Properties of Plough Pan in Cassava and Sugarcane Growing Soils,Khon Kaen Province

Abstract

A study on properties of plough pan in cassava and sugarcane growing soils was carried out in five areas, all located in Khon Kaen Province. There were Satuk, high base subsoil variant soil (PP-1; Ultic Haplustalf), Phon Phisai, sandy variant soil (PP-2; Typic Plinthustult), Yasothon soil series (PP-3; Typic Haplustult) and Satuk soil series (PP-4, PP-5; Typic Paleustults).All soils were deep, having extremely acid to neutral soil reaction and low fertility level. They had gap-graded particle size distribution and medium textural class except for Phon Phisai, sandy variant soil that had coarse textural class. Plough pan was found in all soils, starting at depths between 20-25 cm with the thickness of 15-20 cm, except Phon Phisai, sandy variant soil. Bulk density of these compacted layers ranged from 1.69-1.85 Mg/m3 and soil strength varied between 0.28-6.87 kg/cm2, which were higher than those of directly overlain and underlain layers while saturated hydraulic conductivity (0.03-1.20 cm/hr) being lower. Considering field penetration resistance both in cassava and sugarcane growing soils, the values ranged from 2-10 MPa. Depths of plough pan found in cassava growing soils were shallower than those of sugarcane growing soils whereas general properties of plough pan were rather similar in soils used for growing both plants. There were an exception for bulk density that cassava growing soils had higher values (1.70-1.83 Mg/m3) than did sugarcane growing soils (1.56-1.80 Mg/m3) and for soil strength that the soils used for the former plant showed lower values (0.43-2.79 kg/cm2) than did the soils (0.28-6.87 kg/cm2) used for cultivating the latter plant. However, plant nutrient and organic matter contents at the bottom of topsoil and at the top of plough pan layer were rather similar.