How two ag practices transformed the Brazilian Cerrado

By Guil Signorini, Department of Horticulture and Crop Science, The Ohio State University

A fascinating trait of modern human society is its resilience and ability to adapt to challenges. Two recent South American updates touched on this topic when talking about the latest occurrences in the Brazilian agricultural sector. The first update mentioned innovative financial tools to ease the steep operational costs of growing grain crops in Brazil. A second update defined the 1995 energy sector reform as an essential policy change to incentivize renewable electricity generation. 

Guil Signorini

In this vein, grain crops grown in Brazil offer additional insights. Natural challenges caused by the tropical weather and poor soils were the engine and fuel behind remarkable maneuvers to address production limitations. Back in the 70s, when the expansion of agriculture reached the Cerrado region of Brazil, the soils could be described as follows: sandy or light-textured, naturally poor in nutrients, highly acid (pH between 3.8 and 5.2), little organic matter (between 3% and 5%), high Aluminum saturation (greater than 45%), and little water holding capacity (less than 3 inches in soils with 23-inch effective depth). It was through applied knowledge and technology that the Cerrado was transformed. Fast forward today, the Cerrado is responsible for approximately 50% of the grain production in the country.

During my time in the agronomy school, we students used to hear that “there is not such a thing called poor soils. But there are poorly managed soils.” The thought-provoking quote came from multiple angles and helped us understand that production is possible despite adverse conditions. Several practices were tested and validated to circumvent the challenges imposed by the Cerrado biome. Two of them deserve attention: no-tillage farming and the use of nitrogen-fixing bacteria (NFB).

It is undeniable that research institutions such as EMBRAPA and schools of agricultural sciences played their role in promoting these two practices. A quick search through websites that index scientific papers return over 140,000 studies on no-till in Brazil. When the search turns to nitrogen fixation, 112,000 studies are found for the country. But researching these practices alone would not help growers adapt to Cerrado’s challenges. Machinery developers, farm input suppliers, distribution channels, and independent consultants were all engaged in reducing production constraints. The development we see today must be accredited to the private sector.

EMBRAPA estimates that 75% of the area cultivated with soybeans, corn, and cotton employ no-tillage practices in Brazil. And virtually all areas covered with grain crops in the Cerrado use no-tillage systems. These high adoption rates are backed up with excellent technical results. A long-term study from EMBRAPA shows that no-tillage alone may increase the stock of organic carbon by 12% in a 13-year experiment on marginal lands (perhaps a synonym for poor soils). Soybean yield also experienced a positive impact in the long term. The aggregated production of soybeans in a 30-year experiment was between 24% and 35% higher when no-tillage was compared to three soil-disturbing practices. There is no wonder that the adoption rate of no-tillage is high among soybean and corn growers in Brazil.

When we turn to practices involving NFB, the results are even more surprising. Data from the National Association of Producers and Importers of Inoculants (ANPII, in Portuguese) shows that the use of Bradyrhizobium in soybeans grew at a 13.8% CAGR (compound annual growth rate) from 2009 to 2018. In the same time window, the use of Azospirillumgrew from the ground up to reach a total of 9.1 million doses sold in 2018. It is estimated that four out of five soybean growers use Bradyrhizobium in their operations. The adoption rate is even higher in states under the Cerrado biome. A research agency affirms that the inoculant is used annually in 95% of the land cultivated with soybeans.

It is worth mentioning that the inoculant dose follows a convention in the industry, and it is equivalent to spreading 1.2 million bacteria per seed of soybean or corn at planting. Nevertheless, it is safe to say that the considerable growth in the adoption of inoculants by soybean and corn growers is partly related to the conditions of Cerrado soils. After several seasons under no-tillage, Brazilian growers managed an accomplishment of many midwestern growers: produce soybeans without inputting nitrogen fertilizer.

But there is an additional caveat. In a usual year, Brazil imports 70% of its demand for nitrogen fertilizer. The demand and import expenses would be much higher if Cerrado soybeans required that input. Gladly, inoculants arise as an inexpensive and effective alternative. The technical literature and common practices suggest that established soybean fields need between 0.4 and 0.8 doses of inoculant per acre to produce high yields, costing between $0.57 and $1.13 per acre. Higher doses may be needed in virgin soybean fields or in rotation with sugarcane, for example. A simple comparison is worthwhile. In the absence of inoculants, Cerrado growers would disburse $130 per acre on the cheapest nitrogen fertilizer available (urea) to produce average yields. Growers seeking high yields would spend $208 per acre. Considering the current spike in the cost of fertilizers and the area cultivated with soybeans in Brazil this season, Bradyrhizobium is saving over $10 billion for the soybean industry. What a way to overcome challenges!

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