In order to evaluate the effects of soil depth on the contents of soil organic nitrogen,organic nitrogen forms in apple-pear orchard soil profile were quantified using the method proposed by Bremner in 1965.The result...In order to evaluate the effects of soil depth on the contents of soil organic nitrogen,organic nitrogen forms in apple-pear orchard soil profile were quantified using the method proposed by Bremner in 1965.The results indicated that in addition to the amino sugar-N,all the soil organic N components within the same soil layer in wasteland were more than those in apple-pear orchard soil;with the layer depth increasing,the contents of different organic nitrogen forms in apple-pear orchard soil and wasteland were decreased;and the proportion of each organic N component within total hydrolysable N was different,and the percentages of ammonia N and amino acid-N components within total hydrolysable N were higher,especially the percentage of ammonia N components within total hydrolysable N was the highest.展开更多
Ecological stoichiometry of nitrogen and phosphorus is an important indicator to characterize the nitrogen and phosphorus trophic status in aquatic ecosystems. The study of the spatio-temporal patterns of nitrogen and...Ecological stoichiometry of nitrogen and phosphorus is an important indicator to characterize the nitrogen and phosphorus trophic status in aquatic ecosystems. The study of the spatio-temporal patterns of nitrogen and phosphorus stoichiometry is beneficial to the nitrogen and phosphorus pollution management in pond ecosystems. In this study, 18 groups (36 in total) of typical cascade ponds were selected as long-term observations to investigate the spatial distribution patterns of nitrogen and phosphorus component ratios (ratio of total nitrogen to phosphorus: TN:TP, ratio of dissolved nitrogen to phosphorus: TDN:TDP, ratio of particulate nitrogen to phosphorus: PN:PP) in water bodies in the tropical agricultural watershed of Jinjing. The results showed that the average values of TN:TP and TDN:TDP in the upstream ponds were 26.4 and 53.4, respectively, and were more than those in the downstream (22.95 and 48.1, respectively). In contrast, the PN:PP (13.78) in the upstream was significantly lower than that of the downstream (30.39). Furthermore, the factors of rainfall, agricultural land use and fish farming influenced the spatio-temporal variability of the N:P ratios. The ratios of TN:TP and TDN:TDP were higher in the wet season and lower in the dry season. Agricultural land use and fish farming reduced the ratios of the above three nitrogen and phosphorus components in cascade ponds in the study area. Our results show that strengthening agricultural land pollution control and aquaculture management could help to improve water quality of pond ecosystems in the study area.展开更多
It is of great significance to explore the effects of different tillage practices on total nitrogen and its components in rice-wheat rotation farmland.The experiment was carried out in Jiangyan County,Jiangsu Province...It is of great significance to explore the effects of different tillage practices on total nitrogen and its components in rice-wheat rotation farmland.The experiment was carried out in Jiangyan County,Jiangsu Province of China,and a total of four treatments were set up:minimum tillage(MT),rotary tillage(RT),conventional tillage(CT),and conventional tillage without straw retention(CT0).The total nitrogen(TN),light fraction nitrogen(LFN),heavy fraction nitrogen(HFN),particulate nitrogen(PN),and mineral-associated nitrogen(MN)in 0-20 cm soil were determined.The results show that MT increased TN concentration by2.26%-27.57%compared with the other treatments in 0-5 cm soil,but it lost this advantage in 5-10 cm and 10-20 cm soil.MT altered the concentration of LFN by 6.03%-95.86%,of HFN by 1.68%-20.75%,of PN by 12.58%-96.83%,and of MN by−1.73%-9.83%as compared to RT,CT,and CT0 in 0-5 cm soil,respectively.With the deepened of soil depth,the concentration of TN,LFN,HFN,PN,and MN decreased quickly in MT,which was lower than that in RT and CT at 10-20 cm soil depth.Straw return increased the concentration of TN and its components in 0-20 cm soil.The concentration of TN was extremely significantly positively correlated with that of LFN,HFN,PN,and MN(p<0.01).The variation of TN was significantly positively correlated with that of LFN,HFN,PN,and MN(p<0.01),and LFN showed the highest sensitivity to tillage practice.In general,minimum tillage combined with straw retention increased the concentration of soil TN and its components in topsoil.LFN was the best indicator to indicate the change in soil total nitrogen affected by tillage practice.展开更多
文摘In order to evaluate the effects of soil depth on the contents of soil organic nitrogen,organic nitrogen forms in apple-pear orchard soil profile were quantified using the method proposed by Bremner in 1965.The results indicated that in addition to the amino sugar-N,all the soil organic N components within the same soil layer in wasteland were more than those in apple-pear orchard soil;with the layer depth increasing,the contents of different organic nitrogen forms in apple-pear orchard soil and wasteland were decreased;and the proportion of each organic N component within total hydrolysable N was different,and the percentages of ammonia N and amino acid-N components within total hydrolysable N were higher,especially the percentage of ammonia N components within total hydrolysable N was the highest.
文摘Ecological stoichiometry of nitrogen and phosphorus is an important indicator to characterize the nitrogen and phosphorus trophic status in aquatic ecosystems. The study of the spatio-temporal patterns of nitrogen and phosphorus stoichiometry is beneficial to the nitrogen and phosphorus pollution management in pond ecosystems. In this study, 18 groups (36 in total) of typical cascade ponds were selected as long-term observations to investigate the spatial distribution patterns of nitrogen and phosphorus component ratios (ratio of total nitrogen to phosphorus: TN:TP, ratio of dissolved nitrogen to phosphorus: TDN:TDP, ratio of particulate nitrogen to phosphorus: PN:PP) in water bodies in the tropical agricultural watershed of Jinjing. The results showed that the average values of TN:TP and TDN:TDP in the upstream ponds were 26.4 and 53.4, respectively, and were more than those in the downstream (22.95 and 48.1, respectively). In contrast, the PN:PP (13.78) in the upstream was significantly lower than that of the downstream (30.39). Furthermore, the factors of rainfall, agricultural land use and fish farming influenced the spatio-temporal variability of the N:P ratios. The ratios of TN:TP and TDN:TDP were higher in the wet season and lower in the dry season. Agricultural land use and fish farming reduced the ratios of the above three nitrogen and phosphorus components in cascade ponds in the study area. Our results show that strengthening agricultural land pollution control and aquaculture management could help to improve water quality of pond ecosystems in the study area.
基金This study was partially supported by A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),the National Key R&D Program of China(Grant No.2018YFD0200500)the Special Technology Innovation Fund of Carbon Peak and Carbon Neutrality in Jiangsu Province(BE2022312)+1 种基金the Science and Technology Innovation Project of Chinese Academy of Agricultural Sciences(Agricultural Academy Office(2014)No.216)the Fundamental Research Funds for the Central Public Research Institutes(Grant No.S202010-02).
文摘It is of great significance to explore the effects of different tillage practices on total nitrogen and its components in rice-wheat rotation farmland.The experiment was carried out in Jiangyan County,Jiangsu Province of China,and a total of four treatments were set up:minimum tillage(MT),rotary tillage(RT),conventional tillage(CT),and conventional tillage without straw retention(CT0).The total nitrogen(TN),light fraction nitrogen(LFN),heavy fraction nitrogen(HFN),particulate nitrogen(PN),and mineral-associated nitrogen(MN)in 0-20 cm soil were determined.The results show that MT increased TN concentration by2.26%-27.57%compared with the other treatments in 0-5 cm soil,but it lost this advantage in 5-10 cm and 10-20 cm soil.MT altered the concentration of LFN by 6.03%-95.86%,of HFN by 1.68%-20.75%,of PN by 12.58%-96.83%,and of MN by−1.73%-9.83%as compared to RT,CT,and CT0 in 0-5 cm soil,respectively.With the deepened of soil depth,the concentration of TN,LFN,HFN,PN,and MN decreased quickly in MT,which was lower than that in RT and CT at 10-20 cm soil depth.Straw return increased the concentration of TN and its components in 0-20 cm soil.The concentration of TN was extremely significantly positively correlated with that of LFN,HFN,PN,and MN(p<0.01).The variation of TN was significantly positively correlated with that of LFN,HFN,PN,and MN(p<0.01),and LFN showed the highest sensitivity to tillage practice.In general,minimum tillage combined with straw retention increased the concentration of soil TN and its components in topsoil.LFN was the best indicator to indicate the change in soil total nitrogen affected by tillage practice.