Weed competition and economics are two common barriers to Iowa farmers' investing in tree plantings. This project examined seven weed control strategies and investigated productivity of small grain/forage combinations raised with trees in an effort to suggest management options that would encourage tree planting in the state.

Iowa has over 700 communities that generate municipal biosolids by various treatment means. These biosolids contain valuable nutrients. In this study, municipal biosolids are applied to trees, perennial grasses, and corn/soybean crops in an alley cropping (repeated tree strips combined with crops) system. The goal is to produce economical quantities of biomass and grains with reduced use of fossil fuel-based fertilizers and minimal environmental impacts.

According to the National Christmas Tree Growers Association, Christmas tree production has expanded greatly in the last five years. More than 35.4 million trees were sold in the United States in 1987, a 25.5% increase over the previous year. Even so, nationwide the industry is beginning to suffer from overexpansion, especially in the retail lot markets. Small choose-and-cut operations are still doing well, however, and in most localities, there is a shortage of this type of tree-purchasing option.

Shelterbelts have the potential to influence growth and yield from various cropping systems. On-farm tests were conducted to determine how shelterbelts interacted with corn, corn/soybean, and strip intercropping.

A tree shelterbeit comprised of four rows of hybrid poplars was established near Ogden, Iowa in 1992 to evaluate shelterbeit characteristics and impacts on soil water content and crop growth andyieid. Major emphasis was on testing crops of corn and soybeans. The first three years saw little effects from the shelterbeit, and data from these years will be used to develop a baseline for future measurements. In the fourth and fifth years, corn yield patterns suggested that the shelterbeit increases yields in the zone leeward from the shelterbeit. Soybeans have not shown a response to the presence of the shelterbeit.

The midwestern landscape, which formerly consisted of prairies, wetlands, and forests, is now primarily devoted to agricultural purposes. Unfortunately, the resulting large-scale agricultural production has also produced nonpoint source (NPS) pollution of water, alteration of waterways, and disruption of wildlife habitat. NPS pollution, whether by sediment, fertilizers, or pesticides, is a problem nationwide. The agricultural community has addressed this problem by increasing soil conservation efforts and improving chemical application practices. One Best Management Practice (BMP) is the use of riparian (streamside) vegetative filter strips on watersheds prone to such pollution. Most such filter strips to date consist primarily of cool-season grasses.

Yield data for corn (eight years) and soybeans (six years) were collected and analyzed to determine the impacts of a hybrid poplar shelterbelt on crop production on a central Iowa farm.

Most of the nation's productive forests are in nonindustrial, private ownership. To meet projected demands, timber harvests will need to increase on these lands. Iowa, which has 0.61 million hectares (ha) or approximately 1.5 million acres of commercial forestland, could benefit from capitalizing on this demand. However, the state's timber resource has been generally under-utilized. For example, Iowans have not harvested poletimber and low-grade sawlog materials from their woodlots because the market for such products has been lacking. Killing such trees to make room for better quality material involves costs that do not immediately increase net returns; thus, incentive to manage these woodlands has not been high.