THE INFLUENCE OF CONSERVATIVE TILLAGE SYSTEMS ON PHYSICO-CHEMICAL PROPERTIES AND YIELD UNDER A CAMBIC CHERNOZEM FROM NORTHEASTERN PART OF ROMANIA

The long-term experiment was carried out during 2005-2018, with samples collected on the experimental farm of the University of Agricultural Sciences and Veterinary Medicine in the city of Iasi (47 degrees 07' N latitude, 27 degrees 30' E longitude). The soil under investigation is classified as Cambic Chernozem (WRB) with a clay-loamy texture. Initial physical characteristics of the soil on 0-20 cm depth were: bulk density 1.33 g.cm(-3), pH (1:2.5) 6.23, clay 364.2 g.kg(-1), silt 263.2 g.kg(-1), loam 372.6 g.kg(-1), humus 2.95%. In the last 5 years a continuous maize cropping system was used. The tillage treatments included: (1) No-till: direct drilling in untilled soil with a disc drill without previous removal of residues, using a FABIMAG FG01 seeder (NT); (2) a reduced system using a chisel at 22-25 cm depth, after harvest without overturning the furrow (RT); (3) moldboard ploughing after harvest to a soil depth of 28-30 cm (CT). The crumbled and loosened soil was turned over and thereby residues were fully incorporated into the soil. After the harvest of pre-crop, stubble breaking (disking to the depth 10 cm) was used. Seedbed preparation was applied using a compactor after chisel and conventional tillage. In spring the weeds were suppressed by total herbicides before seeding. Crop-specific fertilization was performed according to good agricultural practice. Combine harvest was performed in October (between 5th and 28th) using a Wintersteiger Delta Plot Combine. Tillage systems affected soil penetration resistance ( PR) under maize crop only for certain soil depths. At 0-5 cm depth, the highest value (0.78 MPa) was recorded on no-till system, whilst in the case of the other two variants the values ranged from 0.56 to 0.61 MPa. In CT variant at 30-40 cm, we noticed a compacted layer (2.54 MPa) indicating the existence of hardpan.