Accumulation Laws of Nitrogen and Phosphorus in Wetland Plants

To study the accumulation regularity of nitrogen and phosphorus in typical constructive plants in coastal wetland,samples of Suaeda glauca(Bunge) Bunge,Phragmites austrahs and Tamarix chinensis Lour,were taken from the Yellow River Delta National Coast Wetland Nature Reserve,nitrogen and phosphorus content in plants was measured and analyzed.The results showed that ① nitrogen and phosphorus content in different wetland plants is correlated;② different species in the same place and the same species in different spaces show different accumulation regularity of nitrogen and phosphorus;③ nitrogen and phosphorus content in plants is closely related to nitrogen and phosphorus content in the habitat;④ nitrogen content in T.chinensis Lour,is the highest,the mean is 11.63 g/kg,and phosphorus content in S glauca(Bunge) Bunge is the highest,the mean is 1.38 g/kg;⑤ nitrogen content in the 3 species:T.chinensis Lour.> S.glauca(Bunge) Bunge > P.australis;⑥ nitrogen content in aboveground parts of all plants is significantly higher than that in underground parts,and phosphorus content in aboveground parts of all plants except S.glauca(Bunge) Bunge is significantly higher than that in underground parts;⑦ nitrogen content in the 3 species in the study area is significantly higher than phosphorus content in these species.

Effect of Inoculation Rhizobium and Response of Soybean-Rhizobium System to Insoluble Phosphate

In order to produce efficiently symbiotic system in acid soils which could be used for the recovery of insoluble phosphate soil and improvement of the fertility, etc., host range of Rhizobium was isolated from the root nodules of wild and cultivated soybean varieties growing in south China, evaluated the effects of Rhizobium on enhance nitrogen fixing activities, phosphorus(P), nitrogen(N) uptakes, growth and yield of soybean under pot and field conditions. The results showed that combined Rhizobium inoculation was more effective than individual Rhizobium inoculation. The combined Rhizobium of CW54 strains had the highest effect, nodule number, nodule weight and nodule nitrogenase activity were markedly stimulated as compared to those of the control U110, respectively. The nitrogen contents in the plants treated with CW54 strains were significantly increased by 43.2% as compared to those of the control U110 in Al-P soil, but statistical significance was not observed in Fe-P soil. By contrast, inoculation with CW54 significantly enhanced phosphorus uptake of plant in Fe-P soil than that in Al-P soil. The effects of inoculation of CW54 strains in a field condition were similar to those of in a pot condition. The total biomass and yield in the plants treated with CW54 strains were significantly increased by 86.4% and 51.4% as compared to those of the control at the time of soybean podding in a field condition, respectively. These results suggested that inoculation Rhizobium was beneficial for soybean nutrient uptake, growth and yield under insoluble phosphate soil conditions.

Effect of arbuscular mycorrhiza on the growth of Camptotheca acuminata seedlings

Camptotheca acuminata seeds were sown in sterilized sands in the greenhouse in February of 2005. After 90-day growth, seedlings were inoculated with three species of arbuscular mycorrhizal fungi （AMF）, Acaulospora mellea, Glomus diaphanum and Sclerocystis sinuosa.. The height, biomass, and absorptions of nitrogen and phosphorus of C. acuminata seedlings inoculated with AMF were investigated. The results showed that the formation of AM promoted the height growth and biomass accumulation of seedlings significantly and improved the absorption of phosphorus in seedlings. The height and biomass of mycorrhizal seedlings were 1.2 and 1.6 times higher than those of the non-mycorrhizal seedlings. The absorption of nitrogen was less influenced by the formation of AM. The nitrogen content in mycorrhizal seedling was equal to that of non-mycorrhizal seedlings. Compared with non-mycorrhizal seedlings, the nitrogen content of mycorrhizal seedlings inoculated with A. mellea changed considerably in the root, stem and leaves. The difference in nitrogen content was not significant between mycorrhizal seedlings inoculated with G. diaphanum and S. sinuosa. The AM formation stimulated the absorption of phosphorus, especially in roots, and also changed the allocation of nitrogen and phosphorus in different organs of seedlings. Compared with non-mycorrhizal seedlings, the ratio of nitrogen and phosphorus in mycorrhizal roots increased, but reduced in stem and leaves.

Analysis of Soil Acidification Trend on the South Bank of Hongze Lake during Recent 30 Years

Based on soil monitoring data in nine sites of Jinhu, Xuyi and Hongze counties on the south bank of Hongze Lake from 1982 to 2013, changes in soil p H, total nitrogen（TN） content, available phosphorus content, organic matter（OM）content and cation exchange capacity（CEC） were analyzed. The results show that due to excessive application of chemical fertilizer in soil on the south bank of Hongze Lake, soil p H reduced by about 2 on average, while TN content and available phosphorus content in soil increased by more than one time and 2-5 times respectively. Soil acidification caused by agricultural production was very serious. In addition, low soil p H resulted in serious loss of soil cation, so that soil CEC in2013 accounted for less than 50% of that in 1982 and affected mineral nutrient metabolism of crops. Therefore, application of calcium, potassium and trace-element fertilizer should be paid more attention to during agricultural production in future.