The experiment was conducted to study the effect of tillage depths and softening on some soil physical properties, potato growth and yield (Solonum Tubersum L.) class Desiree during spring season of 2012. The experiment includes two factors; first, three tillage depths (d); 15 cm (d1), 30 cm (d2) and 45 cm (d3). Second factor: three softening soil (s) for levels: single softening (S1) and double softening (S2) and trible softening (S3). The treatments were distributed as a factorial experiment in three replicates in randomized complete block design. The irrigation was done at 50% depletion from available water, according to crop growth stages, depending on evaporation pan losses. The soil moisture content was measured at two tentions (0.3 , 15) bar before planting, also moisture contents are measured before and after 24 hr. Irrigation for crop maturity stage, to determinate volumetric soil moisture content. Bulk density and soil penetration resistance were measured before planting and after harvesting. Also crop length, root masses and tuber yield were measured at the end of season.
The results showed that:
By increasing tillage depths from 15 to 30 and 45 cm, some physical properties of soil were improved, increasing of volumetric soil moisture content and decreasing of bulk density, soil penetration resistance. Some properties of growth and potato yield were improved. While obtained negative effect of studied soil properties and growth, potato yield at frequency of soil softening.
Positive percentages have been obtained for both physical properties of soil , growth and yield of potato when increasing tillage depths from 15 to 45 cm and soil softening for single , and as follows:
Bulk density, soil resistance for penetration and root length have decreased about 8.00 , 40.00 and 26.32% respectively. Whereas root mass values and yield of potato increase about 39.10 , 42.00% , respectively.