施氮量和磷肥运筹对青贮玉米产量及养分利用的影响

Effects of nitrogen application rate and phosphorus fertilizer management on silage maize yield and nutrient utilization

【目的】探讨不同施氮量和磷肥运筹对青贮玉米产量及养分吸收利用的影响,为青贮玉米的绿色高效栽培提供理论依据。【方法】2021—2022年,以青贮玉米品种桥单6号为试验材料进行田间试验,设N1(减氮20%,240 kg/ha)和N2(常规施氮,300 kg/ha)2个施氮处理,每个施氮水平下分别设3种磷肥施用方式:P1(100%基肥)、P2(50%基肥,50%穗肥)、P3(50%拔节肥,50%穗肥),共6个施肥处理。测定不同施氮量和磷肥施用方式下青贮玉米的干物质积累量、鲜草产量、养分吸收利用量及土壤养分含量和酶活性。【结果】施氮量影响青贮玉米生物量,总体表现为N1处理低于N2处理。磷肥追施可提高青贮玉米生物产量,在N1水平下,P2处理显著高于P3和P1处理(P<0.05,下同);N2水平下,P3处理显著高于P2和P1处理。在各处理组合中,N1P2和N2P3处理的鲜草产量较N2P1处理(常规施肥)增产显著。氮磷素的吸收量也表现为N2处理高于N1处理,同时,追施磷肥可显著提高氮磷养分吸收利用量。在N1水平下,乳熟期的氮磷素吸收量均表现P2>P3>P1;N2水平下则表现为P3>P2>P1。在各处理中,N2P3处理在乳熟期的氮磷素吸收量显著高于N1P2和N2P1处理;与N2P1处理相比,N1P2处理2021年和2022年氮素吸收量分别提高9.52%和9.03%,磷素吸收量分别提高4.69%和9.45%,且玉米磷素与氮素吸收在吐丝期和乳熟期表现出极显著正相关关系(P<0.01)。此外,减氮20%总体会降低磷肥偏生产力,但能提高氮肥偏生产力。与N2P1处理相比,N1P2处理的氮肥偏生产力2021和2022年分别显著提高36.91%和39.62%。N2P3处理磷肥偏生产力显著高于N2P1和N1P2处理;N1P2较N2P1处理,2021和2022年分别提高4.71%和9.51%。减氮20%总体会降低碱解氮和速效磷含量及脲酶和酸性磷酸酶活性,而磷肥追施可提高酶活性,增加土壤速效养分,基本表现为P2和P3处理高于P1处理。在各处理中,N1P2和N2P3较N2P1处理能保持较高的土壤脲酶和酸性磷酸酶活性,促进碱解氮和速效磷的积累,增加植株干物质积累量和氮磷素吸收利用量。【结论】磷肥作追肥提高了土壤酶活性和土壤速效养分,促进了玉米对养分的吸收利用,从而缓解减氮造成的产量损失。从施氮量和磷肥施用方式看,N1P2和N2P3处理表现出氮磷养分资源的高效利用和产量的提高。

【Objective】To investigate effects of different nitrogen application rates and phosphorus fertilizer managements on silage maize yield and nutrient uptake and utilization,and to provide a theoretical basis for ecofriendly and efficient silage maize cultivation technology.【Method】With silage maize Qiaodan 6 as the experimental material,field experiments were conducted from 2021 to 2022.Two treatments of nitrogen application,N1(20%nitrogen reduction,240 kg/ha)and N2(conventional nitrogen application rate,300 kg/ha),were set.Under each nitrogen application rate,three phosphorus fertilizer managements were set:P1(100%basal fertilizer),P2(50%phosphorus fertilizer and 50%ear fertilizer),and P3(50%jointing fertilizer and 50%ear fertilizer),altogether 6 treatments.Dry matter accumulation,fresh grass yield,nutrient uptake and utilization,soil nutrient and enzyme activity of silage maize were determined under different nitrogen application rates and phosphorus managements.【Result】Nitrogen application rates influenced silage maize biomass,and the influence of N1 treatment was smaller than that of N2.Phosphorus fertilizer topdressing increased silage maize biological yield,under N1 nitrogen application rate,silage maize biological yield in P2 treatment was significantly higher than those in P3 and P1 treatments(P<0.05,the same as below);under N2 nitrogen application rate,silage maize biological yield in P3 treatment was significantly higher than those in P2 and P1 treatments.In each combination of treatments,the fresh grass yield in N1P2 and N2P3 treatments were significantly higher than that in N2P1 treatment(conventional fertilization).Nitrogen and phosphorus uptake in N2 treatment was higher than that in N1 treatment,while phosphorus fertilizer topdressing significantly increased nitrogen and phosphorus nutrient uptake and utilization.Under N1 nitrogen application rate,nitrogen and phosphorus uptake in milking stage was as P2>P3>P1 and under N2 nitrogen application rate,it was as P3>P2>P1.In each treatment,nitrogen and phosphorus uptake in N2P3 treatment at milking stage was significantly higher than that of N1P2 and N2P1 treatments.Compared to N2P1 treatment,nitrogen uptake in N1P2 treatment in 2021 and 2022 increased by 9.52%and 9.03%,and the phosphorus uptake increased by 4.69%and 9.45%.At silking stage and milking stage,phosphorus uptake and nitrogen uptake in maize were extremely significantly positively correlated(P<0.01).In addition,reducing nitrogen by 20%generally decreased partial productivity of phosphorus fertilizer,but increased partial productivity of nitrogen fertilizer.Partial productivity of nitrogen fertilizer in N1P2 treatment in 2021 and 2022 was significantly increased by 36.91%and 39.62%,respectively.Partial productivity of phosphorus fertilizer in N2P3 treatment was significantly higher than that in N2P1 and N1P2 treatments;partial productivity of phosphorus fertilizer in N1P2 increased by 4.71%and 9.51%in 2021 and 2022,compared to that in N2P1 treatment.Nitrogen reduction of 20%usually reduced content of alkali-hydrolyzed nitrogen,available phosphorus,urease and acid phosphatase activity,while phosphorus fertilizer topdressing increased enzyme activity and soil available nutrients,and P2 and P3 treatments were higher than P1 treatment.Among treatments,N1P2 and N2P3 could maintain higher soil urease and acid phosphatase activity,promote accumulation of alkali-hydrolyzed nitrogen and available phosphorus,and increase plant dry matter accumulation,nitrogen and phosphorus uptake and utilization compared to N2P1.【Conclusion】Phosphorus fertilizer topdressing increases soil enzyme activity and soil available nutrients,promotes nutrient absorption and utilization of maize,thus lowering yield loss caused by nitrogen reduction.In terms of nitrogen application rate and phosphorus management methods,N1P2 and N2P3 treatments enhance efficient utilization of nitrogen and phosphorus nutrient resources and increase yield.