有机肥不同施用量对宁南土壤团聚体粒级分布和稳定性的影响

Effects of different organic fertilizer treatments on distribution and stability of soil aggregates in the semiarid area of South Ningxia

通过连续3 a有机肥施用田间试验研究了有机肥不同施用量对半干旱旱作区土壤团聚体各层粒径分布和稳定性的影响。试验设计为高肥H（有机肥90000 kg/hm^2）、中肥M（有机肥60 000 kg/hm^2）和低肥L（有机肥30 000 kg/hm^2）3个施肥水平,每个层次设3次重复,供试作物为小麦,品种为西峰26;土壤团聚体的各个粒径分布状况采用干筛法和湿筛法测定。与试验开始时土壤相比,施肥处理0-10 cm和30-40 cm土层〉0.25 mm的水稳性团聚体含量最大增幅分别是35%和75%;0.5 mm以上各粒级的水稳性团聚体含量均呈上升趋势,其中〉5 mm和2-5 mm大粒径团聚体的增加幅度最明显,0.25-0.5 mm的水稳性团聚体含量增加不显著。不同处理间〉5 mm土壤团聚体与〉0.25 mm土壤团聚体含量具有显著性差异。干筛结果表明,土壤中的团聚体主要以〉5 mm土壤团聚体为主,且处理之间差异性主要表现在0-20 cm土层。施肥处理使30-40 cm土层土壤团聚体的稳定性提高,稳定率平均较0-10 cm土层高87%。施肥处理平均重量直径均大于对照,且与〉0.25 mm水稳性团聚体含量呈显著正相关。有机肥不同施用量可显著增加土壤中大团聚体的比例,改良土壤中团聚体的结构;适宜的施肥量在60000 kg/hm^2左右。

A study was conducted on the size distribution and stability of soil aggregates in the semiarid area of South Ningxia after 3-year fertilization.The experiment has three levels of fertilizer treatments,and every level repeated three times.The test crop was wheat Xifeng 26.The distribution of soil aggregates was measured by dry sieving and wet sieving.The results showed that the proportion of the bigger soil aggregates was increased significantly by organic fertilizer treatments and there was a positive correlation between organic fertilizer amount and the proportion.The stability of soil aggregates was also improved by organic fertilizer treatments.Compared with that of natural soil,the content of 〉0.25 mm water-stable aggregates in 0～10 cm and 30～40 cm layers of soil with fertilizer treatments increased by 35% and 75%,respectively;and the content of ≥0.5 mm water-stable aggregates also had a increasing trend,with the greatest increment of that of 5 mm and 2～5 mm water-stable aggregates.On the contrary,the change of the content of 0.25～0.5mm water-stable aggregates was not significant.The significant difference between these treatments was mainly reflected in 〉5 mm and 〉0.25 mm aggregates.After dry sieving,〉5 mm aggregates were the main part.Compared with the control,the content of 〉0.25 mm aggregates increased in varying degrees in organic fertilizer treatments.There was significant difference between these organic fertilizer treatments in 0～20 cm soil layer.Through aggregate stable percentage comparing,organic fertilizer treatments had the most influential effect on 30～40 cm soil layer,and the soil stable percentage of 30～40 cm soil layer was increased by 87% compared to that of 0～20 cm soil layer.The mean weight diameter（MWD） of soil with fertilizer treatment was greater than that of natural soils,and it was significantly correlated with the content of 〉0.25 mm water-stable aggregates.So the organic fertilizer treatments can not only enhance the proportion of bigger aggregates,but also improve the structure of soil,and the suitable amount of organic fertilizer application is about 60 000 kg/hm^2.