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【Objective】Based on the backgroud of lacking effect of organic fertilizers on eutrophication,characteristics of nitrogen losses with organic fertilizers application on purple soil farmland was studied. 【Method】According to the local agricultural habits,swine manure(SM),oil cake(OC),biogas slurry(BS) and commercial organic fertilizer(OF) were selected to compare their N losses by leaching experiment,setting chemical fertilizer treatment as control and no fertilizer treatment as blank. 【Result】(i) Under the conditions in this paper,experimented organic fertilizers can cause nitrogen leaching losses in purple soil farmland,and the loss amount of organic fertilizers(such as BS and OF) are above 30 % higher than chemical fertilizer in a certain condition,the differences between them are significant(P < 0. 05);(ii) The regression coefficients of rainfall intensity and fertilizing amount have significantly positive relation with leaching TN concentration,and the effect of fertilizing amount on nitrogen leaching loss is more important than that of rainfall intensity;(iii) Under the simulating leaching condition,dissolved nitrogen is the main forms in leaching loss,it has occupied 65. 17%-99. 07 % of total nitrogen,which may be related to the nitrogen speciation in organic fertilizer and chemical fertilizer.【Conclusion】Organic fertilizers can cause nitrogen leaching losses in purple soil farmland,and they should be reasonably applied in agriculture. [ABSTRACT FROM AUTHOR]

Alocasia macrorrhiza as used to study the effect of short time wet-dry alternation on its chlorophyll fluorescence parameters. The results showed that short time drought stress did not have obvious effects on plants chlorophyll fluorescence parameter for the first time, but the effect of short time flooding stress was significance. Under the first time flooding stress, the original fluorescence (F0) values of treat A and B were lower than that of the first time drought stress. The maximum fluorescence (Fm), efficiency of primary conversion of light energy of PS II ( Fv/Fm) and photochemical quenching coefficient (qP) obviously increased, especially, treat B significantly increased (P<0.05 ). F0 and Fm of treat C, D and E significantly increased (P <0.05 ), and their Fv/Fm, qP and qN significantly decreased (P <0.05). The results also showed that after the second drought stress, F0 and Fmof treat A and B ascended slightly, their Fv/Fm, qP and qN descended slightly, while F0 of treat C, D and E descended, their Fm, Fv/Fm, / and qN obviously increased with the increasing of flooding depth. It presented that rehydration at low water level in time, especially 1/4 drowned could improve the photosynthesis of Alocasia macrorrhiza, but high water level had stress effect and depressed the growth of plant. So, reducing flooding water level in time could relieve the stress effect and improve plant growth, which was better for deep water stressing plants. [ABSTRACT FROM AUTHOR]

The effects of lead and phosphorus interaction on the antioxidant system and MDA content of Acorus tatarinowii were studied in this paper. The experimental results showed that with the increase of phosphorus concentration, plants SOD, POD and CAT activities increased first and then decreased at the same concentration of lead. SOD, POD, CAT activities were lower at low lead concentration( 1 mmol / L), and increased with lead concentration increased, but decreased at high concentration of phosphorus( 0.5 mmol / L). MDA contents of leaves had opposite changes. Multiple linear regression analysis showed that lead concentration had positive correlation with POD activity, and had negative correlation with CAT activity. Phosphorus concentration was positively correlated with POD activity, and negatively correlated with CAT activity. Setting lead and phosphorus stress concentrations as independent variables X1 and X2, POD activity and CAT activity as dependent variables Y1 and Y2, the regression equations were Y1= 0.230X1- 0.1195X2+ 27. 674, Y2=- 24.888X1+ 6.720X2+ 862.417. Therefore, suitable phosphorus concentration (0.1-0.5 mmol/L) would reduce the activity of high concentration lead, which was good for the growth of Acorus tatarinowii. [ABSTRACT FROM AUTHOR]

The inter space of shale hollow bricks was utilized to enhance the internal oxygen supply capacity of wetland system, so that it could enhance the purification of wetland system. The experimental result indicated that dissolved oxygen (DO) contents and phosphorus removal rates of clay layer and fly ash layer in self-aeration wetland system (system A) were higher than those of artificial enhanced oxygen wetland system (system B), which was opposed in gravel layer. Phosphorus content in waste water treated by system A was slightly lower than that of system B. It presents that the self-aeration wetland system had strong oxygen supply capacity, its internal oxygen supply level and phosphorus purification could rival self-aeration wetland system. [ABSTRACT FROM AUTHOR]