The optimized management of crop fertilization is very important for improving crop yield and reducing the consumption of chemical fertilizers.Critical nutrient values can be used for evaluating the nutritional status...The optimized management of crop fertilization is very important for improving crop yield and reducing the consumption of chemical fertilizers.Critical nutrient values can be used for evaluating the nutritional status of a crop,and they reflect the nutrient concentrations above which the plant is sufficiently supplied for achieving the maximum potential yield.Based on on-farm surveys of 504 farmers and 60 field experimental sites in the drylands of China,we proposed a recommended fertilization method to determine nitrogen(N),phosphorus(P),and potassium(K)fertilizer input rates for wheat production,and then validated the method by a field experiment at 66 different sites in northern China.The results showed that wheat grain yield varied from 1.1 to 9.2 t ha^(-1),averaging 4.6 t ha^(-1),and it had a quadratic relationship with the topsoil(0-20 cm)nitrate N and soil available P contents at harvest.However,yield was not correlated with the inputs of N,P,and K fertilizers.Based on the relationship(exponential decay model)between 95–105%of the relative yield and topsoil nitrate N,available P,and available K contents at wheat harvest from 60 field experiments,the topsoil critical nutrient values were determined as 34.6,15.6,and 150 mg kg^(-1)for soil nitrate N,available P,and available K,respectively.Then,based on five groups of relative yield(>125%,115–125%,105–115%,95–105%,and<95%)and the model,the five groups of topsoil critical nutrient levels and fertilization coefficients(Fc)were determined.Finally,we proposed a new method for calculating the recommended fertilizer input rate as:Fr=Gy×Nr×Fc,where Fr is the recommended fertilizer(N/P/K)input rate;Gy is the potential grain yield;Nr is the N(N_(rN)),P(N_(rP)),and K(N_(rK))nutrient requirements for wheat to produce 1,000 kg of grain;and Fc is a coefficient for N(N_c)/P(P_c)/K(K_c)fertilizer.A 2-year validated experiment confirmed that the new method reduced N fertilizer input by 17.5%(38.5 kg N ha^(-1))and P fertilizer input by 43.5%(57.5 kg P_(2)O_(5) ha^(-1))in northern China and did not reduce the wheat yield.This outcome can significantly increase the farmers’benefits(by 7.58%,or 139 US$ha^(-1)).Therefore,this new recommended fertilization method can be used as a tool to guide N,P,and K fertilizer application rates for dryland wheat production.展开更多
The short-term impacts of urban air pollution on the platelet-lymphocyte ratio (PLR) and neutrophil-lymphocyte ratio (NLR) remain obscure.In this study,we included 3487 urban adults from the Wuhan-Zhuhai cohort.Indivi...The short-term impacts of urban air pollution on the platelet-lymphocyte ratio (PLR) and neutrophil-lymphocyte ratio (NLR) remain obscure.In this study,we included 3487 urban adults from the Wuhan-Zhuhai cohort.Individual inhalation exposure to air pollutants was estimated by combining participants’daily breath volume and ambient concentrations of six air pollutants (includingfine particulate matter (PM_(2.5)),inhalable particulate matter(PM_(10)),nitrogen dioxide (NO_(2)),sulfur dioxide (SO_(2)),carbon monoxide (CO) and ozone (O_(3))).The cumulative impacts were assessed by applying lag structures of up to 7 days before the survey date.Associations of air pollutants with PLR and NLR were assessed using a linear mixed model and Bayesian kernel machine regression (BKMR) model.We found that PLR was negatively related to PM_(2.5)(lag02-lag06),PM_(10)(lag02-lag07),NO_(2)(lag02-lag07),and SO_(2)(lag03-lag05) and NLR was negatively related to PM_(10)(lag05 and lag07).In the BKMR model,a negative joint association between the six-air-pollutant mixture and PLR and NLR was observed,whereas PM_(10)and NO_(2)appeared to be more important than the other pollutants in the mixture.The negative impact of air pollutants was stronger in males,participants with lower body mass index (<24 kg/m^(2)),those cooking meals at home,drinkers,and nonexercisers.In conclusion,short-term exposure to air pollutants is significantly related to PLR and NLR in peripheral blood.PLR and NLR may provide new insight into the molecular mechanism underlying the adverse health impact of air pollutants.展开更多
基金supported by grants from the National Key Research and Development Program of China(2021YFD1900700 and 2018YFD0200401)the China Agricultural Research System(CARS-3)the Science and Technology Research Program of Shaanxi Province,China(2022PT-06)。
文摘The optimized management of crop fertilization is very important for improving crop yield and reducing the consumption of chemical fertilizers.Critical nutrient values can be used for evaluating the nutritional status of a crop,and they reflect the nutrient concentrations above which the plant is sufficiently supplied for achieving the maximum potential yield.Based on on-farm surveys of 504 farmers and 60 field experimental sites in the drylands of China,we proposed a recommended fertilization method to determine nitrogen(N),phosphorus(P),and potassium(K)fertilizer input rates for wheat production,and then validated the method by a field experiment at 66 different sites in northern China.The results showed that wheat grain yield varied from 1.1 to 9.2 t ha^(-1),averaging 4.6 t ha^(-1),and it had a quadratic relationship with the topsoil(0-20 cm)nitrate N and soil available P contents at harvest.However,yield was not correlated with the inputs of N,P,and K fertilizers.Based on the relationship(exponential decay model)between 95–105%of the relative yield and topsoil nitrate N,available P,and available K contents at wheat harvest from 60 field experiments,the topsoil critical nutrient values were determined as 34.6,15.6,and 150 mg kg^(-1)for soil nitrate N,available P,and available K,respectively.Then,based on five groups of relative yield(>125%,115–125%,105–115%,95–105%,and<95%)and the model,the five groups of topsoil critical nutrient levels and fertilization coefficients(Fc)were determined.Finally,we proposed a new method for calculating the recommended fertilizer input rate as:Fr=Gy×Nr×Fc,where Fr is the recommended fertilizer(N/P/K)input rate;Gy is the potential grain yield;Nr is the N(N_(rN)),P(N_(rP)),and K(N_(rK))nutrient requirements for wheat to produce 1,000 kg of grain;and Fc is a coefficient for N(N_c)/P(P_c)/K(K_c)fertilizer.A 2-year validated experiment confirmed that the new method reduced N fertilizer input by 17.5%(38.5 kg N ha^(-1))and P fertilizer input by 43.5%(57.5 kg P_(2)O_(5) ha^(-1))in northern China and did not reduce the wheat yield.This outcome can significantly increase the farmers’benefits(by 7.58%,or 139 US$ha^(-1)).Therefore,this new recommended fertilization method can be used as a tool to guide N,P,and K fertilizer application rates for dryland wheat production.
基金supported by the Key Program of the National Natural Science Foundation of China (No. 91543207)the Major Research Program of the National Natural Science Foundation of China (No. 91843302)。
文摘The short-term impacts of urban air pollution on the platelet-lymphocyte ratio (PLR) and neutrophil-lymphocyte ratio (NLR) remain obscure.In this study,we included 3487 urban adults from the Wuhan-Zhuhai cohort.Individual inhalation exposure to air pollutants was estimated by combining participants’daily breath volume and ambient concentrations of six air pollutants (includingfine particulate matter (PM_(2.5)),inhalable particulate matter(PM_(10)),nitrogen dioxide (NO_(2)),sulfur dioxide (SO_(2)),carbon monoxide (CO) and ozone (O_(3))).The cumulative impacts were assessed by applying lag structures of up to 7 days before the survey date.Associations of air pollutants with PLR and NLR were assessed using a linear mixed model and Bayesian kernel machine regression (BKMR) model.We found that PLR was negatively related to PM_(2.5)(lag02-lag06),PM_(10)(lag02-lag07),NO_(2)(lag02-lag07),and SO_(2)(lag03-lag05) and NLR was negatively related to PM_(10)(lag05 and lag07).In the BKMR model,a negative joint association between the six-air-pollutant mixture and PLR and NLR was observed,whereas PM_(10)and NO_(2)appeared to be more important than the other pollutants in the mixture.The negative impact of air pollutants was stronger in males,participants with lower body mass index (<24 kg/m^(2)),those cooking meals at home,drinkers,and nonexercisers.In conclusion,short-term exposure to air pollutants is significantly related to PLR and NLR in peripheral blood.PLR and NLR may provide new insight into the molecular mechanism underlying the adverse health impact of air pollutants.
