Impacts of low and high input agriculture on landscape structure and function

Document Type


Date of Original Version



The conversion from high to low input agricultural systems has been studied at the field and farm scale but analysis of the effects of conversion at the landscape or regional scale has not previously been attempted. In this paper, we apply existing historical data bases on changing inputs and changing land uses to project possible effects of conversion on productivity and environmental quality on the landscape scale. We chose two areas for the analysis of changing input effects on landscape structure and function. One area is a region defined as the southern half of the lower peninsula of Michigan (Southern Lower Michigan or SLM). The second area is a small watershed, Watershed K of the Little River Watershed, in the Gulf-Atlantic Coastal Plain of Georgia. In SLM, land use data suggest that lower input use will lower per hectare productivity, and that regional production can only be maintained by bringing marginal lands into production. The prime lands not already in crop production in SLM are mostly poorly drained or sandy soils which will require either drainage modifications or supplemental irrigation for crop production. Intensification of input use in SLM during the last 20 years has led to increases in aggregate production, but may have contributed to declining water quality in the Grand River, the major drainage of that region. On Watershed K, corn grain yield was linearly related to N fertilizer application. A hypothetical yield response curve with a yield of 1500 kg/ha of corn grain without nitrogen fertilizer was selected for use in the analysis of changing inputs. Land use data on Watershed K showed that even with no nitrogen input to corn, the aggregate production of corn could be maintained without encroachment on riparian areas which are critical to maintenance of water quality. Our analyses, which are limited to historical data on the relationships among input, yield, and environmental quality, raise many questions about the landscape scale effects of conversion from high to low input systems. Relationships between inputs and yields are poorly understood at the field scale and relationships among inputs, productivity, and environmental quality have not been established at the landscape scale. Our analyses also raise questions about the need to maintain aggregate landscape production in the light of crop surpluses and declining environmental quality. © 1987, Cambridge University Press. All rights reserved.

Publication Title, e.g., Journal

American Journal of Alternative Agriculture