A continuous three-year observation(from May 2008 to April 2011)was conducted to characterize the spatial variation of dissolved inorganic nitrogen(DIN)deposition at eight main forest ecosystems along the north-south ...A continuous three-year observation(from May 2008 to April 2011)was conducted to characterize the spatial variation of dissolved inorganic nitrogen(DIN)deposition at eight main forest ecosystems along the north-south transect of eastern China(NSTEC).The results show that both throughfall DIN deposition and bulk DIN deposition increase from north to south along the NSTEC.Throughfall DIN deposition varies greatly from 2.7 kg N/(ha·yr)to 33.0 kg N/(ha·yr),with an average of 10.6 kg N/(ha·yr),and bulk DIN deposition ranges from 4.1 kg N/(ha·yr)to 25.4 kg N/(ha·yr),with an average of 9.8 kg N/(ha·yr).NH4+-N is the dominant form of DIN deposition at most sampling sites.Additionally,the spatial variation of DIN deposition is controlled mainly by precipitation.Moreover,in the northern part of the NSTEC,bulk DIN deposition is 17%higher than throughfall DIN deposition,whereas the trend is opposite in the southern part of the NSTEC.The results demonstrate that DIN deposition would likely threaten the forest ecosystems along the NSTEC,compared with the critical loads(CL)of N deposition,and DIN deposition in this region is mostly controlled by agricultural activities rather than industrial activities or transportation.展开更多
It is necessary to adjust reaction pH when a single kind of PO4^3- is used as phosphorus source to remove NH4^＋- N in a chemical precipitation process. However, this tedious step could be avoided in experiments that ...It is necessary to adjust reaction pH when a single kind of PO4^3- is used as phosphorus source to remove NH4^＋- N in a chemical precipitation process. However, this tedious step could be avoided in experiments that use the buffering effect of the composite phosphate and employ PO4^3- and HPO4^2- as phosphorus sources, pH was controlled by properly changing the proportion of PO4^3- to HPO4^2-. The influences of pH, material proportion and different addition modes of magnesium on NH4^＋-N removal efficiency were investigated, with NH4^3--N concentration in influent being 200 mg/L. It showed that the ratio of HPO4^2- ： PO4^3- was concerned with phosphorus and NH4^＋-N removal. Under the condition that the total amount of phosphate is definite, the removal efficiency of NH4^＋-N decreased with the enhancement of HPO4^2- concentration, while the efficiency of phosphorus increased. When increasing PO4^3- concentration, it benefited the removal of NH4^＋-N, but the remaining phosphorus was high. The results showed that NH4^＋-N concentration decreased from the initial 200 mg/L to 39.14 mg/L with the remaining PO4^3- at 5.14 mg/L if the ratio of HPO4^2- ： PO4^3- remained at 1：3.展开更多
In order to identify effects of nitrogen(N)and phosphorus(P)on soil nitrogen morphological characteristics and grain yield of oil flax,a two-factor experiment was conducted in a randomized complete block design in typ...In order to identify effects of nitrogen(N)and phosphorus(P)on soil nitrogen morphological characteristics and grain yield of oil flax,a two-factor experiment was conducted in a randomized complete block design in typical semi-arid and hilly-gully area of Loess Plateau with 3 replicates in 2013 and 2014.Two levels of N application included 150 kg/hm2(N2)and 75 kg/hm2(N1).P application included 150 kg P2 O5/hm2(P2)and 75 kg P2 O5/hm2(P1).Temporal and spatial variation of soil nitrate nitrogen(NO3-N)and ammonium nitrogen(NH4+-N)contents in 0-60 cm soil layer,and relationship between soil NO3-N accumulation(SNA)and grain yield of oil flax were analyzed.Results showed that SNA increased with evaluated N application rate in different soil layers(0-20 cm,20-40 cm and 40-60 cm).With the increased P application,SNA increased at N1 level but decreased at N2 level.SNA under N2 P1 treatment increased by 73.33%in 2013 and 74.97%in 2014 respectively,compared with control treatment(CK)at maturity stage.Grain yield of oil flax also increased by 44.27%in 2013 and56.55%in 2014,compared with CK under the same treatment.Correlation analysis showed that SNA in different soil layers were respectively positively correlated with grain yield.In conclusion,this research suggested that the optimal fertilizer application rate was 150 kg N/hm2 and 75 kg P2 O5/hm2 in the Northwest of China.展开更多
基金Under the auspices of Major State Basic Research Development Program of China(No.2010CB833504)Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA05050601)
文摘A continuous three-year observation(from May 2008 to April 2011)was conducted to characterize the spatial variation of dissolved inorganic nitrogen(DIN)deposition at eight main forest ecosystems along the north-south transect of eastern China(NSTEC).The results show that both throughfall DIN deposition and bulk DIN deposition increase from north to south along the NSTEC.Throughfall DIN deposition varies greatly from 2.7 kg N/(ha·yr)to 33.0 kg N/(ha·yr),with an average of 10.6 kg N/(ha·yr),and bulk DIN deposition ranges from 4.1 kg N/(ha·yr)to 25.4 kg N/(ha·yr),with an average of 9.8 kg N/(ha·yr).NH4+-N is the dominant form of DIN deposition at most sampling sites.Additionally,the spatial variation of DIN deposition is controlled mainly by precipitation.Moreover,in the northern part of the NSTEC,bulk DIN deposition is 17%higher than throughfall DIN deposition,whereas the trend is opposite in the southern part of the NSTEC.The results demonstrate that DIN deposition would likely threaten the forest ecosystems along the NSTEC,compared with the critical loads(CL)of N deposition,and DIN deposition in this region is mostly controlled by agricultural activities rather than industrial activities or transportation.
文摘It is necessary to adjust reaction pH when a single kind of PO4^3- is used as phosphorus source to remove NH4^＋- N in a chemical precipitation process. However, this tedious step could be avoided in experiments that use the buffering effect of the composite phosphate and employ PO4^3- and HPO4^2- as phosphorus sources, pH was controlled by properly changing the proportion of PO4^3- to HPO4^2-. The influences of pH, material proportion and different addition modes of magnesium on NH4^＋-N removal efficiency were investigated, with NH4^3--N concentration in influent being 200 mg/L. It showed that the ratio of HPO4^2- ： PO4^3- was concerned with phosphorus and NH4^＋-N removal. Under the condition that the total amount of phosphate is definite, the removal efficiency of NH4^＋-N decreased with the enhancement of HPO4^2- concentration, while the efficiency of phosphorus increased. When increasing PO4^3- concentration, it benefited the removal of NH4^＋-N, but the remaining phosphorus was high. The results showed that NH4^＋-N concentration decreased from the initial 200 mg/L to 39.14 mg/L with the remaining PO4^3- at 5.14 mg/L if the ratio of HPO4^2- ： PO4^3- remained at 1：3.
基金supported by the China Agriculture Research System of Construct Special(CARS-14-1-16)the National Natural Science Programs of China(31360315,31760363 and 31660368)the Fuxi Outstanding Talent Cultivation Plan of Gansu Agriculture University(Gaufx-02J05)。
文摘In order to identify effects of nitrogen(N)and phosphorus(P)on soil nitrogen morphological characteristics and grain yield of oil flax,a two-factor experiment was conducted in a randomized complete block design in typical semi-arid and hilly-gully area of Loess Plateau with 3 replicates in 2013 and 2014.Two levels of N application included 150 kg/hm2(N2)and 75 kg/hm2(N1).P application included 150 kg P2 O5/hm2(P2)and 75 kg P2 O5/hm2(P1).Temporal and spatial variation of soil nitrate nitrogen(NO3-N)and ammonium nitrogen(NH4+-N)contents in 0-60 cm soil layer,and relationship between soil NO3-N accumulation(SNA)and grain yield of oil flax were analyzed.Results showed that SNA increased with evaluated N application rate in different soil layers(0-20 cm,20-40 cm and 40-60 cm).With the increased P application,SNA increased at N1 level but decreased at N2 level.SNA under N2 P1 treatment increased by 73.33%in 2013 and 74.97%in 2014 respectively,compared with control treatment(CK)at maturity stage.Grain yield of oil flax also increased by 44.27%in 2013 and56.55%in 2014,compared with CK under the same treatment.Correlation analysis showed that SNA in different soil layers were respectively positively correlated with grain yield.In conclusion,this research suggested that the optimal fertilizer application rate was 150 kg N/hm2 and 75 kg P2 O5/hm2 in the Northwest of China.
