Vegetableles Production And Environmental Effects By Using Anaerobic Effluent From Swine Farms

Safety utilization of anaerobic effluent is important to control the pollution of wastewater from swine farms. The purpose of this study was to assess the effectiveness of irrigating treated effluent from UASB digester on rape and tomato yield and quality by using different methods ,moerover, to assess the risk of soil,water and air pollution. The results obtained were summarized as follows:l.The rape pot experiment irrigating anaerobic effluent was carried out in the greenhouse. The experiment was conducted based on: a) irrigation with 1/2 fresh water and 1/2 effluent, designated as Q1W1N0;b) irrigation with 2/3 fresh water and 1/3 effluent, designated as Q2W1N0;c) irrigation with 3/4 fresh water and 1/4 effluent and chemical fertilizer designated as Q3W1N60;d) irrigation with 4/5 fresh water and 1/5 effluent and chemical fertilizer designated as Q5W1N140;e) irrigation with fresh water and chemical fertilizer designated as QN300;f) irrigation with fresh water and none of chemical fertilizer designated as QNO. The results showed that diluted effluent irrigation increased the yield of rape, and the yield of rape were increased with increasing the percentage of effluent at the same nitrogen used level, and difference were significant(P <0.05) compared with QN300. Effulent application can achieve satisfactory rape yields, subsitituting chemical fertilizers partially or completely. In experiment,effluent irrigation can save chemical fertilizers by 53.3%,and save fresh water by 16.7% at least. Nitrogen plant uptake was effected by irrigating effluent, and uptake was increased with increasing the percentage of effluent. The results revealed variability in concentration values of heavy metalCu, Zn. The nitrate(NO₃^-) and nitrite(NO₂^-) content increased among four effluent irrigation would have negative impact on safety in vegetables production,which needed study further.2.The tomato experiment was conducted based on: irrigation with original effluent designated as M1;b) irrigation with diluting effluent by adding 50% of fresh water,designated as M2;c) intermittent irrigation with original effluent and fresh water, designated as M3;d) irrigation with fresh water, designated as M4. The experiment results showed that the yield with Ml decreased 22% and quality of tomato had different with M2-M4. Irrigation method M3 could increase Vc content of tomato;Tomato yield with irrigation M3 and M2 were similar to yield of tomato with irrigation method M4. The results revealed variability in concentration values of heavy metal, nitrate(NO₃^-) and nitrite(NO2 ⁾ among four irrigation conditions, but all the concentration values of heavy metal,nitrate(NO3⁾ and nitrite(NC>2⁾ index in tomato fruit was lower than the limits of ministry standard on safety food on fruit vegetable (NY5005-2001).3. Diluted effluent irrigation and diluted effluent irrigation by adding chemical fertilizer would enhance the soil properties, especially organic matter and total nitrogen.The concentration of plant-available N,P,K increased are easy to absorb for growth. Nitrate concentrations in the soil at 0-1 Ocm depth were higher for effluent irrigation, and more effluent irrigation more nitrate accumulation. pH of the soil was decreased by irrigating more effluent^neanwhile EC increased,especially at 0-1 Ocm depth of soil.No Cu,Zn accumulation in the soil by irrigating effluent,but to supply and be benefit for vegetable growth.4. Diluted effluent irrigation resulted in less total nitrogen leaching than fresh water irrigation adding chemical fertilizer in experiment. NC>3 — N of leaching water was majority,NH4+-N concentration were lower by l.OOmg/L. Leaching total nitrogen loss at 0.48%⁴.1% in all treatments,and leaching were closeld related to chemical fertilizer rates,with correlation coefficient,R2,of 0.9327. Total phosphate concentration of leaching water were lower by l.OOmg/L in different treatment,but diluted effluent irrigation.5.Ammonia emmisson after effluent irrigation to land were small within 48 hours^epresenting 0.34%⁰.82% of the irrigation nitrogen, even in the largest volume of effluent irrigation. Dilute effluent applied by irrigation may lead to higher N2O emmisson rates, and emission peaks appeared after 12 hours. Actual CO2 emission rates increased with irrigation dilute effluent, but there was no evidence of a proportional increase in CO2 emmission with increasing effluent application rate.