Enhancing Sustainability in Cotton Production through Reduced Chemical Inputs, Cover Crops, and Conservation Tillage

Enhancing Sustainability in Cotton Production through Reduced Chemical Inputs, Cover Crops, and Conservation Tillage

Summary

Cropping system practices can be used to improve economic returns and reduce environmental impacts. We are using a cotton production study to advance sustainable agriculture concepts that can be applied to other cropping systems. The system relies on cover crop selection and management to optimize conditions for beneficial insect species, reduce pesticide, fertilizer, and herbicide inputs, and uses conservation tillage to reduce labor, machine, and energy costs. These integrated practices are being evaluated for effects on availability of nutrients and water, soil C dynamics, aboveground and belowground biological diversity,predator/prey insect interactions, plant parasitic nematodes, and economic and environmental impacts. Results will be presented to producers at on-farm field days, annual meetings of the Georgia Conservation Tillage Alliance, in e-mail distributions, and on World Wide Web pages. Outreach will also include presentation of results at professional and non-professional meetings.

Objectives/Performance Targets

1. Investigate how management to enhance insect habitat affects key interactions among aboveground insects (predator/prey relationships) and changes in soil biological activity, and in soil chemical and physical characteristics.

   Educate producers about environmental and economic benefits of soil quality in sustainable agriculture systems and expand the network of area producers who provide leadership for further adoption and dissemination of information on sustainable production practices.

Accomplishments/Milestones

Cover crops were established for the first year during fall 2000 on four farms around Tifton, Ga and three farms near Bartow, Ga. Cover crop biomass was determined from all fields prior to killing the cover crops for cotton planting. Cotton planting was a little late due to the drought conditions in the state. Strip killing of the cover crops was initially difficult on a field basis but problems were worked out. Soil samples were collected prior to cotton planting. Cotton planting in rye plots near Tifton was difficult due to the large amount of biomass produced. We are evaluating alternate rye varieties for use in following years to overcome this problem. One producer was not able to plant cotton on rye prior to the end of June cutoff date, however this was not due to the amount of biomass on the field. All of the other producers worked out planting problems and eventually got good cotton stands.

During the cotton growing season soil samples were collect three times to evaluate changes in soil biota in the Blend and Rye+Blend sites of the Ponder, Thompson, and Branch fields. The sample dates represent 1) end of first cover crop season in May, 2) middle of first cotton season in August and, 3) end of first cotton season in November. The samples collected in May occurred at a time when the cover crops appeared to be drying/dying out and the soil was very dry from drought. Around 30% of the May samples are of poor quality due to the extremely dry soil. Organisms too small to identify with our current microscope will be identified in a cooperating lab. Total abundance counts of Insect larvae/nymphs, Collembola, Oribatida, and Mesostigmata have been determined.

Evaluation of soil C and microbial biomass will be conducted on samples this winter.

Beneficial and pest insect numbers were determined weekly on the fields. Identification of insects is ongoing and population dynamics will be evaluated during the winter. Results from the summer observations indicate greater beneficial populations with the presence of crimson clover. The differences between the rye and rye plus legumes are limited most likely due to the limited amount of legume biomass produced. We have adjusted the planting pattern for the fall cover crops to increase the amount of legumes in the rye plus legume blend.

Large populations of Meloidogyne incognita were found in several of the fields. Because of the large plot size (a farm), it is impossible to determine whether the nematode densities are a result of winter cover crop, cropping history, soil texture, etc. Based on analysis of variance, there was no effect of cover crop on densities of M. incognita (P = 0.165). The University of Georgia Cooperative Extension Service recommends rotation with a non-host (e.g., peanut) or use of a nematicide when fall populations of this nematode exceed 150 juveniles/150 cm3. Several of the fields have damaging or potentially damaging populations of M. incognita. Application of Telone II, a fumigant nematicide, is recommended for some fields but should not affect aboveground beneficial insects.

Cover crops were planted in the fall 2001 for the upcoming year.

A two year evaluation of cover crops for beneficial insect habitat was initiated at the Tifton, Fort Valley and Watkinsville locations in the fall of 2001. Additional materials not used in the on-farm study are being evaluated for possible improvements. We are also evaluating some semi-dwarf lines of rye as potential alternatives to the currently used tall varieties of rye.

We are in the process of planning two field day events, one in Tifton and one in Bartow. We have been invited to present the preliminary results of the study at the upcoming Georgia Conservation Tillage Alliance meeting in February. We are also planning on presenting posters at the Southern Conservation Tillage Conference for Sustainable Agriculture to be held in Auburn, summer 2002.

We will continue the project through the cotton growing season of 2003. Field studies of soil and insect components will continue through that time. Alternative cover crop mixtures will be suggested in the final year of the study. We will continue to work with the current producers and present information at field days and grower meetings.

Impacts and Contributions/Outcomes

Impacts to date are limited because this is the first year of the project. However, one producer was so impressed with the effectiveness of the crimson clover cover crop and the good reseeding ability of the crop that he has planted his remaining cotton production acres to this cover crop. We hope to have a similar impact on other producers participating in the project and on the producers that attend the field day activities. We believe that a major impact of the work will be a reduction in the amount of pesticide applied to cotton acreage using the combinations of cover crops evaluated in this project. We also hope to see an increase in cover crop use which can help to improve soil productivity and reduce erosion.

Collaborators: