Study On The Application Effect Of Soybean Nutrient Expert System In Field

China is one of main soybean produce and consume country,but the soybean yield per unit area and total yield are low and are hard to meet the demand of increasing population.Balanced fertilization is crucial for attaining high soybean yields;however,the imbalance of nutrient application widely exists,the simple-quick fertilization recommended method is lacked,and the new fertilization technologies are not paid enough attention in soybean production.Aiming at this situation,we developed the Nutrient Expert System(NE System)combined with the fertilization recommendation method based on yield response and agronomy efficiency,studied the effect of NE application in field,and formed the technology of fertilizer reduction and benefit improvement for soybean combining with Plant Growth Promoting Rhizobacteria(PGPR),rhizobia,and controlled released nitrogen(N)fertilizer in field.The main results are shown as follows:(1)The recommendation fertilization based on the NE is more conducive to increasing seed yield and economic benefit of soybean.Compared with the farmers’practices(FP),the NE and soil testing(ST)recommendation fertilization treatments optimized the dosage and ratio of fertilizers.In spring soybean planting area,ST increased seed yield and economic benefit by 135-478 kg/hm~2and 699-856yuan/hm~2,respectively,compared with FP.NE increased seed yield and economic benefit by 168-1225kg/hm~2and 1096-4610 yuan/hm~2than ST,respectively.In summer soybean planting area,NE increased seed yield and economic benefit by 622-1021 kg/hm~2and 2069-3955 yuan/hm~2compared with FP,respectively.The fertilization recommended based on the NE is more conducive to optimizing and balancing nutrient application and improving seed yield and economic benefit of soybean.Besides,it does not require soil testing and is a simple and efficient method for fertilizer recommendation.(2)The combination of NE and rhizobia,PGPR,and controlled release N fertilizer further decreased the rate of N fertilizer.The reduction of 30%N on the basis of the N rate in NE significantly suppressed soybean growth and high seed yield.The incorporation of rhizobia or controlled release N fertilizer increased seed yield and nutrient uptake of soybean in Zhoukou,and the combined application of rhizobia,PGPR,and controlled release urea presented the best effect.In Harbin,after reducing N fertilizer rate,which combined with rhizobia,PGPR,controlled release urea,and all of them attained the similar high yield as that in NE.(3)After the reduction of 30%N on the basis of NE,the incorporation of rhizobia and PGPR increased microbial abundance.On the basis of the N rate of NE,a 30%reduction of N fertilizer did not significantly affect soil bacterial and fungal abundances at Zhoukou,but the abundance showed an increasing trend after rhizobia and PGPR were incorporated single or together,and different treatments affected soil microbial community composition.At Harbin,soil bacterial and fungal abundances showed a decreasing trend after the reduction of N fertilizer by 30%on the basis of NE,and the incorporation of rhizobia and PGPR did not affect microbial abundance.At Zhoukou,the reduction of N rate did not influence the abundance of soybean root endophytic rhizobia,and the incorporation of rhizobia and PGPR increased their abundances.At Harbin,the reduction of N rate decreased the abundance of soybean root endophytic rhizobia,and the incorporation of rhizobia and PGPR did not influence their abundances.Overall,compared with the FP and ST,the fertilization based on NE optimized fertilizer ratio,and increased seed yield and economic benefit of soybean.The combination of NE and rhizobia,PGPR,and controlled release N fertilizer further decreased N fertilizer rate and increased economic benefit while maintaining high soybean yield,and is a good technology for decreasing chemical fertilization and increasing economic benefit.