施用粪肥和沼液对设施菜田土壤磷素累积与迁移的影响

针对有机蔬菜生产普遍施用粪肥和沼液的现状,利用多年田间定位试验,研究基施不同数量粪肥(CM1:30 t·hm-2;CM2:60t·hm-2;CM3:90 t·hm-2)和追施相同量沼液对有机设施蔬菜产量、土壤磷素累积及其移动性的影响。结果表明,2011—2014年不施粪肥单施沼液处理中(CK:0 t·hm-2粪肥)累积磷素盈余量为290 kg P·hm-2,0~30 cm土层土壤中Olsen-P和磷饱和度(DPS)均超过了磷素淋失的环境阈值。粪肥配施沼液处理显著增加了磷素盈余和磷素在土壤中的累积,试验期间2011—2014年累积磷素盈余量为不施粪肥单施沼液处理的6~22倍。随着粪肥施用量的增加,土壤全磷、Olsen-P、Ca Cl2-P、Mehlich3-P和DPS均迅速增加,当粪肥用量达到60 t·hm-2时,显著增加了0~60 cm土层土壤全磷、Olsen-P、Ca Cl2-P、Mehlich3-P含量和DPS,大量粪肥施用并配施沼液处理使表层土壤DPS接近或达到100%。有机蔬菜生产中盲目大量施用粪肥和沼液,显著增加了土壤磷素累积和淋失风险,4年连续每茬90 t·hm-2粪肥施用并配施沼液处理导致磷素在土壤剖面的迁移到达90 cm土层。与不施粪肥单施沼液处理相比,粪肥配施沼液显著提高了作物产量,但是较多量粪肥投入并没有继续增加作物产量,而显著增加了磷素淋失风险。因此,在有机蔬菜生产中推荐施用不超过30 t·hm-2粪肥并配施沼液模式。

Effects of manure and biogas slurry applications on phosphorus accumulation and mobility in organic vegetable soil under greenhouse

Applications of manure and biogas slurry are widespread in organic vegetable production. In this study, a long-term field experiment was conducted in Yanqing, Beijing, to investigate the yields of vegetable crops and the accumulation and mobility of soil phosphorus (P) under applications of different amounts of manure (CM1:30 t·hm^-2 manure; CM2:60 t·hm^-2 manure; CM3:90 t·hm^-2 manure) with the same amount of biogas slurry. Results showed that total P surplus from 2011 to 2014 was 290 kg P·hm^-2 in the treatment with biogas slurry only (CK:0 t·hm^-2 manure). Both Olsen-P and degree of P saturation (DPS) in 0~30 cm soil depth exceeded the environmental threshold values of P leaching in CK treatment in 2014. Long-term applications of different amounts of manure with the same amount of bio gas slurry significantly increased total P surplus and P accumulation in soil, and the total P surplus in these treatments from 2011 to 2014 was 6~22 times that in CK treatment. Applying 60 t·hm^-2 manure per season in CM2 treatment significantly increased soil total P, Olsen-P, CaCl2-P, Mehlich3-P and DPS in 0~60 cm soil depth, and application of 90 t·hm^-2 manure per season in CM3 treatment significantly in creased these values in 0~90 cm soil depth, compared with the CK treatment. The soil DPS in 0~30 cm soil depth was close to or reached 100% under applications of high manure with biogas slurry. In organic vegetable production, excessive applications of manure and biogas slurry significantly increased soil P accumulation and leaching risk. Phosphorus leaching reached 90 cm soil depth after continuous 4-year applications of 90 t·hm^-2 manure plus biogas slurry per season. Compared with the CK treatment, applying manure with biogas slurry signifi cantly increased vegetable yields. Higher manure applications did not get higher vegetable yields, but significantly increased the risk of P leaching. Considering crop yields and environmental risk caused by soil P accumulation, we recommend the CM1manure (30 t·hm^-2) plus biogas slurry] fertilization strategy for organic greenhouse vegetable production in this region.