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Agronomy QUESTION #2111
Question 1
Integrated soil fertility management (ISFM) is distinguished from conventional fertilizer recommendations by:
  • Replacing all synthetic fertilizers with organic inputs only
  • Combining the use of improved germplasm, mineral fertilizers, and organic resources in a site-specific manner that leverages synergistic interactions — where organic matter improves the efficiency of mineral fertilizers and mineral fertilizers accelerate organic matter decomposition and nutrient release — targeting smallholder farming systems in sub-Saharan Africa and South Asia✔️
  • Using only locally available organic materials regardless of their nutrient content or crop nutrient demand
  • Applying mineral fertilizers at maximum agronomic doses to build soil fertility rapidly
Correct Answer Explanation
ISFM (Vanlauwe et al.) is based on four components: (1) use of improved varieties responsive to inputs, (2) appropriate mineral fertilizer application, (3) organic resource management, and (4) local adaptation. Key insight: organic inputs alone rarely meet crop demand, but combined with mineral fertilizers, organic matter improves fertilizer response through enhanced soil biological activity, water retention, and reduced P-fixation — achieving yield responses greater than either input alone.