The Agricultural and Ecological Trail
One of the most popular features of the Grimes Farm Nature Center is a walking trail with stopping places that demonstrate some of the conservation practices that help to preserve this remarkable agricultural and natural environment. Below is a map of the trail followed by brief descriptions of the features one might notice at each of the numbered stopping places. The numbered stops on the map are also "clickable."
(To get to the trail head, walk northwest from the parking area and cross the footbridge. The trail will take about 60 minutes to walk. The terrain is rather hilly and will require some moderate exertion, but it will be well worth it--there are some wonderful hilltop overlooks.)
Stops on the Trail
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1. At the end of the footbridge, turn left to begin the trail. The large field lying to the west contains about 34 acres (one acre is about the size of a football field). Crops grown in this field alternate year to year between corn and soybeans. Minimum tillage practices leave the previous year's plant residue in place, and special equipment can plant the new crop right through the old crop residue. The old plant material then serves as a mulch to help retain soil moisture and add organic matter to the soil. <<back to the map>> 2. The wooded ravine and the plantings of conifer trees adjacent to this path help create a windbreak. Trees planted on the north and west sides of farm buildings block the strong winter winds and force the air to lift over the top of the trees. This effect lowers energy costs in the buildings of the farmstead. Added benefits include beautifying the site and providing shelter for wildlife. <<back to the map>> 3. Contour Farming. If you glance up the hillside to the west, you'll see a clear example of contour farming—the practice of preparing the land, planting the crops, and cultivating the fields on a level contour around the slope of the hill. Each crop row works like a small dam to hold water on the slope. Water held even briefly has more time to soak into the soil, and the erosion of the topsoil is greatly lessened since the water can't run straight down the hillside. <<back to the map>> 4. This Dogwood Patch on the left side of the trail was planted by birds. Previously eaten seeds passed through the birds as they sat on overhead power lines and fence wires. Small birds and animals use this patch to find food or to find shelter from predators. <<back to the map>> 5. Notice how steep the slope is to the west of the trail. Special care must be taken here when planting row crops. The combination of contour and minimum tillage farming help to conserve the soil by minimizing erosion damage. A formula known as the "Universal Soil Loss Equation" helps conservationists estimate the average amount of soil loss annually. From that estimate, they can assess current soil loss conditions and plan preventive practices. Factors influencing soil loss by water are rainfall, soil type, length of the slope, steepness of the slope, ground cover, and other erosion control factors. <<back to the map>> 6. This irregular corner of the farm does not lend itself to agriculture because of its small size. A wildlife planting of conifer trees and shrubs like dogwood, ninebark, honeysuckle, and elderberry were planted to provide food and shelter for wildlife. Also look for cherry trees, gooseberry bushes, raspberry brambles, and burr oaks. This is a particularly good spot for summertime birding—for years a family of indigo buntings has nested in this tangled corner. <<back to the map>> 7. Rest Stop. Take a moment here to look back to the northeast over the route you just walked. You have gained over 90 feet in elevation from the trailhead at the footbridge. The ridge top field to your northwest is used in a crop rotation schedule. Legumes such as alfalfa and clover hay, used in rotation, help improve the condition of the soil and make it more fertile. <<back to the map>> 8. Here are a few facts to consider as you stroll out toward the hilltop:
<<back to the map>> 9. This area of the farm has steep slopes and is classified as highly erodible if farmed conventionally. The choice here was for trees, specifically walnuts interplanted with conifers. The pines are "trainer" trees that grow together. The walnut trees must grow up to reach light, thus helping to insure a straight growing trunk on the walnuts. <<back to the map>> 10. Lookout Point. From here a view
in any direction provides an opportunity to see a wide variety of land
use practices on this farm and the adjacent private areas. Cropland, forests,
pasture, a highway, a landfill, a housing area, a railroad, and a stream
are all part of this Linn Creek valley vista. <<back to the map>> 11. The Diversion Terrace starts here. It was built to slope downhill slightly to the east and direct surface water from the hillside in a controlled manner. Water that moves slowly has little power to carry soil particles away or cause erosion. Grasses planted in a waterway hold the soil but bend over gently during those times of heavy runoff. Runoff water from heavy rains does not flow evenly off a field. Water will seek the lowest level through natural depressions or channels. If a farmer plants crops through such a water course, the soil will become loose and vulnerable to erosion. Gullies can form as a result. However, if the water course is shaped and seeded to grass cover, the soil under the grass is undisturbed and cleaner water is delivered to Linn Creek. <<back to the map>> 12. Tree Farming is the management of the forest resources to select for more desirable tree species such as walnut or oak. In this area of the Linn Creek floodplain, boxelder, honeylocust, and elm have been culled. New desirable trees were interplanted. Plastic tubes placed around the trunk of these new trees helps protect them from rabbits, beaver, and deer. The tubes also force the new tree to grow tall to reach the light source above. <<back to the map>> 13. A Forest Ecosystem functions as a whole to provide wildlife habitat, hold the soil in place, and regenerate itself through seed production. Trees along a creek help to improve water quality. The leaves improve air quality because they collect dust and absorb gases during photosyhthesis. Trees also reduce noise and increase property values. <<back to the map>> 14. This area of trees is called West Park. It was planted with hybrid poplar, ash, oak, and other species in 1985. While some of these trees were damaged or killed by beaver or deer, overall the planting has done well and provides a new forest for people to enjoy. The benefits of trees are numerous and include beauty, shade, clean air, clean water, soil retention, wood, and wildlife cover. <<back to the map>> 15. The waterway ends here, but the Water Cycle Continues. Water now flows through floodplain grasses before entering Linn Creek. Linn Creek water enters the Iowa River east of Marshalltown and continues to the Mississippi River and Gulf of Mexico. At all points along the way and particularly in the oceans, water evaporates and becomes a part of the air masses that circle the earth. Rainfall returns water to the land to nourish grass, trees, crops, and other living things. <<back to the map>> 16. We hope you enjoyed walking the agricultural and ecological trail. You have seen first hand how Good Soil Stewardship preserves this basic natural resource. You have seen how minimum tillage, contour farming, waterways, forests, and wildlife areas can all work together. In the business of farming today, the knowledge required to apply the best management practices to the land is paramount. Add to this equation the cost of machinery, seed, fertilizer, and appropriate chemicals. Then add factors beyond any person's control such as wet or drought cycles. And then you know that farming is something of a gamble—the payoff is never really assured, but the promise of foods produced keeps farmers optimistic about the role they play in supporting Iowa's economy and preserving Iowa's environmental treasures. <<back to the map>> Grimes
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