Specificity of nitrogen fertilizer application to winter grain crops in highly dry conditions
1995
Filipov, Kh. (Institut po Introduktsiya i Rastitelni Resursi, Sadovo (Bulgaria))
Wheat yields in the regions of South Bulgaria are limited by hydrothermal conditions. Prediction of optimal nitrogen fertilizer application is difficult due to the unforeseeable dynamics of nitrogen in the soil, resulting from the variability in hydrothermal conditions according to periods, the varying usable volume in the soil layers, the reduced nitrogen flow with the mass flow and by diffusion, and the unfavourable value of nitrogen extracted by plants and of its effectiveness. The sort period with down flowing water current leads to the necessity of ending nitrogen fertilizer application by mid-February. Later application has an uncertain effect. Droughts disturb the penetration of nutrient solutions in the leaves and are the reason for the lack of effect of post sprinkle fertilizer application. Water deficit restricts the optimal leaf area index to 5-7m/m2. Bad conditions for post blooming dry weight and nitrogen component accumulation increase the importance of reutilization in grain yield construction.
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