County-Level Assessment of Manure Nutrient Availability Relative to Crop Nutrient Capacity in Iowa
During the twentieth century, agricultural production strived to achieve increased food production in order to satisfy demands. This led to increased farm sizes and an operational separation of crop and livestock production. Society fears that the trend of increasing industrialization of animal agriculture has resulted in concentration of waste products associated with their production over relatively small geographic regions that are spatially segregated from crop production areas. A county level analysis of manure nutrients relative to crop nutrient capacity was conducted to assess the prevalence of these issues in Iowa. Results indicated that in general all counties had sufficient nutrient utilization capacities to value manure as a resource; however, counties in Northwest Iowa are becoming progressively more manure rich, while counties in Southwestern and Central Iowa are becoming progressively more manure poor. This separation of crop and livestock production is becoming more pronounced, indicating that nutrient (especially phosphorus) recovery systems that can concentrate manure nutrients for transport could become more important in maintaining county nutrient balances.