土地利用方式对荒漠土壤有机碳和养分含量的影响

Effects of land use on organic carbon and nutrient contents in desert soil

以未开垦荒漠土壤为对照,研究土地利用方式对荒漠土壤有机碳、全氮和速效磷含量的影响.结果表明,与未开垦荒地相比较,玉米地和刺槐苗圃地土壤总有机碳含量在0-20 cm土层深度分别增加了32%-68%和27%-136%,但是苜蓿地仅在0-10 cm土层增加了48%.在0-20 cm土层深度,玉米地颗粒有机碳含量增加了143%-167%,而苜蓿地和刺槐苗圃地则仅在0-10 cm土层分别增加了217%和550%.在0-30 cm土层深度,玉米地和刺槐苗圃地矿物结合态土壤有机碳含量与未开垦荒地之间差异不显著,而苜蓿地则显著低于未开垦荒地.不同土地利用方式之间矿物结合态有机碳含量的这种变化主要是由于土壤粘粒含量的变化所引起(r=0.69,P<0.01).玉米地和刺槐苗圃地0-30 cm土层土壤全氮含量分别增加了61%和64%,而苜蓿地全氮含量变化不大;玉米地和刺槐苗圃地0-30 cm土层土壤速效磷含量变化不显著,而苜蓿地则降低了80%.

This work was designed to investigate the effects of land use on organic carbon and nutrient contents（total nitrogen and active phosphorus contents） in desert soil. The total organic carbon contents in the soil at 0-20 cm depth of maize field and locust nursery were increased by 32 %-68 %and 27 %- 136 %,respectively,and alfalfa field by 48 % only at 0-10 cm depth, compared with uncultivated desert soil as control. Particulate organic carbon content in 0-20 cm soil layer of maize field was increased by 143 %-167 %,and alfalfa field and and locust nursery in 0-10 cm soil layer by 217 %-550 % ,respectively. At 0-30 cm depth,there was no difference between uncultivated land and maize field and locust nursery in average mineral associated organic carbon contents in soils, but average mineral associated organic carbon in soil of alfalfa field was significantly lower than in uncultivated land, mainly due to higher clay content in the former than in the latter. The soil total nitrogen contents at 0-30 cm depth of maize field and locust nursery were increased by 61 % and 64 % ,respectively,but there was no change in soil total nitrogen contents in soll of alfalfa field. At the soil depth of 0-30 cm, there was no change in active phosphorus contents of maize field and locust nursery, but soil active phosphorus contents of alfalfa field was decreased by 80 %.