滴灌磷肥在灰漠土中运移的研究

Phosphorus migration of monoammonium phosphate via drip-irrigation in gray desert soil

磷在土壤中的迁移是影响农业系统磷利用效率的关键因素之一。应用同位素^(32)P示踪和放射性同位素自显影技术,研究了滴施磷酸一铵在灰漠土中的运移。结果表明:与不施磷处理相比,滴施磷肥可以增加0~15cm土层有效磷的含量。在0~20 cm土层均有不同比例^(32)P的分布,但大部分^(32)P仍集中分布在表层,0~10 cm土层中的^(32)P占总量的72.7%~89.5%,最高可达99%。不同施肥时期磷的运移距离有很大差异,T3(0~20 cm)>T2(0~10 cm)>T1(0~5 cm),这可能是由于干湿交替导致土壤孔隙率变化,进而影响了磷的移动距离。平行于滴灌带方向上磷的运移距离比垂直于滴灌带方向更远。随着正磷酸盐浓度增加,磷的运移距离变大,滴施磷酸一铵处理^(32)P的移动距离达到对照的2倍。

The migration of phosphorus in soil is one of the key factors affecting the P use efficiency in agriculture system.Phosphorus distribution in gray desert soil from monoammonium phosphate(MAP)applied by drip-irrigation was studied by 32P isotope tracing and autoradiography technique in greenhouse.Our results showed that compared with no phosphate treatment(CK),drip fertigation of phosphate fertilizer increased the Olsen P in the 0~15 cm layer.Different proportions of 32P were found in every layers within 20 cm depth and 72.7%~89.5%of the 32P was retained in the 0~10 cm depths.The decreasing order of the migration distance of the P was T3(0~20 cm)>T2(0~10 cm)>T1(0~5 cm),which was mainly attributed to the dry and wet alternation and different soil porosity at different times.The migration of phosphorus,which was in parallel to the drip tape,was more active than that of vertical to the drip tape.The longer distance P migration was with higher P concentration in soil.The 32P migration in treatments of MAP was twice than that of the CK treatment.