Effect Of The Agricultural Usage Of Biogas Slurry On Maize Yield, Quality And Environmental Quality Of Soil

Biogas slurry, the liquid remnant of fully-fermented organic matters like animal dung and human sewage under anaerobic condition, not only contains nutrient elements such as N, P and K, but also is rich in humic acid, organic matter, amino acid, growth hormone, antibiotics, microelements etc. It is a rotten water-soluble active fertilizer, which is more and more wiediy applied in agriculture nowadays.Our experiment utilizes the biogas slurry made from the pig dung of the hoggery, with experimental material of maize is named No 6 Zheng hong. According to the trial design ranged by means of random blo-cking and setting treatent grads of different biogas slurry dosage, we research on the effect of biogas slurry utilized in agriculture on local maize yield, quality and environmental quality of Soil on massif area of Sichuan Province. And also this experiment researchs on the proper dosage of the biogas slurry for the maize planting and the environmental endured ability by the agricultural usage of the biogas slurry. Our maize planting experiment took place at the contracted farmland of a large-scale hoggery in Lin jiang Town, Zi yang City, Sichuan Province. The specific findings are as follows:1. Effect on maize growth and agronomic traits by the agricultural usage of the biogas slurry.In terms of the maize growth period and the agronomic traits, no big difference showed under different treatments, the biggest difference of growth period is three days. The biogas slurry can help the maize grow and each agronomic trait is good, which can bring good growth condition to the maize, especially when the biogas slurry dosage is in the range of 5000～7000kg/667m2, the biogas slurry is similar with the ordinary chemical fertilizer in promoting the maize growth.2. The best biogas slurry dosage range for promoting maize yield and quality.The biogas slurry can increase the maize yield obviously, improve the nutritional quality, raise mineral elements content and promote maize's absorption of N, P and K. Take the maize yield and quality into consideration, the biogas slurry dosage should be controlled in 5000～7000kg/667m2, when the maize yield and quality reached the summit.3. The best biogas slurry dosage range for maize heavy metal content control. The content of Cu, Zn in maize is increasing gradually with the biogas slurry dosage raising, but the largest content do not exceed the limits of Cu, Zn (Cu:10mg/kg, Zn:50mg/kg) in food, comparing the limits in Food Contamination Limit (GB2762-2005), the content of Pb, Cd, Cr, Ni, As, Hg in maize under all the biogas slurry treatments do not exceed the corresponding limits of contamination (no Hg was found in this experiment). This proves that, in this experiment, the agricultural usage of the biogas slurry will not bring heavy metal pollution of food, the miaze planting by biogas slurry meets food-sanitation standard request. Based on an overall consideration of various factors, on the part of this experiment, the heavy metal content in maize would be less than chemical fertilizer treatment when the biogas slurry dosage is in the range of 4000～5000kg/666.7m2. Comparing chemical fertilizer, using biogas slurry can obviously reduce heavy metal content of maize and improve food security to a certain degree.4. The best biogas slurry dosage range for soil fertility and soil environment quality.Comparing the soil before the maize planted, we found that the biogas slurry usage enhanced pH to a certain degree, which could prevent soil acidification. With the dosage raise, total nitrogen, available nitrogen, available kalium and organic matter in soil increase in different levels, and the content of the aforesaid elements under biogas slurry treatments are all higher than that in the chemical fertilizer treatment. The biogas slurry usage increases the mineral elements content in soil evidently and improves the physico-chemical characteristics of soil. When the biogas slurry dosage is within 4000～7000kg/666.7m, all mineral elements content in soil is relatively high. Heavy metal content in soil increases in different pitches with the raise in the biogas slurry dosage, Cr, As content in soil after the biogas slurry usage meets the national standard of ClassⅠsoil, while Pb, Cd, Ni and Hg content meets ClassⅡ. The heavy metal content in soil would be much lower when the biogas slurry dosage is in the range of 4000～6000kg/666.7m2.In terms of the soil fertility and soil environment quality, in this experiment, the biogas, slurry dosage should be controlled within 4000～6000kg/666.7m2, to achieve a good soil fertility, good edatope and high environmental performance.All in all,5000～6000kg/666.7m2 is the best range of biogas slurry dosage from the hoggery for maize planting in the purple soil in massif area of Sichuan Province, in terms of the growth period, maize yield, quality, food security, soil fertility and environmental quality of soil in this experiment.