Prolonged drought affects wheat sowing in northern Paraná

Wheat sowing in the north of Paraná, ideally indicated between March 21st and May 10th, is being hampered by the intense drought in 2018. During this period, the Embrapa Soja weather station recorded 42 days (April 2nd to May 14th) no rain in Londrina (PR). While the historical average (2008 to 2017) of accumulated rainfall during this ideal sowing period is 170 mm, in 2018 it rained only 77 mm. “Since 2009, such a pronounced water deficit has not been recorded in the region, which has serious consequences for wheat cultivation”, explains Embrapa Trigo researcher, Sérgio Ricardo Silva. 

The Department of Rural Economy (DERAL), of the State Secretariat for Agriculture and Supply of Paraná estimates the wheat sowing area in Paraná at 1,42 million hectares. By May 14th, approximately 365 thousand hectares (35%) of the planned area had been sown and the majority (90%) of the crops were in the germination phase. The majority of this sown area is found in the north and west regions and many farmers sowed “in the dust”. “They trusted in the rapid restoration of rains, so as not to compromise the agricultural calendar for the year, that is, to be able to establish the next summer crops within the ideal sowing “window”. Furthermore, they managed to sow wheat within the period recommended by the Agricultural Climate Risk Zoning (ZARC), which is one of the prerequisites for obtaining agricultural financing and insurance”, he says.

For Silva, farmers in the northern region of Paraná, who have not yet sown wheat, are faced with a difficult dilemma: not to grow wheat in 2018 or sowing outside the ideal period. “The first option means not taking the risk of loss of production, however, the farmer will give up an additional source of remuneration with the sale of wheat, and will also increase the total cost of the summer harvest, as the fixed cost of the property cannot be shared with the winter crop”, assesses the researcher. Furthermore, the farmer will not enjoy the direct and indirect benefits of wheat cultivation for the following crop, because he loses the effect of residual fertilization of wheat (which allows the reduction of fertilization of soybeans or corn, especially with phosphorus and potassium) and of the beneficial effect of wheat straw that reduces the infestation of invasive plants (such as horseweed and bittern) in succession crops. On the other hand, sowing outside the ideal period also brings undesirable consequences, says the researcher. “This is because it will be difficult to obtain agricultural financing and insurance, in addition to increasing the risk of water deficit during the grain filling phase and the risk of loss of technological quality of the grains caused by excess rain at harvest”, he analyzes. 

Rain forecast - According to the main meteorological forecasting institutes, there is a high probability of rain in the north of Paraná in the period from May 18th to 19th, followed by a dry period. Weather forecasts can be followed by the Paraná Meteorological System (SIMEPAR) , where the search can be done by municipality, through the topic “Forecast in Paraná” followed by “Search city”. Winter should experience a normal climate situation, as the La Niña phenomenon (which has been of low intensity in 2018) should be practically neutralized by the end of this month. “If these predictions are confirmed, we will be able to have good environmental conditions for the development of the crop from June to August, which will result in a good wheat harvest in the state of Paraná”, assesses the researcher.

Search directions  - Faced with these climatic challenges, the researcher made some recommendations that can help wheat farmers this harvest, considering three situations: 

1st) Crops sown until the end of March, which received enough rain for good germination and initial development of the plants, but were subsequently affected by a long period of drought. In this case, productivity will be partially compromised due to the underdevelopment of the plants. Therefore, the farmer must reduce costs with top dressing and agricultural pesticides, using only the “minimum necessary” in accordance with the guidelines of an Agronomist, as high investments in these inputs will not result in large increases in grain yield, as the The productive potential of the crop has already been compromised. 

 2nd) Crops sown “in dust” in the last few days, before the rains resume. This situation is not agronomically recommended, as it involves serious risks: if the drought continues for more days, the seeds “stored” in dry soil will be exposed to excessive heat on the soil surface, which compromises vigor and germination power; on the other hand, if there is low intensity rain followed by a new period of drought, the seeds may germinate, however, the seedlings do not develop well and may die from dehydration, resulting in crop failures and unevenness. Therefore, the farmer who does not have an irrigation system will be “hostage” to the weather conditions, with no alternative but to hope for the rapid restoration of rain.  

 3rd) Areas intended for wheat cultivation that have not yet been sown. This case must be analyzed very carefully, as the ideal sowing period (with a risk of 20% crop loss, according to ZARC) has already passed. However, the ZARC extends the wheat sowing period in the pioneer north until a maximum of the first ten days of June, whose risks of crop loss increase from 30% on May 10th to 40% on June 10th. The risks are greater in sandier soils, at lower altitudes and for cultivars from intermediate to late cycles. The farmer will be unlikely to obtain agricultural financing and insurance in this situation and, even if he does, the cost will be higher. For the more “bold” farmers in the north of Paraná, who choose to cultivate wheat, assuming greater risk, we advise: not to exceed the date of May 31st to sow, and to do so only after the soil moisture has recharged. up to a depth of 20 cm, checking whether the weather forecast indicates the arrival of new rain in the following days; opt for early cycle cultivars (to reduce the risk of drought during the grain filling phase and rain at harvest); carry out nitrogen fertilization in advance (until tillering begins); and reduce costs with excess fertilizers, pesticides and other products, adopting the practice of “rational management” based on technical indications and crop monitoring.