Feed Safety Research And Soil Pollution - Sewage Irrigation Of Alfalfa Biomass

Alfalfa(MedicagosativaL) is an important high qualiy forage crop with ecological and economic benefits. With rapid development of animal husbandry and re-djusmtent of cropping systems in China, alalfa is receiving more and more attention. In recent years due to the shortage of water resources, the use of sewage or recycled water for alfalfa irrigation gradually developed. Sewage irrigation on the one hand can save water resources, reduce the cost of sewage treatment; On the other hand, the organic matter in sewage can promote the growth of plants. However, due to sewage also contains a variety of heavy metals and other substances, the use of sewage irrigation cause secondary pollution impact on the environment and affect the nutritional quality of alfalfa growing attention has been paid.Pot experiments were conducted to study the effects of different irrigation methods using sewage and reclaimed water on the Alfalfa’s growth, quality and soil environment. Five treatments were set up; W:Tin (wastewater irrigation), W+D:Tin (1:1mixture of sewage and groundwater irrigation), and Z:No.3Tian (reclaimed water irrigation), Z+D:4No. Tin (recycled water and groundwater1:1mixed irrigation), D:5field (groundwater irrigation), the results showed that:Sewage or reclaimed water irrigation, can increase alfalfa plant height and leaf area. Sewage groundwater mixed irrigation or recycled water and groundwater mixed irrigation of alfalfa plant height and leaf area increase the effect more obvious. Biomass accumulation of sewage irrigation of alfalfa and a good role in promoting the growth of the branches, other treatment and clean water irrigation treatment, can also play a role in the promotion, but the effect is not as sewage irrigation. Compared with groundwater irrigation, sewage or sewage and groundwater mixed irrigation of alfalfa chlorophyll synthesis have an impact, resulting in sewage irrigated alfalfa photosynthetic efficiency decreased accumulation of organic matter is bound to decline. Using reclaimed water or recycled water and groundwater mixed irrigation, photosynthetic efficiency and groundwater irrigation of alfalfa can be much the same.Mixed sewage groundwater irrigation or the mixed irrigation recycled water and groundwater are added alfalfa vivo N, P, K content; short period of sewage irrigation conducive to the absorption of Ca, with the continuous extension of the irrigation time, this advantage is obvious slowly; sewage irrigation treatments alfalfa promoting absorption of Fe, but has no such effect in the reclaimed water for irrigation; sewage and reclaimed water for irrigation, alfalfa body Cu Zn content of a substantial increase. Sewage irrigated initially promote the accumulation of crude protein, crude protein content in late sewage irrigation to reduce the concentration of crude fiber has increased. The mixed irrigation to some extent promote the accumulation of crude protein, crude fiber content while reducing; sewage for irrigation is not conducive to the accumulation of soluble sugars, soluble sugars using recycled water for irrigation or recycled mixed irrigation water and groundwater the alfalfa body can the accumulation of groundwater treatment under the same. Using reclaimed water for irrigation of pasture in accordance with the quality standard, two forage.Sewage and reclaimed water for irrigation, the alfalfa the body Pb, Cd content mixed irrigation can reduce Pb, Cd cumulative amount, but still higher than the level of groundwater irrigation. Feed hygiene in accordance with national standards (GB13078-2001), the standard value of the country Pb≤8mg/kg, Cd≤1mg/kg. Sewage irrigation with reclaimed water irrigation under excessive content of Pb, Cd did not exceed the standard. Mixed irrigation should be taken. The increase in heavy metal content in the soil can be irrigated with sewage, but due to the ability of alfalfa adsorption of heavy metals, can be attached to a lot of heavy metals in the soil. Low heavy metal content of sewage irrigated alfalfa is not interested in the irrigation area of land caused by heavy metal contamination.This study suggests that, from the quality of alfalfa and growth situation, sewage and reclaimed water for irrigation water, and mixed irrigation can reduce the adverse effects, including reclaimed water and groundwater irrigation effect is best, suitable for irrigation water; from the soil pollution situation, the processing quality of soil are not caused by two times pollution. Above all, Z+D was the most suitable irrigation method.