Nitrogen dynamics of cover crops with sorghum for increased sustainability

Nitrogen dynamics of cover crops with sorghum for increased sustainability

Summary

A comparison of multiple winter rotational crops with summer sorghum under high and low nitrogen fertility was continued in North Florida. Winter crop rotations planted in Fall 2013 were harvested in May for yield, and analyzed for tissue nitrogen. Sorghum was planted in May and harvested in September and October, 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 through October, 2014. One undergraduate student was trained in field methods related to resin measurements, and on the benefits and establishment procedures for winter rotation crops in North Florida. A pot study comparing clover inoculums in support of field work was also harvested. Data from the pot project showed that inoculum selection significantly affected clover dry matter yields and nitrogen fixation.

Objectives/Performance Targets

1. 1. Ascertain yields and tissue nitrogen concentrations of sorghum grown under high and low fertility in rotation with winter cover crops.

2. 2. Monitor soil nitrogen pools and organic matter content, and quantify monthly availability of nitrogen in the rooting zone of sorghum and winter cover crops, and correlate with crop yields and tissue nitrogen concentrations.

Accomplishments/Milestones

1. 1. Sorghum was planted in May, 2014 and harvested in fall.

1. 1. Winter rotational crops planted in 2013 were harvested.

1. 1. Winter rotational crops were planted in fall, 2014.

1. 1. Sorghum and winter rotations from 2013 were analyzed for nitrogen.

1. 1. Collection of soil available nitrate data continued until the end of the second year of sorghum, October 2014.

1. 1. A pot study to investigate potential variances in fixed nitrogen by clover as an effect of inoculums and application method in support of field objectives was harvested and the data analyzed

1. 1. Plots were shown to and experimental design discussed with company representatives and potential producers on multiple occasions, including individual site visits and farm field days. Results from 2013 were presented in an oral presentation at the ASA-CSSA-SSSA Annual International Meeting in Long Beach, CA.

Impacts and Contributions/Outcomes

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

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

1. 1. 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.

1. 1. Trained four undergraduate students on planting, managing, harvesting, and data collection from winter cover crops.

This research will demonstrate the feasibility and potential issues associated with certain rotational cropping systems in the Southeast.

Collaborators: