The amount and quality of the yield, depends mainly on the genetic characteristics of the crop, its yield potential and the specific quality characteristics that become apparent under specific production conditions.
Plants need a suitable soil, a certain amount of water, a sum and a temperature distribution appropriate to their needs in order to optimally complete a full development cycle culminating in the production of a crop. Depending on the soil and climatic conditions in a given area, these requirements can be met to varying degrees. The proper growth and development of plants can be impaired not only by deficiencies of important nutrients or water in the soil, but even by short-term adverse weather conditions, e.g. the occurrence of frost, strong winds, flooding, as a result of which they are damaged and yields are significantly reduced.
In the future, the selection of crop species, their varieties and the agrotechnical process of their cultivation will be strongly influenced by ongoing climate change, so it is useful to know the forecasts for the coming years and decades.
Knowledge of the climatic conditions of agriculture, the so-called agroclimatic conditions, has been systematised as a result of many years of research and is the basis for teaching at all levels of education in agricultural schools. However, constant climatic changes mean that much of these studies already need to be updated and take into account projections of climatic conditions in the coming years.
The most visible effect of a warming climate is the acceleration of plant development and the lengthening of the growing season. A rise in temperature accelerates the timing of the onset of vegetation and subsequent development phases, as well as harvesting dates. In the case of cereals, it is assumed that a 1o C increase in temperature at the grain-filling stage shortens this period by 5%, at the same time causing a 5% decrease in yield. An increase in temperature means that warm-season crops such as maize, sunflowers and grapevines can be grown more easily in Poland. In the case of maize, however, it should be pointed out that in recent years there has been a growing problem with insufficient water availability for this crop in the months of its intensive growth, i.e. July and August. Nearly snow-free winters and dry springs result in a negative soil water balance and storm rainfall is not retained in the agricultural space. With the observed global warming, this trend is expected to worsen. Rising temperatures and a lengthening of the growing season are forecast to extend the range towards northern Europe for crops such as maize, sunflower, soybean and grapevine. In Central Europe, where Poland is located, analyses using climate scenarios up to the end of the 21st century do not indicate the need for significant changes in crop patterns, with the exception of maize. Warming may even result in a slight increase in crop productivity, but provided that significant changes are made to agricultural practices. This generally refers to a change in the timing of agrotechnical treatments and a new approach to the selection of crop varieties and water management. In the latitude of Poland, a 2o C warming of the growing season should increase, for example, wheat productivity by about 10%; and in southern Europe, this figure will decrease by a similar amount. More on this topic. The predicted climate change will also result in lower yields of potatoes, rye, and will probably not affect the yields of sugar beet. As a whole, the failure of Polish agriculture to adapt to changing climatic conditions could result in a 5 to 30 per cent decline in agricultural production.
In taking preventive action we need to consider:
- breeding of crop species and varieties more resistant to drought and high temperatures,
- better frost protection for orchards,
- develop practices that reduce the susceptibility of agricultural crops to diseases and pests, both new and those already known but operating under new conditions,
- improved monitoring of the spread of pests and diseases,
- introduction of new cultivation methods and water-saving techniques,
- improving water management and retention systems in the environment,
- improving ventilation and cooling systems for livestock housing.
In the short-term perspective of the early 2020s, we can still expect to see only two seasons instead of four: wet, or at least humid (winter and early spring) and dry and hot (late spring, summer and autumn). Territorial variations will also be apparent: the centre of Poland will suffer from a permanent shortage of precipitation, the north and south of Poland from a periodic shortage of precipitation. For this reason, it is already becoming necessary to take special care of soil quality and the availability of water for plants – parameters that are very strongly linked to each other. Increasing the organic matter content of the soil plays a special role in improving these, especially in regions with predominantly sandy soils, such as the centre of Poland. Each percentage increase in the humus content of the soil allows tens and hundreds of tonnes of plant-available water to be retained in the soil, improving conditions for the development and growth of crops. At the same time, it is an effective method of reducing carbon dioxide emissions through its retention in the soil (organic carbon). The formation of humus is a long-term process, so these measures cannot continue to be postponed.