Balanced Fertilization along with Farmyard Manures Enhances Abundance of Microbial Groups and Their Resistance and Resilience against Heat Stress in a Semi-arid Inceptisol

Abstract

The impact of long-term (36-year) application of balanced fertilizers and farmyard manures (FYM) on the abundance of microbial groups (bacteria, fungi, actinomycetes, Pseudomonas, Azotobacter, ammonia-oxidizing bacteria) and their resistance and resilience against heat stress was investigated in a semi-arid Inceptisol at New Delhi, India. Surface soils from selected treatments [control, nitrogen (N), N and phosphorus (P), NP and potassium (K), NPK + FYM] under a maize crop were assessed immediately after sampling (0-day) and at 1, 14, 28, and 56 day(s) after heat stress (48 °C for 24 h). The heat stress significantly reduced the microbial groups by 20 to 80%. Recovery after stress was 60 to 100% within 56 days. Resistance and resilience of fungi and actinomycetes were greater than other groups of organisms. Ammonia-oxidizing bacteria (AOB) were found to be most sensitive with the lowest resistance index. Application of NPK + FYM was most effective in enhancing the resistance and resilience of soil microorganisms against heat stress.

Keywords:

• Abiotic stress
• ammonia-oxidizing bacteria
• fertilizers
• microbes
• rhizosphere

Acknowledgments

The authors are thankful to Dr. Lata for her helpful discussion and Dr. V. Verma and Dr. S. C. Kaushik for technical advice during the experiment. Sarvendra Kumar is highly grateful to IARI (ICAR), New Delhi, for awarding him a junior research fellowship and for providing facilities to carry out this investigation.