INVESTIGATIONS ON NITROGEN NUTRITION INDICES OF CABBAGE AND CUCUMBER
For the investigations vegetables with different nitrogen requirements, viz.: late cabbage and cucumber, were selected The nitrogen fertilizer rates, from 0 to 900 kg N/ha, were applied against a uniformly high phosphorus-potassium fertilization level. In the growing season plant and soil samples were taken with the purpose of:
- establishing the indicative part of the given plant ilustrating most exactly nitrogen nutrition degree;
- determining the range of the indicative nitrogen form content in the growing season depending on the nitrogen fertilization level;
- determining critical levels of mineral nitrogen in the soil.
It has been assumed that the nitrogen nutrition status of plants will be estimated by means of analyzing plants for N-NO3 content and soil for nitrate and ammonium nitrogen content in arable layer.
N-NO3 was determined in air-dry matter of plants and in dry soil using the methods with brucine (soil and cucumbers) or brucine and phenol-disulphonic acid application (cabbage). N-NH4 in soil was determined using the Nessler's reagent.
The investigations have shown that:
- This selection has been made on a basis of the