that by following Zarc's recommendations, farmers run fewer risks, that is, they are less subject to climate adversities and can still benefit from the Programa de Garantia da Atividade Agropecuária (Proagro) and also by the Programa de Subvenção ao prêmio do Seguro Rural (PSR).

It is important to highlight that many financial agents only release rural credit for crops in areas zoned by Zarc, especially in the case of medium producers who access the National Support Program for Medium Rural Producers (Pronamp).

Onion

Onion is certainly the most used vegetable around the world, it is a basic ingredient in almost all dishes, especially in Brazil. The culture is produced in different Brazilian locations, but is more concentrated in the South region, parts of the Southeast such as São Paulo and Minas Gerais, parts of the Central-West such as Goiás, and also in parts of the Northeast such as the states of Bahia and Pernambuco. All of this represents around 95% of national production.

Despite being present in almost all Brazilian dishes, production in our country ranks 13th in the world, with production around 1.6 billion tons per year. In fact, in Brazil it is possible to produce onions in different harvests per year due to the extension of the territory and the climate diversity found here.

In general, however, onion production is concentrated in the months of March to November and is sufficient to almost exclusively supply the domestic market, that is, we almost do not export onions.

According to the researcher from Embrapa Hortaliças de Brasília, it is important that producers only use tested and recommended cultivars for each location and time of year, as there is a basis with technical guidance from assistance and rural extension companies that are qualified in each area.

How crop climate risk is assessed

There are several criteria to assess the climate risk for a given crop, and one of them that is considered very important in the program is for the producer to pay attention to areas that have already had the occurrence of white rot, considered a of the main diseases that can even lead to total loss of onion production.

And of course, one of the most impactful points that made onions the first vegetable to enter Zarc is that the crop is greatly influenced by meteorological conditions, that is, water availability, light, temperature and rainfall are crucial elements for the crop development. In fact, due to the high sensitivity of onions to lack of water, cultivation is carried out almost exclusively irrigated.

Due to these factors, the onion cultivars available for production in Brazil are divided into two groups: short days (requiring at least 12 hours of daily light to bulbify) and intermediate days (requiring 13 hours or more of daily light).

Thinking about the climatic risks and the needs of each cultivar, Zarc established the planting dates (ten days) in municipalities favourable to onion cultivation, which were separated with climatic risk levels of 20%, 30% and 40% depending on the following criteria:

• Severe water deficiency when not reaching the minimum limit of the water needs satisfaction index (ISNA), in a rain-fed system;
• Very low and harmful temperatures for the crop due to the probability of occurrence of minimum temperature values lower than or equal to 11°C; Very high and harmful temperatures for the crop due to the probability of maximum temperature values exceeding 34°C;
• Excessive rain or excess water harmful to the crop through the probability of accumulated precipitation greater than 130 mm in the final stage of maturation and at harvest;
• Excess rain or excess water through the probability of occurrence of accumulated precipitation greater than 150 mm, in the crop implementation phase when done through direct sowing or planting seedlings;
• Excess rain or excess water due to the probability of occurrence of accumulated precipitation greater than 210 mm, in the crop implementation phase when done using bulblets.

Where to find the results

Zarc's national studies meet the objectives of the National Agricultural Climate Risk Zoning Program. Compliance with the planting dates recommended by Zarc is mandatory for producers who wish to access the Agricultural Activity Guarantee Program (Proagro) and the Rural Insurance Subsidy Program (PSR). The onion Zarc results are available on the Map in the Indicator Panel and in the Zarc Plantio Certo app (IOS, Android).

Reference: MAPA - Mapa inclui cebola no Zoneamento de Risco Climático