Dissolved Constituents in Agricultural Drainage Waters

2017 ◽  
Vol 60 (3) ◽  
pp. 847-859 ◽  
Author(s):  
Brett A Zimmerman ◽  
Amy L Kaleita
Keyword(s):  
Literature Review ◽  
Cropping Systems ◽  
Ionic Composition ◽  
Calcium Nitrate ◽  
Growing Season ◽  
Subsurface Drainage ◽  
Mineral Weathering ◽  
Agricultural Drainage ◽  
Drainage Waters ◽  
Chloride Concentrations

Abstract. Efflux of dissolved solutes in agricultural subsurface drainage systems adversely affects the ecosystems of receiving waters, degrades soil fertility, and represents an economic loss to farmers. These solutes are frequently studied without regard to their associated ions, which play a fundamental role in their transport characteristics. In this study, we conducted a literature review to identify major dissolved constituents in agricultural drainage waters characteristic of central Iowa and pinpointed causes of variability in the leaching rate of these constituents. This literature review is complemented by a thorough field investigation that analyzes major solute concentrations with respect to seasonal conditions, common cropping systems, and relationships among ions. Results from this investigation reveal that primary dissolved constituents consist of bicarbonate, calcium, nitrate, magnesium, chloride, sodium, and sulfate (in order of decreasing ppm concentration). Analysis of seasonal drainage samples showed that bicarbonate, calcium, and magnesium were present at greater concentrations during the post-growing season, while nitrate and chloride concentrations were greatest during the growing season. Seasonal variability of sulfate and sodium was negligible. Continuous corn and corn in annual rotation with soybeans had greater magnesium and chloride concentrations than soybeans in annual rotation with corn. Conversely, calcium concentrations were greater for soybean cropping systems compared to corn cropping systems. Bicarbonate and nitrate were not significantly different among any of the cropping systems. A strong correlation between bicarbonate and calcium suggests that agricultural lime dissolution was caused by mineral weathering, rather than by acidification due to N fertilizer applications or nitrification. An analysis of observed drainage flows, pH, and temperatures suggested that these parameters were not good indicators of differences in ionic composition. Keywords: Bicarbonate, Dissolved ions, Nitrate, pH, Subsurface drainage.

Electrical Conductivity of Agricultural Drainage Water in Iowa

2017 ◽  
Vol 33 (3) ◽  
pp. 369-378 ◽  
Author(s):  
Brett A Zimmerman ◽  
Amy L Kaleita
Keyword(s):  
Electrical Conductivity ◽  
Environmental Conditions ◽  
Major Ions ◽  
Ionic Composition ◽  
Field Investigation ◽  
Drainage Water ◽  
Specific Electrical Conductivity ◽  
Agricultural Drainage ◽  
Bulk Electrical Conductivity ◽  
Drainage Waters

Abstract. Assessing the effectiveness of management strategies to reduce agricultural nutrient efflux is hampered by the lack of affordable, continuous monitoring systems. Generalized water quality monitoring is possible using electrical conductivity. However environmental conditions can influence the ionic ratios, resulting in misinterpretations of established electrical conductivity and ionic composition relationships. Here we characterize specific electrical conductivity (k25) of agricultural drainage waters to define these environmental conditions and dissolved constituents that contribute to k25. A field investigation revealed that the magnitude of measured k25 varied from 370 to 760 µS cm-1. Statistical analysis indicated that variability in k25 was not correlated with drainage water pH, temperature, nor flow rate. While k25 was not significantly different among drainage waters from growing and post-growing season, significant results were observed for different cropping systems. Soybean plots in rotation with corn had significantly lower conductivities than those of corn plots in rotation with soybeans, continuous corn plots, and prairie plots. In addition to evaluating k25 variability, regression analysis was used to estimate the concentration of major ions in solution from measured k25. Regression results indicated that HCO3-, Ca2+, NO3-, Mg2+, Cl-, Na2+, SO42- were the major drainage constituents contributing to the bulk electrical conductivity. Calculated ionic molal conductivities of these analytes suggests that HCO3-, Ca2+, NO3-, and Mg2+ account for approximately 97% of the bulk electrical conductivity. Keywords: Electrical conductivity, Salinity, Subsurface drainage, Total dissolved solids.

scholarly journals Effect of Heat Resource Effectiveness Change on Rice Potential Yield in Southern China

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 896
Author(s):  
Qing Ye ◽  
Xiaoguang Yang ◽  
Wenjuan Xie ◽  
Junmeng Yao ◽  
Zhe Cai
Keyword(s):  
Southern China ◽  
Cropping Systems ◽  
Reduction Rate ◽  
Growing Season ◽  
Scientific Basis ◽  
Yield Reduction ◽  
Percentage Increase ◽  
Potential Yield ◽  
Effective Heat ◽  
Rice Growing Season

During the rice growing season, farmers’ decisions about cropping systems and seed varieties directly affect the utilization of heat resource, and eventually affect the potential yield. In this study, we used the hourly accumulated temperature model to calculate the available heat resource as well as the effective heat resource in southern China. We conducted a spatiotemporal analysis of the heat resource effectiveness during rice growing season and an impact assessment of heat resource effectiveness on rice potential yield and cereal yield reduction. The results showed that, during the period of 1951–2015, heat resource effectiveness generally declined in the rice cropping area of southern China. And this decrease worsened during the most recent three decades compared with the period of 1951–1980. A strong correlation was detected between heat resource effectiveness and rice potential yield in the study area. When the effective heat resource during the growing season increased by 1 °C·d, rice potential yield would increase by 14 kg ha−1. For each percentage increase in heat resource effectiveness, the rice potential yield reduction rate would go down by 0.65%. This agro-climatological study aims to offer a scientific basis for rice production decisions in southern China, such as when to plant, which varieties to choose and so on.

scholarly journals Identifying maize yield and precipitation gaps in Uganda

2021 ◽  
Vol 3 (5) ◽  
Author(s):  
Terence Epule Epule ◽  
Driss Dhiba ◽  
Daniel Etongo ◽  
Changhui Peng ◽  
Laurent Lepage
Keyword(s):  
Cropping Systems ◽  
Growing Season ◽  
Maize Yield ◽  
Sub Saharan Africa ◽  
World Bank Group ◽  
Precipitation Data ◽  
Yield Data ◽  
Yield Gaps ◽  
Maize Yields ◽  
Growing Season Precipitation

AbstractIn sub-Saharan Africa (SSA), precipitation is an important driver of agricultural production. In Uganda, maize production is essentially rain-fed. However, due to changes in climate, projected maize yield targets have not often been met as actual observed maize yields are often below simulated/projected yields. This outcome has often been attributed to parallel gaps in precipitation. This study aims at identifying maize yield and precipitation gaps in Uganda for the period 1998–2017. Time series historical actual observed maize yield data (hg/ha/year) for the period 1998–2017 were collected from FAOSTAT. Actual observed maize growing season precipitation data were also collected from the climate portal of World Bank Group for the period 1998–2017. The simulated or projected maize yield data and the simulated or projected growing season precipitation data were simulated using a simple linear regression approach. The actual maize yield and actual growing season precipitation data were now compared with the simulated maize yield data and simulated growing season precipitation to establish the yield gaps. The results show that three key periods of maize yield gaps were observed (period one: 1998, period two: 2004–2007 and period three: 2015–2017) with parallel precipitation gaps. However, in the entire series (1998–2017), the years 2008–2009 had no yield gaps yet, precipitation gaps were observed. This implies that precipitation is not the only driver of maize yields in Uganda. In fact, this is supported by a low correlation between precipitation gaps and maize yield gaps of about 6.3%. For a better understanding of cropping systems in SSA, other potential drivers of maize yield gaps in Uganda such as soils, farm inputs, crop pests and diseases, high yielding varieties, literacy, and poverty levels should be considered.

scholarly journals Soil microbial biomass and function are altered by 12 years of crop rotation

2016 ◽  
Author(s):  
Marshall D. McDaniel ◽  
A. Stuart Grandy
Keyword(s):  
Microbial Community ◽  
Microbial Biomass ◽  
Crop Rotation ◽  
Soil Microbial Biomass ◽  
Cropping Systems ◽  
Growing Season ◽  
Plant Biodiversity ◽  
Soil Microbial ◽  
Catabolic Potential ◽  
And Function

Abstract. Agriculture-driven declines in plant biodiversity reduce soil microbial biomass, alter microbial functions, and threaten the provisioning of soil ecosystem services. We examined whether increasing temporal plant biodiversity (by rotating crops) can partially reverse these trends and enhance microbial biomass and function. We quantified seasonal patterns in soil microbial biomass, respiration rates, extracellular enzyme activity, and catabolic potential three times over one growing season in a 12-year crop rotation study at the W.K. Kellogg Biological Station LTER. Rotation treatments varied from one to five crops in a three-year rotation cycle, but all soils were sampled under corn to isolate historical rotation effects from current crop effects. Inorganic N, the stoichiometry of microbial biomass and dissolved organic C and N varied seasonally, likely reflecting fluctuations in soil resources during the growing season. Soils from biodiverse cropping systems increased microbial biomass C by 28–112 % and N by 18–58 % compared to monoculture corn. Rotations increased potential C mineralization by as much as 64 %, and potential N mineralization by 62 %, and both were related to substantially higher hydrolase and lower oxidase enzyme activities. The catabolic potential of the microbial community, assessed with community-level physiological profiling, showed that microbial communities in monoculture corn preferentially used simple substrates like carboxylic acids, relative to more diverse cropping systems. By isolating plant biodiversity from differences in fertilization and tillage, our study illustrates that crop biodiversity has overarching effects on soil microbial biomass and function that last throughout the growing season. In simplified agricultural systems, relatively small increases in plant biodiversity have a large impact on microbial community size and function.

scholarly journals Policy-Driven Sustainable Saline Drainage Disposal and Forage Production in the Western San Joaquin Valley of California

2020 ◽  
Vol 12 (16) ◽  
pp. 6362
Author(s):  
Amninder Singh ◽  
Nigel W. T. Quinn ◽  
Sharon E. Benes ◽  
Florence Cassel
Keyword(s):  
Root Zone ◽  
Subsurface Drainage ◽  
Drainage Water ◽  
Agricultural Drainage ◽  
Forage Production ◽  
Tall Wheatgrass ◽  
San Joaquin River ◽  
Agricultural Drainage Water ◽  
Irrigation Drainage ◽  
Root Zone Salinity

Environmental policies to address water quality impairments in the San Joaquin River of California have focused on the reduction of salinity and selenium-contaminated subsurface agricultural drainage loads from westside sources. On 31 December 2019, all of the agricultural drainage from a 44,000 ha subarea on the western side of the San Joaquin River basin was curtailed. This policy requires the on-site disposal of all of the agricultural drainage water in perpetuity, except during flooding events, when emergency drainage to the River is sanctioned. The reuse of this saline agricultural drainage water to irrigate forage crops, such as ‘Jose’ tall wheatgrass and alfalfa, in a 2428 ha reuse facility provides an economic return on this pollutant disposal option. Irrigation with brackish water requires careful management to prevent salt accumulation in the crop root zone, which can impact forage yields. The objective of this study was to optimize the sustainability of this reuse facility by maximizing the evaporation potential while achieving cost recovery. This was achieved by assessing the spatial and temporal distribution of the root zone salinity in selected fields of ‘Jose’ tall wheatgrass and alfalfa in the drainage reuse facility, some of which have been irrigated with brackish subsurface drainage water for over fifteen years. Electromagnetic soil surveys using an EM-38 instrument were used to measure the spatial variability of the salinity in the soil profile. The tall wheatgrass fields were irrigated with higher salinity water (1.2–9.3 dS m−1) compared to the fields of alfalfa (0.5–6.5 dS m−1). Correspondingly, the soil salinity in the tall wheatgrass fields was higher (12.5 dS m−1–19.3 dS m−1) compared to the alfalfa fields (8.97 dS m−1–14.4 dS m−1) for the years 2016 and 2017. Better leaching of salts was observed in the fields with a subsurface drainage system installed (13–1 and 13–2). The depth-averaged root zone salinity data sets are being used for the calibration of the transient hydro-salinity computer model CSUID-ID (a one-dimensional version of the Colorado State University Irrigation Drainage Model). This user-friendly decision support tool currently provides a useful framework for the data collection needed to make credible, field-scale salinity budgets. In time, it will provide guidance for appropriate leaching requirements and potential blending decisions for sustainable forage production. This paper shows the tie between environmental drainage policy and the role of local governance in the development of sustainable irrigation practices, and how well-directed collaborative field research can guide future resource management.

Use of ionic and zwitterionic (Tris/BisTris and HEPES) buffers in studies on hemoglobin function

1992 ◽  
Vol 72 (4) ◽  
pp. 1611-1615 ◽  
Author(s):  
R. E. Weber
Keyword(s):  
Binding Sites ◽  
Ionic Composition ◽  
Oxygen Affinity ◽  
Chloride Concentration ◽  
Anion Binding ◽  
Chloride Binding ◽  
Ph Values ◽  
Two Temperatures ◽  
Ethanesulfonic Acid ◽  
Chloride Concentrations

The functional characteristics of hemoglobin (Hb) depend on oxygenation-linked proton and anion binding and thus on solvent buffer groups and ionic composition. This study compares the oxygenation properties of human Hb in ionic [tris(hydroxymethyl)aminomethane (Tris) and BisTris] buffers with those in zwitterionic N-2-hydroxy-ethylpiperazine-N′-2-ethanesulfonic acid (HEPES) buffer under strictly controlled chloride concentrations at different pH values, two temperatures, and in the absence and presence of the erythrocytic cofactor, 2,3-diphosphoglycerate (DPG). In contrast to earlier studies (carried out at the same or different chloride concentrations) it shows only small buffer effects that are manifested at low chloride concentration and high pH. These observations suggest chloride binding to the Tris buffers, which reduces the interaction with specific chloride binding sites in the Hb. The findings indicate that HEPES allows for more accurate assessment of Hb-oxygen affinity and its anion and temperature sensitivities than ionic buffers and advocates standard use of HEPES in studies on Hb function. Precise oxygen affinities of Hb dissolved in both buffers are defined under standard conditions.

Rotational Cropping Systems to Reduce Cheat (Bromus secalinus) Densities

2006 ◽  
Vol 20 (2) ◽  
pp. 445-452 ◽  
Author(s):  
Jon C. Stone ◽  
Thomas F. Peeper ◽  
Amanda E. Stone
Keyword(s):  
Winter Wheat ◽  
Great Plains ◽  
Cropping Systems ◽  
Control Strategies ◽  
Growing Season ◽  
Grain Sorghum ◽  
Economic Returns ◽  
Southern Great Plains ◽  
Net Returns ◽  
Bromus Secalinus

In the Southern Great Plains, producers of hard red winter wheat seek sustainable methods for controlling cheat and improving economic returns. Experiments were conducted at two sites in north-central Oklahoma to determine the effect of cheat management programs, with various weed control strategies, on cheat densities and total net returns. The cheat management programs, initiated following harvest of winter wheat, included conventionally tilled, double-crop grain sorghum (Sorghum bicolorL.) followed by soybean (Glycine maxL.); and continuous winter wheat. Rotating out of winter wheat for one growing season increased yield of succedent wheat up to 32% and 42% at Billings and Ponca City, respectively. Dockage due to cheat in the succedent wheat was reduced up to 78% and 87% by rotating out of winter wheat for one growing season at Billings and Ponca City, respectively. Cheat management programs including a crop rotation with herbicides applied to the grain sorghum, except for an application of atrazine + metolachlor at Ponca City, improved total net returns over the nontreated continuous wheat option. Cheat panicles in the succedent wheat were reduced up to 87% by rotation out of winter wheat for one growing season.

Breeding lucerne for Australia's southern dryland cropping environments

2001 ◽  
Vol 52 (2) ◽  
pp. 153 ◽  
Author(s):  
A. W. Humphries ◽  
G. C. Auricht
Keyword(s):  
Literature Review ◽  
Cropping Systems ◽  
Soil Conditions ◽  
Saline Soils ◽  
Breeding Strategies ◽  
Forage Legume ◽  
Grain Production ◽  
Acidic Soils ◽  
Dryland Salinity ◽  
Cereal Production

Lucerne is a deep-rooted perennial forage legume with an important role in preventing dryland salinity in southern Australian cropping regions. Annual cereal production has created a water-use imbalance, which is placing the industry under threat through rising saline watertables and resultant dryland salinity. Lucerne is being incorporated into cropping systems to reduce groundwater recharge and improve the sustainability of grain production. Existing lucerne varieties have been developed for the animal industries, primarily for the areas with high rainfall or irrigation. The new challenge is to develop lucernes specifically for southern Australian cropping systems. This paper provides a background literature review of the breeding challenges that are anticipated in the development of these new types of lucerne. Lucerne is intolerant of acidic soils, waterlogging, saline soils, and intensive grazing. Other important attributes covered include the ability of the plant to fix nitrogen with existing rhizobia and be resistant to diseases that affect lucerne and other crops in the rotation. Finally, this paper addresses some of the breeding strategies that will be used to screen lucerne germplasm for tolerances to these soil conditions and diseases.

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