Rome: FAO, 2003. — 88 pp. — (FAO Fertilizer and Plant Nutrition Bulletin 14).
ISBN 92-5-105038-4.Nutrient-balance assessments are valuable tools for delineating the consequences of farming on soil fertility. Various approaches and methods for different situations have been used. This bulletin presents a state-of-the-art overview of nutrient-balance studies. It brings out the evolution of the approaches and methods, provides for comparisons among them, features the improvements made and highlights remaining issues. This analysis will be useful in further development of the assessment methodologies as reliable tools for devising time-scale soil fertility management interventions.C o n t e n t s.
Introduction.
Spatial and temporal context.
System flows and estimations.
Assumptions – their validity and reliability margins.
Upscaling and its validity.
Socio-economic factors and their role in nutrient balances.
Methodologies for Assessing Soil Nutrient Balances.
Macrolevel.
Sub-Saharan Africa soil nutrient-balance study, FAO, 1983-2000.
Nutrient-balance studies in Africa, IFDC approach.
National soil surface nitrogen balances, OECD.
Soil nutrient audits for China.
Sub-Saharan Africa soil nutrient-balance study, FAO, 2003.
Mesolevel.
Soil nutrient-balance study Kisii District, Kenya.
Soil nutrient-balance study, southern Mali.
Nutrient-balance studies in India.
Sub-Saharan Africa soil nutrient-balance study, FAO, 2003.
Microlevel.
NUTMON – nutrient monitoring for tropical farming systems.
Participatory nutrient management in southern Mali.
Nutrient balances for niche management.
General Discussion.
Uncertainties.
Sampling.
Available nutrients.
Spatial data.
Upscaling.
Impact.
Conclusions and Caveats.
Macrolevel.
Mesolevel.
Microlevel.
Caveats.
Validation.
Gaps.
Usefulness for policy-makers.
Presentation of outcomes.
Specific problems for each scale level. 82
References.
