Design and Development of a Variable Rate Applicator for Real-Time Application of Fertilizer

Variable rate technology offers a sustainable, efficient, and cost-effective solution for fertilizer application. A study was conducted to design and develop a variable rate fertilizer applicator to detect real-time deficiency of N within the field and apply it per requirement of the crop. The microcontroller system was designed to receive a signal from the N sensor and send a signal to the pulse-width-modulation valve to vary the rotational speed of the hydraulic motor resulting in variation in the rotation of the metering mechanism drive shaft based on the recommended amount of fertilizer. During the field study, three replications were conducted, each of which was divided into four plots. The response time between the N sensing and fertilizer discharging fell within the range of 3.49 to 4.90 s. Fertilizer applied using the developed variable rate applicator indicated that when the fertilizer rate is increased from N1 to N4 (kg ha−1), NDVI increased from 0.56 to 0.78 and drive shaft rotational speed decreased from 20 to 0 rpm in order to apply the fertilizer at a rate of 0.00 instead of 78.36 kg ha−1. Using the developed applicator demonstrates that this technology could reduce environmental impact, making farming more sustainable.

Modelling approach for Data Analysis

A Decision Support System (DSS) is an interactive, computer-based system that helps users in making decisions. Besides the provision of storing and data retrieval, DSS enhances information access and retrieval functions. Designing a DSS for agriculture enables farmers to make effective decisions for higher yield and lower production costs. Precision agriculture, through the use of remote sensing, geographical information systems, global positioning systems, soil testing, yield monitors and variable rate technology, provide a number of inputs into the DSS. Case studies are presented where the DSS is designed to optimize specific inputs, such as water consumption or pesticide applications by employing precision agriculture through information and communication technology.

Site-Specific Management of Cotton Root Rot Using Airborne and High-Resolution Satellite Imagery and Variable-Rate Technology

Cotton root rot is a century-old cotton disease that now can be effectively controlled with Topguard Terra fungicide. Because this disease tends to occur in the same general areas within fields in recurring years, site-specific application of the fungicide only to infested areas can be as effective as and considerably more economical than uniform application. The overall objective of this research was to demonstrate how site-specific fungicide application could be implemented based on historical remote sensing imagery and using variable-rate technology. Procedures were developed for creating binary prescription maps from historical airborne and high-resolution satellite imagery. Two different variable-rate liquid control systems were adapted to two existing cotton planters, respectively, for site-specific fungicide application at planting. One system was used for site-specific application on multiple fields in 2015 and 2016 near Edroy, Texas, and the other system was used on multiple fields in both years near San Angelo, Texas. Airborne multispectral imagery taken during the two growing seasons was used to monitor the performance of the site-specific treatments. Results based on prescription maps derived from historical airborne and satellite imagery of two fields in 2015 and one field in 2016 are reported in this article. Two years of field experiments showed that the prescription maps and the variable-rate systems performed well and that site-specific fungicide treatments effectively controlled cotton root rot. Reduction in fungicide use was 41%, 43%, and 63% for the three fields, respectively. The methodologies and results of this research will provide cotton growers, crop consultants, and agricultural dealers with practical guidelines for implementing site-specific fungicide application using historical imagery and variable-rate technology for effective management of cotton root rot. Keywords: Airborne imagery, Cotton root rot, High-resolution satellite imagery, Prescription map, Variable-rate application.

Integration of Aerial Imaging and Variable-Rate Technology for Site-Specific Aerial Herbicide Application

As remote sensing and variable-rate technology are becoming more available for aerial applicators, practical methodologies for effective integration of these technologies are needed for site-specific aerial applications of crop production and protection materials. The objectives of this study were to demonstrate how to integrate an airborne multispectral imaging system and an IntelliStar variable-rate aerial application system for site-specific management of the winter weed henbit. The airborne imaging system was used to acquire natural color and near-infrared (NIR) images of a fallow field near College Station, Texas, for mapping the infestation of henbit shortly before herbicide application. The images were then rectified, classified, and converted to a binary prescription map with the full application rate on infested areas and the zero rate on non-infested areas. The variable-rate aerial application system mounted on an agricultural aircraft was used to apply glyphosate over the field based on the prescription map. Airborne imagery was collected 14 days after the herbicide application. The as-applied map along with the prescription map and the post-application imagery were used to assess the performance of the site-specific application. Spatial and statistical analysis results showed that the imaging system was effective for mapping henbit infestations and for assessing the performance of site-specific herbicide application, and that the variable-rate system accurately delivered the product at the desired rate to the prescribed areas for effective control of the weed. The methodology and results from this study will be useful for aerial applicators to incorporate airborne imaging and variable-rate application systems into their aerial application business to increase their capabilities and profits. Keywords: Aerial application, As-applied map, Henbit, Imaging system, Prescription map, Variable-rate technology.