Effects Of Different C/N Ratios On The Process Of Aerobic Compost And The Content Of Humus And Its Components

The large-scale livestock and poultry has produced a lot of fecal residue and waste water,not only causing the serious environment pollution,causing the spread of the diseases,and wasting the nutrient resources as well,which will endanger health of human being.The composting is the best means and method to realize the efficient utilization of fecal residue and waste water,which is of great significance for increasing the efficiency and quality of the composting for the extensive application of composting.The composting process was affected by many factors such as C/N ratio,temperature,pH and moisture et al,and among which is the C/N ratio.A compoting test was conducted with five different C/N ratios: C/N =15,20,25,30,35 to reveal the effects of C/N ratio on the composting process,total nutrient content,seed germination index,total organic carbon,ammonium nitrate nitrogen,the contents and and various components of humus.The main results are as follows:1.During the composting,the temperature of composting is three stages: the heating stage,the high temperature continuous stage and the cooling stable stage.Treatment with C/N ratio of 30 is the fastest heating and the longest duration of above60?.The ammonium nitrogen content of each treatment decreased with the composting,and at the end of the composting,the ammonium nitrogen content in the treatment of C/N=30 decreased by 24.26% and the ammonium nitrogen loss was least.The order of nitrate nitrogen in each treatment was C/N15 > C/N20 > C/N25 >C/N30 > C /N35.2.The total organic carbon(TOC)content of each C/N15~C/N35 treatment decreased with the composting.At the end of compost,the total organic carbon content was decreased by 25.93%?35.22%?43.22%?43.58%and 47.88%,respectively.The total nitrogen content was lost during the composting process,but the nitrogen loss of T3(C/N=25),T4(C/N=30)and T5(C/N=35)was significantly smaller than that of TI(C/N=15)and T2(C/N=20).At the end of composting,except for T1(C/N=15),the total nitrogen content decreased slightly,and the other treatments increased.The increase range was 5.93%,6.19%,5.08% and 16.80% respectively.The C/N ratios of each treatment were 13.4,13.4,13.2,15.0 and 15.3 at the end of composting,respectively.3.Compared with the early composting,the total nutrient content increased at the end of the composting,and the increase in T1 to T5 was 12.63%,18.41%,45.79%,35.43% and 44.64% respectively,and the maximum increase was C/N=25.4.The seed germination index(GI)increased with the increase of C/N.At the end of the composting,the indexes of GI for the treatment in T1 and T2 were 50% <GI < 80%(basic maturity).The other treatments were GI>80%(completely decomposed).5.During the composting process,the total humic acid and free humic acid of each treatment decreased.At the end of composting,the total humic acid content was T2(C/N=20),the highest was 13.32%,and T4(C/N=30)was the lowest,which was8.89%.The order of total humic acid content for each treatment was T2(C/N=20)>T3(C/N=25)>T1(C/N=15)>T5(C/N=35)> T4(C/N=30).Compared with the the early composting,the total humic acid content for each treatment reduced to2.08%,2.21%,4.35%,7.37% and 4.47% respectively,and decreased by 15.08%,14.20%,25.66%,45.32% and 29.16%.Free humic acid is the main component of total humic acid.The content of free humic acid in T1(C/N=15)to T5(C/N=35)was13.95%,13.97%,14.80%,15.99 and 14.97% to 8.21%,12.50%,12.32%,7.78% and10.62% at the end of compost,respectively.6.At the beginning of composting,the content of Hu Min acid in T1 to T5 decreased rapidly and reached its lowest point on the third day of composting.The T1 to T5 treatment decreased to 1.46%,1.52%,1.90%,2.16% and 1.82% from 1.76%,1.88%,2.25%,2.33% and 2.19% before composting,respectively.The change trend of fulvic acid was opposite to that of Hu Min acid.At the end of composting,the content of fulvic acid from T1 to T5 was 0.67%,1.06%,0.61%,0.79% and 0.93%respectively.The H/F ratio in 5 treatments increased with the fermentation process of composting,and the humification degree increased.