Bacteria to Fungi Ratio and Organic Carbon in No-till Ultisols after Applications of Corn Residues and Poultry Manure

Abstract

No-till system may greatly increase soil organic carbon (SOC), and modify soil structure and water retention properties in the plough layer. Additions of organic materials of contrasting C and N ratio in no-till system require better understanding because they could cause a shift in the bacterial to fungi ratio. We studied the effects of short-term additions of 10 t ha -1 dry corn residues (CNS10) and 10 t ha -1 poultry manure (PM10) on bacteria-fungi ratio and other properties in a no-till ultisols. Results showed that PM10 improved SOC content of soil by 49.7% while CNS10 added 14.2% of SOC to the soil. There were significant (p < 0.05) increases in total N and available P in PM10 soils. Total N ranged from 4.8 g kg -1 in the control to 8.1 g kg -1in PM10, while available P increased by 117% compared with the control. Application of 10 t ha -1 poultry manure caused a major shift in microbial community towards greater bacterial population, whereas, dry corn residues encouraged significant shift towards greater fungi population. Relationships showed highly significant positive correlation between bacteria and clay content (r = 0.714, p = 0.01), and negative correlation with sand. Result also showed that fungal population increased with increasing sand content. These results indicate that addition of 10 t ha -1 of poultry manure in a no-till management leads to significant increases in bacterial population, SOC, total N and available P. This method can therefore be recommended to farmers where reserve C and N as well as increased mineralization are needed.