Third consecutive La Niña? What to expect from soybean yields in the US, Brazil and Argentina • farmdoc daily

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International long-range forecast models point to the possibility of a third consecutive La Niña event this year. It is not uncommon to see La Niña occur in two successive seasons. This happened in 2021-2022 and in 2011-2012. However, it is rare to see three consecutive La Niña events. But what could this mean for soybean production in Brazil, the United States and Argentina? This article presents descriptive analyzes of deviations from the trend line of soybean yields over the past 30 years in these countries, the three largest soybean producers and exporters in the world, to predict what to expect from yields soy this year. However, the strength of individual La Niña events and various climatic factors make each event unique.

Probability of the La Niña forecast

La Niña is a pattern of ocean temperature and wind anomalies in the Pacific Ocean, which affects weather patterns around the world. According to the National Oceanic and Atmospheric Administration (NOAA) definition, during La Niña, surface winds across the entire tropical Pacific are stronger than usual, and most of the tropical Pacific Ocean is colder. than normal. During La Nina events, conditions across South America favor increased precipitation in northern Brazil and decreased precipitation in Argentina and southern Brazil. In the United States, generally speaking, wetter than normal conditions are typically found in the Pacific Northwest and Midwest region.

The Pacific Ocean has been in the La Niña phase for two years. The first occurred from late August 2020 to April 2021. It was followed by the current La Niña, which started in August 2021 and is still ongoing. According to the Climate Prediction Center (CPC/IRI) Official Probabilistic El Niño-Southern Oscillation (ENSO) Outlook, 12 May. If that happens, it will be the third consecutive La Niña for the first time in two decades.

Significant impacts of the ENSO phenomenon on world agriculture have been identified, generating losses or gains in activity depending on the region and the phase of the phenomenon. Iizumi et al., (2014) estimated global ENSO effects on yields of major agricultural commodities. They reported that El Niño is likely to improve the global average soybean yield by 2-5%. On the contrary, during La Niña years, global average soybean yields tend to be lower than expected. The interest of the relationship between yields and ENSO is based on the possibility of having seasonal climate forecasts several months in advance for a given crop cycle.

Yields of soybeans in Brazil

In Brazil, with nearly all of the acreage harvested by the third week of May, production is expected to reach 4,550 million bushels, down 10.4% from last season, according to the National Supply Company. (Conab). The expected yield is 45 bushels per acre. The average soybean yield is 5.3 bushels per acre below trend (-11%). La Nina events favor increased rainfall in northern Brazil and decreased rainfall in southern Brazil. Such was the case this year when southern Brazil is plunged into drought.

In the states of Rio Grande do Sul, Paraná and Mato Grosso do Sul, yields were 42% lower than last season, according to the Conab report. These three southern states account for 38% of national soybean production. On the positive side, Mato Grosso – the largest Brazilian producer of soybeans – and other states in the Brazilian Midwest, North and Northeast recorded a record harvest in 2021-2022 (see farmdoc dailyFebruary 25, 2022).

Brazil has had very different soybean yields over the past two La Niña years (see the last two blue dots in Figure 1). While in 2021/22 yields were below trend, in the 2020/21 season average soybean yield was 3.1 bushels per acre above trend (+6%), with a record production of 5,076 million bushels. This disparity can be explained by the climatic differences in Brazil and the wide distribution of soybeans across the country, from north to south. And the last time three consecutive episodes of La Niña occurred, in 2001, yields were 12% above the trend line.

Figure 1 shows the relationship between ENSO phases and soybean yield levels. Note that five of the six very high yield levels (residual standard deviation from the trend line greater than one) occurred in La Niña agricultural years. In addition, two out of five very low yield levels occurred in La Niña crop years, two in El Niño and one in Neutral. Thus, it is not possible to see a strong relationship between La Nina episodes and the level of soybean yield in Brazil.

Soybean yields in Argentina

With 84% of 2021/22 soybeans harvested by May 19, according to Argentina’s Ministry of Agriculture, Livestock and Fisheries (MAGyP), production estimates are 1,543 million bushels, as says the Bolsa de Cereales in Buenos Aires. And the estimated yield is approximately the same as the previous crop, about 42 bushels per acre.

The last two episodes of La Nina, the 2020/21 and 2021/22 crop years, did not generate extremely low yields, however, in both cases yield values ​​were below the 3 bushel trend line per acre, or -6% (see the last two blue dots in Figure 2). During these two agricultural campaigns, rainfall has been below average in parts of the Pampa region (states of Buenos Aires, Córdoba, Entre Rios, La Pampa and Santa Fe), which provides 95% of the production of soybeans in the country. And the last time three consecutive episodes of La Niña occurred, in 2001, yields were 7% above the trend line in Argentina.

Figure 2 shows a relationship between ENSO phases and soybean yield levels in Argentina. The majority of red dots (returns during El Niño years) are above the trend line and the majority of blue dots (returns during La Niña years) are below the trend line. This pattern reflects the relationship reported in different studies (Casa et al., 2021; see daily farmdocDecember 17, 2020): A negative (positive) effect of La Niña (El Niño) soybean yields in Argentina.

However, there is a high level of dispersion in the relationship. If we focus on the extreme values ​​(residual standard deviation from the trend line greater than one), note that five out of six very high yield levels occurred during El Niño campaigns. In addition, three out of four very low yield levels occurred during La Niña crop years. These data suggest a very low probability of having very high yields in La Niña years and very low yields in El Niño years.

U.S. soybean yields

In 2021, the U.S. soybean crop was 4,440 million bushels, up 5% from 2020, according to the U.S. Department of Agriculture (USDA). With record yields in 21 states, the average soybean yield was 51.4 bushels per acre, 0.4 bushels above 2020 and the second highest on record. During the last two episodes of La Nina, crop years 2020 and 2021, soybean yields were above the trend line by 1.4 and 1.5 bushels per acre, or 3%, respectively (see both last blue dots in Figure 3). And the last time three consecutive episodes of La Niña occurred, in 2001, returns were 2% below the trend line.

Figure 3 shows a slight relationship between ENSO phases and US soybean yield levels, with the majority of red dots (yields in El Niño years) above the trend line. This trend mirrors the relationship reported in other studies (Iizumi et al., 2014), a positive effect of El Niño on US soybean yields. Climatologists of El Niño events have developed over the past few decades and found that in general, warmer and slightly drier winter conditions occur in the Midwest during El Niño.

If we focus on the extreme values ​​(residual standard deviation greater than one from the trend line), note that two out of three very high yield levels occurred during El Niño campaigns and one during a La Niña year. In addition, three out of four very low yield levels occurred in neutral years, and only one in a La Niña year. Therefore, this is evidence of a weak effect of ENSO on US soybean yields.

Summary

This report analyzes the relationship between soybean yields and ENSO phases from 1992 to 2022 for Brazil, the United States and Argentina, the world’s leading producers and exporters. Soybean yields in recent crop years, both under La Niña conditions, show different results between countries and crop years. A very low yield (11% below the trend line) occurred in Brazil for the last harvest, and a yield above the trend line was obtained in the previous one (+6%). In Argentina, returns were below expected values ​​for both years (-6%) and in the United States above the trend line (+3%).

Over the past 30 years, data shows a strong relationship between ENSO episodes and soybean yield levels in Argentina and a weaker relationship in the United States and no relationship in Brazil. It is important to emphasize that each La Niña event is different in terms of strength, duration and direct impacts. Thus, predicting impacts on soybean yields is not easy.

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