Adhering to agrotechnical deadlines is a practically cost-free and at the same time very yield-forming measure. Among the most important is the sowing date. Current crop recommendations state the optimum sowing date for a given variety in a specific area of the country. It is sometimes claimed that someone sowed much later or earlier than recommended, but the yield was still high.
This is usually the result of particularly favourable weather conditions, rather than the fact that the optimum sowing date was not determined correctly. The dates given in the agrotechnical recommendations of plant breeders refer to the average weather conditions most frequently encountered in our country. Therefore, sowing or planting crops at these dates carries the least risk of poor overwintering in the case of winter crops, or of water shortages or too low temperatures for spring crops. For some cereal species, such as wheat, we also have facultative forms in cultivation, where sowing of these varieties is possible either in autumn, late autumn or spring. However, before sowing these varieties in late autumn, it is important to find out how the variety overwinters in my growing area, whether the risk of it overwintering poorly is too high. In the absence of such information, you can take the risk of sowing on your own farm, on a small area, so that you do not suffer significant losses in the event of poor overwintering. When setting up such an in-house “experiment”, it is better, unlike usual, for the winter to be harsh, as this will allow you to better verify the winter hardiness of the facultative variety you have sown at home.
It is possible to estimate the approximate optimum sowing date of a crop, which can be useful especially under climate change conditions. Using wheat as an example: we plan to reach 4 tillers before winter, each tillering is 120 degree-days, for a total of 480 degree-days – knowing the expected end of the growing season and the average daily temperatures, it is possible to calculate the necessary number of days and therefore the sowing day corresponding to our plan.
The climatic changes we have been observing for a number of years, the lack of cold and snowy winters, mean that the vegetation of winter crops ceases for a shorter period of time, allowing increasingly late autumn sowings and increasingly earlier spring sowings, but with an increasing risk of damage in the event of normal winter conditions.
Timely sowing of fertilisers, especially nitrogen fertilisers, timely implementation of plant protection measures or application of foliar fertilisers is very important. The recommended deadlines have been selected in such a way as to maximise the efficiency of the applied inputs, ensure their optimal use, do not harm the crops or the environment and limit the residues of the applied chemicals in plant products to the legally required level. Timely harvesting means, first and foremost, that losses during the harvesting period can be reduced (yield-protective effect) and that the highest quality crops can be obtained.
Individual crop varieties, even within a single species, can have different thermal, water and nutrient requirements. Also, their susceptibility to disease as well as their degree of pest infestation can vary considerably. Therefore, their sowing dates, the nature and timing of fertilisation, as well as the method of necessary protection may be different. For example, under the same climate and soil conditions, different varieties of winter wheat (e.g. forage and quality) may require different production technology, from sowing through fertilisation and protection to harvesting.
Adherence to the correct agronomic timetable is mainly determined by the intensity of work on the farm, the availability of equipment, means of production and the course of weather conditions. The first three factors are largely within the farmer’s control, and if, for example, sowing of oilseed rape seeds is delayed by a few days due to a failure of the seed drill, the farmer should pay more attention to a more thorough pre-season inspection of the drill or provide himself with alternative equipment in subsequent years. In addition to technical measures, such as aggregating equipment, or cultivation measures, such as direct seeding or so-called “strip till”, the characteristics of varieties that tolerate a delayed or accelerated sowing date can be used. We have no control over the course of weather conditions, and the observed climatic changes often increase the risk of not carrying out operations within the recommended agrotechnical deadline. Typical situations include:
- prolonged drought or continuous rainfall does not allow sowing within the agrotechnical deadline,
- a prolonged period with precipitation does not allow the crop to be harvested,
- a sudden change in the weather does not allow the completion of cultivation operations in progress,
- the occurrence of a number of days with precipitation or strong winds makes it impossible to carry out protective measures.
However, more and more verifiable weather forecasts come to the rescue, which, assuming 1-2 days’ notice, provide a useful picture of expected weather conditions, e.g. the timing and amount of rainfall, the occurrence of heat or frost. This allows treatments to be better organised and executed within the ‘weather window’, without surprises. One such weather service which is already used by many farmers is meteo.pl, provided free of charge by the ICM, University of Warsaw. Even more accurate weather data, because it comes from the farmers’ own weather stations, is very useful for:
- forecasting the course of the weather for the coming days,
- monitoring the development of plant diseases (e.g. potato blight, apple scab) or plant pests (e.g. weevils, potato beetle, European corn borer) and signalling when to eradicate these pathogens, supplemented – very importantly – by the farmer’s field observations,
- determining the timing of nitrogen fertiliser applications (within the framework of existing legislation),
- calculation of the climatic water balance for their growing area.
It is not necessary to have a weather station on every farm – sharing such a station, e.g. between farmers in the same village, is a much cheaper solution with benefits for many users at the same time. All agrotechnical measures must be recorded in the crop or field documentation, with justification, creating the farm’s own knowledge of their suitability.