Monsoon rains finally begin in Brazil


Rainfall in the country’s grain production region was disrupted by a developing La Niña event.
One of the most amazing aspects of world weather is that no matter how adverse conditions seem to get at times, when it is time for the seasons to change, they tend to change. Sometimes they are a little late and sometimes a little early, but one of the few things mankind can truly count on is the seasonal changes in weather patterns. After several weeks of frustrating dryness in parts of Brazil’s center west grain and oilseed production region, monsoonal rainfall has finally arrived.

One of the more interesting aspects to Brazilian weather is the long growing season that occurs from October into April. Producers learned a few decades ago that seasonal rains usually last long enough in Brazil for at least two different crops to be produced — one right after the other. Getting both crops planted and harvested in optimum conditions can be a bit of a challenge because the first crop has to be planted during a more unreliable rainfall period and if the rains are not timely or abundant enough, it can result in notable delays to planting — similar to that of this year. Delayed early season planting can delay the first harvest season and in turn, that results in delays in planting the second season crop, which is also dependent upon seasonal rainfall.

A part of the annual rain in Brazil is driven by a monsoon pattern not much different from that which operates in India, Southeast Asia and Mexico. However, monsoonal patterns are driven by changes in the earth’s angle to the sun, which makes them highly dependable.

India’s monsoon usually starts within the first week or two of June and quite often within the first few days of that month. Similarly, monsoon patterns in both hemispheres seem to occur like clockwork with Brazil normally starting in Mato Grosso and Goias in late September. The Brazilian monsoon normally expands to the south into Parana, São Paulo and Minas Gerais by the end of October. Back in the “olden days” of farming when only one crop was produced, producers timed their planting to coincide with the start of the monsoon season and there was always plenty of moisture to support the one crop no matter when the rainy season started or stopped.

Weather Disruptions

Delays in the arrival or departure of monsoon patterns are usually the result of influence from other weather patterns that become anomalous. One of the more familiar of these larger weather patterns that interfere with monsoonal precipitation is La Niña and El Niño events. ENSO events (a generic term for both La Niña and El Niño) will impact the start and stop dates for monsoonal patterns and can change the intensity of the seasonal rainfall. However, eventually the change in the earth’s angle to the sun will bring an end to, or a start of, monsoonal precipitation.

This year’s start to monsoonal rainfall in Brazil was disrupted by a developing La Niña event. La Niña was delaying the shift of weather patterns in the Southern Hemisphere, resulting in drier-than-usual conditions from the Amazon River Basin southward into Mato Grosso, Goias, Tocantins and parts of Minas Gerais.

Rarely will the monsoon season fail to evolve, and in Brazil, that failing rate is much lower than it is in India, Mexico or Southeast Asia. That makes years like this in which seasonal rainfall is notably late a bit of an enigma. The significant rain event that affected southern and center south Brazil in early October was a fluke event that saved a big part of the nation’s grain and oilseed production area from suffering from prolonged dryness like that of Mato Grosso. That can be said with confidence because the monsoon season was not under way in early October and it was not until just recently that it began.

Producers may not have much of a clue as to how blessed they were this year to get the early October rainfall, but they did know enough to get out and plant aggressively while the moisture was in place.

The fast pace of planting in southern Brazil this spring offsets the delays in planting in Mato Grosso and Goias resulting in what appears to be a normal planting pace for the nation as a whole. But in actuality, the planting season is notably late in Mato Grosso and Goias — two extremely important production areas — and quite early in São Paulo, Parana and southern Minas Gerais. In the meantime, the usual late September planting in Mato Grosso has occurred either with little to no moisture or is just now beginning. That raises the potential for some negative impact on second season crops that normally follows the early crop.

Second season corn and cotton in Mato Grosso have to be planted in January and February to leave adequate time for crop development before seasonal monsoon moisture abates from the region. In a normal year, this occurs from late March through April. First season crops in Brazil planted several weeks late will be harvested late, leading to late planting of second season crops. Late season crops are dependent upon seasonal rains lasting long enough for crops to have adequate subsoil moisture to tap into after monsoonal rains end. Planting the second season crops a few weeks late raises the potential for monsoonal moisture to end before crops have passed the moisture sensitive reproductive phase of development, resulting in a rising potential for production cuts.

Even though Brazil’s seasonal rains have finally arrived and crop planting will be aggressive over the next few weeks, there is potential that second season corn and cotton planted may run short on subsoil moisture while reproduction and filling takes place. That could reduce production.

The bottom line for Brazil is that when monsoonal rainfall is delayed, there is normally sufficient rainfall to support the early crop quite favorably and production is rarely affected. Second season crops, however, do sometimes come up with poor yields and quality because after being planted late, the annual rains end on time, leaving the ground in a decreasing moisture environment. Therefore, no changes in production potential should be anticipated in Brazil because of the erratic start to rainfall, but it will be imperative that seasonal rains continue as late as possible in 2018 to support second season crops.


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