Michael J. Buschermohle

Perspectives on delineating management zones for variable rate irrigation

Up to 40% of soil available water content variance was explained by pie shape zoning.Dynamic zoning strategy may be needed if soil spatial arrangement varies by depth.Soil ECa and satellite images were useful attributes for irrigation zone delineation. This study aimed at investigating the performance of multiple irrigation zoning scenarios on a 73ha irrigated field located in west Tennessee along the Mississippi river. Different clustering methods, including k-means, ISODATA and Gaussian Mixture, were selected. In addition, a new zoning method, based on integer linear programming, was designed and evaluated for center pivot irrigation systems with limited speed control capability. The soil available water content was used as the main attribute for zoning while soil apparent electrical conductivity (ECa), space-borne satellite images and yield data were required as ancillary data. A good agreement was observed among delineated zones by different clustering methods. The new zoning method explained up to 40% of available water content variance underneath center pivot irrigation systems. The ECa achieved the highest Kappa coefficient (=0.79) among ancillary attributes, hence exhibited a considerable potential for irrigation zoning.

Studying uniform and variable rate center pivot irrigation strategies with the aid of site-specific water production functions

Novel site-specific water production functions (WPFs) were developed and tested.New zoning procedures for variable rate irrigation were established.The k-NN WPF accurately predicted cotton yield under supplemental irrigation.Sector zoning was predicted to enhance cotton yield under supplemental irrigation. Irrigation management has evolved into a top priority issue since available fresh water resources are limited. Water production functions (WPFs), mathematical relationships between applied water and crop yield, are useful tools for irrigation management and economic analysis of yield reduction due to deficit irrigation. This study aimed at (i) designing and evaluating site-specific WPFs (using k nearest neighbors (k-NN), multiple linear regression, and neural networks), (ii) simulating yield maps for uniform, sector control VRI, and zone control VRI center pivot systems using the site-specific WPFs, (iii) using the best WPF to investigate different cotton irrigation and zoning strategies using integer linear programming, and (iv) comparing soil-based and WPF-based zones for sector control VRI systems. A two-year cotton irrigation experiment (2013-2014) was implemented to study irrigation-cotton lint yield relationship across different soil types. The site-specific k-NN WPFs showed the highest performance with root mean square error equal to 0.131Mgha-1 and 0.194Mgha-1 in 2013 and 2014, respectively. The result indicated that variable rate irrigation with limited sector control capability could enhance cotton lint yield under supplemental irrigation when field-level spatial soil heterogeneity is significant. The temporal changes in climate and rainfall patterns, however, had a great impact on cotton response to irrigation in west Tennessee, a moderately humid region with short season environment. We believe site-specific WPFs are useful empirical tools for on-farm irrigation research.

A ONE-YEAR STUDY OF A SUPPLEMENTAL AIR DISTRIBUTION SYSTEM FOR GREENHOUSES

The effect of a supplemental air distribution system was evaluated in a greenhouse producing tomatoes (Lycopersicon esculentum Mill cv. Trust). The system used centrifugal fans to force warmer air from above the canopy through a perforated duct extending longitudinally through each double-canopy row, with the goal of improving yield and decreasing energy use. The experiment employed two commercial-size greenhouses, one as the treatment greenhouse with the air distribution system and one as the control using conventional air handling. The experiment duration was two growing seasons (spring and fall crop). The system significantly reduced vertical temperature and relative humidity gradients while the heater was on during the spring. The treatment greenhouse consumed 9% less fuel and exhibited 14% greater yield than the control house. The net benefit from the treatment greenhouse was estimated as slightly less than

Measuring Relative Humidity in a Stagnant Environment

1000 for the spring season, and the benefit/cost ratio of the system was four to one. However, the benefits observed during the spring did not repeat for the fall season. There were no appreciable environmental differences between the greenhouses, and the yields were essentially the same. Because of capital and operating costs, the treatment greenhouse experienced a net economic loss of near

Automatic Section Control Technologies and GPS Auto-guidance Systems Adoption in Cotton Production

300 in the fall. The difference between fall and spring results is explained by the different relationship between plant size and climate during those seasons; the combination of small plants and cold weather in the spring can benefit the most from this type of air circulation system. The results from a single spring/fall trial suggest that the system could be valuable to producers, but only in the spring.

Effects of optical sensing based variable rate nitrogen management on yields, nitrogen use and profitability for cotton

Commercially available relative humidity sensors were evaluated when: 1) placed in chemically controlled relative humidity environments, 2) buried in stored corn with moisture contents in the range 10% to 26% db (40% to 95% equilibrium relative humidity), and 3) placed in changing relative humidities controlled with an environmental control chamber. Responsive elements in these sensors were made of a hygroscopic material sensitive to water vapor in stagnant environments. Observations were made over about a two-year period. The sensors were successfully used to determine moisture content of stored corn by measuring equilibrium relative humidity. Relative humidity indications were linearly related to corn moisture content. Sensors as calibrated at the factory gave very good indications of relative humidities over saturated solutions of LiC1 and K2SO4. However, sensors calibrated to operate in high relative humidity environments indicated a lower than theoretical relative humidity when exposed to the K2SO4 environment for only a short time. Many of the sensors, when moved from a low to a high relative humidity, approached equilibrium with the high relative humidity environment in a stair-step fashion. Equilibrium when sensors were moved from a high to a low relative humidity environment was approached more smoothly.

Influence of Management Strategies on Sustainability of Row Crop Production using the Field to Market Fieldprint Calculator

Using data from a survey of cotton producers in 14 US states, and a bivariate probit regression, this study examined the effects of the following measured parameters on the adoption of Automatic Section Control (ASC) technologies and GPS Auto-Guidance (AG) systems: age, education, farm size, field geometry, information sources, as well as the use of specific production practices and other Precision Agriculture (PA) technologies. Results suggest that younger, more educated producers, consulting farm dealers for information about PA technologies, using other PA technologies, and managing larger farming operations located in counties with more irregularly shaped fields are more likely to adopt ASC technologies and AG systems. Predicted adoption probabilities estimated using regression results suggest the use of other PA technologies and farm dealers as a source of precision farming information have the largest impact on the probability of adopting ASC by cotton farmers. Additionally, these results suggest farmers with operations in eastern Arkansas, western Tennessee, and a couple of counties in middle Tennessee are more likely to adopt ASC technologies. Producers in these regions had the highest percentages of users of other PA technologies and farm dealers to obtain PA information.

The Effects of Three Module Types on Cotton Ginning and Fiber Quality

This research evaluated the profitability and nitrogen (N) efficiency of real time on-the-go optical sensing measurements (OPM) for variable-rate (VRT) N management for cotton. Two forms of OPM-based VRT N management and the existing farmer practice (FP) were used to determine N rates applied to cotton on 21 farm fields in the lower Mississippi River Basin states of Louisiana, Mississippi, Missouri and Tennessee, USA. A modified version of the Schabenberger and Pierce on-farm experimentation model was used to evaluate VRT N management and landscape, soil and weather factors on lint yields, N rates, N efficiency (lint yield divided by N rate) and net returns. Field level mean lint yields were not different between VRT and FP. VRT decreased N rates applied on four fields and increased N rates applied on four other fields. However, landscape, soil and weather attributes specific to fields influenced VRT N rates. VRT N rates were similar to FP N rates on the other fields in the study. N efficiency was not improved with VRT N management. N rates were not low enough to increase N efficiency. Changes in lint yields and N rates due to VRT coupled with USDA NRCS Environmental Quality Incentive Program cost-share payments were not sufficient to produce higher net returns relative to FP N management at the field level. In this multi-site, multi-year study, yields and net returns from VRT were not different from FPs which did not utilize variable rate N management.

Effectiveness of Physical and Chemical Pretreatments in Enhancing Cotton Gin Trash In Vitro Ruminant Digestibility

Abstract. Increasing agricultural sustainability will enable the world to meet present needs while continuously improving future generation’s ability to meet their own needs. This can be done not only by lessening our environmental impacts, improving human health, and improving the well-being of agricultural communities, but also by increasing productivity to meet current as well as future food, fuel, and clothing demands. In a proactive effort to measure and promote sustainable agriculture, an initiative entitled Field to Market, The Keystone Alliance for Sustainable Agriculture has been formed. This initiative joins various food companies, agribusinesses, producers, commodity groups, and conservation programs to provide leadership, scientific information, and collaboration on improvements that can be made in crop productivity, environmental quality, and human and community well-being. As a result of this initiative, the Field to Market Fieldprint Calculator has been developed to give producers the ability to see how their crop production management strategies impact the sustainability of their farming operation. This educational tool provides producers with general information on what management strategies are most likely to improve or lessen their impacts, or ‘Fieldprint’, on energy use, climate impact, soil loss and water use. Data from several Tennessee producers have been analyzed using the Fieldprint Calculator. Certain factors were found to influence sustainability, through the quantification of energy usage and greenhouse gas emissions. Because the calculator quantifies its sustainability indices on a per pound of crop produced basis, maintaining yield is an important factor. For example, irrigating in a severe drought year proved to be more sustainable than dryland systems because yields were maintained. Using variable rate application (VRA) of fertilizers has the potential to reduce the amount of energy used and greenhouse gases emitted because less fertilizer, on average, will be applied. In turn, this reduces the amount of nutrients that could ultimately pollute surrounding waterbodies. Using the Fieldprint calculator in such a way demonstrates that being sustainable and reducing ‘Fieldprints’ can not only increase producers’ profitability, but also reduce the impacts from agriculture on the environment.

High-resolution prediction of soil available water content within the crop root zone

Traditionally seed cotton has been stored in modules from the time it was harvested until it was ginned. These modules have been formed using additional equipment and operators. In an effort to improve the efficiency of cotton production by reducing the number of operators and equipment, two newer harvesters have been introduced which form modules on the harvester. These modules are smaller than the traditional modules, one being an approximately half-sized rectangular module and the other having a round cross section holding approximately one fourth the seed cotton of a traditional module. Data and samples were obtained at seven gins located in four states to determine if significant problems in ginning were related to the newer modules. Cotton degradation was observed when loose seed cotton was placed at the ends of modules and when modules were