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Articles 1 - 21 of 21

Full-Text Articles in Life Sciences

What's In Your Nitrogen Budget?, Robert Mikkelsen Aug 2012

What's In Your Nitrogen Budget?, Robert Mikkelsen

Robert Mikkelsen

No abstract provided.


Magnesium: An Overlooked Nutrient?, Robert Mikkelsen Jun 2011

Magnesium: An Overlooked Nutrient?, Robert Mikkelsen

Robert Mikkelsen

Magnesium nutrition of plants is frequently overlooked and shortages can adversely impact plant growth. Many essential functions require adequate Mg supplies... the most visible being its role in chlorophyll and photosynthesis... but less visible reactions are also dependent on an adequate supply of Mg. When needed, a variety of soluble and slowly soluble Mg sources are available to meet crop demands.


Container Substrate Temperatures Affect Mineralization Of Composts, Helen T. Kraus, Robert Mikkelsen, Stuart L. Warren Jan 2000

Container Substrate Temperatures Affect Mineralization Of Composts, Helen T. Kraus, Robert Mikkelsen, Stuart L. Warren

Robert Mikkelsen

Traditional N mineralization studies have been conducted by soil scientists using soils and temperatures found in field production. As temperature, in part, governs the rate of mineralization, and container substrates reach much higher temperatures than do soils, the effect of these elevated temperatures on mineralization must be considered to begin to understand N mineralization in container substrates during production. The N mineralization patterns of three composts [turkey (Meleagris gallopavo) litter, yard waste, and municipal waste] were determined under three temperature regimes (45, 25, and 45/25 °C). More organic N was mineralized from composted turkey litter (CTL) than from municipal ...


Beneficial Use Of Swine By-Products: Opportunities For The Future, Robert Mikkelsen Jan 2000

Beneficial Use Of Swine By-Products: Opportunities For The Future, Robert Mikkelsen

Robert Mikkelsen

No abstract provided.


A Comparison Of Three Methods For Determining Root-Knot Nematode Infection Of Cotton Roots, Robert G. Mcbride, Robert Mikkelsen Jan 1999

A Comparison Of Three Methods For Determining Root-Knot Nematode Infection Of Cotton Roots, Robert G. Mcbride, Robert Mikkelsen

Robert Mikkelsen

Three methods for determining the extent of infection of cotton roots (Gossypium hirsutum L.) by root-knot nematode, Meloidogyne incognita (Kofoid and White) Chitwood, were compared. Root-knot nematode eggs were added to pots containing either sterilized soil or soil amended with rye, and cotton seedlings were planted. Cotton root systems were then assessed for infection/damage after 14 and 28 days of exposure. At the 14-day sampling, the roots were stained, using the lactophenol acid fuchsin method and the juvenile nematodes counted. At the 28-day samplings, the cotton roots were given a visual rating for nematode-induced root galling (0-100), and the ...


Swine Waste Disposal Dilemma, Robert Mikkelsen Jan 1995

Swine Waste Disposal Dilemma, Robert Mikkelsen

Robert Mikkelsen

The swine industry has grown rapidly in North Carolina in the past decade, with the majority of the growth occurring in a few counties in the Coastal Plain region of the state. With this expansion has come the problem of swine waste disposal. Mr. Blevins, a local farmer in this region, has been raising swine since 1985. The swine waste on his farm is collected in an anaerobic lagoon and then irrigated onto a bermudagrass (Cynodon dactylon(L.) Pers.) pasture where cattle are fed using intensive rotational grazing techniques. A study of Mr. Blevins' farm revealed very high nitrate concentrations ...


Using Hydrophilic Polymers To Control Nutrient Release, Robert Mikkelsen Jan 1994

Using Hydrophilic Polymers To Control Nutrient Release, Robert Mikkelsen

Robert Mikkelsen

Using diverse technological approaches, many types of delivery devices have been used to supply plant nutrients at a controlled rate in the soil. One new approach is the use of hydrophilic polymers as carriers of plant nutrients. These polymers may be generally classified as 1) natural polymers derived from polysaccharides, 2) semi-synthetic polymers (primarily cellulose derivatives), and 3) synthetic polymers. By controlling the reaction conditions when forming the polymers, various degrees of cross-linking, anionic charge, and cationic charge can be added, thereby changing their effectiveness as fertilizer carriers. When fertilizer-containing solutions are mixed with hydrophilic polymers to form a "gel ...


Addition Of Gel-Forming Hydrophilic Polymers To Nitrogen Fertilizer Solutions, Robert Mikkelsen, A David Behel Jan 1993

Addition Of Gel-Forming Hydrophilic Polymers To Nitrogen Fertilizer Solutions, Robert Mikkelsen, A David Behel

Robert Mikkelsen

Environmental and economic concerns are causing a search for more effective fe rtilizer products and improved methods for managing existing fertilizers. This laboratory and greenhouse study was conducted to determine if the addition of gel-forming hydrophilic polymers to N fertilizer solutions could reduce N leaching loss and increase plant uptake of N. In the first experiment, a solution of urea ammonium nitrate (UAN, 32% N) was mixed with a variety of polymers at three concentrations, band applied to a sandy soil, and leached weekly for six weeks. Nitrogen leaching losses were reduced from 0 to 45% during the first four ...


Controlled-Release Fertilizers To Increase Efficiency Of Nutrient Use And Minimize Environmental Degradation - A Review, Avi Shaviv, Robert Mikkelsen Jan 1993

Controlled-Release Fertilizers To Increase Efficiency Of Nutrient Use And Minimize Environmental Degradation - A Review, Avi Shaviv, Robert Mikkelsen

Robert Mikkelsen

Total world consumption of fertilizer N, P2 O5, and K2O in 1990 / 1991 was 78. 37. and 26 million tons per annum respectively, with a projected yearly increase of demand of about 2 to 3% . Trends in crop production (maize and wh eat) in the last four decades s how that N application rates increased about 15 times whereas its accumulation in grain increased only 3 to 4 times. At the same time nutrient recovery by crops remained relatively low (e .g. a bout 50% for N). This represents a potentially alarming situation from environmental, economic and resource conservation points ...


The Effect Of Selenium On Sulfur Uptake By Barley And Rice, Robert Mikkelsen, Hongfu Wan Jan 1990

The Effect Of Selenium On Sulfur Uptake By Barley And Rice, Robert Mikkelsen, Hongfu Wan

Robert Mikkelsen

Because of their chemical and physical similarities, plant uptake of sulfur and selenium are closely related. Barley and rice were grown in greenhouse solution culture to examine the synergistic interactions between sulfate and selenate in plant uptake. In the presence of low concentrations of solution sulfate, shoot and root yields were decreased with additions of selenate. However, when sulfate was present in elevated concentrations, no selenium-induced yield reductions occurred. A synergistic interaction between sulfate and selenate caused an increase in the shoot sulfur concentrations with increasing concentrations of selenate at low sulfate solution concentrations. At elevated sulfate concentrations, no synergism ...


Biuret In Urea Fertilizer, Robert Mikkelsen Jan 1990

Biuret In Urea Fertilizer, Robert Mikkelsen

Robert Mikkelsen

Urea has become the leading form of N fertilizer worldwide. Historically there has been concern about biuret formed during the manufacturing of urea fertilizer and the potential adverse effect of biuret on plant growth. In this paper, the fate of biuret in soils and its phytotoxicity is reviewed. Biuret is mineralized by many soil micoorganisms, but the process is much slower than for urea. Excessively high biuret concentrations can damage seedlings and, like urea, should not be placed in close proximity to germinating seeds. Crop tolerance to biuret varies according to the plant species, soil conditions, fertilizer placement, and method ...


Phosphorus Fertilization Through Drip Irrigation, Robert Mikkelsen Jan 1989

Phosphorus Fertilization Through Drip Irrigation, Robert Mikkelsen

Robert Mikkelsen

Although P fertilization through drip irrigation systems has not been widely recommended, a review of currently available literature indicates this fertilizer application technique can offer many advantages when performed properly. Using drip irrigation to apply P fertilizer allows nutrient placement directly into the plant root zone during critical periods of nutrient demand. Less P fertilizer is generally required to achieve sufficient tissue P concentrations and equivalent yields when it is drip-applied than with other application methods. The distribution of drip-applied P in soil depends on soil properties, the source of P fertilizer, the rate of application, and the amount of ...


Factors Affecting Selenium Accumulation By Agricultural Crops, Robert Mikkelsen, Albert L. Page, Frank T. Bingham Jan 1989

Factors Affecting Selenium Accumulation By Agricultural Crops, Robert Mikkelsen, Albert L. Page, Frank T. Bingham

Robert Mikkelsen

The accumulation of selenium by plants is of concern worldwide. Many regions grow crops that contain insufficient Se to meet animal nutritional requirements. In these locations with low Se, efforts have been made to increase tissue Se concentrations. Other areas have problems with excessive Se found in vegetation grown on seleniferous soils. Plant species vary in their ability to accumulate and tolerate Se. Selenium accumulator plants can accumulate extremely high Se concentrations (several thousand mg Se kg-1) when grown in seleniferous soils, whereas typical agricultural crops have a much lower Se tolerance (<50 mg Se kg>-1 ). It has been suggested that Se may ...


Application Of Urea Phosphate And Urea Sulfate To Drip-Irrigated Tomatoes Grown In Calcareous Soil, Robert Mikkelsen, Wesley Jarrell Jan 1987

Application Of Urea Phosphate And Urea Sulfate To Drip-Irrigated Tomatoes Grown In Calcareous Soil, Robert Mikkelsen, Wesley Jarrell

Robert Mikkelsen

The potential benefit of acid applied through drip urrigation on soil nutrient availability, plant nutrition, and yield was studied. Tomatoes (Lycopersicon esculentum Mill., cv. Better Boy) were grown in a P-deficient calcareous loam soil in 114-L plastic-lined cans. Phosphorus was added weekly through drip irrigation as urea phosphate (UP) (17-19-0) at four concentrations (0, 20, 40, 80 kg P/ha). Two other treatments entailed 40 kg P/ha soil-banded triple superphosphate (TSP) (0-20-0) with or without the addition of drip­ applied urea sulfate (US) (15-0-0-16). Urea sulfate was added at the rate equivalent to the titratable acidity of the 40 ...


Tva Fluid Fertilizers Chapter Two - Agronomic Aspects, Eugene C. Sample, Gary W. Akin, Robert Mikkelsen Jan 1984

Tva Fluid Fertilizers Chapter Two - Agronomic Aspects, Eugene C. Sample, Gary W. Akin, Robert Mikkelsen

Robert Mikkelsen

No abstract provided.


Tva Fluid Fertilizers Chapter One- History, Growth, And Status, Robert Mikkelsen Jan 1984

Tva Fluid Fertilizers Chapter One- History, Growth, And Status, Robert Mikkelsen

Robert Mikkelsen

No abstract provided.


Tva Fluid Fertilizers Chapter Four - Chemical Properties, A W. Frazier Jan 1984

Tva Fluid Fertilizers Chapter Four - Chemical Properties, A W. Frazier

Robert Mikkelsen

No abstract provided.


Tva Fluid Fertilizers Chapter Five - Production, Handling, And Use Of Anydrous Ammonia And Status, G. M. Blouin, H. L. Kimborough, W. J. Sharratt Jan 1984

Tva Fluid Fertilizers Chapter Five - Production, Handling, And Use Of Anydrous Ammonia And Status, G. M. Blouin, H. L. Kimborough, W. J. Sharratt

Robert Mikkelsen

No abstract provided.


Greenhouse Techniques For Soil-Plant-Fertilizer Research, S E. Allen, G L. Terman, L B. Clements, Robert Mikkelsen May 1976

Greenhouse Techniques For Soil-Plant-Fertilizer Research, S E. Allen, G L. Terman, L B. Clements, Robert Mikkelsen

Robert Mikkelsen

PART 2: Special problems and procedures Principles of nutrient uptake in pot experiments


Greenhouse Techniques For Soil - Plant - Fertilizer Research, S E. Allen, G L. Terman, L B. Clements, Robert Mikkelsen May 1976

Greenhouse Techniques For Soil - Plant - Fertilizer Research, S E. Allen, G L. Terman, L B. Clements, Robert Mikkelsen

Robert Mikkelsen

PART 3: Design & sample calculaitons for specific types of experiments Typical greenhouse report References


Greenhouse Techniques For Soil-Plant-Fertilizer Research, S E. Allen, G L. Terman, L B. Clements, Robert Mikkelsen May 1976

Greenhouse Techniques For Soil-Plant-Fertilizer Research, S E. Allen, G L. Terman, L B. Clements, Robert Mikkelsen

Robert Mikkelsen

PART 1: Introduction Greenhouse facilities General techniques