The effect of intensive organo-mineral fertilization on the yield of greenhouse cucumbers and the mineralization of nitrogen-containing organic compounds in soil

The effect of nutrition with nitrogen at 0, 200, 400, 600 and 800 kg/ha against the background of P200K200 and a manure nutritional level of 50, 100, and 200 t/ha, on the vegetative and reproduction behavior of the plants of cv. Sandra and on the process of ammonifying, was studied during the period 1988 - 1990 in non-heated plastic houses. It has been established that increasing the nitrogen level up to 600 kg/decare increases the cucumber yield. This is best expressed at a nutrition level of 50 t/ha and the poorest expression is at 200 t/ha. The highest yield - 112 350 kg/ha, has been achieved when fertilizing with N600P200K200 + 150 t of manure per ha, the yield increases in comparison with the fertilization with N200P200K200 + 50 t of manure (the control), being 73.90%. Increasing the nitrogen level up to 600 kg/ha increases the development of ammonifying bacteria, as well as the potential ammonifying and urease activities, and decreases the protease activity of soil.