Potential impact of climate changes in the field crops production

Abstract

There is evident stagnation or decline in grain yield, as well as high variability in yields, depending on the environment in many countries in recent years, including Serbia and the Republic of Srpska. The causes of this variation were mainly due to the variation of the climatic factors, the onset of drought and the rise in temperatures. Expected changes and especially negative ones will most likely be reflected in the agriculture of southern Europe, especially the Mediterranean, and yield of main field crops. The most negative effects in the area of the continental climate will be in the Pannonian Region which includes Serbia, Croatia, Hungary, Bulgaria and Romania, R. Srpska as a part of Bosnia and Herzegovina. This area will be affected by more frequent waves of heat and drought, with no greater possibility of avoiding by shift of sowing time or other cropping measures. Based on a detailed analysis of climatic factors in the multy-annual period it can be emphasised that some changes in terms of temperature and precipitation occurred. The causes of drought mainly come from the atmosphere and affect our country and show clearly that the climate is changing in our area. Based on these facts, we must have the right answers in order to mitigate if not to completely eliminate these effects. Agronomic aspect of looking into the problem requires a good knowledge of our crop needs for primary vegetative factors as well as temperature and moisture. Annual air temperatures in the investigated period increased not only at the annual level, but also in the vegetative period of winter wheat and particularly maize. The temperature increase is particularly dangerous in the vegetative period of maize during the three months of June, July and August by almost 2 °C. Precipitations at a monthly level of the vegetative period or a total per year do not provide such a picture. Besides the lack in July, normally the warmest month, by and large, precipitations are somewhat higher than the reference 30-year period 1971-2000. This fact tells us that precipitations are more frequent in other parts of the year, which is more favourable for winter small grain cereals,at least when regarding warmer years (especially in the wet years as it is known in the case of extremely wet 2010 yr when it was vice versa). A man can hardly influence the quantity and distribution of rainfall, therefore his actions to combat drought are mainly of indirect character. This comprises a good knowledge of the problems and prediction. For this, we need a lot of knowledge of agronomy, genetics, ecology, physiology, and relevant technical and economic possibilities. If we start from the assumption that the main goal is to provide sufficient and safe quantities of food for our population, then we need to focus on what we have in our hands and begin with it. In the fight against drought, regular and specific cultivation practices are used along with an adequate assortment of crops with more tolerance to drought. Out of regular practices, soil tillage, particularly conservation tillage, proper fertilization, elimination of all possible mistakes in sowing should be taken into account as for optimal time and plant density. Care treatments are a useful tool which can eliminate the adverse effects and create favourable conditions for the growth and development of cultivated crops, ranging from the usual ones to some special ones that retain moisture and prevent moisture loss by encouraging its more efficient and economical use. Appropriately established crop rotations with greater diversification of crops provide better tolerance of extreme moisture, which is particularly the case of winter wheat. Our research shows inferiority of continuous cropping of both crops compared with different crop rotations. However, when comparing crop rotations with each other then it can be noticed that the proper setting, even under extreme conditions, provides better results. As for maize it is evident that all increases of moisture are suitable for it as it is related to the warmer part of the year, either as direct rainfall during the summer or indirectly if the reserve is provided from a period when there are more precipitations during the autumn, winter and spring. Moisture improves the efficiency of all other cultivation practices. In the case of its extended absence followed by high temperatures it is quite the opposite.