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Prof. Rameshwar Kanwar
Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA 50011, USA

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0 Climate Change
0 Drainage
0 Food Security
0 Hydrology

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Research article
Published: 18 May 2021 in Ozone: Science & Engineering
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An ozonation study was conducted for inactivating Fusarium oxysporum, which causes Fusarium wilt, the most serious soil-borne disease in hydroponic cultivation systems. Samples of conidial suspensions of F. oxysporum were treated with ozone gas generated at two ozone gas-phase compositions: oxygen feed and air feed. Oxygen feed ozonation resulted in 0% viability of the pathogen for all ozone dosages tested, including the lowest measurable ozone dosage of 1 mgO3/L. For air feed ozonation, multiple regression with the Akaike information criterion (AIC) for model selection was used to find the effects of the ozone dosage O3 (mgO3/L) and the duration of ozonation (time), O3 (min), on the viability (%) of the pathogen at 5 °C and 21 °C. At 5 °C, the viability was found to be linear in O3; at 21 °C, the viability was linear in O3 and quadratic in O3, and the interaction of O3 and O3 was also found to be significant. The novelty of this study was to use oxygen as feed gas for ozonation for disinfestation of Fusarium oxysporum. This is a significantly different approach from any previously published work on fungal plant pathogen disinfestation. Ozonation with air feed was effective only at high ozone dosages and low temperature (5 °C). The findings of this research clearly show and imply that high-concentration ozone, carried by oxygen feed, is an efficient and sustainable alternative to chemical fungicides in the treatment of Fusarium wilt in hydroponic nutrient solutions because ozone decomposes quickly to oxygen, resulting in an environmentally safe and nontoxic residue.

ACS Style

Nahed Msayleb; Ramesh Kanwar; Huaiqing Wu; J. (Hans) van Leeuwen. Effects of Ozonation on the Viability of Fusarium Oxysporum Conidia in Hydroponic Nutrient Solutions. Ozone: Science & Engineering 2021, 1 -9.

AMA Style

Nahed Msayleb, Ramesh Kanwar, Huaiqing Wu, J. (Hans) van Leeuwen. Effects of Ozonation on the Viability of Fusarium Oxysporum Conidia in Hydroponic Nutrient Solutions. Ozone: Science & Engineering. 2021; ():1-9.

Chicago/Turabian Style

Nahed Msayleb; Ramesh Kanwar; Huaiqing Wu; J. (Hans) van Leeuwen. 2021. "Effects of Ozonation on the Viability of Fusarium Oxysporum Conidia in Hydroponic Nutrient Solutions." Ozone: Science & Engineering , no. : 1-9.

Review
Published: 07 January 2021 in Sustainability
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This paper summarizes the findings of an extensive review of literature that was conducted to understand the historical state of the food, energy, and water nexus in the Lake Atitlan basin and to recommend incentive-based, long-term sustainable policies to become a significant driver to Guatemala’s tourism industry and GDP growth. The SWAT (Soil and Water Assessment Tool) was implemented in the basin to work towards the goal of simulating nutrient loading. A key conclusion of this review study is for the local population to have advocacy for the “zero wastewater discharge to Lake Atitlan” initiative to bring long-term benefits to lake water quality. One of the recommended policy decisions is to seek external financing from international agencies like the World Bank at low-cost interest (IDA Loans) to implement waste management systems and pay this external debt by putting a small but affordable tax on tourists visiting the lake. Once a culture of zero municipal effluent discharge to Lake Atitlan is adopted by the local population, the livelihood of residents will become sustainable and the standard of living will increase because of improved water and air quality, making Lake Atitlan a haven of tourism for Guatemala and lifting its economy.

ACS Style

Timothy Neher; Michelle Soupir; Rameshwar Kanwar. Lake Atitlan: A Review of the Food, Energy, and Water Sustainability of a Mountain Lake in Guatemala. Sustainability 2021, 13, 515 .

AMA Style

Timothy Neher, Michelle Soupir, Rameshwar Kanwar. Lake Atitlan: A Review of the Food, Energy, and Water Sustainability of a Mountain Lake in Guatemala. Sustainability. 2021; 13 (2):515.

Chicago/Turabian Style

Timothy Neher; Michelle Soupir; Rameshwar Kanwar. 2021. "Lake Atitlan: A Review of the Food, Energy, and Water Sustainability of a Mountain Lake in Guatemala." Sustainability 13, no. 2: 515.

Review
Published: 24 November 2020 in Sustainability
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The small Mediterranean country of Malta, an island located between Italy and North Africa, has been facing and will continue to face water stress and scarcity in the coming years, receiving the designation as the most water stressed country in Europe. In the past, Malta’s water challenges were centered around water quantity concerns, but in more recent years, the severity of their water stress has been strengthened by the deterioration of the groundwater quality and quantity. Through the over-extraction of their groundwater, saltwater intrusion has steadily occurred into their freshwater aquifer systems, worsening their groundwater quality for both domestic and agricultural purposes. The objective of this paper is to conduct an extensive review on the history of Malta’s water problems and how Malta is working to combat its water scarcity concerns. Additionally, this paper investigates the impact of Malta’s water scarcity on its food and energy security challenges. Our study concludes that while Malta has obstacles to overcome in their pursuit of water security and sustainable development, the future remains hopeful, with several alternatives still available. Some of the alternatives explored in this review include wastewater reuse, increased awareness, use of alternative energy sources, rainwater harvesting, and implementation of nation-wide strategic water policies.

ACS Style

Lindsey Hartfiel; Michelle Soupir; Rameshwar Kanwar. Malta’s Water Scarcity Challenges: Past, Present, and Future Mitigation Strategies for Sustainable Water Supplies. Sustainability 2020, 12, 9835 .

AMA Style

Lindsey Hartfiel, Michelle Soupir, Rameshwar Kanwar. Malta’s Water Scarcity Challenges: Past, Present, and Future Mitigation Strategies for Sustainable Water Supplies. Sustainability. 2020; 12 (23):9835.

Chicago/Turabian Style

Lindsey Hartfiel; Michelle Soupir; Rameshwar Kanwar. 2020. "Malta’s Water Scarcity Challenges: Past, Present, and Future Mitigation Strategies for Sustainable Water Supplies." Sustainability 12, no. 23: 9835.

Journal article
Published: 12 October 2019 in Journal of Environmental Management
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A long-term poultry manure fertilizer study was initiated in 1998 and continued until 2009 under corn-soybean (CS) rotation. To match changing landscape trends, the plots were switched to continuous corn (CC) from 2010 to 2017. In both CS and CC phases, poultry manure (PM) was applied at the crop rotation recommended agronomic N rate and either half (CC phase) or double (CS phase) the recommended rate. Urea-ammonium nitrate (UAN) was applied to comparison plots at the crop recommended application rate (168 kg N ha−1 and 224 kg N ha−1 for the CS and CC phases, respectively) throughout the study. The objectives of this study include evaluation of the economic benefits of long-term PM application at various rates (PM2, PM, and PM0.5), and the impact of poultry manure application on soil health and nutrient levels, crop yield, and drainage water quality. Lower NO3–N concentrations were reported in drainage from PM treated plots when compared to UAN fertilizer applied at the same agronomic rate. Of the parameters tested for soil health analysis after twenty years of repeat application, particulate organic matter (POM) present was significantly greater in the PM treated soils (6.1–6.7 g kg soil−1) when compared to UAN plots (4.6 g kg soil−1), showing potential for stabilized soil particles, increased infiltration and water-holding capacity. The results show a consistent positive impact of manure application on corn and soybean yields when compared to yields observed in UAN treated plots. During the CS phase, we estimated the same average revenue per dollar spent for PM and UAN treatments, while the average return rate for PM2 was 1% lower; during CC phase,15% increased return rates were observed when PM0.5 and PM were compared against the UAN treatment. When managed properly, PM application to cropland is a sustainable option for diversifying agroecosystems, improving soil health and improving farm economics.

ACS Style

Natasha L. Hoover; Ji Yeow Law; Leigh Ann M. Long; Ramesh S. Kanwar; Michelle L. Soupir. Long-term impact of poultry manure on crop yield, soil and water quality, and crop revenue. Journal of Environmental Management 2019, 252, 109582 .

AMA Style

Natasha L. Hoover, Ji Yeow Law, Leigh Ann M. Long, Ramesh S. Kanwar, Michelle L. Soupir. Long-term impact of poultry manure on crop yield, soil and water quality, and crop revenue. Journal of Environmental Management. 2019; 252 ():109582.

Chicago/Turabian Style

Natasha L. Hoover; Ji Yeow Law; Leigh Ann M. Long; Ramesh S. Kanwar; Michelle L. Soupir. 2019. "Long-term impact of poultry manure on crop yield, soil and water quality, and crop revenue." Journal of Environmental Management 252, no. : 109582.

Journal article
Published: 14 December 2016 in Notulae Botanicae Horti Agrobotanici Cluj-Napoca
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The pepper producers in the Republic of Macedonia have used drip irrigation systems to increase yield in recent years, but more research is still needed, related to irrigation scheduling and precise requirement of nitrogen fertilizer to maximise pepper yield. Therefore, a two year experiment was conducted in a plastic house to determine the nitrogen fertilizer use efficiency (NFUE) and yield potential of pruned pepper as affected by irrigation and fertilization regime. Four experimental treatments were applied in this study. Three of the treatments were drip fertigated (DF1, DF2, DF3), while the fourth treatment was furrow irrigated with conventional fertilization (ØB). The labelled urea with 1% concentration of a stable isotope of nitrogen (15N) was applied for determination of NFUE. The results of this study clearly showed that increased NFUE and pepper yield depend on irrigation and fertilization regime. Namely, NFUE was significantly increased with the application of nitrogen fertilizer through drip irrigation system as compared to conventional fertilization with furrow irrigation. Also, drip fertigation frequency positively affects percentage increase of NFUE. Furthermore, our results showed that drip fertigation treatments resulted in significantly higher pepper yields in comparison to conventional fertilization. Also, drip fertigation frequency at four and two days (DF2 and DF1) resulted in higher yields when compared with drip fertigation scheduled by using tensiometers (DF3). Generally, to reach acceptable pepper yield with high NFUE, we recommend drip fertigation with a frequency of two to four days combined with two main shoots of pruned pepper in order to increase farmer’s income and to minimize the environmental impact.

ACS Style

Vjekoslav Tanaskovik; Ordan Cukaliev; Rameshwar S. Kanwar; Lee K. Heng; Mile Markoski; Velibor Spalevic. Nitrogen Fertilizer Use Efficiency of Pepper as Affected by Irrigation and Fertilization Regime. Notulae Botanicae Horti Agrobotanici Cluj-Napoca 2016, 44, 525 -532.

AMA Style

Vjekoslav Tanaskovik, Ordan Cukaliev, Rameshwar S. Kanwar, Lee K. Heng, Mile Markoski, Velibor Spalevic. Nitrogen Fertilizer Use Efficiency of Pepper as Affected by Irrigation and Fertilization Regime. Notulae Botanicae Horti Agrobotanici Cluj-Napoca. 2016; 44 (2):525-532.

Chicago/Turabian Style

Vjekoslav Tanaskovik; Ordan Cukaliev; Rameshwar S. Kanwar; Lee K. Heng; Mile Markoski; Velibor Spalevic. 2016. "Nitrogen Fertilizer Use Efficiency of Pepper as Affected by Irrigation and Fertilization Regime." Notulae Botanicae Horti Agrobotanici Cluj-Napoca 44, no. 2: 525-532.

Journal article
Published: 01 April 2016 in Journal of Environmental Management
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Application of poultry manure (PM) to cropland as fertilizer is a common practice in artificially drained regions of the Upper Midwest United States. Tile-waters have the potential to contribute pathogenic bacteria to downstream waters. This 3-year study (2010–2012) was designed to evaluate the impacts of manure management and tillage practices on bacteria losses to drainage tiles under a wide range of field conditions. PM was applied annually in spring, prior to planting corn, at application rates ranging from 5 to 40 kg/ha to achieve target rates of 112 and 224 kg/ha nitrogen (PM1 and PM2). Control plots received no manure (PM0). Each treatment was replicated on three chisel-plowed (CP) plots and one no-till (NT) plot. Tile-water grab samples were collected weekly when tiles were flowing beginning 30 days before manure application to 100 days post application, and additional grab samples were obtained to target the full spectrum of flow conditions. Manure and tile-water samples were analyzed for the pathogen, Salmonella spp. (SALM), and fecal indicator bacteria (FIB), Escherichia coli (EC), and enterococci (ENT). All three bacterial genera were detected more frequently, and at significantly higher concentrations, in tile-waters draining NT plots compared to CP plots. Transport of bacteria to NT tiles was most likely facilitated by macropores, which were significantly more numerous above tiles in NT plots in 2012 as determined by smoke-testing. While post-manure samples contained higher concentrations of bacteria than pre-manure samples, significant differences were not seen between low (PM1) and high (PM2) rates of PM application. The highest concentrations were observed under the NT PM2 plot in 2010 (6.6 × 103 cfu/100 mL EC, 6.6 × 105 cfu/100 mL ENT, and 2.8 × 103 cfu/100 mL SALM). Individual and 30-day geometric mean ENT concentrations correlated more strongly to SALM than EC; however, SALM were present in samples with little or no FIB.

ACS Style

C.E. Hruby; M.L. Soupir; T.B. Moorman; M. Shelley; R.S. Kanwar. Effects of tillage and poultry manure application rates on Salmonella and fecal indicator bacteria concentrations in tiles draining Des Moines Lobe soils. Journal of Environmental Management 2016, 171, 60 -69.

AMA Style

C.E. Hruby, M.L. Soupir, T.B. Moorman, M. Shelley, R.S. Kanwar. Effects of tillage and poultry manure application rates on Salmonella and fecal indicator bacteria concentrations in tiles draining Des Moines Lobe soils. Journal of Environmental Management. 2016; 171 ():60-69.

Chicago/Turabian Style

C.E. Hruby; M.L. Soupir; T.B. Moorman; M. Shelley; R.S. Kanwar. 2016. "Effects of tillage and poultry manure application rates on Salmonella and fecal indicator bacteria concentrations in tiles draining Des Moines Lobe soils." Journal of Environmental Management 171, no. : 60-69.

Journal article
Published: 01 January 2012 in Transactions of the ASABE
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Macropores are the primary mechanism by which fecal bacteria from surface-applied manure can be transported into subsurface drains or shallow groundwater bypassing the soil matrix. Limited research has been performed investigating fecal bacteria transport through specific macropores identified in the field. The objective of this research was to better understand how fecal bacteria, using Escherichia coli (E. coli) as an indicator organism, are transported through naturally occurring macropores and potential interactions between the macropore and soil matrix domains in the field under controlled experimental conditions. Direct injection/infiltration tests were conducted in two naturally occurring, surface-connected macropores (biopores) that penetrated to the subsurface drain depth, as identified by smoke tests. Data included total drain flow rate (baseflow rate and biopore flow rate), biopore inflow rate, and Rhodamine WT and E. coli concentrations in the drains. Analysis techniques included determining increases in subsurface drain flow rates due to the infiltration tests and percentage of the injected concentration reaching the subsurface drains after dilution with the drain baseflow. In the absence of data for mechanistic models, empirically based rational polynomial models were compared to the more commonly utilized lognormal distribution for modeling the load rate breakthrough curves. Load estimates were derived from integrated forms of these empirical functions, and percent reductions were calculated for Rhodamine WT and E. coli. Peak total drain flow rates increased nearly two-fold due to direct injection into the biopores. Less than 25% of the initial concentrations injected into the biopores reached the drain after dilution with the baseflow in the drain. Lognormal distributions best fit the Rhodamine WT load rate breakthrough curves (R2 = 0.99 for both biopores) and the E. coli load rate data for one of the biopores (R2 = 0.98). A rational fractional polynomial model that tailed off more slowly best fit the E. coli load rate data for the other biopore (R2 = 0.98). Approximately one log reduction was estimated for E. coli loads due to interaction with the soil profile as water flowed through the tortuous path of the biopores; in other words, the soil surrounding the biopore filtered approximately 90% of the E. coli load that entered the biopore compared to approximately 75% for Rhodamine WT. Considering that applied animal manure can contain millions of bacteria per mL, high concentrations and loads are still possible in the subsurface drain flow if macropores are present.

ACS Style

Garey Fox; M. M. Marvin; Jorge A Guzman; C. K. Hoang; R. W. Malone; R. S. Kanwar; Martin Shipitalo. E. coli Transport through Surface-Connected Biopores Identified from Smoke Injection Tests. Transactions of the ASABE 2012, 55, 2185 -2194.

AMA Style

Garey Fox, M. M. Marvin, Jorge A Guzman, C. K. Hoang, R. W. Malone, R. S. Kanwar, Martin Shipitalo. E. coli Transport through Surface-Connected Biopores Identified from Smoke Injection Tests. Transactions of the ASABE. 2012; 55 (6):2185-2194.

Chicago/Turabian Style

Garey Fox; M. M. Marvin; Jorge A Guzman; C. K. Hoang; R. W. Malone; R. S. Kanwar; Martin Shipitalo. 2012. "E. coli Transport through Surface-Connected Biopores Identified from Smoke Injection Tests." Transactions of the ASABE 55, no. 6: 2185-2194.

Book chapter
Published: 12 August 2011 in Soil hydrology, land use and agriculture: measurement and modelling
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This chapter presents a summary of long-term studies conducted in Iowa, USA to evaluate the effects of several land-use practices (tillage and crop...

ACS Style

A. Bakhsh; R. S. Kanwar. Land use and agricultural management systems: effects on subsurface drain water quality and crop yields. Soil hydrology, land use and agriculture: measurement and modelling 2011, 312 -328.

AMA Style

A. Bakhsh, R. S. Kanwar. Land use and agricultural management systems: effects on subsurface drain water quality and crop yields. Soil hydrology, land use and agriculture: measurement and modelling. 2011; ():312-328.

Chicago/Turabian Style

A. Bakhsh; R. S. Kanwar. 2011. "Land use and agricultural management systems: effects on subsurface drain water quality and crop yields." Soil hydrology, land use and agriculture: measurement and modelling , no. : 312-328.

Journal article
Published: 20 July 2011 in Sustainability
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This study applied a broad continuum of risk analysis methods including mean-variance and coefficient of variation (CV) statistical criteria, second-degree stochastic dominance (SSD), stochastic dominance with respect to a function (SDRF), and stochastic efficiency with respect to a function (SERF) for comparing income-risk efficiency sustainability of conventional and reduced tillage systems. Fourteen years (1990–2003) of economic budget data derived from 35 treatments on 36 experimental plots under corn (Zea mays L.) and soybean (Glycine max L.) at the Iowa State University Northeast Research Station near Nashua, IA, USA were used. In addition to the other analyses, a visually-based Stoplight or “probability of target value” procedure was employed for displaying gross margin and net return probability distribution information. Mean-variance and CV analysis of the economic measures alone provided somewhat contradictive and inconclusive sustainability rankings, i.e., corn/soybean gross margin and net return showed that different tillage system alternatives were the highest ranked depending on the criterion and type of crop. Stochastic dominance analysis results were similar for SSD and SDRF in that both the conventional and reduced tillage system alternatives were highly ranked depending on the type of crop and tillage system. For the SERF analysis, results were dependent on the type of crop and level of risk aversion. The conventional tillage system was preferred for both corn and soybean for the Stoplight analysis. The results of this study are unique in that they highlight the potential of both traditional stochastic dominance and SERF methods for distinguishing economically sustainable choices between different tillage systems across a range of risk aversion. This study also indicates that the SERF risk analysis method appears to be a useful and easily understood tool to assist farm managers, experimental researchers, and potentially policy makers and advisers on problems involving agricultural risk and sustainability.

ACS Style

Eihab M. Fathelrahman; James C. Ascough Ii; Dana L. Hoag; Robert W. Malone; Philip Heilman; Lori J. Wiles; Ramesh S. Kanwar. Continuum of Risk Analysis Methods to Assess Tillage System Sustainability at the Experimental Plot Level. Sustainability 2011, 3, 1035 -1063.

AMA Style

Eihab M. Fathelrahman, James C. Ascough Ii, Dana L. Hoag, Robert W. Malone, Philip Heilman, Lori J. Wiles, Ramesh S. Kanwar. Continuum of Risk Analysis Methods to Assess Tillage System Sustainability at the Experimental Plot Level. Sustainability. 2011; 3 (7):1035-1063.

Chicago/Turabian Style

Eihab M. Fathelrahman; James C. Ascough Ii; Dana L. Hoag; Robert W. Malone; Philip Heilman; Lori J. Wiles; Ramesh S. Kanwar. 2011. "Continuum of Risk Analysis Methods to Assess Tillage System Sustainability at the Experimental Plot Level." Sustainability 3, no. 7: 1035-1063.

Journal article
Published: 24 February 2010 in Water, Air, & Soil Pollution
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Diverting the infiltrating water away from the zone of N application can reduce nitrate–nitrogen (NO3–N) leaching losses to groundwater from agricultural fields. This study was conducted from 2001 through 2005 to determine the effects of N-application methods using a localized compaction and doming (LCD) applicator and spoke injector on NO3–N leaching losses to subsurface drainage water and corn (Zea mays L.)–soybean (Glycine max L.) yields. The field experiments were conducted at the Iowa State University’s northeastern research center near Nashua, Iowa, on corn–soybean rotation plots under chisel plow system having subsurface drainage ‘tile’ system installed in 1979. The soils at the site are glacial till derived soils. The N-application rates of 168 kg-N ha−1 were applied to corn only for both the treatments each replicated three times in a randomized complete block design. For combined 5 years, the LCD N-applicator in comparison with spoke injector showed lower flow weighted NO3–N concentrations in tile water (16.8 vs. 20.1 mg L−1) from corn plots, greater tile flow (66 vs. 49 mm), almost equivalent NO3–N leaching loss with tile water (11.5 vs. 11.3 kg-N ha−1) and similar corn grain yields (11.17 vs. 11.37 Mg ha−1), respectively, although treatments effects were found to be non-significant (p = 0.05) statistically. The analysis, however, revealed that amount and temporal distribution of the growing season precipitation also affected the tile flow, NO3–N leaching loss to subsurface drain water, and corn–soybean yields. Moreover, the spatial variability effects from plot to plot in some cases, resulted in differences of tile flow and NO3–N leaching losses in the range of three to four times despite being treated with the same management practices. These results indicate that the LCD N-applicator in comparison with spoke injector resulted in lower flow weighted NO3–N concentrations in subsurface drain water of corn plots; however, strategies need to be developed to reduce the offsite transport of nitrate leaching losses during early spring period from March through June.

ACS Style

Allah Bakhsh; Ramesh S. Kanwar; J. L. Baker. N-Application Methods and Precipitation Pattern Effects on Subsurface Drainage Nitrate Losses and Crop Yields. Water, Air, & Soil Pollution 2010, 212, 65 -76.

AMA Style

Allah Bakhsh, Ramesh S. Kanwar, J. L. Baker. N-Application Methods and Precipitation Pattern Effects on Subsurface Drainage Nitrate Losses and Crop Yields. Water, Air, & Soil Pollution. 2010; 212 (1):65-76.

Chicago/Turabian Style

Allah Bakhsh; Ramesh S. Kanwar; J. L. Baker. 2010. "N-Application Methods and Precipitation Pattern Effects on Subsurface Drainage Nitrate Losses and Crop Yields." Water, Air, & Soil Pollution 212, no. 1: 65-76.

Original articles
Published: 04 December 2009 in Journal of Crop Improvement
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Availability and pollution of freshwater water supplies will be the dominant issues for the global society in the 21st century. With increasing population and climate change scenarios, the demand for water will continue to increase for agriculture, especially irrigation, and other economic uses to meet food, fiber and energy-security needs of the society. At the same time, there is good likelihood that the availability of freshwater will decrease with the fast melting of world's major glaciers. In addition, the water quality of rivers, lakes, oceans, and aquifers will further degrade from the discharge of domestic, municipal, industrial, and agricultural water. Currently, more than five million people die every year because of water-borne diseases and 1.5 billion get sick every year because of poor sanitation or use of poor quality drinking water. Therefore, water-resource management will continue to be of great importance, and global society needs to develop strategies on developing efficient methods for water use and management/reuse of poor quality water for agriculture. The objective of this chapter paper is to highlight some of the water challenges of the 21st century and identify some of the innovative water management strategies and agricultural practices that can be used in agricultural watersheds to improve water quality and water availability for all needs of society. This chapter also discusses issues related to global warming, melting of glaciers, rise of sea levels, and how these issues will affect water sustainability and food security issues of the 21st century.

ACS Style

Ramesh Kanwar. Sustainable Water Systems for Agriculture and 21stCentury Challenges. Journal of Crop Improvement 2009, 24, 41 -59.

AMA Style

Ramesh Kanwar. Sustainable Water Systems for Agriculture and 21stCentury Challenges. Journal of Crop Improvement. 2009; 24 (1):41-59.

Chicago/Turabian Style

Ramesh Kanwar. 2009. "Sustainable Water Systems for Agriculture and 21stCentury Challenges." Journal of Crop Improvement 24, no. 1: 41-59.

Journal article
Published: 01 January 2008 in Soil Research
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Water in excess of evapotranspiration follows topographically defined flow paths and can affect spatial subsurface drainage patterns. This 1993–2003 field study was conducted near Nashua, Iowa, to delineate the subsurface drainage clusters and identify the landscape and hydrologic variables that contributed significantly in discriminating these clusters. A digital elevation model was developed using 6695 elevation data measurements collected with GPS navigation system across 36 field plots (0.4 ha in size each). A spherical model was used to interpolate the elevation data within a Spatial Analyst tool of ArcGIS software. Plot-scale average topographic attributes of elevation, slope, aspect, and curvature were derived using the Zonal function in the Spatial Analyst tool. Hydrologic attributes of flow direction, flow length, and flow accumulation were derived using the Hydrology module of Spatial Analyst tool after performing Fill function for the sink areas. Annual normalised subsurface drainage data and plot-scale derived soil and topographic attributes were used in the cluster and discriminant analysis, respectively, to investigate their relationships. Stepwise discriminant analysis identified elevation and flow accumulation as the variables that discriminated the subsurface drainage clusters of low, medium, and high categories significantly (P = 0.01). The role of elevation and flow accumulation was verified using discriminant functions that predicted all members of the high drainage cluster accurately with zero error rates. GIS data layer of subsurface drainage clusters also showed that high drainage clusters were located at the lower elevation levels and were in close agreement with the elevation and flow accumulation data layers. The results of this study indicate that elevation and flow accumulation GIS data layers can be used as a guideline to minimise nutrient losses through subsurface drainage water.

ACS Style

A. Bakhsh; R. S. Kanwar. Soil and landscape attributes interpret subsurface drainage clusters. Soil Research 2008, 46, 735 -744.

AMA Style

A. Bakhsh, R. S. Kanwar. Soil and landscape attributes interpret subsurface drainage clusters. Soil Research. 2008; 46 (8):735-744.

Chicago/Turabian Style

A. Bakhsh; R. S. Kanwar. 2008. "Soil and landscape attributes interpret subsurface drainage clusters." Soil Research 46, no. 8: 735-744.

Journal article
Published: 15 July 2007 in Geoderma
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Agricultural system models are tools to represent and understand major processes and their interactions in agricultural systems. We used the Root Zone Water Quality Model (RZWQM) with 26 years of data from a study near Nashua, IA to evaluate year to year crop yield, water, and N balances. The model was calibrated using data from one 0.4 ha plot and evaluated by comparing simulated values with data from 29 of the 36 plots at the same research site (six were excluded). The dataset contains measured tile flow that varied considerably from plot to plot so we calibrated total tile flow amount by adjusting a lateral hydraulic gradient term for subsurface lateral flow below tiles for each plot. Keeping all other soil and plant parameters constant, RZWQM correctly simulated year to year variations in tile flow (r2 = 0.74) and N loading in tile flow (r2 = 0.71). Yearly crop yield variation was simulated with less satisfaction (r2 = 0.52 for corn and r2 = 0.37 for soybean) although the average yields were reasonably simulated. Root mean square errors (RMSE) for simulated soil water storage, water table, and annual tile flow were 3.0, 22.1, and 5.6 cm, respectively. These values were close to the average RMSE for the measured data between replicates (3.0, 22.4, and 5.7 cm, respectively). RMSE values for simulated annual N loading and residual soil N were 16.8 and 47.0 kg N ha−1, respectively, which were much higher than the average RMSE for measurements among replicates (7.8 and 38.8 kg N ha−1, respectively). The high RMSE for N simulation might be caused by high simulation errors in plant N uptake. Simulated corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] yields had high RMSE (1386 and 674 kg ha−1) with coefficient of variations (CV) of 0.19 and 0.25, respectively. Further improvements were needed for better simulating plant N uptake and yield, but overall, results for annual tile flow and annual N loading in tile flow were acceptable.

ACS Style

L. Ma; R.W. Malone; P. Heilman; D.L. Karlen; R.S. Kanwar; C.A. Cambardella; S.A. Saseendran; L.R. Ahuja. RZWQM simulation of long-term crop production, water and nitrogen balances in Northeast Iowa. Geoderma 2007, 140, 247 -259.

AMA Style

L. Ma, R.W. Malone, P. Heilman, D.L. Karlen, R.S. Kanwar, C.A. Cambardella, S.A. Saseendran, L.R. Ahuja. RZWQM simulation of long-term crop production, water and nitrogen balances in Northeast Iowa. Geoderma. 2007; 140 (3):247-259.

Chicago/Turabian Style

L. Ma; R.W. Malone; P. Heilman; D.L. Karlen; R.S. Kanwar; C.A. Cambardella; S.A. Saseendran; L.R. Ahuja. 2007. "RZWQM simulation of long-term crop production, water and nitrogen balances in Northeast Iowa." Geoderma 140, no. 3: 247-259.

Journal article
Published: 15 July 2007 in Geoderma
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Management of agricultural fields based on yield patterns may help farmers adopt environmentally friendly farming practices. Our objective was to investigate landscape and hydrologic attributes that affect spatial clusters of corn (Zea mays L.)–soybean (Glycine max L.) yields. The study was conducted at Iowa State University's northeastern research center near Nashua, Iowa, from 1993 to 1998. The yield data, normalized for annual climatic variability, were used in cluster and discriminant analysis, and the landscape and hydrologic data were overlain using ArcGIS software. Three clusters of low, medium and high categories were formed using 10 iterations with zero convergence options and satisfying the R2, pseudo F-statistic and cubic clustering criteria. The spatial clusters, however, varied greatly over space and time domain for the study period. The map overlay analysis using ArcGIS showed that high yield clusters were affected by soil and lower elevation levels in the below average precipitation year of 1994. The annual normalized subsurface drainage volume, nitrate leaching losses, soil type and topographic attributes of slope, aspect, and curvature were used in stepwise discriminant analysis to identify the variables significantly related to the clusters. Soil and topographic attributes of curvature and aspect contributed significantly in cluster formations for four of the six years at P ≤ 0.15. The results suggest that cluster and discriminant analysis can be useful for identification of soil and topographic attributes affecting corn and soybean yield patterns, which can help in delineation of management zones for site specific management practices.

ACS Style

A. Bakhsh; R.S. Kanwar; R.W. Malone. Role of landscape and hydrologic attributes in developing and interpreting yield clusters. Geoderma 2007, 140, 235 -246.

AMA Style

A. Bakhsh, R.S. Kanwar, R.W. Malone. Role of landscape and hydrologic attributes in developing and interpreting yield clusters. Geoderma. 2007; 140 (3):235-246.

Chicago/Turabian Style

A. Bakhsh; R.S. Kanwar; R.W. Malone. 2007. "Role of landscape and hydrologic attributes in developing and interpreting yield clusters." Geoderma 140, no. 3: 235-246.

Journal article
Published: 15 July 2007 in Geoderma
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An accurate and management sensitive simulation model for tile-drained Midwestern soils is needed to optimize the use of agricultural management practices (e.g., winter cover crops) to reduce nitrate leaching without adversely affecting corn yield. Our objectives were to enhance the Agricultural Production Systems Simulator (APSIM) for tile drainage, test the modified model for several management scenarios, and then predict nitrate leaching with and without winter wheat cover crop. Twelve years of data (1990–2001) from northeast Iowa were used for model testing. Management scenarios included continuous corn and corn–soybean rotations with single or split N applications. For 38 of 44 observations, yearly drain flow was simulated within 50 mm of observed for low drainage (< 100 mm) or within 30% of observed for high drain flow. Corn yield was simulated within 1500 kg/ha for 12 of 24 observations. For 30 of 45 observations yearly nitrate-N loss in tile drains was simulated within 10 kg N/ha for low nitrate-N loss (< 20 kg N/ha) or within 30% of observed for high nitrate-N loss. Several of the poor yield and nitrate-N loss predictions appear related to poor N-uptake simulations. The model accurately predicted greater corn yield under split application (140–190 kg N/ha) compared to single 110 kg N/ha application and higher drainage and nitrate-N loss under continuous corn compared to corn/soybean rotations. A winter wheat cover crop was predicted to reduce nitrate-N loss 38% (341 vs. 537 kg N/ha with and without cover) under 41-years of corn-soybean rotations and 150 kg N/ha applied to corn. These results suggest that the modified APSIM model is a promising tool to help estimate the relative effect of alternative management practices under fluctuating high water tables.

ACS Style

R.W. Malone; N. Huth; P.S. Carberry; L. Ma; T.C. Kaspar; D.L. Karlen; T. Meade; R.S. Kanwar; P. Heilman. Evaluating and predicting agricultural management effects under tile drainage using modified APSIM. Geoderma 2007, 140, 310 -322.

AMA Style

R.W. Malone, N. Huth, P.S. Carberry, L. Ma, T.C. Kaspar, D.L. Karlen, T. Meade, R.S. Kanwar, P. Heilman. Evaluating and predicting agricultural management effects under tile drainage using modified APSIM. Geoderma. 2007; 140 (3):310-322.

Chicago/Turabian Style

R.W. Malone; N. Huth; P.S. Carberry; L. Ma; T.C. Kaspar; D.L. Karlen; T. Meade; R.S. Kanwar; P. Heilman. 2007. "Evaluating and predicting agricultural management effects under tile drainage using modified APSIM." Geoderma 140, no. 3: 310-322.

Journal article
Published: 01 July 2007 in Geoderma
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ACS Style

R.W. Malone; L. Ma; D.L. Karlen; T. Meade; D. Meek; P. Heilman; R.S. Kanwar; J.L. Hatfield. Empirical analysis and prediction of nitrate loading and crop yield for corn–soybean rotations. Geoderma 2007, 140, 223 -234.

AMA Style

R.W. Malone, L. Ma, D.L. Karlen, T. Meade, D. Meek, P. Heilman, R.S. Kanwar, J.L. Hatfield. Empirical analysis and prediction of nitrate loading and crop yield for corn–soybean rotations. Geoderma. 2007; 140 (3):223-234.

Chicago/Turabian Style

R.W. Malone; L. Ma; D.L. Karlen; T. Meade; D. Meek; P. Heilman; R.S. Kanwar; J.L. Hatfield. 2007. "Empirical analysis and prediction of nitrate loading and crop yield for corn–soybean rotations." Geoderma 140, no. 3: 223-234.

Journal article
Published: 09 December 2006 in Water, Air, & Soil Pollution
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Understanding the temporal distribution of NO3-N leaching losses from subsurface drained ‘tile’ fields as a function of climate and management practices can help develop strategies for its mitigation. A field study was conducted from 1999 through 2003 to investigate effects of the most vulnerable application of pig manure (fall application and chisel plow), safe application of pig manure (spring application and no-tillage) and common application of artificial nitrogen (UAN spring application and chisel plow) on NO3-N leaching losses to subsurface drainage water beneath corn (Zea mays L.)–soybean (Glycine max L.) rotation systems as a randomized complete block design. The N application rates averaged over five years ranged from 166 kg-N ha−1 for spring applied manure to 170 kg-N ha−1 for UAN and 172 kg-N ha−1 for fall applied manure. Tillage and nitrogen source effects on tile flow and NO3-N leaching losses were not significant (P < 0.05). Fall applied manure with CP resulted in significantly greater corn grain yield (10.8 vs 10.4 Mg ha−1) compared with the spring manure-NT system. Corn plots with the spring applied manure-NT system gave relatively lower flow weighted NO3-N concentration of 13.2 mg l−1 in comparison to corn plots with fall manure-CP (21.6 mg l−1) and UAN-CP systems (15.9 mg l−1). Averaged across five years, about 60% of tile flow and NO3-N leaching losses exited the fields during March through May. Growing season precipitation and cycles of wet and dry years primarily controlled NO3-N leaching losses from tile drained fields. These results suggest that spring applied manure has potential to reduce NO3-N concentrations in subsurface drainage water and also strategies need to be developed to reduce early spring NO3-N leaching losses.

ACS Style

A. Bakhsh; R. S. Kanwar; C. Pederson; T. B. Bailey. N-Source Effects on Temporal Distribution of NO3-N Leaching Losses to Subsurface Drainage Water. Water, Air, & Soil Pollution 2006, 181, 35 -50.

AMA Style

A. Bakhsh, R. S. Kanwar, C. Pederson, T. B. Bailey. N-Source Effects on Temporal Distribution of NO3-N Leaching Losses to Subsurface Drainage Water. Water, Air, & Soil Pollution. 2006; 181 (1):35-50.

Chicago/Turabian Style

A. Bakhsh; R. S. Kanwar; C. Pederson; T. B. Bailey. 2006. "N-Source Effects on Temporal Distribution of NO3-N Leaching Losses to Subsurface Drainage Water." Water, Air, & Soil Pollution 181, no. 1: 35-50.

Journal article
Published: 01 December 2006 in JAWRA Journal of the American Water Resources Association
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ACS Style

Rameshwar S. Kanwar. EFFECTS OF CROPPING SYSTEMS ON NO3-N LOSSES TO TILE DRAIN1. JAWRA Journal of the American Water Resources Association 2006, 42, 1493 -1501.

AMA Style

Rameshwar S. Kanwar. EFFECTS OF CROPPING SYSTEMS ON NO3-N LOSSES TO TILE DRAIN1. JAWRA Journal of the American Water Resources Association. 2006; 42 (6):1493-1501.

Chicago/Turabian Style

Rameshwar S. Kanwar. 2006. "EFFECTS OF CROPPING SYSTEMS ON NO3-N LOSSES TO TILE DRAIN1." JAWRA Journal of the American Water Resources Association 42, no. 6: 1493-1501.

Journal article
Published: 01 April 2005 in JAWRA Journal of the American Water Resources Association
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Grouping of nitrate‐nitrogen (NO3‐N) leaching losses from agricultural fields into spatial clusters can help determine the cause/effect relationships for their occurrence. This study was designed to investigate the spatial relationships of low, medium, and high NO3‐N leaching losses clusters with soil and landscape attributes using cluster and discriminant analysis and the map overlay capability of a geographical information system (GIS). Field measured data of a six‐year (1993 through 1998) study on NO3‐N leaching losses from 36 experimental fields at the Iowa State University's northeastern research center near Nashua, Iowa, were normalized on an annual basis to compare over the years. The cluster analysis resulted in the formation of three clusters based on the satisfactory evaluation criteria of pseudo‐F statistic, cubic clustering criterion, and R2 values. The discriminant analysis, carried out on the basis of clusters, identified elevation and subsurface drainage as the factors that contributed significantly (p > 0.01) in discriminating among these clusters. The verification of discriminant functions developed on these factors predicted the cluster membership for all the groups with an overall accuracy of 86 percent. The map overlay analyses of GIS showed that spatial occurrence of the clusters transporting high NO3‐N leaching losses was affected by the interaction of soil type and elevation levels.

ACS Style

Allah Bakhsh; Ramesh S. Kanwar. SPATIAL CLUSTERS OF SUBSURFACE DRAINAGE WATER NO3-N LEACHING LOSSES. JAWRA Journal of the American Water Resources Association 2005, 41, 333 -341.

AMA Style

Allah Bakhsh, Ramesh S. Kanwar. SPATIAL CLUSTERS OF SUBSURFACE DRAINAGE WATER NO3-N LEACHING LOSSES. JAWRA Journal of the American Water Resources Association. 2005; 41 (2):333-341.

Chicago/Turabian Style

Allah Bakhsh; Ramesh S. Kanwar. 2005. "SPATIAL CLUSTERS OF SUBSURFACE DRAINAGE WATER NO3-N LEACHING LOSSES." JAWRA Journal of the American Water Resources Association 41, no. 2: 333-341.

Conference paper
Published: 02 December 2004 in Proceedings of the Integrated Crop Management Conference
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ACS Style

Melissa R. Cheatham; R. S. Kanwar; J. Lorimor; H. Xin; C. Pedersen. Poulty Manure Impacts on Water Quality. Proceedings of the Integrated Crop Management Conference 2004, 1 .

AMA Style

Melissa R. Cheatham, R. S. Kanwar, J. Lorimor, H. Xin, C. Pedersen. Poulty Manure Impacts on Water Quality. Proceedings of the Integrated Crop Management Conference. 2004; ():1.

Chicago/Turabian Style

Melissa R. Cheatham; R. S. Kanwar; J. Lorimor; H. Xin; C. Pedersen. 2004. "Poulty Manure Impacts on Water Quality." Proceedings of the Integrated Crop Management Conference , no. : 1.