March – critical negative minimum temperatures

The late winter weather conditions at the end of February and the beginning of March will lead to an interruption of the vegetation processes in the winter cereal crops. The expected colder-than-usual weather for the season until mid-March will restrain the premature, undesirable development in fruit trees, which was triggered by the unusually high February temperatures. During this period, the forecast negative minimum temperatures, down to and below minus 10°C, will be critical for the most advanced stone fruit species (almond, apricot, peach) that have entered the flower bud stage, and in some places in the extreme southern regions – the flowering stage.

During the second half of March, a gradual increase in temperatures is expected. At the end of the second ten-day period, average daily values close to the biological minimum required for the resumption of vegetation in the autumn-sown crops are forecast.

A substantial improvement in thermal conditions and an activation of vegetation processes in agricultural crops is expected to occur during the third ten-day period. At the end of March, the tillering stage will prevail in wheat. The third leaf stage will be observed in part of the late-sown stands.

The expected precipitation in March, around the monthly norm, will increase the soil moisture reserves in the one-metre and deeper soil layers. At the end of February, in most of the arable regions, the level of soil moisture reserves in winter cereal crops in the 100 cm soil layer was below 90% of field capacity. The lowest reserves, below 75% of field capacity, are reported in Northwestern Bulgaria (agrometeorological stations: Knezha, Novachene) and in some of the northeastern regions (agrometeorological stations: Razgrad, Tsarev Brod, Dolni Chiflik), where precipitation in January and February was significantly below the climatic norms.

In March, suitable conditions for carrying out the extremely important preventive plant protection spraying in fruit crops will occur during the third ten-day period.

The frequent precipitation during the first and second ten-day periods of March will maintain a high moisture content in the upper soil layers, which will hinder the implementation of pre-sowing tillage on the areas designated for sowing early and medium-early spring crops. For this reason, there is a likelihood of missing the agrotechnical deadlines for sowing sunflower. In mid-March, the agrotechnical period (15–20.03) for sowing sunflower in Southern Bulgaria begins, and in the middle of the third ten-day period (25.03–5.04) – in the Danubian Plain.

Source: NIMH