scholarly journals MITIGATION OF HEAT STRESS EFFECTS ON POTATO GROWTH BY CALCIUM AND NITROGEN APPLICATION DURING STRESS

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 596f-596 ◽  
Author(s):  
Ahmed A. Tawfik ◽  
Jiwan P. Palta
Keyword(s):  
Heat Stress ◽  
Sandy Loam ◽  
Leaf Tissue ◽  
Maximum Temperature ◽  
N Application ◽  
Total N ◽  
Stress Effects ◽  
Loam Soil ◽  
Potato Growth ◽  
The Impact

The optimum temperature regime for Solanum tuberosum cv. Russet Burbank is usually 20/15°C day/night. We studied the impact of heat stress (30/25°C, day/night) on the growth of this heat sensitive cultivar under controlled conditions (UW-Biotron). Plants were grown in sandy-loam soil which tested at 1500 Kg/ha Ca. Plants were at the maximum temperature for 6h during the middle of the day with a photoperiod of 14 hrs. All pots received identical amounts of total N (rate: 225 Kg N ha1.). The treatments were: (1) NSN: non-split N (N application 1/2 emergence, 1/2 two wks later): (2) SPN: split-N (1/2 emergence 1/6 at 2, 5 and 8 wks later); (3) SPN+Ca: Split-N+Ca (Ca at 2, 5 and 8 wks after emergence, total Ca from CaNO3 was 113 Kg ha1). Total leaf FWT and DWT was significantly reduced in NS treatment by heat stress at 13 wks as compared to optimum conditions. However, this was not reduced in SPN and SPN+Ca. Under heat stress: (a) SPN + Ca gave the highest leaf FWT and DWT, stomatal conductance, transpiration rate, and leaflet tissue Ca content; (b) Young expanding leaflets gave higher growth rate with SPN and SPN + Ca than NSN; (c) Ca content of mature leaflet decreased progressively in both NSN and SPN but not in SPN + Ca. Our results show that application of Ca and N during heat stress can mitigate stress effects and that maintenance of a certain level of calcium in leaf tissue is important under heat stress.

Yield and Nutrient Uptake of Peppers (Capsicum annuum) Grown with Dairy Manure Compost and Fertigated Nitrogen

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 495c-495
Author(s):  
Nancy E. Roe
Keyword(s):  
Capsicum Annuum ◽  
Sandy Loam ◽  
Leaf Tissue ◽  
Soil Improvement ◽  
Dairy Manure ◽  
Total N ◽  
Manure Compost ◽  
Loam Soil ◽  
Intensively Managed ◽  
N Rates

The use of compost as an organic source of nutrients and soil improvement may help to increase the sustainability of intensively managed vegetables. Bell pepper (Capsicum annuum L.) transplants were planted into silver-colored polyethylene mulched beds in a sandy loam soil amended with 0 or 22.4 Mg·ha–1 dairy manure compost. Preplant P was added to all beds at 78 kg·ha–1. During the season, N (as NH4NO3) was added about every 10 days. Total N rates for the season were: 0, 32, 65, or 96 kg·ha–1. Percent of N in pepper leaf tissue increased from a low of 2.7% without N to3.8% at the high N rate. Leaf P concentrations were higher in 0 N plots than in other rates. Compost resulted in higher leaf concentrations of Ca. There was an interaction of compost and N rates for percent of culls. Compost increased percentage of culls with 0 or 32 kg·ha–1 N, but decreased or did not affect cull percentage at 65, or 96 kg·ha–1 N. Compost did not affect other yield parameters measured. Marketable yields increased from 11 Mg·ha–1 with 0 N to 18 Mg·ha–1 with high N, although the regression was not significant, due to extreme variability within the field.

scholarly journals Aphid and Flea Beetle Control on Tobacco with Insecticides Applied in the Transplant Water, 1997

1998 ◽  
Vol 23 (1) ◽  
pp. 300-301
Author(s):  
Paul J. Semtner ◽  
William B. Wilkinson
Keyword(s):  
Sandy Loam ◽  
Flea Beetle ◽  
Calculated Data ◽  
Leaf Tissue ◽  
Ambient Temperatures ◽  
Untreated Check ◽  
Tobacco Seedlings ◽  
Loam Soil ◽  
X 24 ◽  
The Impact

Abstract Various insecticides applied as transplant water treatments and transplant drench (TPD) were compared with foliar and soil treatments for TA and TFB control and for the impact of treatment on yield of flue-cured tobacco. Tests were conducted on a Chesterfield-Mayodan-Bourne sandy loam soil at the Southern Piedmont Agric. Res. and Ext. Cntr., Blackstone, VA. Eleven treatments and an untreated check were established in a RCB design with 4 replications Plots, 4 X 40 ft (1 row X 24 plants), were separated by single untreated guard rows. The Temik treatment was applied in a 14-inch band using a tractor-mounted-Gandy granular applicator and immediately covered with 6 inches of soil at bed formation on 15 May (Ambient temperature 75-78 °F, soil temperature, 70 °F, soil pH, 5.6; weather, sunny; soil moisture, good). The Admire drench treatment was applied to tobacco seedlings in 288-cell float trays 24 hrs before transplanting. The treatment was applied with a CO2-pressurized backpack sprayer that delivered the desired rates of Admire 240 FS in 0.46 gal of water/1,000 plants through 8003LP tips at 20 psi. Treatments were watered in with about 1 gal of water immediately after application. ‘Coker 371 Gold’ flue-cured tobacco was transplanted and the transplant water (TPW) treatments were applied in 204 gpa with a dipper at 4 fl oz/plant on 20 May. The weather was sunny, and soil and ambient temperatures were 70 °F and 78-81 °F, respectively. Foliar applications of Orthene were applied on 11 and 31 Jul with a CO2-pressurized backpack sprayer that delivered 30 gpa at 50 psi through 3 TX-12 nozzles/row. Except for insect control, tobacco production followed recommendations of the Virginia Cooperative Extension Service. Dipel 4 L (Bacillus thuringienis) was applied for tobacco hornworm control on 3 Jul. TA were counted on the upper 4 leaves of 10 plants/plot about once a week from 6 to 10 wks after transplanting. On 22 Aug, TA damage was rated for each plot on a scale of 0 to 10: 0 = no signs of TA feeding; 10 = all leaves showing severe damage resulting from TA infestations including hon-eydew, sooty mold, necrotic leaf tissue and exuviae. TFB feeding holes were counted on 10 plants/plot at 2 to 4 wk after transplanting. Tobacco was harvested as it ripened, weighed, graded by a USDA/AMS inspector, and yields and prices were calculated. Data were analyzed by ANOVA and significantly different means were separated by Waller-Duncan K-ratio t-test (K = 100). TA count data were transformed to log10 (x + 1) before analysis.

Effect of seed-placed urea fertilizer and N-(n-butyl)thiophosphoric triamide (NBPT) on emergence and grain yield of barley

1999 ◽  
Vol 79 (4) ◽  
pp. 491-496 ◽  
Author(s):  
C. A. Grant ◽  
L. D. Bailey
Keyword(s):  
Sandy Loam ◽  
Stand Density ◽  
Field Studies ◽  
Urease Inhibitor ◽  
Barley Seedling ◽  
N Application ◽  
Urea Fertilizer ◽  
Loam Soil ◽  
Final Yield ◽  
The Impact

Seedling damage from excess seed-placed urea fertilizer can be a major problem in one-pass seeding and fertilizing systems. Field studies were conducted on a clay loam and a fine sandy loam soil over 3 yr to evaluate the impact of seed-placed urea N, with and without the addition of the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) on stand density and growth of barley. Seedling damage, as indicated by reduction in stand density, occurred on both soil types at rates of seed-placed N as low as 40 kg N ha−1. Addition of NBPT to the urea fertilizer increased stand density at N levels where damage occurred with the untreated urea. Dry matter yield at heading generally was unaffected by N application or use of NBPT; however, final yield was increased by use of NBPT in four of five site-years. Use of NBPT appears promising as a method of reducing the risk of seedling damage from seed-placed urea fertilizer, thus increasing the rate of urea-N that can be safely placed with the seed. Key words: Urease inhibitor, seedling toxicity, ammonia

scholarly journals Tobacco Insect Control with Insecticides Applied in the Transplant Water, 1996

1998 ◽  
Vol 23 (1) ◽  
pp. 298-299
Author(s):  
Paul J. Semtner ◽  
William B. Wilkinson
Keyword(s):  
Ambient Temperature ◽  
Sandy Loam ◽  
Leaf Tissue ◽  
Insect Control ◽  
Black Stone ◽  
Untreated Check ◽  
Tobacco Seedlings ◽  
Loam Soil ◽  
X 24 ◽  
Water Treatments

Abstract Various insecticides applied as transplant water treatments were compared with foliar and soil treatments for TA and TFB control and for their effects on the yield of flue-cured to bacco. Tests were conducted on a Chesterfield-Mayodan-Bourne sandy loam soil at the Southern Piedmont Agricultural Agric. Res. and Ext. Cntr., Black-stone, VA. Eleven treatments and an untreated check were established in a RCB design with 4 replications. Plots, 4 X 40 ft (1 row X 24 plants), were separated by single untreated guard rows. The Temik treatment was applied in a 14-inch band using a tractor mounted-Gandy granular applicator and immediately covered with 6 inches of soil at bed formation on 21 May (soil temperature 75 °F ambient temperature, 88 °F, soil pH, 5.6; weather, sunny; soil moisture, good). The Admire drench treatment was applied to tobacco seedlings in 288-cell float trays 24 hrs before transplanting. The treatment was applied with a CO2-pressurized backpack sprayer that delivered 1 fl oz of Admire 240 FS in 1.84 gal of water/1,000 plants through 8003LP tips at 20 psi. Treatments were watered in with an additional 1 gal of water immediately after application. ‘Coker 371 Gold’ flue-cured tobacco was transplanted and the transplant water (TPW) treatments were applied in 204 gal solution/acre with a Holland plunger-type transplanter on 21 May. The weather was sunny, and soil and ambient temperature was 75 °F and 88-91 °F, respectively. Foliar applications of Orthene were applied on 3 Jul and 8 Aug with a CO2-pressurized backpack sprayer that delivered 28 gpa at 60 psi through TX-12 nozzles (3 per row. The weather was clear, wind speed was less than 5 mph, and ambient temperature was 84-86°F at each application. Except for insect control, tobacco production followed Virginia Cooperative Extension recommendations. Dipel 4 L (Bacillus thuringiensis) was applied for tobacco hornworm control on 3 Jul. TA were counted on the upper 4 leaves of 10 plants/plot about once a week from 6 to 10 wks after transplanting. On 22 Aug, TA damage was rated for each plot on a scale of 0 to 10: 0 = no signs of aphid feeding; 10 = all leaves showing severe damage resulting from TA infestations including honeydew, sooty mold, necrotic leaf tissue, and exuviae. TFB feeding holes were counted on 5 plants/plot on 2 and 26 Jun, 2 and 5 wks after transplanting. Tobacco was harvested and cured and yield was determined. Data was analyzed by ANOVA and significantly different means were separated by Waller-Duncan K-ratio t-test (K = 100). TA count data were transformed to log10 (x + 1) before analysis.

scholarly journals Insect Control on Flue-Cured Tobacco with Systemic Insecticides, 1994

1995 ◽  
Vol 20 (1) ◽  
pp. 258-259
Author(s):  
Paul J. Semtner ◽  
William B. Wilkinson III
Keyword(s):  
Agricultural Research ◽  
Sandy Loam ◽  
Block Design ◽  
Calculated Data ◽  
Sooty Mold ◽  
Systemic Insecticides ◽  
Loam Soil ◽  
Extension Center ◽  
Water Treatments ◽  
The Impact

Abstract This experiment was conducted to evaluate various systemic insecticides applied as soil or transplant water treatments followed by foliar applications of Orthene for TA and TFB control on fluecured tobacco and to determine the impact of treatment on tobacco yield and price. The experiment was conducted at the VPI & SU Southern Piedmont Agricultural Research and Extension Center, Blackstone, VA. Eleven treatments and an untreated control were established in a randomized complete block design with 4 replications. Plots, 4 × 40 ft (1 row × 24 plants), were separated by single guard rows. Pretransplant soil treatments of most liquid formulations were applied broadcast with a CO2-pressurized tractor sprayer that delivered 30.4 gal/acre at 40 psi through 8003LP tips on 29 Apr (Ambient temperature, 85-89°F, soil temperature, 75°F; soil pH, 5.8; OM, 2%). Treatments were immediately incorporated by double disking. The Furadan and Temik treatments were applied during bed formation and immediately covered with 6 to 8 inches of soil on 17 May. Furadan 4F was diluted 50:50 in water and applied in a narrow stream (< 1-inch wide) in the row using a peristaltic pump. Temik was applied in a 14 inch band using a tractor mounted- Gandy granular applicator. The soil moisture was good for both the pretransplant soil and bedding treatments. ‘K-326’ flue-cured tobacco was transplanted into experimental plots in a Chesterfield-Mayodan-Bourne sandy loam soil on 18 May. A measuring cup was used to apply transplant water (TPW) treatments of Orthene and Admire in 4 fl oz/plant (204 gal/acre) at the base of each plant in the treatment plots. Virginia Cooperative Extension recommendations were followed for production of the crop. Foliar applications of Orthene and Dipel were applied on 6 Jul with a CO2-pressurized backpack sprayer that delivered 30 gal/acre through 3 TX-12 tips at 60 psi. TA populations were estimated on the upper 4 leaves of 10 plants/plot about once a week from 5 to 11 wk after transplanting. On 25 Aug, TA damage was rated on a scale of 0 to 10 where 0 = no aphid damage or sooty mold and 10 = very severe necrosis of leaves and extensive sooty mold. TFB and TFB feeding holes in the most damaged leaf were counted on 10 plants/ plot. Tobacco was harvested as it ripened, weighed, graded by a USDA/AMS inspector, and yield and price were calculated. Data were analyzed by ANOVA and significantly different means were separated by WD (K-ratio = 100). Aphid count data were transformed to Log10(x + 1) before analysis.

Effect of macropore flow on the transport of surface-applied cow urine through a soil profile

Soil Research ◽  
2000 ◽  
Vol 38 (1) ◽  
pp. 13 ◽  
Author(s):  
R. G. Silva ◽  
K. C. Cameron ◽  
H. J. Di ◽  
N. P. Smith ◽  
G. D. Buchan
Keyword(s):  
Sandy Loam ◽  
N Leaching ◽  
Macropore Flow ◽  
N Transformations ◽  
Total N ◽  
Lysimeter Experiment ◽  
Cow Urine ◽  
Loam Soil ◽  
Leaching Experiments ◽  
Soil Pores

A field lysimeter experiment was conducted to determine the effect of macropore flow on the transport of surface-applied cow urine N through soil. The lysimeters (500 mm diameter by 700 mm depth) used for this experiment were collected from Templeton fine sandy loam soil (Udic Ustochrept), which had been under ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) pasture for 9–10 years. The effect of macropore flow on urine-N leaching was determined by leaching experiments under 0.5 kPa and 0 kPa water tensions (suctions) imposed on top of the lysimeter using a disc tension infiltrometer. The 0.5 kPa suction prevented soil pores >600 µm diameter from conducting water and solutes, while the 0 kPa suction allowed conduction under ‘field saturated’ condition. Pores >600 µm diameter transmitted about 98% of the total nitrogen (N) leached below 700 mm depth. The main form of N transmitted under 0 kPa was ammonium (NH4 -N), accounting for 10.5% of the total N applied at 0 kPa suction. This was significantly higher than the amount of NH 4 -N leached at 0.5 kPa suction, which accounted for 0.17% of N applied. The urea-N in the leachate reached 16 mg/L at 0 kPa suction, and accounted for 1.6% of the total N applied. No urea was detected in the leachate at the 0.5 kPa suction. The concentrations and amounts of nitrate (NO3 -N) leached were very low and did not differ between the two suctions. The forms and amounts of N leached were affected by the interactions of macropore flow and N transformations in the soil, and the environmental conditions during the two leaching events. From this work, it is recommended that stock should be removed 1–2 days before irrigation water is applied as this will allow animal urine to diffuse into soil micropores and thus decrease N leaching by macropore flow.

Soil water drying and recharge rates as affected by tillage under continuous barley and barley-canola cropping systems in northwestern Canada

2001 ◽  
Vol 81 (1) ◽  
pp. 45-52 ◽  
Author(s):  
R H Azooz ◽  
M A Arshad
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Sandy Loam ◽  
Time Domain Reflectometry ◽  
Sandy Loam Soil ◽  
Soil Conditions ◽  
Silt Loam ◽  
Silt Loam Soil ◽  
Loam Soil ◽  
The Impact

In areas of the northwestern Canadian Prairies, barley and canola are grown in a short growing season with high rainfall variability. Excessively dry soil in conventional tillage (CT) in dry periods and excessively wet soil in no-tillage (NT) in wet periods could cause a significant decrease in crop production by influencing the availability of soil water. The effects of CT, NT and NT with a 7.5-cm residue-free strip on the planting rows (NTR) on soil water drying (–dW/dt) and recharge (dW/dt) rates were studied in 1992 and 1993 during wet and dry periods to evaluate the impact of NTR, NT and CT systems on soil moisture condition. The soils, Donnelly silt loam and Donnelly sandy loam (both Gray Luvisol) were selected and soil water content by depth was measured by time domain reflectometry. Water retained at 6 matric potentials from –5 to –160 kPa were observed. In the field study, –dW/dt was significantly greater in CT than in NT in the silt loam for the 0- to 30-cm layer during the first 34 d after planting in 1992. The 0- to 30-cm soil layer in CT and NTR dried faster than in NT during a period immediately following heavy rainfall in the silt loam in 1993. The drying coefficient (–Kd ) was significantly greater in CT and NTR than in NT in the silt loam soil in 1993 and in the sandy loam soil in 1992 in the top 30-cm depth. The recharge coefficient (Kr) was significantly greater in NT and NTR than in CT for the silt loam soil. The NTR system increased the –dW/dt by 1.2 × 10-2 to 12.1 × 10-2 cm d-1 in 1992 and 1993 in the silt loam soil and by 10.2 × 10-2 cm d-1 in 1993 in the sandy loam soil as compared with NT. The dW/dt was 8.1 × 10-2 cm d-1 greater in NTR in 1992 and 1993 in the silt loam soil and was 1.9 × 10-2 greater in NTR in 1992 than in CT in the sandy loam soil. The laboratory study indicated that NT soils retained more water than the CT soils. The NTR practice maintained better soil moisture conditions for crop growth than CT in dry periods than NT in wet periods. Compared with NT, the NTR avoided prolonged near-saturated soil conditions with increased soil drying rate under extremely wet soil. Key words: Water drying, water recharge, water depletion, wet and drying periods, hydraulic properties, soil capacity to retain water

scholarly journals Effectiveness of Straw Mulch on Infiltration, Splash Erosion, Runoff and Sediment in Laboratory Conditions

2014 ◽  
Vol 22 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Leila Gholami ◽  
Kazimierz Banasik ◽  
Seyed Hamidreza Sadeghi ◽  
Abdulvahed Khaledi Darvishan ◽  
Leszek Hejduk
Keyword(s):  
Soil Loss ◽  
Sandy Loam ◽  
Soil Aggregates ◽  
Sediment Concentration ◽  
Runoff Coefficient ◽  
Splash Erosion ◽  
Straw Mulch ◽  
Conservation Treatment ◽  
Loam Soil ◽  
The Impact

Abstract Mulches have extraordinary potential in reducing surface runoff, increasing infiltration of water into the soil and decreasing soil erosion. The straw mulches as a biological material, has the ability to be a significant physical barrier against the impact of raindrops and reduce the detachment of soil aggregates. The present study is an attempt to determine the efficiency of straw mulch as conservation treatment in changes in the splash erosion, time-to-runoff, runoff coefficient, infiltration coefficient, time-to-drainage, drainage coefficient, sediment concentration and soil loss. The laboratory experiments have been conducted for sandy-loam soil taken from deforested area, about 15 km of Warsaw west, Poland under lab conditions with simulated rainfall intensities of 60 and 120 mmh–1, in 4 soil moistures of 12, 25, 33 and 40% and the slope of 9%. Compared with bare treatments, results of straw mulch application showed the significant conservation effects on splash erosion, runoff coefficient, sediment concentration and soil loss and significant enhancement effects on infiltration and drainage. The results of Spearman-Rho correlation showed the significant (p < 0.05) correlation with r = –0.873, 0.873, 0.878 and 0.764 between rainfall intensity and drainage coefficient, downstream splash, sediment concentration and soil loss and with r = –0.976, 0.927 and –0.927 between initial soil moisture content and time-to-runoff, runoff coefficient and infiltration coefficient, respectively.

scholarly journals Mineralization of pig slurry compost treated with retorted oil shale and dicyandiamide in two contrasting soils

2021 ◽  
Vol 56 ◽  
Author(s):  
Luanna Corrêa Monteiro ◽  
Celso Aita ◽  
Janquieli Schirmann ◽  
Stefen Barbosa Pujo ◽  
Diego Antônio Giacomini ◽  
...  
Keyword(s):  
Oil Shale ◽  
Clay Soil ◽  
Sandy Loam ◽  
Sandy Loam Soil ◽  
N Immobilization ◽  
Pig Slurry ◽  
Mineral N ◽  
Total N ◽  
Loam Soil ◽  
C And N

Abstract: The objective of this work was to evaluate carbon and nitrogen mineralization in the soil after the application of composts produced in an automated composting plant, using pig slurry (PS) with and without the addition of retorted oil shale (ROS) and dicyandiamide (DCD) during composting. Laboratory studies were carried out for 180 days on two soils with contrasting characteristics: sandy-loam Typic Paludalf and clay Rhodic Hapludox, which were managed for more than 10 years under a no-tillage system. The composts were thoroughly mixed with the soils. The mineralization of the C and N from the compost was evaluated by measuring continuously CO2 emissions and periodically mineral N (NH4+ + NO3-) content in the soils, respectively. The mineralization of the C from the compost without ROS and DCD was higher in the sandy-loam soil (20.5%) than in the clay soil (13.9%). Similarly, 19.4% of the total N from the compost was mineralized in the sandy-loam soil and 10.9% in the clay soil. The presence of ROS in the compost reduced C mineralization by 54%, compared with the treatment without additives, in the sandy-loam soil and caused net N immobilization in both soils during incubation. The addition of DCD during PS composting did not affect the mineralization of the C and N from the compost in both soils. The addition of ROS during the composting of PS favors the retention of the C from the compost in the soil, especially in the sandy-loam one, but results in a net N immobilization.

scholarly journals Nitrogen and Potassium Application Scheduling Effects on Drip-irrigated Tomato Yield and Leaf Tissue Analysis

HortScience ◽  
1997 ◽  
Vol 32 (2) ◽  
pp. 230-235 ◽  
Author(s):  
Salvadore J. Locascio ◽  
George J. Hochmuth ◽  
Fred M. Rhoads ◽  
Steve M. Olson ◽  
Alan G. Smajstrla ◽  
...  
Keyword(s):  
Sandy Soil ◽  
Sandy Loam ◽  
Leaf Tissue ◽  
Fine Sand ◽  
Application Rate ◽  
Sandy Loam Soil ◽  
Time Of Application ◽  
Tomato Yield ◽  
Loam Soil ◽  
Petiole Sap

Tomato (Lycopersicon esculentum Mill.) was grown with drip irrigation on an Arredondo fine sand and on an Orangeburg fine sandy loam to evaluate the effect of N and K time of application on petiole sap, leaf-N and -K concentrations, fruit yield, and to determine N and K sufficiency ranges in leaf tissue. On the sandy soil, N—K at 196-112 kg·ha-1 were applied 0%, 40%, or 100% preplant with the remainder applied in 6 or 12 equal or in variable applications in 12 weeks. With the variable application rate, most nutrients were applied between weeks 5 and 10 after transplanting. On the sandy loam soil that tested high in K, only N (196 kg·ha-1) was applied as above. Petiole sap K concentration declined during the season, but was not greatly affected by treatment. Petiole NO3-N concentrations decreased during the season from 1100 to 200 mg·L-1, and the decrease was greater with preplant N treatments. On the sandy soil, marketable fruit yields were lowest with 100% preplant, intermediate with 100% drip applied (no preplant N), and highest with 40% preplant and 60% drip applied. With 100% drip applied, yields were higher with 12 even applications than with either six even weekly applications or with 12 variable N and K applications. With 40% preplant, timing of application had little effect on yield. On the sandy loam soil in 1993, yields were highest with 100% preplant, intermediate with 40% preplant and 60% drip applied, and lowest with all N drip applied. In 1994 when excessive rains occurred, yields were similar with all preplant and with split N applications. Petiole N concentration was correlated with tomato yield, especially at 10 weeks after transplanting. The best correlation between sap-N and total yields occurred between 4 and 6 weeks at Gainesville and between 4 and 10 weeks at Quincy.

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