灌溉方式对石灰性褐土团聚体分布特征、稳定性及养分含量的影响

Effects of irrigation methods on distribution characteristics,stability and nutrient contents of calcareous brown soil aggregates

为探明不同灌溉方式对石灰性褐土团聚体分布特征、稳定性及养分含量的影响,于2016—2021年在山西农业大学小麦研究所韩村试验基地开展大田定位试验。设连续微喷灌(SI)、连续滴灌(DI)、连续漫灌(FI)和第1、2、5年漫灌与第3、4年微喷灌轮换(RI)4个处理。定位5年后,测定土壤>0.25 mm团聚体重量百分含量(DR0.25、WR0.25)、平均重量直径(MWD)、几何平均直径(GMD)、破坏率(PAD)、分形维数(D)等土壤团聚体粒径分布、稳定性指标,以及土壤水稳性团聚体有机碳、有效磷、速效钾含量等养分指标,并对水稳性团聚体分布特征、稳定性及养分含量进行了相关分析。结果表明:1)机械稳定性团聚体在0~10 cm土层SI、DI和RI处理均以0.5~1 mm为优势粒径(FI为<0.25 mm),在10~20 cm土层DI、FI和RI处理均以>5 mm为优势粒径(SI为0.5~1 mm),在20~50 cm土层各灌溉处理的优势粒径则均为>5 mm;水稳性团聚体在0~50 cm土层4种灌溉处理均以<0.25 mm为优势粒径,但FI处理的重量百分比最高。2)SI和DI处理在0~50 cm土层有效提高了WR0.25、降低了D,且MWD、GMD总体上高于FI和RI处理,并在30~50 cm土层显著降低了PAD,而FI、RI处理的这些稳定性指标受土层深度影响较大。3)与其他2个处理相比,SI、DI处理在0~50 cm土层提高了土壤水稳性大团聚体(>0.25 mm)有机碳、有效磷、速效钾含量,尤其在提高0~30 cm土层有效磷含量和30~50 cm土层速效钾含量上效果更为显著。4)相关性分析表明,土层、WR0.25、MWD、GMD、PAD、D、水稳性大团聚体养分含量(有机碳、有效磷、速效钾)之间的相关性均达到显著(P<0.05)或极显著(P<0.01)水平。综上所述,微喷灌、滴灌水肥一体化更有利于改善土壤结构和性状,促进土壤大团聚体形成,提高水稳性团聚体稳定水平及养分含量,应值得推广应用。

A field experiment was conducted at the Hancun Experimental Base of the Wheat Research Institute,Shanxi Agricultural University,from 2016 to 2021 to explore the effects of different irrigation methods(continuous micro-sprinkler irrigation,SI;con-tinuous drip irrigation,DI;continuous flooding irrigation,FI;and annual rotation of flooding irrigation and micro-sprinkler irrigation,RI)on the distribution characteristics,stability,and nutrients contents of calcareous brown soil aggregates.After five years of posi-tioning,>0.25 mm aggregates weight percentage of machine-stable aggregates(DR0.25)and water-stable aggregates(WR0.25),mean weight diameter(MWD),geometric mean diameter(GMD),destruction rate(PAD),fractal dimension(D),and nutrients(organic car-bon,available phosphorus,and available potassium)contents of soil water-stable aggregates were determined.In addition,the correla-tions among the distribution characteristics,stability,and nutrients contents of soil water-stable aggregates were analyzed.The main results were as follows:1)In the 0-10 cm soil layer,the dominant particle sizes of mechine-stable soil aggregates of treatments SI,DI,and RI were 0.5-1 mm,that of treatment FI was<0.25 mm.In the 10-20 cm soil layer,the dominant particle sizes of mechine-stable soil aggregates of treatments DI,FI,and RI were>5 mm,while that of treatment SI was 0.5-1 mm;that for all treatments were>5 mm in the 20-50 cm soil layer.The dominant particle size of the water-stable aggregate of the four treatments was<0.25 mm in the 0-50 cm soil layer,but the highest percentage of weight was observed in FI.2)SI and DI effectively increased WR0.25,reduced D,and resulted in higher MWD and GMD overall in the 0-50 cm soil layer,as well as decreased PAD in the 30-50 cm soil layer com-pared to FI and RI.However,the aggregates stability indices of treatments FI and RI were largely affected by the soil depth.3)Com-pared to FI and RI,SI and DI resulted in higher contents of organic carbon,available phosphorus,and available potassium in soil wa-ter-stable macro-aggregates(>0.25 mm),and had obvious advantages in increasing available phosphorus content in the 0-30 cm soil layer and available potassium content in the 30-50 cm soil layer.4)The results of the correlation analysis showed that the relation-ships between soil depth,WR0.25,MWD,GMD,PAD,D,and nutrients(organic carbon,available phosphorus,and available potassi-um)contents of soil water-stable macro-aggregates were significant(P<0.05)or extremely significant(P<0.01).Overall,SI and DI were more advantageous in improving the structure and properties of soil,promoting the formation of soil macro-aggregates,and in-creasing the level of stability and nutrients contents of water-stable aggregates,and should be popularized and applied.