About

Gary R. Sands is a professor affiliated with the University of Minnesota, specializing in water management, water quality, and the sustainability of agricultural systems. His research focuses on the environmental impacts of agricultural drainage, particularly how subsurface drainage affects aquatic ecosystems, nitrate losses, and soil temperature in cold climates. Sands has contributed to the development and application of models such as DRAINMOD to assess the effects of drainage practices on water quality and hydrology in agricultural landscapes. His work includes evaluating the potential of cover crops to reduce nitrate loss and exploring drainage design and management strategies to meet both agronomic and environmental goals. Sands' research has been widely cited, reflecting his significant role in advancing understanding of agricultural drainage systems and their influence on environmental sustainability.

Research topics

• Mathematics
• Biology
• Chemistry
• Meteorology
• Geography
• Environmental science
• Agronomy
• Engineering
• Ecology

Selected publications

• Beyond the Outlet: How Lateral Seepage Shapes Controlled Drainage Performance in Sandy Soils

  Open MIND · 2026-02-26

  dataset

  Field data for controlled drainage

  DOI

• Beyond the Outlet: How Lateral Seepage Shapes Controlled Drainage Performance in Sandy Soils

  Mendeley Data · 2026-02-26

  datasetOpen access

  Field data for controlled drainage

  PublisherDOI

• A review on enhancing water productivities adaptive to the climate change

  Journal of Water and Climate Change · 2025-02-05 · 5 citations

  reviewOpen access

  ABSTRACT Crop water requirements depend on climate, soil, and plant characteristics, necessitating responsive and adaptive irrigation systems for efficient water use. The objectives of this study include assessing the implementation of irrigation technology and its impact on water use efficiency, reviewing smart irrigation systems employed as irrigation management systems, and introducing evapotranspirative irrigation technology as a straightforward smart irrigation approach. Globally, research on irrigation technologies highlights significant potential for water conservation. Smart irrigation system, as a facet of irrigation system management, is considered a strategic approach for effective irrigation implementation. The adoption of micro-irrigation systems in cultivated crops shows promising results in enhancing water productivity and significantly increasing yield rates, but smallholder farmers resist due to high costs. This study introduces innovative approaches using simple automatic technology based on the principle of evapotranspiration, aiming to mitigate high costs. This technology is designed to distribute water optimally at the highest evapotranspiration rate during prolonged dry periods. The key success indicators focus on water productivity, encompassing crop water, irrigation water, and total water. The evapotranspirative irrigation system is pivotal in regulating evapotranspiration rates, resulting in reduced water evaporation and increased land and water productivities, making it adaptive to the impacts of climate change.

  PublisherOA PDFDOI

• Predicting nitrate‐nitrogen loads in subsurface drainage as a function of fertilizer application rate and timing in southern Minnesota

  Journal of Environmental Quality · 2020 · 3 citations

  Senior authorCorresponding
  • Environmental science
  • Agronomy
  • Mathematics

  -N losses for a corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] rotation in southern Minnesota, using fertilizer application timing and rate and growing season precipitation as inputs. The equations were developed using the results of the field-scale hydrologic and N simulation model DRAINMOD-NII, first calibrated and validated for three sites in southern Minnesota, and then run with different combinations of N fertilizer application rates and timings. Fertilizer timing treatments included a single application in the fall or spring and a split-spring application (half applied preplant and the remaining applied as sidedress). The predictive regression equations showed that the split fertilizer application timing could reduce regional N loads by 28% compared with spring or fall applications. Greater reductions were predicted when the split timing was combined with lower N fertilizer rates. Utilizing the split application timing and reducing the fertilizer rate by 10 and 30% showed 33 and 41% reductions in N loads, respectively, compared with current fertilizer management practices. Such reductions in fertilizer application rates could be achieved through the use of variable-rate nitrogen (VRN) fertilizer technologies. Results of this modeling study indicate that synchronizing fertilizer application with crop requirements and utilizing VRN technologies could significantly reduce N loads to surface waters in southern Minnesota.

  PublisherDOI

• Effects of fertilizer timing and variable rate N on nitrate–N losses from a tile drained corn-soybean rotation simulated using DRAINMOD-NII

  Precision Agriculture · 2019-05-18 · 12 citations

  articleSenior author
  PublisherDOI

• Advances in Drainage: Selected Works from the Tenth International Drainage Symposium

  Transactions of the ASABE · 2018-01-01 · 6 citations

  articleOpen access

  Abstract. This article introduces a special collection of fourteen articles accepted from among the 140 technical presentations, posters, and meeting papers presented at the 10th International ASABE Drainage Symposium. The symposium continued in the tradition of previous symposia that began in 1965 as a forum for presenting and assessing the progress of drainage research and implementation throughout the world. The articles in this collection address a wide range of topics grouped into five broad categories: (1) crop response, (2) design and management, (3) hydrology and scale, (4) modeling, and (5) water quality. The collection provides valuable information for scientists, engineers, planners, and others working on crop production, water quality, and water quantity issues affected by agricultural drainage. The collection also provides perspectives on the challenges of increasing agricultural production in a changing climate, with ever-greater attention to water quality and quantity concerns that will require integrated technical, economic, and social solutions. Keywords: ASABE Drainage Symposium, crop response, design and management, hydrology and scale, modeling, water quality.

  PublisherOA PDFDOI

• Triangle Graphs Development for Estimating Methane and Nitrous Oxide Gases Emission from the System of Rice Intensification (SRI)

  Journal of Environmental Science and Technology · 2017-06-15 · 7 citations

  articleOpen access

  Background and Objective: SRI paddy field occasionally experiences aerobic soil conditions that emit complicated greenhouse gases due to biophysical processes. Understanding these emission patterns, as well as the amount, is important to determine the proper mitigation action to take. This study was carried out to produce a simple method to estimate CH 4 and N 2 O using easily measure environmental parameters that might be used to simulate the mitigation of non-CO 2 emissions. Materials and Methods: Two Artificial Neural Network (ANN) models were developed to estimate methane (CH 4 ) and nitrous oxide (N 2 O) fluxes based on three selected variables. Based on the models, patterns of CH 4 and N 2 O emissions in SRI paddy fields were presented in the form of a triangle graph that can be used to estimate emissions from the easily measured soil pH, soil moisture and air temperature. A sensitivity test (Spearmans correlation test) was used to statistically analyze data. Results: ANN models were developed to estimate emission fluxes based on three selected variables of soil pH, soil moisture and air temperature that could produce R 2 0.96 and 0.82 for CH 4 and N 2 O, respectively. CH 4 emission in the SRI paddy field increased with air temperature but decreased when soil moisture decreased, while N 2 O emissions were mostly stable at all times regardless of changes in soil moisture and air temperature. In general, a higher soil pH produced higher CH 4 and N 2 O emissions. The triangle graph shows that in SRI paddy field with soil pH, soil moisture and air temperature range 4.30-5.30, 0.354-0.524 m 3 mG 3 , 29.0-32.5EC, respectively; it could be a sink or emission of methane until more than 45 mg mG 2 dayG 1 and be able to emit nitrous oxide to more than 6 g mG 2 dayG 1 . Conclusion: SRI paddy field can be emission source of CH 4 and N 2 O. The graphs can be used to identify mitigation action that can be implemented to lower emissions by showing the set-point value of soil moisture. For example, in an air temperature of 29.4 o C and soil pH condition of 4.8, to minimize the emission of CH 4 and N 2 O, the soil moisture should be less than 0.418 m 3 mG 3 .

  PublisherOA PDFDOI

• Subsurface (Tile) Agricultural Drainage

  Oxford Research Encyclopedia of Environmental Science · 2016-11-22

  reference-entry1st authorCorresponding

  Agricultural (tile) drainage enables agricultural production on millions of hectares of arable lands worldwide. Lands where drainage or irrigation (and sometimes both) are implemented, generate a disproportionately large share of global agricultural production compared to dry land or rain-fed agricultural lands and thus, these water management tools are vital for meeting the food demands of today and the future. Future food demands will likely require irrigation and drainage to be practiced on an even greater share of the world’s agricultural lands. The practice of agricultural drainage finds its roots in ancient societies and has evolved greatly to incorporate modern technologies and materials, including the modern drainage plow, plastic drainage pipe and tubing, laser and GPS-guided installation equipment, and computer-aided design tools. Although drainage brings important agricultural production and environmental benefits to poorly drained and salt-affected arable lands, it can also give rise to the transport of nutrients and other constituents to downstream waters. Other unwanted ecological and hydrologic environmental effects may also be associated with the practice. The goal of this article is to familiarize the reader with the practice of subsurface agricultural drainage, the history and extent of its application, and the benefits commonly associated with it. In addition, environmental effects associated with subsurface drainage including hydrologic and water quality effects are presented, and conservation practices for mitigating these unwanted effects are described. These conservation practices are categorized by whether they are implemented in-field (such as controlled drainage) versus edge-of-field (such as bioreactors). The literature cited and reviewed herein is not meant to be exhaustive, but seminal and key literary works are identified where possible.

  PublisherDOI

• Measuring Crop Response to Subsurface Drainage with Satellite Remote Sensing

  2016-09-07

  articleSenior author

  <abstract> <b><sc>Abstract.</sc></b> This research focused on evaluating remote sensing and combine-yield monitor data as tools for assessing the effectiveness of subsurface drainage. Differences in crop response were studied between field areas with and without subsurface drainage, as well as between field areas possessing subsurface drainage at different spacings. The major characteristics including crop type, vegetation index, image date, soil type and drainage intensity were explored. Two vegetation indices (VIs), Normalized Difference Vegetation Index (NDVI) and Tasseled Cap Transformation (TCT), derived from Landsat 5 satellite images were utilized. Two study sites located in South-central Minnesota with seven silty-clay soil types and eight Landsat 5 images from 1991, 1995, and 2001 were used to assess the presence of subsurface draiange. April-June precipitation was 50% and 48% above average for 1991 and 2001 and 5% below average for 1995. The results showed that the differences in crop response between field areas with and without subsurface drainage were discernible using remote sensing. However, the degree of discernability between drained and undrained treatments using VIs was dependent crop year and soil texture. In wetter years, the fields had greater variations in VIs, especially for finer textured soils. Vegetation index values between field areas possessing varying subsurface drainage intensities were at times discernible on both fine and coarse-textured soil types. This may be caused by low precipitation during August, which led to greater deficit moisture stress on narrower spaced drainage treatments.

  PublisherDOI

• Developing optimum subsurface drainage design procedures

  Acta Agriculturae Scandinavica Section B - Soil & Plant Science · 2015-03-27 · 5 citations

  article1st authorCorresponding

  The DRAINMOD simulation model was used to investigate combinations of drain depth and spacing for major soils of southern Minnesota to maximize profitability and minimize drained volume and surface runoff. Six soil types (Canisteo, Harps, Nicollet, Normania, Okoboji, and Webster) and three locations (Lamberton, Waseca, and Willmar) were included in the original study and one soil-location combination was reported on, herein (Webster–Waseca). Four drain depths (90, 105, 120, and 135 cm) were used and drain spacings were selected to simulate drainage coefficients from 3.2 to 19 mm/day. Soil input files for DRAINMOD were created using a combination of measured data from field sampling (soil texture and bulk density), data estimated with the Rosetta soil parameter model/van Genuchten equation (water retention curves), and publicly available data (soil permeability). Long-term simulations were conducted for each location using 90 years of historical climate data (1915–2005). Outputs from DRAINMOD were used to create “performance” indices that enable the concurrent consideration of profitability, drainage volumes, and surface runoff, when choosing drain depth and spacing. A spreadsheet design tool was developed to compute and display these indices, based on a few simple user inputs to define cost and crop price. Internal rate of return was used as the basis for profitability considerations. Results obtained indicated that in general, profitability may be increased with increased drain depth and spacing, due to system costs associated with narrower drain spacings. It was found that when considering both profitability and drainage volume, deeper, more widely spaced drainage systems were generally preferable, because of increased profitability and decreased drainage volumes.

  PublisherDOI

Frequent coauthors

• Jeffrey S. Strock

  University of Minnesota

  23 shared

• Ian D. Moore

  18 shared

• Chris Roberts

  Welsh Government

  16 shared

• Bruce Wilson

  15 shared

• Gary W. Feyereisen

  15 shared

• Bradley J. Hansen

  14 shared

• Paul M. Porter

  University of Minnesota

  13 shared

• Hans Kandel

  North Dakota State University

  11 shared

Education

• Ph.D., Chemical & Agricultural Engineering

  Colorado State University

Awards & honors

• Groundbreaker Award, Drainage Contractor Magazine (2023)
• ASABE Blue Ribbon Awards (2002, 2003, 2017)
• Richard C. Newman Outreach Award (2010)