西藏主要农区农田土壤肥力状况研究

SOIL FERTILITY OF CROPLANDS IN MAJOR AGRICULTURAL AREAS OF TIBET

西藏由于其特殊的地理位置、气候类型和地质历史以及耕作习惯,使其具有特殊的土壤特征.在2002～2004年间,我们对西藏主要农业区的林芝、拉萨、日喀则、山南等4地(市)的农田土壤进行了采样分析,分析结果显示:4地(市)农田土壤酸碱性由弱酸性至弱碱性(pH 6.5～9.0);养分的基本状况是有机质含量在5～50 g/kg之间,变幅较大,N素少(全N 0.2～2 g/kg,速效N 20～80 mg/kg),P素缺(全P 0.22～1.42 g/kg,速效P1～133 mg/kg),K素(全K 1.9～12.2 g/kg,速效K 80～1290 mg/kg)和微量元素比较丰富(Cu10～443mg/kg,Zn47～266mg/kg,Fe 1880～7550mg/kg,Mo0.2～6.6mg/kg,Mn 196～736mg/kg,B 0.5～138mg/kg).

Tibetan croplands possess their unique soil characteristics due to the special geographical location, climate type, and geological records of Tibet and the cultivation practices of the local farmers. Soil samples from farmlands in Linzhi, Lhasa, Ricaze and Shannan, the major agricultural areas of Tibet, were collected and analyzed in the period from 2002 to 2004. The results showed that the soils varied from weakly acidity （pH 6.5） to weakly alkalinity （pH 9.0）, and from 5 to 50 g/kg in organic matter contents, were inadequate in soil N （ total N 0.2 - 2 g/kg, and readily available N 20 - 80 mg/kg）, deficient in P （ total P 0.22 - 1.42 g/kg, and readily available P 1 - 133 mg/kg）, but rich in K （ total K 1.9 - 12.2 g/kg, and readily available K 80 - 1290 mg/kg） and microelements （Cu 10 - 443 mg/kg, Zn 47 - 266 mg/kg, Fe 1880 - 7550 mg/kg, Mo 0.2 - 6.6 mg/kg, Mg 196 - 736 mg/kg, B 0.5 - 138 mg/kg）.