2012 Annual Report
1a.Objectives (from AD-416):
Developing improved soil management and agronomic practices which are economically and environmentally sustainable. Modify existing farming systems and develop new production systems that, through use of conservation tillage and intensive cropping practices, improve profitability and reduce economic risks by enhancing carbon storage, plant available water, and soil productivity and quality.
1b.Approach (from AD-416):
A series of cooperative projects will be established between Auburn University and National Soil Dynamics Laboratory (NSDL) scientist directly related to the inhouse research project entitled "Conservation Systems Research for Improving Environmental Quality and Producer Profitability". The project will primarily support graduate student research programs. Field plots research will be established to determine the relationships between soil management practices and production management systems to improvements in soil quality such as water infiltration, aggregate stability, bulk density, soil strength, nutrient cycling, and biological activity. Improvements in these indicators will be correlated to crop yields, in order to evaluate their economic impacts as well as environmental impacts.
Over the past decade, Auburn University and USDA-ARS at Auburn, AL, have conducted a test evaluating crop productivity and landscape variability at E.V. Smith Research and Extension Center. The 20 acre site is representative of Coastal Plain landscapes and soils of the region. Initially (2001-2008), the test evaluated cotton and corn yield and associated agronomic parameter variability across the site. Due to drought conditions over several seasons, corn was replaced in the rotation by double-cropped wheat-soybean in 2009. In addition, variable Nitrogen (N) rates were superimposed on the experiment at that time. Since its inception, the experimental design has been a randomized complete block with six replications that traverse the landscape variability.
One of the underlying goals of the experiment is to more fully understand interactions among agronomic management and soil landscapes for improved precision management strategies. Management zones, the basis for precision management applications, were developed for this site using conventional precision management data and tools including field-scale electrical conductivity mapping and terrain attributes developed from digital elevation modeling analyzed within a global information system (GIS). In addition, an Order 1 Soil Survey (1:3000) was created using conventional National Cooperative Soil Survey (NCSS) standards, with individual soil delineations serving as an additional approach to zone development. Although some similarities were observed in the zones developed by these two different approaches, significant differences in the resulting zones were observed.
Over the last couple of seasons, relatively higher amounts of wheat yield variability (2009-2010) were explained by combinations of N rate and terrain attributes (40 to 72%) than cotton yield variability (27 to 56%). Both wheat (2009-2010) and cotton yields (2009-2011) were significantly different among both management zones and soil delineations, which is consistent with findings from previous years. Thus, zones developed using the conventional multivariate Geographical Information Systems (GIS) approach or a detailed soil survey could effectively serve as a basis for precision management for this site. One of the advantages of this test is to be able to evaluate the interaction of N rates and zone approach on productivity; the assumption being a significant interaction suggests N would require unique management within each zone, providing justification for a precision versus a whole-field approach. Our results suggest no significant interaction between the conventional zones and N rates for both wheat (2009-2010) and cotton (2009-2011) yields. However, significant interaction was observed between soil delineations and N rates in 2009 for both wheat and cotton. This suggests the Order 1 soil survey may have slightly more applicability for the basis of variable N management at this site, although further analyses are needed over multiple years.