摘要
红壤固磷能力强,但合理间作可促进磷吸收,减少磷固定。本研究基于连续4年的田间定位试验,分别设置玉米大豆间作(MI)和玉米单作(MM)2种种植模式,不施磷肥(P0)、施P_(2)O_(5)60 kg·hm^(-2)(P60)、施P_(2)O_(5)90 kg·hm^(-2)(P90)及施P_(2)O_(5)120 kg·hm^(-2)(P120)4个施磷水平,采用改良的Hedley磷分级法,研究了玉米大豆间作对玉米根际土壤磷组分的影响及其磷梯度响应;通过随机森林模型,探究了不同磷组分对土壤磷活化系数(PAC)的贡献。玉米大豆间作提高了红壤施磷处理的总磷含量和磷有效性。与玉米单作相比,P0水平下间作玉米根际土壤速效磷含量显著提高70.4%(P<0.01)。玉米大豆间作显著促进了红壤磷的活化和向活性磷库的转化。在P0和P90水平下,间作土壤PAC较单作分别显著提高87.4%(P<0.05)和34.6%(P<0.01)。间作使红壤活性磷库占总磷比例平均提高15.1%。其中无机活性磷组分中Resin-P在P120水平下含量较单作显著提高53.7%(P<0.05),有机活性磷库中碳酸氢钠浸提有机磷(NaHCO3-Po)含量在P0、P120水平下分别显著提高117.0%、25.6%(P<0.05)。间作使红壤稳定性磷库占总磷比例降低1.1%,差异不显著。在P90水平下,稳定性磷库中稀盐酸浸提无机磷(Conc.HCl-Pi)含量较单作显著降低40.2%(P<0.01)。随机森林模型显示土壤无机磷是PAC的主要决定因素,其中去除水溶性无机磷(Resin-Pi)的预测值时,土壤PAC的均方差增加14.7%。玉米大豆间作显著提高了玉米根际土壤有效磷含量及土壤PAC,提高了玉米根际土壤活性磷库、中稳性磷库的比例,同时降低了稳定性磷库的比例,玉米大豆间作对磷库的活化在中低施磷水平下作用显著,在高施磷水平下活化作用不明显,而其中土壤无机磷组分对PAC影响较大。说明玉米大豆间作促进了红壤磷的活化和向活性磷库的转化,特别是在中低施磷条件下,而在高施磷(P120)条件下间作红壤磷的活化作用不明显。
Phosphorus limits the growth of crops and is easily fixated to red soil;however,reasonable intercropping can promote phosphorus absorption and reduce phosphorus fixation.Studying the effects of maize and soybean intercropping on phosphorus transformation and mobilization in red soil in the southwestern drylands under different phosphorus application levels is of great significance.Based on four consecutive years of field positioning experiments,two planting modes—maize and soybean intercropping and maize monocropping—were set;four phosphorus application levels—no phosphate fertilizer(P0),60 kg∙hm^(-2)of P_(2)O_(5)(P60),90 kg∙hm^(-2)of P_(2)O_(5)(P90),and 120 kg∙hm^(-2)of P_(2)O_(5)(P120)—were also implemented.The effects of maize and soybean intercropping on phosphorus fractions in maize rhizosphere soil and the response of soil phosphorus to the phosphorus gradient were studied using modified Hedley phosphorus classification method.The contribution of different phosphorus fractions to the soil phosphorus activation coefficient(PAC)was investigated using a random forest model.Maize and soybean intercropping increased the available phosphorus content and phosphorus availability in red soil under phosphorus fertilization.Compared with maize monocropping,at P0 level,the available phosphorus content of the intercropping maize rhizosphere soil increased significantly by 70.4%(P<0.01).Maize and soybean intercropping greatly promoted the mobilization of phosphorus in red soil and conversion to the active phosphorus pool.At P0 and P90 levels,the soil PAC of intercropping was significantly increased by 87.4%(P<0.05)and 34.6%(P<0.01),respectively,compared with that of monocropping.Intercropping also increased the proportion of active phosphorus pool to total phosphorus by 15.1%averagely.Among them,the Resin-P content in the inorganic active phosphorus component at the P120 level was significantly increased by 53.7%(P<0.05),compared with in monocropping.Furthermore,the NaHCO3-Po(organic P extracted by sodium bicarbonate)content in the organic active phosphorus pool was significantly increased by 117.0%and 25.6%,at the P0 and P120 levels,respectively(P<0.05).Intercropping reduced the proportion of stable phosphorus pool in red soil by 1.1%of the total phosphorus.At P90 level,the content of Conc.HCl-Pi(inorganic P extracted from concentrated hydrochloric acid)in the stable phosphorus pool was significantly decreased by 40.2%(P<0.01)compared with maize monocropping.The random forest model showed that soil inorganic phosphorus was the main determinant of PAC,and the mean square error of PAC increased by 14.7%when the predicted value of water-soluble inorganic phosphorus(Resin-Pi)was removed.Maize and soybean intercropping significantly increased the available phosphorus content and PAC in maize rhizosphere soil,increased the proportion of active phosphorus pool and moderately stable phosphorus pool,and decreased the proportion of stable phosphorus pool in maize rhizosphere soil.The mobilization effect of maize and soybean intercropping on the phosphorus pool was significant at low and medium phosphorus levels,but not at high phosphorus level,while soil inorganic phosphorus components had a greater effect on PAC.The results showed that maize and soybean intercropping promoted the mobilization of phosphorus and the conversion of phosphorus to the active phosphorus pool in red soil,especially under conditions of medium and low phosphorus application.However,the effect of the intercropping of maize and soybean on the mobilization of phosphorus in red soil was not obvious under the condition of high phosphorus application.
作者
苏丽珍
赵红敏
侯贤锋
陈源
肖靖秀
郑毅
汤利
SU Lizhen;ZHAO Hongmin;HOU Xianfeng;CHEN Yuan;XIAO Jingxiu;ZHENG Yi;TANG Li(College of Resources and Environment,Yunnan Agricultural University,Kunming 650201,China;Yunnan Open University,Kunming 650599,China)
出处
《中国生态农业学报（中英文）》
CAS
CSCD
北大核心
2023年第4期558-566,共9页
Chinese Journal of Eco-Agriculture
基金
国家自然科学基金项目(32260805,31760615)
国家重点研发计划项目(2017YFD0200207)
云南省重大科技专项计划(202102AE090030)资助。
关键词
玉米大豆间作
施磷水平
土壤Hedley磷分级
磷活化系数
红壤
Maize/soybean intercropping
Phosphorus application level
Soil Hedley phosphorus grading
Phosphorus activation coefficient
Red soil
