Crop Management for the Greater Utilization of Symbiotically Fixed Nitrogen

Two field studies were conducted at Urbana, Illinois, to evaluate different crop management systems to increase the utilization of symbiotically fixed nitrogen. The first 3-year study of simulated aerial interseeding of forage legumes, alfalfa, red clover, and sweetclover into standing soybeans was undertaken to examine the potential nitrogen contribution from forage legumes under interseeding competition. Results indicated that light and moisture were the most limiting environmental factors. Early seeding dates (late July and early August), in maturity group II and III soybeans were not acceptable because growth was restricted by low light intensities beneath the soybean canopy, high moisture conditions under the canopy which led to increased seedling diseases, and low moisture conditions which limited germination and early seedling development. It was determined that suitable forage legume stands could be obtained by the simulated aerial seeding techniques used but growth potential of the interseeded legume was limited by early frost and cool wet springs which delay soybean and corn planting. Vigorous legume growth in the spring may result in poor seedling emergence in the following crops under moisture stress conditions. The nitrogen contributions from the interseeded legumes ranged from 20-50 kg N/ha in the above-ground portion of the forage legumes with a potential of 150-190 kg N/ha obtained from monocultures of the same legumes without competition from soybeans.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Agronomy

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Ebelhar, M. Wayne

• Agriculture, Agronomy

Language dc:language

eng

Identifier

(UMI)AAI8114414

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/68470