Study on elements of the field management practices applied in winter cereals grown after stubble predecessor. Investigation on cultivation of winter barley after winter wheat predecessor

The results from two field trials performed during 2004-2006 were analyzed. The first trial investigated the effect of nitrogen fertilization on two winter barley varieties - Aheloy 2 and Emon (check variety was Kaskadyor 3), involving 3 nitrogen rates against phosphorus background: 6 and 120 kg/ha N. Barley was sown after two previous crops: maize for forage and winter wheat. The second trial investigated the response of 6 barley varieties to the sowing term and rate. Two typical winter type varieties were involved: Radul and Tsvetelina, as well as three winter-spring type varieties - Obzor, Kaskadyor and Veslets, and one spring type variety - Fink. Sowing was done with two sowing rates [400 and 600 germinating seeds /g.s./ per m2] at 3 sowing terms: optimal /1st-5th October/, late autumn /25th-30th November/ and late spring (March). The first trial established that 6-row variety Aheloy 2 realized higher productive potential under the conditions of Dobroudja region in comparison to 2-row varieties Kaskadyor 3 and Emon. Averaged for the period of investigation, highest yields from barley were obtained after fertilization with N120, the relative effect from the increased nitrogen rate being highest after previous crop maize for silage; fertilization with a rate higher than N60 did not have a significant positive effect on grain yield. Previous crop winter wheat was more suitable for growing of barely under the conditions of Dobroudja region in long-term aspect due to two general reasons: better physical properties of soil as affected by pre-sowing ploughing and post-effect of the higher nitrogen rates of the previous crop on the succeeding barley. This does not exclude higher yields during individual years of epiphytoty obtained after previous crop fodder maize. When sowing barley within the agrotechnical terms optimal for autumn crops it is recommendable to include in the variety structure frost-resistant varieties (such as Radul) and winter-spring type varieties with good regeneration ability after the winter /such as Veslets/. When sowing barley in spring as a main crop or for strengthening areas damaged by frost, winter-spring types are preferable; typical winter varieties should not be sown. The optimal sowing rate for good wintering varieties sown in autumn is 400 g.s./m2; increasing to 600 g.s./m2 is recommendable for varieties with lower ability of wintering, and thus ensuring better crop density under the risky climatic conditions of Dobroudja region. At early spring sowing of barley the optimum sowing rate is 500-600 g.s./m2 because it provides a sufficient number of spike-bearing stems under conditions of a rather shortened tillering period.