CANCELLED - Bed Design as a Management Tool Affecting Soil Microbial Dynamics, Community Structure, and Soil Sustainability in a Dryland Cotton Production System

Background/Question/Methods

Soil temperature in dry-land cotton production systems can influence soil microflora activity and nutrient availability, and plant production. Field maintenance practices and soil temperature needs at planting could result in altered microbial dynamics as the season progresses. For conventional tilled cotton system on the Southern High Plains pitched beds are used to reduce erosion and increase temperatures at planting. However, as bed design could influence soil temperature dynamics, this study was designed to investigate the impacts of bed design on DTRsoil, microbial responses, and nutrient dynamics, determine the impacts of bed design on cotton growth, crop development, and yield and evaluate seasonal microbial responses to DTRsoil conditions. The two-bed designs that were evaluated are 1: traditional pitched beds with 40 in centers and 2: flatbeds with no-till. For each treatment six, 4-meter plots with five rows per plot were established in 2014 at the TTU farm in Lubbock, TX. These plots were sampled in 2014, 2015, 2016, and 2017. Soil samples to 15 cm depth were collected starting in May and followed monthly through November for each year. Microbial biomass carbon, enzymatic activities, FAME, and carbon usage by bacteria and fungi along with nutrient dynamics and soil moisture were evaluated.

Results/Conclusions

Bed design did impact soil temperature dynamics and moisture status, especially during the hottest and driest portions of the growing season. Pitched beds were warmer than flatbeds at both depths, and experienced a higher DTRsoil through the growing season. Subsequently, the flatbeds had the greater emergence and subsequent yields compared with pitched beds. The lower levels with reduced DTRsoil could reflect higher turn-over of the biomass or that microbial biomass carbon is insensitive a metric to evaluating bed designs. Moreover, Flat-bed design had a beneficial impact on microbial community composition due to the higher fungi abundance in comparison with the Pitched beds across the growing season. Bed design is one management tool that could be employed in cotton production systems across the SHP to ameliorate soil temperature variability and the high DTRsoil that occurs in the region. The Flatbed (no-till) performed best under dry climates and limited precipitation, with yields, often being equal to or higher than Pitched bed (tillage) practices, suggesting that it may become an important climate-change adaptation strategy for dryland region.