The research was conducted on the reddish preluvosoil located NE of Bucharest at 44.4988 latitude and 26.2507
longitude, under no irrigation.
The experiment was bifactorial organized according to the method of subdivided parcels in 4 repetitions where:
factor A – the crop rotation comprised five graduations: a1 –monoculture; a2 two-year rotation: 1. wheat, 2. corn; a3
– three-year rotation: 1. soy, 2. wheat, 3. corn; a4 – four-year rotation: 1. peas, 2. wheat, 3. sugar beet, 4. corn and
factor B – nitrogen fertilization varying when phosphorus fertilization is constant: b1 – N0P70