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

Project Overview

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

Annual Reports

Commodities

  • Agronomic: corn, grass (misc. perennial), hay
  • Animals: sheep

Practices

  • Animal Production: feed/forage, free-range
  • Crop Production: intercropping, conservation tillage
  • Education and Training: on-farm/ranch research, participatory research
  • Natural Resources/Environment: biodiversity
  • Pest Management: cultural control, mulches - living
  • Production Systems: agroecosystems
  • Soil Management: organic matter, soil quality/health

    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 USA 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/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 mono culture 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 4% whereas Medicago truncatula Gaertn. reduced corn yields by 17%. Corn yields were reduced approximately 62% 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 USA. 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 2 research were to (i) evaluate the effects of planting date and seeding rate of ‘George’ and ‘Orion’ medics on grain and forage yield of corn under irrigated conditions, (ii) 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 University of Wyoming 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 USA. 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/ft² 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 (i) evaluate the effects of these legumes on forage yield of corn under irrigated conditions, (ii) determine the yielding potential as a forage when intercropped with silage corn under irrigated conditions. Replicated field experiments were conducted at the University of Wyoming Extension Center at Torrington, WY and the Chuck Jones farm near Huntley, WY. 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 1998-1999 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/ft², 2 years following interseeding seedling populations could be as high as 66 plants/ft². The year 2 results are preliminary. We plan further data collection later this spring. The regeneration is 3 and perhaps 8 times the initial interseeded seedling population.

    Project objectives:

    1. Evaluate 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.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.