| Biogas slurry is organic waste anaerobic fermentation products, it can be used as a source of manure instead of chemical fertilizer. As a organic fertilizer, it does not only benefit for reduce agriculture inputs, but also can be used to remission water resource tension and increase water use efficiency. And finally promote our agriculture to develop efficiently, healthy and sustainably.Present in the study,in order to study the influence the application of biogas slurry on the maize yields, maize quality and soil quality and for the purpose of verifying the appropriate quantity and year limit and in order to test Digestion capacity and carrying capacity of biogas slurry in the soil-maize system in the Calcareous purple of hilly regions under dryland rotation mode, a filed study was conducted in the research field of Baisheng Animal Husbandry Development Co., Ltd. in Yanjiang, Ziyang City, Sichuan Province by using Zhcnghong No.6(provided by Zhenghong seed Co., Ltd. of Sichuan agriculture university) as seed materials and by using fully fermented anaerobic fermentation slurry in the pig digester as biogas slurry materials. The results are as follows:1. Optimum application rate of biogas slurry for improving soil fertilizer under dryland rotation modeBiogas slurry is both a nutrient-rich organic fertilizer, and a good soil conditioner. In the long-term application of biogas slurry, soil permeability could be improved, soil fertilizer could be enhanced, and thus contributing to the yield of crops. In the present study, after a term of maize-wheat-maize rotation cultivation, soil pH was significantly optimized as well as soil TN, AN, AP, AK, OM and CEC when the quantity of biogas were kept in the range of75t/hm2-105t/hm2. The soil quality under appropriate biogas slurry treatments was much better than that of conventional fertilizer treatment.2. Optimum application rate of biogas slurry for increasing soil microbe content and enzyme activity under dryland rotation modeWhen comparing the soil microbial volume and soil enzyme activity among all the treatments, those of biogas slurry were much better than CK and conventional fertilizer treatments (#1and#2). Microbial number were highly increased under75-90t/hm2, meanwhile, soil enzyme activity maintained at optimal levels on condition of biogas slurry75-90t/hm, in this situation, soil bacteria, fungi and actinomycetes were increased and Urinary enzymes, catalase and other enzymes were in a state of relative balance, that is to say, optimum application rate of biogas slurry improved soil biological environment and the microecology.3. Appropriate application rate of biogas slurry for increasing maize yield and quantity under dryland rotation modeAmong the biogas slurry treatments, maize yields were almost increased with the increase of additional rate of biogas slurry, when biogas slurry was90t/hm2(#8), yield of maize was the highest, which emerged10434.27kg/hm and it was53.38%and8.84%higher that those of water and fertilizer treatment (#1and#2). However, yield of maize was slightly decreased under biogas slurry105t/hm2, it indicated that exceed biogas would not as well as benefit for its yield improvement.Meanwhile, nutritional quality (contents of protein content, fat, starch, total acid, soluble ash and vitamin C) of maize under the same treatments between the first and the third quarter were similar and they varied (increased first and then decreased) with the increase of biogas slurry additional rate. Similarly, the nutritional quality of maize under the biogas slurry rate ranging of75-90t/hm2was better than other treatments. This finding symbolized that it was highly related to biogas slurry application rate while not the cumulative time.4. Influence of use of biogas slurry on accumulation and translocation of heavy metals in the soil-maize system under dryland rotation modeCompared with the original soil, contents of Cd、Cr、Pb、As、Hg were unsteadily but slightly increased without exceed the national environmental permission with the biogas adding. After cultivation rotation of three terms, contents of heavy metals were increased both in soils and in maize. However, they were still maintaining clean or basic clean (about0.1for slightly pollution) under the national standard by fuzzy comprehensive evaluation, in a word, no heavy metal risks were emerged.Contents of heavy metals of all treatments were farther lower than the food limit standard value, although under the biogas slurry90t/hm2, As was detected to be the minimum limit factor, it would be37year for safe food consumption under the same treatment. However, the monitoring of heavy metals and other harmful substancein the crop should not be slacked caused by the complexity of composition of biogas slurry and combined pollution.5. Influence of soil-maize system on digestion and carrying capacity of biogas slurry under dryland rotation modeConsidering maize yields, maize quality, food safety, quality of soil fertility and soil environment, In the term of maize-wheat-maize system and under drought-drought rotation cultivation mode, maximum endurance of biogas slurry in purple soil of Sichuan hilly and mountainous areas, and the carrying capacity was in the range of135-157t/hm2, which indicated the importance of maintaining the balance of biogas slurry inputs and the environmental endurance capacity. Overall, application of biogas slurry must be deeply considered and effective control to balance food security nd environmental sustainability. |
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