| The scale expansion and intensification of planting and breeding is the trend ofagricultural development in the Hebei plain. Biogas fermentation "interface" technology isthe key link of planting and breeding, which take aquaculture wastes as raw materials.Aiming at the insecurity problems of "burn seedlings" in the biogas application inagricultural industrial park, which is raising as one large-scale planting of agriculturalindustrial park. The study is about biogas on vegetables for security and appropriateapplication, in order to provide an efficient technical support of establishing a materialcycle model which connect cultivation and breeding. The experiment was used biogas andmanure as fertilizer and irrigated at different concentrations, Do the system analysis bymeasuring the characteristics of vegetable growth, yield, quality, nutrient uptake, heavymetals of vegetables and soil. The experimental results showed that:1. Biogas can promote the growth of vegetables. The application of biogas to cowpeausing biogas slurry as fertilizer, when treated with biogas residue there was no significantdifference. Compared with the contrast，the differences is significant except T2(biogas andwater ratio of1:8) when used manure as fertilizer, there were no significant difference inother treatment. After biogas slurry was irrigated to cabbage, the yield increase by13.75%~21.72%, which was significantly. Compared with contrast (CK, water irrigation),theyield of T2was the highest, But when compared with T1(biogas and water ratio1:4), T3(biogas and water ratio1:12), the treatment difference was not significant. And thedifferences between processing were not significant compared with contrast.2. The application of biogas helps to improve the quality of vegetables. Using biogasfor irrigation, can improved the soluble sugar, soluble protein content, lower the crudefiber content in cowpea angle and Chinese cabbage. In the treatment of T1, T2, T3,soluble sugar content of cowpea angle increased by7.8%~14.4%, the soluble proteinincreased by8.3%~19.4%, the crude fiber decreased by3.6%~13.6%. The soluble sugarin cabbage increased by8.3%~13.9%, soluble protein increased by18.1%~30.3%, crudefiber decreased by12.8%~34.9%. The nitrate content of the two vegetables decreasedsignificantly,compared with862.14mg/kg that was planted by conventional fertilizationand was far below the national standards set forth in3000mg/kg. Therefore, the applicationof biogas can significantly improve the quality of vegetables, meeting the demand oftechnical requirements of pollution-free vegetable production. 3. Biogas can promote vegetable nutrient absorption and increase soil availablenutrient.In mature harvest, when used biogas residue as fertilizer, the nitrogen uptake of T1,T2and T3treatment were higher than the control, and has significant difference, but thedifference between treatments was not significant. T2processing has the highest nitrogencontent. When used manure as fertilizer, the differences between each treatment were notsignificant but T2absorb nitrogen was higher than other processing.With the increasing demand of cowpea for phosphorus and potassium, the content ofphosphorus and potassium in the plants of each treatments have reached a significant levelcompared with the control, while no significant difference between treatments, thephosphorus content of T1treatment was the highest. The absorption of potassium of T2treatment was the maximum, which was significant difference compared with the control.The NPK concentrations in each treatment after the harvest of Chinese cabbage werehigher than the control and the differences were significant. But there was no significantdifference between different treatments.The content of inorganic nitrogen in the soil after cowpea harvest show that, using theresidue as base fertilizer or manure as fertilizer, the inorganic nitrogen content of T1, T2,T3in topsoil (0-15cm) were not significantly different with the control and othertreatments. But the nitrate and ammonium nitrogen content of T1processing was thehighest. The trend of the inorganic nitrogen content in15-30cm soil was the same oftopsoil. The content of inorganic nitrogen in the soil after cabbage harvest show that, theinorganic nitrogen content in topsoil were higher than the control and the difference wassignificant, but the difference among the treatments was not significant. The inorganicnitrogen content only T1treatment was higher than the control in15-30cm soil layer andthe different was significant, but the difference among the treatments was not significant.However, the higher the slurry concentration, the higher of soil inorganic nitrogen content,indicating that slurry concentration affects the release of available nitrogen in the soil.The content of available phosphorus and potassium was consistent with the trend ofthe inorganic nitrogen. Surface soil phosphorus and potassium levels were higher than thecontrol and the difference was significant. Phosphorus and potassium content increasedwith the increasing concentrations of biogas slurry. Biogas can help increase NPK content,improve soil fertility and promote the absorption and use of available nutrients.4. The content of heavy metals in vegetable and soil all meet the national standardsThe results showed that the heavy metal content in vegetables were not exceeded andheavy metal content of the soil has met the national primary standard of soil environmentalquality. However, the Cu content in biogas exceeded the national technical regulationsprescribed amount of land in vegetables, which was related to additives in pig feed.Comprehensive test results shows that the overall effects of using biogas residue as base fertilizer and the concentrations of T2treatment to promote growth and nutrientuptake of vegetables, soil nutrient content, quality and soil quality (heavy metals) wasgood, which was in line with the technical production of pollution-free vegetablesrequirements. |
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