Potential of a Corn/Annual Medic Intercropping System for Weed Control, Reduced Soil Erosion and Improved Forage Production

1996 Annual Report for SW96-029

Project Type: Research and Education
Funds awarded in 1996: $95,100.00
Projected End Date: 12/31/1999
Matching Non-Federal Funds: $15,127.37
Region: Western
State: Wyoming
Principal Investigator:
James Krall
University of Wyoming

Potential of a Corn/Annual Medic Intercropping System for Weed Control, Reduced Soil Erosion and Improved Forage Production

Summary

Objectives:

1. Evaluation of the most appropriate pasture legume species for effective weed suppression when undersown in irrigated corn.
2. Determine the appropriate seeding rate and sowing time of the selected annual medic to maximize weed suppression.
3. Investigate the regenerative capabilities of the selected annual medic and its potential to compete with weeds in a continuous-corn cropping system.
4. Establish the potential for improving livestock production from grazing the corn stubble/legume pasture mix in autumn following corn harvest.

Abstract

Advantages of an inter-cropping farming system, which contains a legume species, includes reduced soil erosion, weed suppression, improved soil fertility and improved forage quality. Many of the farmers in the central high great plains of the U.S. graze corn (Zea mays L.) stalks and are looking at ways to improve this fall pasture resource. However, no information is available on inter-cropping annual legumes with irrigated corn in the region. The objective was to evaluate for the most appropriate pasture legume species, which could be used in the development of a irrigated corn and legume system. To accomplish this experiments were conducted under irrigation at three sites in year 1. Eight legume species were evaluated in corn in comparison to monoculture corn under both a weed-free and weedy condition. Corn yields were reduced by the presence of legume in some treatments while others were comparable to the check yields. Medicago lupulina L. reduced corn yields by four percent whereas Medicago truncatula Gaertn. reduced corn yields by 17 percent. Corn yields were reduced approximately 62 percent by the presence of weeds regardless of legume species. The legumes did not significantly suppress weed growth. The results indicate that a mostly weed free field will be required to maximize corn and legume production. M. lupulina appears to offer the greatest potential for intercropping with irrigated corn in the central high great plains. Based on the finding of the year 1 trial “George” (Medicago lupulina L.) and “Orion” (Medicago sphacrocarpus L.) medics were selected for further study. The objectives of year two research were to evaluate the effects of planting date and seeding rate of George and Orion medics on grain and forage yield of corn under irrigated conditions and to determine the effect of planting date and seeding rate on George and Orion forage production when intercropped with grain and silage corn under irrigated conditions. Replicated field experiments were conducted at the UW Research and Extension Center at Torrington. The results from these experiments provided further evidence that a corn-medic intercropping system may be a viable option for producers in the central high great plains.

The system worked for both silage and grain corn production. A silage production system would be more suitable if the main objective of the producer is to get good quality fall grazing for livestock. If grain corn production is the goal of the farmer then George medic is the best medic species to incorporate into the intercropping system. George medic allows for increased forage production while having the least effect on corn yields. To allow for optimal corn and medic production George medic should be planted at a seeding rate of 32 pure live seed per square foot at the time of corn planting, and bentazon should be added to a herbicide tank mixture with imazethapyr, pendimethalin, and NIS. In year three, George medic and alfalfa were evaluated for intercropping potential with corn. The objectives of the research were to evaluate the effects of these legumes on forage yield of corn under irrigated conditions and determine the yield potential as a forage when intercropped with silage corn under irrigated conditions. Replicated field experiments were conducted at the UW Extension Center at Torrington and the Chuck Jones farm near Huntley. The results from these experiments provided evidence that a corn-medic intercropping system has varied performance from year to year. The forage potential of annual medics under a corn silage system in 1998 and 1999 did not perform to a level that was anticipated indicating that further refinement of the practice is needed. The spring regenerative ability of George medic is encouraging. The year following interseeding, populations were 24 plants per square foot; two years following interseeding, seedling populations could be as high as 66 plants per square foot. The year two results are preliminary. We plan further data collection later this spring. The regeneration is three and perhaps eight times the initial interseeded seedling population.

This study provided further evidence that a corn-medic intercropping system may be a viable option for producers in southeastern Wyoming. The system has been shown to work in both silage and grain corn production. A silage production system would be more suitable if the main objective of the producer is to get good quality fall grazing for livestock. If grain corn production is the goal of the farmer then George medic is the best medic species to incorporate into the intercropping system. George medic allows for increased forage production while having the least effect on corn yields. To allow for optimal corn and medic production George medic should be planted at a seeding rate of 32 pure live seed per square foot at the time of corn planting, and bentazon should be added to the herbicide tank mixture with imazethapyr, pendimethalin, and NIS.

The final year study provided further evidence that a corn-medic intercropping system may be a viable option for producers in certain areas of central high great plains. The system can work in both silage and grain sprinkler irrigated corn production. A silage production system would be more suitable if the main objective of the producer is to get good quality fall grazing for livestock. If grain corn production is the goal of the farmer then George medic is the best medic species to incorporate into the intercropping system. George medic allows for increased forage production while having the least effect on corn yields. The spring regenerative ability of George medic is encouraging.

Potential Benefits

Medic/corn intercropping has the greatest potential to impact sprinkler-irrigated corn. It is estimated that 60 percent of the corn acreage in Wyoming is under sprinkler irrigation. In Wyoming alone, this practice could provide additional ground cover, improve the pasture resource, and improve soil quality on over 53,000 acres.

Farmer Adoption and Direct Impact

It is still too early to assess the farmer adoption. However, based on the interest expressed by producers at field days there is a strong likelihood that acreage in southeastern Wyoming may be seeded to the legumes with corn. In 1999 a farmer did cooperate on this project as previously described. The results were disappointing. However, it is believed that by altering sowing and irrigation practices medic production can be improved. If an interested farmer cooperator can be identified a field demonstration will be conducted in 2000.

Reaction from Farmers and Ranchers

Several comments during plot tours were made by farmers expressing interest in the establishment of alfalfa using the corn/legume system. Chuck Jones, now deceased, was enthusiastic and very supportive. He took it upon himself to look at broadcast seeding of medic prior to the first cultivation of corn.

Future Recommendations or New Hypotheses

Is it possible to develop a corn/medic system that is reliant upon the soil seed bank for medic establishment? If so, is a corn/medic, corn/medic, medic forage three-year rotation system sustainable?

This summary was prepared by the project coordinator for the 2000 reporting cycle.