Tube Pre

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ART USB Dual Tube Pre $149 The ART USBDualTubePre is a compact, dual-channel tube preamp designed for any basic recording system. Capable of operating as a standalone unit with USB audio interface, or as an expander for any digital system with S/PDIF digital input, each channel in the USBDualTubePre delivers superior tube tone in a fully featured input strip.Each input of the USBDualTubePre has independent input gain control and output level, phase inversion, low frequency roll-off, true 48V phantom power, and a user-defeatable optocompressor circuitcapable of ensuring superior dynamic control of any input source.For monitoring, an 1/8" mini headphone jack with level and monitor mix controls allow latency-free monitoring of the inputs while recording, as well as playback monitoring of audio mix via USB bus. The monitor mix is also routed to 1/4" TRS (balanced) outputs with separate level control for control room monitor source.The USB interface is fully USB compliant. No special drivers are needed.

Art Usb Dual Tube Pre $149 The ART USBDualTubePre is a compact, dual-channel tube preamp designed for any basic recording system. Capable of operating as a standalone unit with USB audio interface, or as an expander for any digital system with S/PDIF digital input, each channel in the USBDualTubePre delivers superior tube tone in a fully featured input strip.Each input of the USBDualTubePre has independent input gain control and output level, phase inversion, low frequency roll-off, true 48V phantom power, and a user-defeatable optocompressor circuitcapable of ensuring superior dynamic control of any input source.For monitoring, an 1/8" mini headphone jack with level and monitor mix controls allow latency-free monitoring of the inputs while recording, as well as playback monitoring of audio mix via USB bus. The monitor mix is also routed to 1/4" TRS (balanced) outputs with separate level control for control room monitor source.The USB interface is fully USB compliant. No special drivers are needed.Two-channel tube-based Mic/Instrument preamp computer interfaceExtremely low noise discrete front end with variable input and output controlsAdvanced optical output compressor to simplify recording and prevent overloadUSB connectivity to desktop and laptop computersS/PDIF output for expanding inputs on digital workstations and computer interfacesLatency free Monitoring Mix and Level controlsBalanced XLR for lo-Z applications and 1/4" hi-Z inputs for instrument DI applicationsSeparate Gain, Phase Invert, Low Cut Filter and Compressor switches on each inputSelectable Dual or Stereo operation of output controlsSwitch selectable Inserts on each channelInsert jacks provide a preamp direct out for each channelStereo/ Dual operation of Optical CompressorMono switch for single input monitoringS/PDIF Sample Rate switch selectable between 44.1K and 48KPrecision LED metering of both the preamp and A/D sectionsBuilt-in low noise +48 Volt phantom power supplyCompact, stackable all aluminum chassis

Drawmer 1960 Mic Pre/Tube Compressor $2250 Combining eight active tube stages and the low noise and reliability of solid state electronics, the Drawmer 1960 provides the ultimate direct interface between the sound source and the recording medium. The Drawmer 1960 is a two channel unit with each channel comprised of a completely natural sounding "soft knee" vacuum tube compressor and an extremely low noise microphone pre-amplifier with switchable 48 volt phantom power. A further auxiliary instrument pre-amp with EQ is also provided. This powerful combination of the classic valve circuit, offering unsurpassed tonality, and the low noise balanced microphone input with up to 60dB of gain has allowed engineers throughout the world to exploit the full potential of high performance condenser microphones. An example of this would be the direct to digital stereo recording of live classical music without the necessity of a mixing console. The Compressor: Because the compressor is a soft knee type, it requires few controls. Strictly speaking, a soft knee design does not have a rigidly defined threshold but the title 'Threshold' has been retained for the "amount of compression" control for the sake of familiarity. The Threshold range is continuously variable between infinity and -24dB, the theory being that signals below the threshold are essentially unprocessed and the signals exceeding this threshold are subjected to increasing amounts of gain reduction dependent on by how much they exceed the threshold._The attack and release times are switchable rather than being continuously variable and this method of operation falls into line with that of its all valve predecessors. Attack simply offers a-choice of slow, medium and fast whilst release has six settings. Positions one to four have fixed release times whilst positions five and six are two different programme dependent release time modes making the unit ideally suited to programme material with complex dynamics such as complete stereo mixes and vocals. Interestingly, the attack times are further modified by the choice of release setting so the range of choices are wider than it might first appear. Because compression is a form of controlled gain reduction, a stage of make-up amplification follows the compressor section giving a range of +20dB. The VU meters may be switched to monitor either the amount of gain reduction taking place or the output signal level and the two channels may be used either independently or as a stereo pair, depending on the setting of the stereo link switch. The side chain access points may be used to patch in equalisers to enable the compressor to act as a de-esser. As with other Drawmer products, the by-pass switch offers a choice of Normal. By-pass and Side Chain Listen modes so that if you have patched in any additional side chain processing, you can easily monitor what effect it is having. In addition to the balanced microphone and line inputs on the rear of the unit an auxiliary input on the front panel gives dir

Drawmer 1969 Mercenary Edition Mic Pre Amp/Tube Compressor $2575 The 1969 Mercenary Edition, derived from a collaboration between two of the audio industry's most established names, Drawmer (UK) and Mercenary Audio (USA), Fletcher - Producer/Engineer, Mercenary Audio incorporates new tube circuits designed to add warmth to mic/line signals, and the instrument (DI) pre-amp has its own tube stage enabling classic overdrive effects when inserting guitar, bass and other instruments. Retaining the concept of twin mic pre-amps, the 1969 uses 'Burr-Brown'op amps for a silkier sound - and a phase reverse switch available in instrument, mic and line modes increases versatility. The 1969 employs true stereo link operation with channel one's threshold, attack and release controls becoming master to both channels. Stereo link also offers a BIG position which retains bass frequencies by rolling off the detection signal at 100 Hz minimizing undesirable pumping during compression. Output gain make-up can be independently controlled on each channel. 2 mic/line pre-amps with variable gain, 48V phantom power, filters and phase reverse Instrument tube pre-amp with variable gain, EQ, phase reverse and brightness boost 2 soft-knee tube compressors with variable threshold, attack, release and output gain True stereo link operation with BIGposition for retaining bass frequencies Side chain access and side chain listen facility VU metering of gain reduction and output levels Individual +4dB/-10dB inserts Balanced +4dB XLR input/output connectors

Used Drawmer 1969 Mercenary Edition Mic Pre Amp/Tube Compressor $2343.25 The 1969 Mercenary Edition, derived from a collaboration between two of the audio industry's most established names, Drawmer (UK) and Mercenary Audio (USA), Fletcher - Producer/Engineer, Mercenary Audio incorporates new tube circuits designed to add warmth to mic/line signals, and the instrument (DI) pre-amp has its own tube stage enabling classic overdrive effects when inserting guitar, bass and other instruments. Retaining the concept of twin mic pre-amps, the 1969 uses 'Burr-Brown'op amps for a silkier sound - and a phase reverse switch available in instrument, mic and line modes increases versatility. The 1969 employs true stereo link operation with channel one's threshold, attack and release controls becoming master to both channels. Stereo link also offers a BIG position which retains bass frequencies by rolling off the detection signal at 100 Hz minimizing undesirable pumping during compression. Output gain make-up can be independently controlled on each channel. 2 mic/line pre-amps with variable gain, 48V phantom power, filters and phase reverse Instrument tube pre-amp with variable gain, EQ, phase reverse and brightness boost 2 soft-knee tube compressors with variable threshold, attack, release and output gain True stereo link operation with BIGposition for retaining bass frequencies Side chain access and side chain listen facility VU metering of gain reduction and output levels Individual +4dB/-10dB inserts Balanced +4dB XLR input/output connectors

Used Summit Audio Mpc-100A Tube Pre-Amp And Compressor/Limiter $1955.59 The single channel Summit Audio MPC-1OOA tube preamplifier and compressor/limiter accepts line, microphone, and Hi-Z input signals. Using both tubes and solid state technology in synch with the Jensen mic transformer, the MPC-100A lends a detailed sound with harmonically complex overtones. The ultra-fast compressor is ideal for optimizing signals prior to entering the digital domain. Other details include impedance matching (loading) control on the Hi-Z input so passive guitars and bass pickups have a whole new level of tone control, true VU metering, and multiple outputs. And with the Summit Audio MPC-100A tube preamp's 3 separate gain controls, you have endless tonal variations from clean to saturated for whatever sound you need."Clean" to "Saturated" valve soundsSoft Clipping LED indicatorsHI-Z instrument input with impedance matching controlTwo stages of vacuum tube gain controls3 Position attack and release controlsHigh quality VU meter for output and gain reduction meteringContinuously variable output level control+4 dB balanced and -10 dB unbalanced outputStereo linkable with a second MPC-100AJensen mic transformer

Summit Audio Mpc-100A Tube Pre-Amp And Compressor/Limiter $2149 The single channel Summit Audio MPC-1OOA tube preamplifier and compressor/limiter accepts line, microphone, and Hi-Z input signals. Using both tubes and solid state technology in synch with the Jensen mic transformer, the MPC-100A lends a detailed sound with harmonically complex overtones. The ultra-fast compressor is ideal for optimizing signals prior to entering the digital domain. Other details include impedance matching (loading) control on the Hi-Z input so passive guitars and bass pickups have a whole new level of tone control, true VU metering, and multiple outputs. And with the Summit Audio MPC-100A tube preamp's 3 separate gain controls, you have endless tonal variations from clean to saturated for whatever sound you need."Clean" to "Saturated" valve soundsSoft Clipping LED indicatorsHI-Z instrument input with impedance matching controlTwo stages of vacuum tube gain controls3 Position attack and release controlsHigh quality VU meter for output and gain reduction meteringContinuously variable output level control+4 dB balanced and -10 dB unbalanced outputStereo linkable with a second MPC-100AJensen mic transformer

Summit Audio MPC-100A Tube Pre-Amp and Compressor/Limiter $1955.59 The single channel Summit Audio MPC-1OOA tube preamplifier and compressor/limiter accepts line, microphone, and Hi-Z input signals. Using both tubes and solid state technology in synch with the Jensen mic transformer, the MPC-100A lends a detailed sound with harmonically complex overtones. The ultra-fast compressor is ideal for optimizing signals prior to entering the digital domain. Other details include impedance matching (loading) control on the Hi-Z input so passive guitars and bass pickups have a whole new level of tone control, true VU metering, and multiple outputs. And with the Summit Audio MPC-100A tube preamp's 3 separate gain controls, you have endless tonal variations from clean to saturated for whatever sound you need.

Used Drawmer 1960 Mic Pre/Tube Compressor 889406476844 $1125 Combining eight active tube stages and the low noise and reliability of solid state electronics, the Drawmer 1960 provides the ultimate direct interface between the sound source and the recording medium. The Drawmer 1960 is a two channel unit with each channel comprised of a completely natural sounding "soft knee" vacuum tube compressor and an extremely low noise microphone pre-amplifier with switchable 48 volt phantom power. A further auxiliary instrument pre-amp with EQ is also provided. This powerful combination of the classic valve circuit, offering unsurpassed tonality, and the low noise balanced microphone input with up to 60dB of gain has allowed engineers throughout the world to exploit the full potential of high performance condenser microphones. An example of this would be the direct to digital stereo recording of live classical music without the necessity of a mixing console. The Compressor: Because the compressor is a soft knee type, it requires few controls. Strictly speaking, a soft knee design does not have a rigidly defined threshold but the title 'Threshold' has been retained for the "amount of compression" control for the sake of familiarity. The Threshold range is continuously variable between infinity and -24dB, the theory being that signals below the threshold are essentially unprocessed and the signals exceeding this threshold are subjected to increasing amounts of gain reduction dependent on by how much they exceed the threshold._The attack and release times are switchable rather than being continuously variable and this method of operation falls into line with that of its all valve predecessors. Attack simply offers a-choice of slow, medium and fast whilst release has six settings. Positions one to four have fixed release times whilst positions five and six are two different programme dependent release time modes making the unit ideally suited to programme material with complex dynamics such as complete stereo mixes and vocals. Interestingly, the attack times are further modified by the choice of release setting so the range of choices are wider than it might first appear. Because compression is a form of controlled gain reduction, a stage of make-up amplification follows the compressor section giving a range of +20dB. The VU meters may be switched to monitor either the amount of gain reduction taking place or the output signal level and the two channels may be used either independently or as a stereo pair, depending on the setting of the stereo link switch. The side chain access points may be used to patch in equalisers to enable the compressor to act as a de-esser. As with other Drawmer products, the by-pass switch offers a choice of Normal. By-pass and Side Chain Listen modes so that if you have patched in any additional side chain processing, you can easily monitor what effect it is having. In addition to the balanced microphone and line inputs on the rear of the unit an auxiliary input on the front panel gives dir

Ibanez Tsa15 Tube Screamer 15W 1X12 Tube Guitar Combo Amp $449.99 The Ibanez Tube Screamer is one of the best overdrive pedals ever produced, hands down, and the TSA15 tube combo amp features a true Tube Screamer circuit that delivers that same legendary overdrive. The TSA15 combo features a 12" Celestion Seventy 80 speaker and can deliver everything from natural clean sounds; fat crunch tones; and even warm, smooth overdriven tones with the modified TS9 circuit built right into the amp.Guitarists normally have to depend on a separate effect pedal to get the distinctive, warm overdrive sounds of a tube amp. No more! The new TSA15 Tube Combo Amp has a genuine Tube Screamer circuit built right into the front end for all the warm tube overdrive punch and crunch youll need. Includes footswitchable functionality with Tube Screamer Overdrive, Tone, and Level controls. IFS2G footswitch sold separately.15W all-tube combo2 x 12AX7 tubes (Pre)2 x 6V6 tubes (Power)Genuine Tube Screamer circuit built into the front endControls: Tube ScreamerOverdrive, Tone, Level; AmpTreble, Bass, VolumeModes: Pentode15W; Triode5W12" Celestion Seventy 80 Speaker

Used Ibanez Tsa15h Tube Screamer 15W Tube Guitar Amp Head $260.99 Guitarists normally have to depend on a separate effect pedal to get the distinctive, warm overdrive sounds of a tube amp. Not anymore. The Ibanez TSA15H tube amp has a genuine Tube Screamer circuit, built right into the front end, for all the warm tube overdrive punch and crunch you'll need. The all-tube amp head features 2 - 12AX7 preamp tubes and 2 - 6V6 power tubes. The result is loud, balanced sound that cuts through the mix with plenty of full, meaty guitar tone. Built with rugged Ibanez craftsmanship, this guitar amp head is sure to last for many years, able to stand up to the toughest conditions of heavy gigging. Includes footswitchable function with Tube Screamer Overdrive, Tone, and Level controls. Ibanez TSA112C speaker cabinet and IFS2G footswitch sold separately.15W All-tube head2 x 12AX7 tubes (Pre)2 x 6V6 tubes (Power)Genuine Tube Screamer circuit built into the front endControls: Tube ScreamerOverdrive, Tone, Level; AmpTreble, Bass, VolumeModes: Pentode15W; Triode5W

Ibanez Tsa15h Tube Screamer 15W Tube Guitar Amp Head $299.99 Guitarists normally have to depend on a separate effect pedal to get the distinctive, warm overdrive sounds of a tube amp. Not anymore. The Ibanez TSA15H tube amp has a genuine Tube Screamer circuit, built right into the front end, for all the warm tube overdrive punch and crunch you'll need. The all-tube amp head features 2 - 12AX7 preamp tubes and 2 - 6V6 power tubes. The result is loud, balanced sound that cuts through the mix with plenty of full, meaty guitar tone. Built with rugged Ibanez craftsmanship, this guitar amp head is sure to last for many years, able to stand up to the toughest conditions of heavy gigging. Includes footswitchable function with Tube Screamer Overdrive, Tone, and Level controls. Ibanez TSA112C speaker cabinet and IFS2G footswitch sold separately.15W All-tube head2 x 12AX7 tubes (Pre)2 x 6V6 tubes (Power)Genuine Tube Screamer circuit built into the front endControls: Tube ScreamerOverdrive, Tone, Level; AmpTreble, Bass, VolumeModes: Pentode15W; Triode5W

Studio Projects Vtb-1 Tube Blend Mic Preamp $149.99 The new Studio Projects VTB-1 Tube Blend Mic Preamp is the ultimate in low-cost microphone preamplifier technology. Incorporating true class A/B switching, the VTB-1 is a totally discrete circuit. Unique to the VTB-1 mic preamp is the Tube Drive circuit based on a a 12AX7 tube that allows the user to blend as little or as much of the Tube Drive as desired. The Studio Projects VTB-1 allows the user the most flexibility of any mic pre in its price class.The VTB-1 preamp allows you to go from a pristine solid state sound to any combination of Tube Drive you choose - even hard distortion for guitars and bass! The Studio Projects VTB-1 is must-have device as the perfect mic preamplifier for any microphone!A superb vocal mic pre with warm transparent characterGreat for use as a tube DI boxIdeal for production, broadcast, and voice over workPerfect for the professional and home project studio

Giardinelli Trumpet Lube Pre-pack $2.99 The Giardinelli Trumpet Lube Pre-pack includes premium multi-purpose grease and premium valve oil. The multi-purpose grease is packed in a lipstick-style tube. Use it for lubrication and protection when assembling your trumpet. The premium valve oil's leak-proof bottle makes application easy, and the oil is safe for all metal finishes.

Giardinelli Trumpet Lube Pre-Pack $2.99 The Giardinelli Trumpet Lube Pre-pack includes premium multi-purpose grease and premium valve oil. The multi-purpose grease is packed in a lipstick-style tube. Use it for lubrication and protection when assembling your trumpet. The premium valve oil's leak-proof bottle makes application easy, and the oil is safe for all metal finishes.

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Effect of pre emergence weedicide on soil metabolic activity in inceptisol soil

Effect of pre emergence weedicide on soil metabolic activity

        in laboratory  under ambient condition in inceptisol soil.

     Megha V. Nagmote and  A. D. Kadlag

Department of Soil Science and Agriculture Chemistry

Mahatma  Phule Krishi Vidyapeeth, Rahuri-413722,

 Dist. Ahmednagar, Maharashtra.

 

-----------------------------------------------------------------------------------Abstract : The present investigation was carried out by conducting an incubation study. The incubation study was carried out in laboratory under ambient condition at Department of Soil Science and Agricultural Chemistry, Post Graduate Institute, M.P.K.V., Rahuri during 2002-03 to asses the periodical soil microbial population and enzyme activities viz., urease, acid phosphatase and dehydrogenase. The application of alachlor @ 1.0, 2.0 and 4.0 kg a.i. ha-1 were recorded the higher urease activity at 21st days (20.97, 20.83 and 20.85 mg NH4-N 100 g-1 soil hr-1 respectively) The acid phosphatase activity in laboratory incubation were increased at 21st days by alachlor @ 1.0, 2.0 and 4.0 kg a.i. ha-1 (9.532, 9.985 and 9.761 µMP g-1 soil hr-1, respectively). The soil dehydrogenase activity was higher at 21st days of incubation by the pre emergence weedicides.

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Soil is a storehouse of plant nutrients for the growth and development of crop plants. The fertility of soil is governed by the enzymes that may be exoenzymes (free enzymes) or endoenzymes released from disintegration of cells. Nutrient cycling in soil involves biochemical and physiochemical reactions with the biochemical processes being mediated by microorganisms, plant roots and soil animals. All biochemical reactions are catalysed by enzymes. The microbes are small but their role in improving agricultural productivity and soil health is profound. Looking at the huge workforce of invisible tiny microbes, working wonders, doing thankless jobs silently for human welfare, one cannot but appreciate ‘Yes, the small is always beautiful (Anonymous, 2000).

Materials and Methods

The incubation study was carried out in laboratory under ambient condition at Department of Soil Science and Agricultural Chemistry, Post Graduate Institute, M.P.K.V., Rahuri during 2002-03 to asses the periodical soil microbial population and enzyme activities viz., urease, acid phosphatase and dehydrogenase. There   are    fourteen    treatment   comprised of pre emergence weedicide application viz., oxyfluorfen, alachlor, fluchloralin and pendimethalin in graded dose, weedy check and weed control. The soil of used for laboratory study is grouped under Inceptisol soil order belonging to Sawargaon (Pather)   soil   series.

Soil enzyme assay

Urease enzyme assay (Urea amidohydrolase,  EC 3.5.1.5) 

                   The urease enzyme assay was carried out according to the method described by Tabatabai and Bremner (1972).

Reagents used Tris (hydroxymethyl) amino methane (THAM) buffer, 0.05 M, pH 9.0 ,Urea solution - 0.2 M, Potassium chloride – 2.5 M – Silver sulphate (100 ppm) (KCl – Ag2SO4) solution, Sodium hydroxide - 2.5 %, Boric acid - 2 %, Mixed indicator, Working boric acid solution, H2SO4 -  0.1 N (Stock Solution)

Method - Five gram of soil was taken in 50 ml of clean dry conical flask. In each conical flask 0.2 ml of toluene and 9 ml of THAM buffer were added. The conical flask was incubated in water both for 30 minutes at 370c temperature. The conical flasks  were  replaced  from  the water bath and approximately 35 ml of potassium chloride silver sulphate solution (KCl – Ag2SO4)   was  added.    The content    was shaken    for few seconds and diluted to 50 ml volumetric flasks and were inverted several times and allowed to settle. Twenty milliliters of supernatant liquid was used for ammonical nitrogen (NH4-N) estimation by micro-kjeldahl method.

Acid phosphatase enzymeassay(Orthophosphoric monoester phosphohydrolase, EC 3.1.3.2) - For the assay of acid phosphatase enzyme, extraction was done by the method of Tabatabai and Bremner (1969). Reagents - Modified universal buffer (MUB) stock solution,   Modified Universal Buffer (MUB), pH 6.5, Na - b - Glycerophosphate - 0.1 M, Ammonium molybdate - 5 %, Perchloric acid - 60 %, Aminonapthol sulphonic acid (ANSA), Standard phosphorus solution - 0.01 M.

Method - Acid phosphatase enzyme was extracted from soil by the procedure of Tabatabai and Bremner (1969). Five gram of soil was taken  in  50 ml conical flask. In each conical flask 1 ml toluene, 20 ml modified universal buffer (MUB pH 6.5) and 5 ml of Na-b-glycerophosphate were added. The flask were replaced from water bath and kept in boiling water bath for 15 minutes to kill the enzyme activity. The content was filtered and 5 ml of extract was used for colour development. For colour development the procedure given by King (1932) was used. Five ml of filtrate was pipetted out in clean dry   25 ml volumetric flaks to which 1 ml of ammonium molybdate, 1.2 ml of perchloric acid and 1 ml of ANSA were added and final volume was made to 25 ml with distilled water for colour development. The absorbance was read on Spectronic-20 at 663 nm after 30 minutes against blank. The amount of inorganic phosphorus produced was calculated from the standard curve and  the  acid  phosphatase  activity  was  expressed in terms of mM ‘P’ g-1  soil hr-1.

Calibration of standard curve - In a series of 25 ml volumetric flask 0, 0.1, 0.2, 0.3 ….. 1 ml of 0.01 M phosphorus solution were pipetted out in triplicates. Rest of the procedure was same as described in the colour development. The standard curve was plotted on a graph paper taking mM of phosphorus concentration value against the absorbance at 663 nm.

Dehydrogenase enzyme assay - The dehydrogenase enzyme activity assay was carried out by the method described by Casida et al. (1964).

Procedure - Taken 6 screwed capped test tube of 15 ml capacity, one gram finely powdered soil in each of the tube were added, then added 500 mg FYM in each tube, one ml of 3 % TTC and 0.5 ml of 1 % glucose in each tubes were imposed, taped the tubes so that no air bubble remain in soil. A thin layer of water should form above the soil.Incubated for 12 hrs.Added 10 ml of methanol. Vigorously shaked the flasks and allowed to stand in dark for 24 hrs. Withdraw supernant and measure colour intensity using blue filter at 480 nm on Spectronic-20. The absorbance was proportional to the concentration of TPF formed.

Result and Discussion –

The periodical soil urease enzyme activity as influenced by the pre emergence weedicides in incubation study are presented in (Table 1). The urease enzyme activity was numerically increased up to 21 days of incubation over 7 and 14 days of incubation in all the weedicide application. The maximum urease enzyme activity was recorded in alachlor pre emergence weedicide application @ 1.0, 2.0 and 4.0 kg a.i. ha-1 (20.97, 20.83 and 20.65 mg NH4-N 100 g-1 soil hr-1 respectively) followed by fluchloralin @ 0.75, 1.50 and 3.0 kg a.i. ha-1 (19.88, 19.65 and 18.93 mg NH4-N 100 g-1 soil hr-1 respectively).  The urease enzyme activity at 45 and 60 days of incubation were drastically reduced in all the pre emergence weedicide application.  The reduction in urease enzyme activity might be related with the decreased soil microbial population and enzyme concentration in soil. This observation is corroborated with the Ramesh et al. (2000)

                   The soil acid phosphatase enzyme activity as influenced by the levels of different pre emergence weedicides under laboratory conditions are presented in (Table 2).  The highest soil acid phosphatase activity at 21 days of incubation was observed in pre emergence application of alachlor @ 1.0, 2.0 and 4.0 kg a.i. ha-1 (9.532, 9.985 and 9.761 mM P g-1 soil hr-1 respectively) followed by fluchloralin application @ 0.75, 1.50 and 3.00 kg a.i. ha-1 (9.341, 8.829 and 8.934 mM P g-1 soil hr-1 respectively).  These observations revealed that use of alachlor as pre emergence weedicide is more beneficial for soil acid phosphatase activity followed by fluchloralin.  This might be ascertained that these weedicides did not inhibit the microbial population in soil which in turn resulted in higher soil acid phosphatase activity.  These results are in accordance with Pozo et al. (1994) and Nagaraja et al. (1998).

                          The soil dehydrogenase activity as influenced by the application of pre emergence weedicide are depicted in (Table 3). It was maximum in lower dose of alachlor @ 1.0 kg a.i. ha-1 fluchloralin and pendimethalin @ 0.75 kg a.i. ha-1 (0.384, 0.451 and 0.497 m mol formazon g-1 soil day-1 respectively).  The variation in soil dehydrogenase activity might be because of microbial population and their activity in soil.  The 21 days of incubation showed the higher soil dehydrogenase activity by application of alachlor @ 1.0, 2.0 and 4.0 kg a.i. ha-1 (0.631, 0.653 and 0.697 m mol g-1 soil day-1 respectively). The fluchloralin weedicide also showed the higher soil dehydrogenase activity at 45 days (0.475, 0.485 and 0.359 m mol g-1 soil day-1 respectively) and 60 days of incubation (0.346, 0.374 and 0.364 m mol g-1 soil day-1 respectively). 

Conclusions - The application of alachlor pre emergence weedicide recorded the maximum urease activity at 21st days of an incubation followed by fluchloralin. The highest acid phosphatase activity was recorded at 21st days of an incubation by alachlor as pre emergence weedicide. The maximum dehydrogenase activity was observed at 21st days of incubation by the pre emergence weedicide.

References –

Anonymous. 2000. Microbes for sustainable agriculture Indian Fmg. pp. 39-41.

Casida, L.E., Klein, D.A. and Santro, T. 1964.  Soil dehydrogenase activity.  Soil Sci. 98 : 371-376.

Nagaraja, N.S., Ramakrishna Parama, V.R. and Siddaramappa, R. 1998.  Effect of attrazine on urea N. mineralization and activity of some soil enzymes.  J. Indian Soc. Soil Sci. 46(2) : 182-192.

Pozo, L., Salmeron, V., Rodelas, B., Martinez-Toleds, M.V. and Gonzatez-Lopez, J. 1994.  Effect of herbicide alachlor on soil microbial activities.  Ecotoxicol.  3(1) : 4-10.

Ramesh, A., Joshi, O.P. and Billore, S.D. 2000.  Effect of herbicides on soil dehydrogenase and urease activity in soybean.  Indian J. agric. Sci. 70(4) : 218-219.

Tabatabai, M.A. and Bremner, J.M. 1969.  Use of nitrophenyl phosphate for assay of soil phosphatase activity. Soil Biol. Biochem. 1 : 301-307.

                                           

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 1.      Effect of pre emergence weedicide on perodical urease enzyme activity in inceptisol soil under laboratory condition

 

Sr. No.

Treatment

Urease enzyme activity

(mg NH4-N 100 g-1 soil hr-1)

 

7 days

14 days

21 days

45 days

60 days

1.

Oxyfluorfen

0.5 kg a.i. ha-1

15.58

16.65

18.68

11.98

11.84

2.

Oxyfluorfen

1.0 kg a.i. ha-1

14.61

15.84

18.32

11.83

11.57

3.

Oxyfluorfen

2.0 kg a.i. ha-1

14.32

14.68

17.90

11.58

10.92

4.

Alachlor

1.0 kg a.i. ha-1

17.95

17.98

20.97

15.65

14.79

5.

Alachlor

2.0 kg a.i. ha-1

17.88

17.93

20.83

14.93

14.55

6.

Alachlor

4.0 kg a.i. ha-1

16.98

17.78

20.65

14.73

14.17

7.

Fluchloralin 0.75 kg a.i. ha-1

16.96

16.96

19.88

13.87

13.68

8.

Fluchloralin 1.50 kg a.i. ha-1

16.72

16.88

19.65

13.53

12.83

9.

Fluchloralin

3.0 kg a.i. ha-1

15.47

16.65

18.93

13.28

12.75

10.

Pendimethalin 0.75 kg a.i. ha-1

16.98

16.89

19.81

13.85

13.92

11.

Pendimethalin 1.50 kg a.i. ha-1

16.87

16.77

19.45

13.69

13.69

12.

Pendimethalin 3.0 kg a.i.ha-1

15.25

15.93

18.89

12.85

13.55

13.

Weedy check

13.99

14.32

16.69

15.22

16.30

14.

Control

14.03

14.48

17.27

16.37

16.63

( Initial urease enzyme activity – 13.98 mg NH4-N 100 g-1 soil hr-1)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 2.      Effect of pre emergence weedicide on perodical acid phosphatase enzyme activity in inceptisol soil under laboratory condition

 

Sr. No.

Treatment

Acid phosphatase enzyme activity 

(µM P g-1 soil hr-1)

 

7 days

14 days

21 days

45 days

60 days

1.

Oxyfluorfen

0.5 kg a.i. ha-1

3.753

6.345

7.952

5.689

4.657

2.

Oxyfluorfen

1.0 kg a.i. ha-1

2.922

5.861

7.637

5.851

4.491

3.

Oxyfluorfen

2.0 kg a.i. ha-1

2.848

5.980

7.485

5.948

4.648

4.

Alachlor

1.0 kg a.i. ha-1

4.942

7.831

9.532

6.985

5.899

5.

Alachlor

2.0 kg a.i. ha-1

4.893

7.989

9.985

6.743

5.736

6.

Alachlor

4.0 kg a.i. ha-1

4.628

7.574

9.761

6.538

5.758

7.

Fluchloralin 0.75 kg a.i. ha-1

4.782

7.953

9.341

6.854

5.635

8.

Fluchloralin 1.50 kg a.i. ha-1

3.831

6.795

8.829

6.481

5.813

9.

Fluchloralin

3.0 kg a.i. ha-1

3.788

6.647

8.934

5.973

5.987

10.

Pendimethalin 0.75 kg a.i. ha-1

3.831

6.893

8.685

6.343

5.435

11.

Pendimethalin 1.50 kg a.i. ha-1

3.688

6.576

8.742

5.718

4.988

12.

Pendimethalin 3.0 kg a.i.ha-1

3.423

6.487

8.533

5.895

4.713

13.

Weedy check

2.632

5.742

6.861

5.431

4.328

14.

Control

2.471

5.396

6.438

5.287

3.986

(Initial  phosphatase enzyme activity – 2.392 µM P g-1soil hr-1)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 3.      Effect of pre emergence weedicide on perodical acid dehydrogenase enzyme activity in inceptisol soil under laboratory condition

 

Sr. No.

Treatment

Soil dehydrogenase enzyme activity

(µmol formazon g-1 soil day-1)

 

7 days

14 days

21 days

45 days

60 days

1.

Oxyfluorfen

0.5 kg a.i. ha-1

0.292

0.438

0.477

0.375

0.267

2.

Oxyfluorfen

1.0 kg a.i. ha-1

0.361

0.489

0.468

0.343

0.257

3.

Oxyfluorfen

2.0 kg a.i. ha-1

0.288

0.476

0.484

0.324

0.219

4.

Alachlor

1.0 kg a.i. ha-1

0.384

0.587

0.631

0.384

0.285

5.

Alachlor

2.0 kg a.i. ha-1

0.373

0.595

0.653

0.393

0.274

6.

Alachlor

4.0 kg a.i. ha-1

0.352

0.583

0.697

0.358

0.224

7.

Fluchloralin 0.75 kg a.i. ha-1

0.451

0.432

0.584

0.475

0.346

8.

Fluchloralin 1.50 kg a.i. ha-1

0.487

0.484

0.578

0.485

0.374

9.

Fluchloralin

3.0 kg a.i. ha-1

0.342

0.573

0.530

0.359

0.361

10.

Pendimethalin 0.75 kg a.i. ha-1

0.497

0.481

0.655

0.447

0.291

11.

Pendimethalin 1.50 kg a.i. ha-1

0.343

0.597

0.587

0.452

0.337

12.

Pendimethalin 3.0 kg a.i.ha-1

0.381

0.442

0.688

0.466

0.245

13.

Weedy check

0.245

0.332

0.442

0.316

0.259

14.

Control

0.203

0.248

0.327

0.283

0.134

(Initial  dehydrogenase enzyme activity – 0.269 µmol formazon g-1 soil day-1)

 

 

 

 

 

 

 

 

 

 

 

 

 

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