Regularities of sowing alfalfa productivity formation while using different types of nitrogen fertilizers in cultivation technology

Abstract

The provision of alfalfa with the nutrients throughout the whole growing period is an important factor in influencing the yield. We researched the content of mineral nitrogen in the typical black soil and the productivity of green mass of sowing alfalfa. As a result of research, we have found that the use of CAM in comparison with ammonium nitre in the norm of 90 kg/ha increased the total nitrogen content in the green mass of alfalfa by 0.17%. The mineral compounds of nitrogen in the podzolized black soil were 36%-87% higher compared with the variant without fertilizers. Increasing the rate of phosphorus from 60 to 90 kg/ha increased the content of total phosphorus in sowing alfalfa by 0.09%-0.11% and potassium by 0.19%-0.23% respectively. When using the CAM rate N180 on the P60K60 background the highest yield of green alfalfa (43.5 t/ha) was obtained, the difference comparing to N110P90K120 did not exceed 5%. Correlative and regressive modeling allowed to establish that the content of mineral nitrogen is minimal (15 mg/ha) in the phase of restoration of alfalfa vegetation in the control variant and further was noted its rapid increase to 26-28 mg/kg on the background of nitrogen fertilizer application in doses N150-N180. In the flowering phase, a significant (19.4%-39.8%) decrease of calculated indices of the content of nitrogen mineral compounds was noted, but there appeared a steady dynamics of growth of these indices in the variants with high doses of nitrogen fertilizers. The optimal doses of fertilizer application have been determined at the level from 120 to 145 kg per 1 ha which provides yields of green mass at the level of 45-47 t/ha. The variability of productive features affirms the maximum impact on alfalfa productivity at mineral nutrition background-68.5%, the weather conditions account for 21.5%, the interaction of these factors takes 5.1%, and the influence of unaccounted factors is at the level of 4.9%.