| Low nutrient use efficiency caused by irrational fertilization,and impossibility of soil test based fertilizer recommendation for small-holder farmers drive the great need to establish a fertilizer recommendation method based on big data and models.In this study,we adopted the Quantitative Evaluation of the Fertility of Tropical Soils(QUEFTS)model to analyze multiple-year-site data to study the relationship between grain yield and nutrient uptake to obtain the balanced nutrient uptake parameters for soybean in China,and to analyze yield response,agronomic efficiency,indigenous nutrient supply,and yield gap at different treatments.On the basis,principle and methodology of fertilizer recommendation for soybean based on yield response and agronomic efficiency was established and Nutrient Expert(NE)for Soybean was built using computer software technology and field validation was conducted to further test and improve this fertilizer recommendation.Meanwhile,multi-plot experiments for several years were conducted to validate the long-term effects of Nutrient Expert for Rice in field conditions.The main results are as follow:1.Totally 584 on-farm experiments were collected in China's major soybean-producing regions from 2000 to 2015,to determine the relationship between grain yield and nutrient uptake in the above-ground plant dry matter using QUEFTS model.The model predicted a linear increase in grain yield if nutrients were taken up in balanced amounts until yield reached about 60-70%of yield potential.To produce 1000 kg seed yield,55.4 kg N,7.9 kg P,and 20.1 kg K were required in the above-ground plant dry matter,and the corresponding internal efficiencies(IE)were 18.1 kg seed per kg N,126.6 kg seed per kg P,and 49.8 kg seed per kg K.And the N:P:K ratios for the linear part of the relationship were 1:0.14:0.36 for soybean in China.2.Nutrients removal by soybean seed was calculated using QUEFTS model to provide guidance for rational fertilization and increase nutrient use efficiency.To produce 1000 kg seed yield,the requirement of N,P,and K in seed were 48.3,5.9,and 12.2 kg.When the target yield reached 80%of potential yield,seed uptake of N,P,and K accounted for 87.1%,74.1%,and 60.8%of total above-ground uptake.3.There was a large yield gap(376 kg/ha)between attainable yield with OPT and actual yield with FP.On average,yield response to N,P and K fertilizer application were 0.40,0.39 and 0.39 t/ha,relative yield to N,P and K were 0.79,0.78 and 0.79,indigenous N,P and K supply were 126.0,20.5 and 47.8 kg/ha,agronomic efficiency to N,P2O5 and K2O application were 8.9,7.8 and 8.8 kg/kg,respectively.Relative yield was used to classify the soil indigenous nutrient supply,and low,median and high were 0.73,0.84 and 0.91 for N,0.72,0.84 and 0.92 for P;0.71,0.84 and 0.91 for K.A significant negative linear correlation was obvious between yield response and relative yield,and significant linear relationship was existed between yield response and agronomic efficiency.4.Nutrient Expert(NE)for Soybean based on yield response,agronomic efficiency,and QUEFTS model was established and field validations were conducted in 2014 to 2015.Seed yield was high with NE compared with farmers' practices(FP)and soil testing(ST),increased by 11.2%and 3.2%.NE also improved nitrogen use efficiencies than FP and ST,increased by 17.8%and 6.8%for recovery efficiency(REN),171.0%and 32.1%kg/kg for agronomic efficiency(AEN),respectively.Meanwhile,NE balanced the nutrients used and made benefit for soil.And the net profit for farmers was improved 10.1%and 2.7%,compare with FP and ST.5.The results from field validation at seven provinces for rice in 2013 to 2015 showed that,compare with FP and ST,NE reduced 4.9-7.1%of N and 8.1-16.8%of K fertilizer,and increased 1.8%of P fertilizer.The yield was increased by 3.5-6.3%.The average AEN,REN and PFPN were improved by 15.6-23.6%,8.4-12.2 percentage point,and 7.5-9.1%,respectively.In summary,the fertilizer recommendation method based on Nutrient Expert was theoretically supported by the large agronomic database from large number of field experiments,which included soil indigenous nutrient supply and the relationship between yield response and agronomic efficiency.Multi-site-year experiments showed that,Nutrient Expert could increase soybean and rice yield and profit,balance the fertilizer use,and improve nutrient use efficiency,and thus has a promising future for adoption by farmers when soil testing is not timely or available. |
PDF Full Text Request