Effect of a combined machine parts depths, soil depths and manure application on soil saturated hydraulic conductivity

Abstract

Field experiments were conducted to study the effect of a combined machine parts depths, soil depths and application of manure (cow residual) on the soil saturated hydraulic conductivity (Ks). The soil was plowed and disturbed at two levels. The top layer were plowed by the two bodies of moldboard plow which they were one of the combined machine parts, the deep soil layers were disturbed by two subsoilers which were the second part of the combined machine. The manure was mixed with plowed and the disturbed soils by the three shallow tines of the combined machine (third part). Manure was broadcasted by the manure feeding mechanism which the machine was provided with. Randomize Complete Block design (RCBD) was used with three replicates to carry out the experiments. The experiments parameters were two moldboard plow depths (20cm (M20) and 30cm (M30)), three subsoiler depths (20 (S20), 30 (S30) and 40cm (S40)). These three subsoiler depths were used with moldboard plow depth of 20cm only, whereas, the other three subsoiler depths (10 (S10), 20 (S20) and 30 (S30)) were used with moldboard depth of 30cm. The combination of the moldboard plow depths and the subsoiler depths gave three machine depths (40, 50 and 50cm) i.e M20S20, M20S30, M20S40, M30S10, M30S20 and M30S30. These treatments were conducted without and with manure application of 45.5 ton ha−1. The experiments were conducted in silty laom soil. The soil saturated hydraulic conductivity (KS) was measured after soil plowing and crop harvesting (two periods) for soil depths of d1 (0-10), d2 (10-20), d3 (20-30), d4 (30-40), d5 (40-50) and d6 (50-60). The results showed that KS increased with machine depth, It increased by 20.39% and 41.18% and by 12.90% and 21.03% after soil plowing and crop harvesting (the beginning and the end the season) respectively, when the operating depth of machine was increased from (M20S20)to (M20S30) and (M20S40), M depth remained constant at 20cm whereas, the subsoiler depth increased from 20 to 30 and 40cm. However, increasing the machine depths from (M30S10) to (M30S20) and (M30S30), Ks increased by 19.44 and 36.11% and by 15.15 and 33.33% at the beginning and end of the season respectively, (the operating depth of M increased to 30cm and remained constant whereas S depth increased from 10 to 20 and 30cm). compared with operating depth of 10cm. Ks of the soil treated with manure decreased by 4.65% after plowing operation. However, Ks increased by 35.48% after crop harvesting compared with untreated soil. Ks decreased after soil plowing and at the end of crop growth season with plowing depth. However, Ks decreased as the soil depth increased.