The Effect of the Conventional and Modified Subsoilers on the Aggregate Stability in Clay Soil during Sun Flower Crop Growth Stages (Helianthus annus L.)

Abstract

A filed experiment was conducted at agriculture college research station, Garmit Ali, Basrah University in 2014. The soil texture is clay. Three plow types were used namely modifiled subsoiler, conventional subsoiler and moldboard plow. The first two plows (subsoilers) were used at operating depths of 30, 40 and 50 cm. The moldboard plow was used at operating depth of 25 cm. These plow types were used to study their effect on the Aggregate Stability of the clay soil in first of the season (T1) middle of the season (T2) and after crop harvesting (T3). The soil properties measurements were taken for different depths, d1 (0-15), d2(15-30), d3(30-40) and d4(40-50) cm. The crop used in the experiments was sun flower ( Helianthus annus L.). The following abbrivations are used for the modified and conventional subsoilers operating depths 30, 40, and 50 cm, which are they S1D1, S1D2, and S1D3 and S2D1, S2D2 and S2D3 respectively. For the moldboard plow depth of 25 cm MT is used. The control treatment is given (NT). The experiments were conducted using R.C.B.D. design for three replicates. The filed was divided into three equal area blocks. Each block was divided into eight experimental units. The experimental parameters were randomly distributed on experimental untis. The crop seeds were planted on 4/4/2014. The irrigation was added according to the difficiency in the water level of water evaporation basin. The addition of water was 100% of the measured evaporation value with another 20% as leaching requirement. The crop harvesting date was 4/7/2014. The results showed: The plowing operation reduced The plowing operation increased MWD compared with unplowed soil (NT). The highest value for MWD was recorded for S1D3 while the lowest value recorded for MT. The results showed that MWD decreased with depth but it increased with season growth progress.