Urban Dynamics: Methodology For Temporal Database Development

Patuxent River Watershed
Agricultural Land Use Change

Historical maps and records indicate that there are specific parameters guiding the selection of lands for agricultural use.

Of primary importance is the physical condition of the land. Areas of good soil quality are selected for development first, followed by areas of moderate, and then low, quality. Slope of the land is also an important condition. Low lying lands are ideal for cultivation, while areas of moderate to steep slopes tend to require more labor to work. Third, consideration must be given to the existing land use or land cover of the area. If an area of low slope and high quality soils is covered by trees or urban structures, a good deal more energy and effort must be put toward its conversion to farm land. Lands best suited for agriculture are those that are already cleared and do not have seasonal (wetlands) or permanent conditions that interfere with cultivation.

In seventeenth century Maryland, the first European settlers selected lands to farm that had previously been under cultivation by the native population. These cleared lands were typically in low lying tidewater areas with favorable soil conditions. As these lands were developed, agricultural land use followed the waterways in to the Piedmont area where good soils and low slopes prevailed.

As important as the condition of the land, it is also critical that lands developed for agriculture have appropriate access to transportation networks. Crops can be grown on a variety of land conditions, but if there is no way to transport the harvest to market, there is little agricultural value in the land. Prior to the mid-1800s farm lands were located along waterways where goods could be loaded on ships and exported for profit. After the 1850s, when railroad expansion created an alternative method for the shipment of agricultural products, interior land areas could be put under cultivation. The development of road networks in the interior allowed agricultural development to consume areas left vacant because of their distance from waterways or railroads.

The following table shows the time periods and corresponding data sets used to develop the temporal agricultural land use database.

The following graph illustrates the data sources available to determine agricultural land use in the seven counties of the Patuxent Basin. The graph highlights the differences between the land use acreages for each data set.

The type of source materials available determined the actual procedures that were used. A geographic information system (GIS) was used to assemble and integrate the data.

The following crosswalk provides an overview of the data sources and their classes that were considered in the development of the temporal agricultural database.

Census of Agriculture methods

NRI methods

GIRAS methods

CCAP methods

MRLC methods

DRG methods