Precision Turfgrass Management (PTM) by Spatial Mapping of Variability in Soil Properties and Turfgrass Stress with Mobile Sensor Platforms

Summary

Spatial and temporal variability of soil, climatic, plant, and irrigation application aspects are challenges for traditional agriculture and turfgrass/landscape sites. Precision Agriculture (PA) evolved as a means to facilitate site-specific management in contrast to uniform whole-field management. Precision Turfgrass Management (PTM), similar to PA, must evolve into a more site-specific management approach that supports sustainable practices and enhanced efficiency of inputs. This project involves developing the foundational PTM equipment, techniques, and other protocols for improved efficiency of imput application as related to water, cultivation, fertilization, and salinity control.

Situation

Site-specific management requires site-specific information – i.e., information from the site to make management decisions that maximize environmental stewardship and input efficiency by applying inputs only: where needed; when required; and in the quantity required. Spatial and temporal variability of soil, climatic, plant, and irrigation application aspects are challenges for traditional agriculture and complex turfgrass/landscape sites. Precision Agriculture (PA) developed as a means to facilitate site-specific management in contrast to uniform whole-field management. Our research and educational efforts has been to foster Precision Turfgrass Management (PTM), based on PA principles, as a concept to support a greater degree of site-specific management than currently possible in order to promote sustainable practices and greater efficiency of inputs. PTM requires accurate and timely information be obtained by integration of sensor and electronic technologies, including: global positioning systems (GPS), geographic information systems (GIS), and plant, soil, and/or climatic sensors via mobile platforms, in-place, or combinations. However, there are considerable differences between PA and PTM in terms: a) of mapping equipment requirement; b) challenges to carry the information through to the end user; and c) specific field applications. Only as these issues are addressed can PTM progress as a concept to enhance environmental stewardship and input efficiency.

Response

One of the best means to improve environmental management of turfgrass sites is to foster a new holistic, science-based concept targeted to this goal by laying the foundations for the concept to flourish – i.e., foster PTM --- since holistic concepts can be adopted in the regulatory realm as well as the site-specific level. The “concept approach” is the same means that we used stating in 2004 to foster a BMPs based program for water-use efficiency and conservation on turfgrass sites – which has now become the model for all water users in GA (i.e. BMPs model to management water conservation with the state golf course superintendents taking the lead in adoption) and was stated in the Council for Agriculture Science and Technology (CAST) special publication No. 27 as the best model for the turfgrass industry on a nation-wide basis. Since PTM offers the potential for a whole new management concept for a greater degree of site-specific turfgrass management and could have significant impact on the turfgrass industry, similar to what PA has on agricultural crop management, we are focusing considerable attention to building the PTM foundations. The first requirement for PTM has been to develop appropriate spatial mapping platforms that are mobile and rapid. PA did not progress until mobile sensor platforms were developed to accurately measure spatial variability of key soil properties related to plant performance as well as plant characteristics; however, these devices were not suitable for turfgrass situations. Recently, cooperative work between the Toro Company and our program have developed/tested the first equipment that could determine key soil and plant characteristics in turf systems – prior to this only remote or ground level plant aspects were being determined and practical applications were not evolving, similar to the same experience in PA. We continued development and testing of mobile platform equipment beyond the initial units provided by the granting company which were targeted to spatial mapping of soil moisture and soil compaction by determining surface zone volumetric water content (VWC), turf performance or stress by NDVI (normalized differential vegetative) using spectral reflectance; and penetrometer resistance (PR) for soil compaction spatial mapping. Our latest device was developed for spatial soil salinity mapping by: a) determination of apparent soil conductivity (ECa) using ER and 4-wenner probe array at three soil depths, and b) turf performance by NDVI by spectral reflectance. Second, to avoid issues and challenges that hindered development of PA and to stimulate development of PTM, a through comparison was conducted of PA and PTM in terms of driving forces, challenges, and field applications. This has been reported in the Precision Agriculture Journal as the first foundational review and assessment of PTM in the science literature with a companion paper in a professional turfgrass manager venue. Third, in the Precision Agricultural Journal paper, we defined the most important field applications that had the potential to be achieved in the near future. For each of these field applications, a series research studies with research papers and counterpart papers for turfgrass professional growers were initiated as well as oral presentations for both audiences. The six key field applications with papers in progress are: 1. Defining site-specific management units (SSMU) on non-saline sites – SSMU information is essential to achieve the purposes of PTM stated earlier as well as to assist irrigation scheduling, aid in evaluating efficiency of the irrigation system, and correct in-place sensor placement. Defining SSMUs is a key for use of spatial mapping for not just water management applications but for other field applications. For example, accurate determination of SSMUs could change how golf course soil sampling is done on fairways in a manner to allow greater site-specific fertilization, liming, and gypsum applications based on needs within a SSMU area. 2. Determining the best locations (key indicator sites) for placement of in-situ sensor arrays within representative SSMU areas. Where to place in-situ soil sensors has been a consistent problem; but by using the SSMU concept, placement can be accomplished on a science basis. Carefully selected sites for in-place sensors would allow real-time and more robust on-going data with the least number of sensor locations. 3. For current irrigation systems, evaluation of system design across the whole site for degree of uniformity of water application (distribution uniformity, DU) based on soil moisture distribution rather than the traditional catch-can approach to determine if the system is efficient – i.e. the core of an New WaterAudit approach. The New WaterAudit approach would be in contrast to the current catch-can approach; and would allow full area assessment rather than only small areas. 4. For the salinity monitoring unit, the primary field application would be to identify areas of salt accumulation, especially in the surface few inches. This would make it possible to apply site-specific salt leaching; thereby, conserving water and controlling salt movement. To-date, irrigation for leaching has been only crudely estimated and the whole area was irrigated. This application is a Salinity Audit. The development of salt-tolerant seashore paspalum by UGA breeders has allowed more saline irrigation water to be used rather than high quality water, but salinity control is essential for environmental stewardship. 5. Site specific soil cultivation can be achieved using the penetrometer resistance spatial mapping data when the readings are obtained at field capacity to normalize soil moisture conditions. This would result in enhanced efficiency of labor and energy, while reducing equipment wear. 6. For community sports fields, spatial mapping of the surface for soil moisture, irrigation distribution patterns, soil hardness, and plant performance could be used to increase player safety, field playability, and water conservation. Soil hardness is primarily a function of soil compaction and soil dryness (inducded by improper irrigation coverage or scheduling) and is an important factor for player safety and field playability. The fourth foundation is for each of the above six field applications, we are developing specific protocols; with the term “protocol” used in a very broad sense to refer to all aspects necessary to achieve detailed site assessment information and carry it though to the end-user in a practical, useful manner. Lack of consistent and practical protocols was a factor that hindered acceptance of PA.

Impact

As with any new concept, it is important to provide the key foundational information for the turf industry and science audiences: a) to understand the concept; and b) to confront any issues that may hinder progress or adoption. Since this is the first time that mobile platforms and the systematic concepts have been developed for data acquisition (beyond units obtaining only spectral data) in turfgrass systems, we have concentrated on the four “responses” noted above. The initial presentations of the PTM concept and associated research to turf manager, irrigation industry, and science venues started in late 2007 and then in 2008, with scientific presentations at the 9th International Precision Agriculture Conference and the ASA-CSSA-SSSA Annual Meetings as well as a foundational paper in Golf Course Management magazine defining PTM and the various applications. As a result of the PA Conference, we were invited to develop a concept paper for the Precision Agriculture Journal which was published initially on-line in August 2009. Additionally, a Crop Science paper has been accepted; another Crop Science paper in review; and a concept paper published for professional turfgrass growers. Papers are in development in all of the six field applications. While PTM is not confined to golf courses, an article in the September/October issue of the USGA Green Section Record (Vol. 47, issue 5; p. 14-16) by C. Hartwiger, USGA Agronomist stated: “The conclusion is that in the not-too-distant future, golf courses superintendents are going to base the application of course inputs ---including water, fertilizer, and cultural practices such as aeration, and soil salinity management --- on computer generated, color-coded maps that reflects thousands, if not millions of data points. This is going to happen because societal pressure and government-imposed mandates will incrementally improve a property's resource management. And it is going to happen because conservation of resources, without altering the end product to the golfer, will be better for the business of golf”.

State Issue

Agricultural Profitability and Sustainability

Details

• Year: 2009
• Geographic Scope: International
• County: Spalding
• Program Areas:
  • Agriculture & Natural Resources