Агроекологічні аспекти просторово-часової динаміки урожайності соняшнику

<p>Dynamics of sunflower yield in agricultural enterprises in the administrative districts of the Poltava region for the period 1995-2016 have been explored. Agroecological zoning of the Poltava region that is based on dynamic productivity features sunflower have been performed. We founded that sunflower yield fluctuated in the farms of Poltava region from 13.36±1.40 to 21.81±1.89 t/ha within 1995-2016. The lowest level of variation (CV) of sunflower yields during the study period was 28.33% and the highest was 49.03%. The great yield range was caused by spatial variation component. The analysis of sunflower yield revealed clear trends which can be described by the third polynomial order. Specific terms of polynomial curve of the third order can be meaningfully interpreted and applied to describe the dynamics of sunflower yield. The free coefficient of the polynomial reflects the level of sunflower productivity in the starting period. The value of the function at the point of local minimum points to the "bottom" of the dynamics of productivity culture. The maximum productivity reflects a balance between factors of the agroeconomical and agrotechnological nature and also the biological potential of the sunflower. Parameters and special trend point of sunflower yield can be explained by landscape cover diversity indicators, topographic wetness index, erosion factors and their interaction. According to the forecast value of growth rate the study plots were divided into three groups of agriculture environment, namely: with low potential of growth (b &lt;0.044), moderate growth potential (0.044 &lt;b &lt;0.051), and high growth potential (b&gt; 0.051). Sunflower yield variability which is outside the polynomial trend can be described by four multidimensional factors that explained up to 84.9% of variability. These factors were characterized by definite spatial and temporal variability. The most typical oscillation period is 4.4 years and 2.2 years, whereas the longest period was 11 years. We also determined some periods of 5.5 and 7.3 years. We determined some clusters or agro-ecological zones by factor analysis. The highest yield potential of sunflower was registered for agro-ecological zone with disruptive areas in the east of study region. The area with lowest productive capacity was determined for agro-ecological zones in the northwest. We determined the transitional zones concerning the yields characteristic in the center and eastern part of study region.</p>