Abstract:
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 (47º07` N latitude,
27º30` 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.
