| Poultry production in China is becoming increasingly concentrated, both at the farm and regional level. Currently, a growing problem associates with intensive poultry production is the utilization of the large amounts of poultry manure produced. Poultry manure as well as its effects on the urban development and environmental pollution has become the primary organic sources in agricultural sustainability. Nitrogen and phosphorus loss in runoff from poultry manure has been identified as important contributor to nonpoint-source pollution. Properly management practices of poultry manure are crucial to the development of agricultural sustainability. But in areas of intensive poultry production, large amounts of poultry manure are often applied as fertilizer to local agricultural land. To assess the agronomic and water quality implications of poultry manure applications, we quantified the properties variation of soil basic nutrient after poultry manure long-time applied by intensive investigation in Hai'an county, Jiangsu Province. After this basic data obtained, field experiments were conducted to elucidate effects of poultry manure on the dynamic characteristics of nitrogen (N) and phosphorus (P) and its potential environmental impacts in paddy soils. The objectives of this dissertation was to determine the accumulation and transfer regulation of N and P released from poultry manure after it applied in paddy fields. The results indicated as follows.1. Compared with chemical fertilized soil, there were significant increase of soil organic carbon and basic soil physical properties, including increase of soil bulk density and decrease of soil porosity, and the providing capacities of soil nitrogen, phosphorus and potassium were also improved by long-term poultry manure application.2. Long-term poultry manure application could not only enhance the content of soil total nitrogen, hydrolysis-N and nitrate-N in cultivated horizon, but also change the distribution status of these nutrient in profile soil. The distrubition characteristics of N tended to decrease in soil profile, howere, Nitrate-N accumulation under organic management practices were always higher than that under chemiacl fertilizer managed, and there was an obvious tendency of nitrogen movement downward to depth soil profile by manure application.3. The level of P were increased significantly after long-term poultry manure injected into soil. The content of available-P in cultivated soil with manure practices varied from 75.5 mg/kg to 1 OOmg/kg. The loss of P from fields recieving surface applications of poultry manure influenced surface water quality. There was high risk to stimulate eutrophication.4. The content of soil dissolved organic carbon (DOC) and nitrogen (DON) were increased significantly under chicken manure management practice, and the percentage of DOC/SOC, DON/TN were higher than under chemical fertilizer practice. Correlation analysis indicated that there was significantly positive relationship between DOC and DON in both different fertilization and soil layers. The same as the content of DOC and DON in the whole soil profile with soil nutrient.5. The concentration of Nitrate-N (N03*-N), Ammonium-N (NHZ-N) in surface water from rice fields increased sharply after chicken manure application initially. Especially, the concentration of NHU+-N enhanced significantly when urea applied to fields and it reached the highest with maximum value of 42.6mgL'1 in 2 or 3 days. However, the concentration of N03"-N was lower than NH4+-N and the time reached peak value was later 2 days than NH/-N. Both of them decreased and tended to stability as one week time passed.6. The dynamic variation of N concentration in percolate water were affected obviously by chicken manure. The concentration of NlV-N varied from 0.27 mg-L"1 to 6.49 mg-L'1, and then reached the peak value after 7 days. The concentration of NO3*-N in percolate water increased with the rate of chicken manure and gradually cumulated at soil profile. Nitrogen was leached away mainly in the form of NO3*-N and the maximum leaching loss was 9.44 mg-L"1 in rice field. It created the potential for transport of NO3*-N to groundwater lead to pollution if chicken manure applied amount exceeding 30 t-hm*2.7. In addition, the concentration of total phosphorus (TP) in surface water increased significantly with the rate of chicken manure application. It took 2 or 3 days to increase the maximum, then the concentration of TP decreased quickly. The concentration of TP in percolate water at different soil profile with chicken manure was comparatively higher than that with chemical fertilizer treatments. The rate of P solubility and transfer in soils was accelerated by chicken manure, and the concentration of TP in percolate water were greater than the critical level associated with eutrophication in freshwater systems.;... |
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