Effects of chemical fertilizer nitrogen substitution by biogas slurry on yield, quality and growth charac-teristics of winter wheat

A field experiment was conducted to study the effects of different ratios of chemical fertilizer nitrogen substitution by biogas slurry on yield, growth characteristics(development progress, plant height dynamic, population dynamic and dry matter accumulation dynamic), quality and heavy metal content of winter wheat. The results showed that winter wheat yield increased significantly(P-2, 18.14% higher than the treatment with total chemical fertilizer nitrogen(Ncf). There were no significant differences between the yields of 100%Nbs and Ncf(P>0.05). The 1000-kernels weight presented a significant declining trend(PPPPP>0.05). The contents of these grain heavy metal of each treatment were lower than the maximum levels of contaminants in foods. When the ratio of chemical fertilizer nitrogen substitution by biogas slurry raised above 50%, because of the prolonged growth duration and the increased basal internode length could lead to lodge and yield reduction, and because of greater use of biogas slurry could lead to the risk of secondary pollution. Therefore, in our preliminary study, in this experiment, the optimal ratio of chemical fertilizer nitrogen substitution by biogas slurry was 50%.