SOIL CLASSIFICATION, DISTRIBUTION AND PROPERTIES IN ORANGE PLANTING AREAS IN HAM YEN DISTRICT, TUYEN QUANG PROVINCE

Abstract

The study results of soils classification showed that thera are 4 main groups with 14 soils units in the region of Ham Yen, Tuyen Quang province. Of which there are 6 soils units are planting the orange that cluded yellowish red soils on metamorphicrocks, yellowish red soils on claystons, yellowish soils on sandtones and red yellow soils on granite rocs. The small area are soils of yellowish brown on old alluvial and yellowish brown soils on limestones. These soils are very acidic to acidic, organic is poor to high. Total nitrogen content is low to high, available phosphorus is also low, mostly <10 mg/100g soils and phosphorus are also very poor. Total potassium is low <1%. Exchange cation as calcium and magnesium are low, mostly <4 me/100g soil.