Nitrogen dynamics of cover crops with sorghum for increased sustainability

Nitrogen dynamics of cover crops with sorghum for increased sustainability

Summary

A comparison of fallow, rye (Secale cereale), Camelina sativa, sugar beet (Beta vulgaris), and clover (Trifolium pratense) winter rotations with summer sorghum (Sorghum bicolor) under high and low nitrogen fertility was initiated in North Central Florida. Sorghum planted in May, 2013 was harvested, and winter rotation crops were established following sorghum harvest. Soil nitrate pools were quantified on a monthly basis with the use of soil incubated ion exchange resin bags. Two undergraduate students were trained in field methods related to resin measurements, and on the benefits and establishment procedures for winter rotation crops in North Central Florida.

Objectives/Performance Targets

Sorghum production in the Southeast has receieved increased attention recently for feed and energy, in part because it is relatively low input compared to many crops. Nevertheless, rotational crops will be critical to help enhance sustainable production of sorghum in the region. Therefore the objectives of the current project were to 1) quantify the effects of winter rotation crops on summer sorghum dry matter yield and tissue nitrogen concentration under low and optimum fertilizer N input; and 2) characterize soil N cycling, especially N mineralization, in the differing sorghum rotations under low and optimum fertilizer N input.

Accomplishments/Milestones

Accomplishments that have been completed to date addressing the objectives include

• • Sorghum was harvested in summer 2013 following 2012-2013, and yield data was analyzed and plant samples are being processed for tissue nitrogen concentrations.

• • 2013-2014 winter cover crops were established in the Fall and will be harvested in the next reporting period.

• • Monthly soil N mineralization data collection for the project began in September.

Accomplishment that are left to do include;

• • Continue collection of soil N cycling data, including mineralization data and soil N pools

• • Harvest 2013-2014 winter rotation crops and measure yields and tissue nitrogen concentrations

• • Plant 2014 sorghum and collect yield and tissue nitrogen data on the sorghum

• • Plant 2014-2015 winter rotation crops

Impacts and Contributions/Outcomes

Impacts or outcomes that have been achieved to date related to the project included:

• • Training of corporate clientele about the importance of rotation/cover crops with sorghum for sustainable sorghum production during Fall of 2013. This was achieved through field tours and discussions with their agronomists.

• • Training of two undergraduate Agronomy students about how to plant and manage winter cover crops in the region and why they are important.

Impacts or outcomes to be achieved in the future related to the project included:

• • This research will quantify available nitrogen to a summer sorghum crop following winter rotational crop production.

• • This research will address potential changes in soil properties and soil nitrogen pools as a result of winter rotational cropping in sandy soils common to the Southeast.

• • This research will benefit producers by demonstrating the need for reduced nitrogen inputs in sorghum cropping systems through the use of rotational cropping, thereby reducing grower costs and increasing sustainability.

• • It is expected that information genereated from this project will be disseminated in scientific publications and oral presentations to interested stakeholders, including growers and the academic community.

Collaborators: