Yield of Trickle-irrigated Tomatoes as Affected by Time of N and K Application

Tomatoes (Lycopersicon esculentum Mill.) were grown on polyethylene-mulched beds of an Arredondo fine sand during two seasons to evaluate the effects of trickle-applied N and/or K, percentages of trickle-applied N and K (50%, 75%, and 100%), and schedules of N and K application on fruit yield, and leaf and shoot N and K concentrations. The daily irrigation requirement, calculated at 47% of the water evaporated from a U.S. Weather Service Class A pan (Epan), was met by the application of 4.6 mm to 7.2 mm water/day. Fertilizer was injected weekly in a variable (2% to 12.5% of the total amount weekly) or constant (8.3% of the total amount weekly) schedule during the first 12 weeks of each season. Trickle-applied nutrients and trickle-applied percentage of nutrients interacted in their effects on early, midseason, and total marketable fruit yields. When N + K and N were trickle-applied, the mean early total marketable fruit yield decreased linearly from 25.3 t·ha-1 to 16.3 t·ha-1 as the trickle-applied percentage of nutrients increased from 50% to 100%; but when K was trickle-applied (100% preplant-applied N), yields were not affected by the trickle-applied percentage (mean 26.3 t·ha-1). The weekly schedule of N and K injection had no effect on fruit yield or other characteristics. Higher leaf N and K concentrations early in the season were obtained when the respective nutrient was 50% to 100% preplant-applied than when the respective nutrient was 75% to 100% trickle-applied; but late in the season, higher concentrations were obtained when the respective nutrient was trickle-applied. Higher yields, however, were associated with higher early season leaf N concentrations rather than with higher late-season leaf N or K concentrations.

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Computing Maize Crop Coefficients in the Port Harcourt area, Nigeria, using a Class a Pan Evaporimeter

Outlook on Agriculture ◽

10.1177/003072709702600309 ◽

1997 ◽

Vol 26 (3) ◽

pp. 185-189 ◽

Cited By ~ 1

Author(s):

J.M. Ayotamuno ◽

A.J. Akor ◽

S.C. Teme ◽

E.W.U. Essiet ◽

N.O. Isirimah ◽

...

Keyword(s):

Potential Evapotranspiration ◽

Crop Coefficient ◽

Grain Filling ◽

Maize Crop ◽

Class A ◽

Port Harcourt ◽

The Mean ◽

Crop Coefficients ◽

Tropical Climates ◽

Class A Pan

Farmers in hot tropical climates know the importance of irrigation, but for irrigation to be used effectively the water requirement of the crop must be known. This is computed as the product of the potential evapotranspiration (PET) and the crop coefficient (Kc). While the PET can easily be obtained through various methods, including pan evaporimeters, the Kc in the Port Harcourt area for maize and other crops was not known. The main objective of this research, therefore, was to obtain maize crop coefficients at different stages of growth using non-weighing water table lysimeters and a class A pan. The estimated mean maize evapotranspiration (ET) values for the establishment, vegetative, pollination, and grain-filling stages were 29,98,84 and 98 mm, respectively. Values ranging from 0.18 to 1.08 were calculated for the mean crop coefficients for 10-day periods.

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Yield of papaya irrigated with fractions of Class A pan evaporation in a semiarid environment.

The Journal of Agriculture of the University of Puerto Rico ◽

10.46429/jaupr.v88i1-2.2731 ◽

1969 ◽

Vol 88 (1-2) ◽

pp. 1-10

Author(s):

Ricardo Goenaga ◽

Edmundo Rivera ◽

Carlos Almodóvar

Keyword(s):

Drip Irrigation ◽

Fruit Weight ◽

Water Requirement ◽

Class A ◽

Irrigation Treatments ◽

Marketable Fruit ◽

The Tropics ◽

Optimum Water ◽

Class A Pan ◽

Semiarid Conditions

There is a scarcity of information regarding the optimum water requirement for papaya (Carica papaya) grown under semiarid conditions with drip irrigation in the tropics. A two-year study was conducted to determine water requirement, yield, and fruit quality traits of papaya cv Red Lady subjected to five levels of irrigation. The irrigation treatments were based on Class A pan factors that ranged from 0.25 to 1.25 in increments of 0.25. Drip irrigation was supplied three times a week on alternate days. Results showed significant effects of irrigation on number of fruits, yield and fruit length. Irrigation treatments did not have a significant effect on brix (sweetness). Highest marketable fruit weight (75,907 kg/ha) was obtained from plants irrigated according to a pan factor of 1.25. It was concluded that papaya grown under semiarid conditions should be irrigated according to a pan factor of not less than 1.25.

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686 PB 230 RESEARCH AND DEVELOPMENT OF A MINIATURE PAN EVAPORIMETER FOR GAUGING THE DIFFERENCE BETWEEN EVAPOTRANSPIRATION AND EFFECTIVE RAINFALL

HortScience ◽

10.21273/hortsci.29.5.531b ◽

1994 ◽

Vol 29 (5) ◽

pp. 531b-531

Author(s):

Christopher L. Browne ◽

Thomas W. Cook

Keyword(s):

Pacific Northwest ◽

Reference Evapotranspiration ◽

Effective Rainfall ◽

Pan Evaporation ◽

Irrigation Requirement ◽

Class A ◽

The Pacific ◽

Pan Coefficient ◽

The Difference ◽

Class A Pan

Knowledge of the current irrigation requirement of well-watered grass provides the basis for efficient scheduling of turf and landscape irrigation. A portable, miniature pan evaporimeter has been developed to conveniently provide this information for localized micro-climates. The underlying equation for the instrument is: IRnet = (Kpan • Epan - Kpan • R) where IRnet is the net irrigation requirement of healthy, non-stressed grass; Kpan is the pan coefficient for the instrument; Epan is accumulative pan evaporation; Kpan • Epan is “reference evapotranspiration”; and Kpan • R is a measure of effective rainfall received. This equation was established using turfgrass sites located throughout the Pacific Northwest over a 3-year period. The sites were in proximity to U.S. Class “A” pan evaporimeters, and were automatically irrigated using moisture sensors. Tests of the miniature evaporimeter against automated meteorological stations have determined the factors that influence its pan coefficient, and therefore its ultimate design.

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DISTRIBUIÇÃO DA EVAPORAÇÃO EM ESTUFA PLÁSTICA NA PRIMAVERA

Irriga ◽

10.15809/irriga.2001v6n3p120-127 ◽

2001 ◽

Vol 6 (3) ◽

pp. 120-127

Author(s):

Reginaldo Ferreira Santos ◽

Antonio Evaldo Klar

Keyword(s):

Spatial Variability ◽

Pan Evaporation ◽

Spring Season ◽

Class A ◽

Agricultural Sciences ◽

E Mail ◽

Center Area ◽

Class A Pan

DISTRIBUIÇÃO DA EVAPORAÇÃO EM ESTUFA PLÁSTICA NA PRIMAVERA Reginaldo Ferreira SantosCentro de Ciências Exatas e Tecnológica da UNIOESTE- CP 711CEP 858114-110, Cascavel, PR - Fone: 0XX45 2203155. E-mail: [email protected] Evaldo KlarDepartamento de Engenharia Rural - Faculdade de Ciências Agronômica- UNESP - CEP 18603-970 - Botucatu, SP. CP: 237. E-mail: [email protected] 1 RESUMO O presente trabalho teve como objetivo avaliar a distribuição da evaporação no interior de uma estufa plástica, com uma cultura de pimentão, através da variabilidade espacial e comparar a evaporação dos microevaporímetros com os valores do Tanque classe "A". O experimento foi conduzido no Campus da Universidade Estadual Paulista - FCA/UNESP, no período de primavera, em estufa plástica de polietileno de baixa densidade (PEBD). Na distribuição da evaporação em estufa com orientação norte/sul, verificou-se que as maiores evaporações ocorreram nas extremidades sul e norte tendente ao lado oeste. Já as menores evaporações localizaram-se no centro. No período de primavera, a evaporação média nos microevaporímetros superestimou em 55% a evaporação determinada no Tanque classe "A". UNITERMOS: evaporação, geoestatística, estufa. SANTOS, R.F, KLAR, A.E. EVAPORATION DISTRIBUTION INSIDE A PLASTIC TUNNEL IN THE SPRING SEASON 2 ABSTRACT The main aim of this study was to verify the evaporation distribution inside a plastic tunnel, with pepper crop, oriented to north/south, through spatial variability and to compare Class A Pan evaporation to punctual evaporations of 40 equidistant microevaporimeters placed from 50cm the soil. The study was carried out at the College of Agricultural Sciences/UNESP, Botucatu – SP in the spring season. The highest evaporation occurred next to north and to south sides of the tunnel, with tendency to west. Consequently, the lowest evaporations occurred at the center area. The microevaporimeter evaporations were 55% higher than those obtained from Class A Pan. KEYWORDS: evaporation distribution, microevaporimeter.

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Nutrient Concentrations in Soil Solution in an Alfisol under Grapefruit Production

HortScience ◽

10.21273/hortsci.33.3.498d ◽

1998 ◽

Vol 33 (3) ◽

pp. 498d-498

Author(s):

Z.L. He ◽

A.K. Alva ◽

D.V. Calvert ◽

D.J. Banks ◽

Y.C. Li

Keyword(s):

Soil Solution ◽

Fine Sand ◽

Drainage Water ◽

Tree Canopy ◽

Nutrient Concentrations ◽

Sour Orange ◽

Parallel Study ◽

Ph Measurements ◽

The Mean ◽

N Rates

A field experiment was conducted in a Riviera fine sand (Alfisol) with 25-year-old `White Marsh' grapefruit trees on Sour orange rootstock to monitor the downward transport of nutrients from fertilization practices. Fertilizer was applied as either dry granular broadcast (three applications/year) or fertigation (15 applications/year) at N rates of 56, 112, 168, and 336 kg/ha per year using a N:P:K blend (1.0:0.17:1.0). Soil solution was sampled bi-weekly from suction lysimeters, installed under the tree canopy, about 120 cm from the tree trunk, at two depths representing above (120 cm) and below (180 cm) the hard pan. The concentrations of K, Ca, and Mg were greater at the 180- than at 120-cm depth, whereas, the converse was true with respect to the concentration of P in soil solution. Over a 2-year period, the mean concentrations of P and K varied from 0.031-0.976 and 150-250 mg·L–1, respectively. Increased rate of fertilization also appeared to increase the concentrations of Ca and Mg in the soil solution. This could be due to effects of slight acidification of the soil with increased rates of ammonium form of N. A parallel study on pH measurements has shown evidence of soil acidification, under the tree canopy, with increased rates of ammonium fertilization. In a bedded grove, the soil solution above the hard pan is likely to seep into the water furrow, which is discharged into the drainage water.

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A novel approach for nitrogen diagnosis of wheat canopies digital images by mobile phones based on histogram

Scientific Reports ◽

10.1038/s41598-021-92431-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Xin Qi ◽

Yanan Zhao ◽

Yufang Huang ◽

Yang Wang ◽

Wei Qin ◽

...

Keyword(s):

Neural Network ◽

Mobile Phones ◽

Mean Value ◽

Wheat Cultivars ◽

N Content ◽

Color Parameters ◽

The Neural Network ◽

The Mean ◽

Leaf N Content ◽

Leaf N

AbstractThe accurate and nondestructive assessment of leaf nitrogen (N) is very important for N management in winter wheat fields. Mobile phones are now being used as an additional N diagnostic tool. To overcome the drawbacks of traditional digital camera diagnostic methods, a histogram-based method was proposed and compared with the traditional methods. Here, the field N level of six different wheat cultivars was assessed to obtain canopy images, leaf N content, and yield. The stability and accuracy of the index histogram and index mean value of the canopy images in different wheat cultivars were compared based on their correlation with leaf N and yield, following which the best diagnosis and prediction model was selected using the neural network model. The results showed that N application significantly affected the leaf N content and yield of wheat, as well as the hue of the canopy images and plant coverage. Compared with the mean value of the canopy image color parameters, the histogram could reflect both the crop coverage and the overall color information. The histogram thus had a high linear correlation with leaf N content and yield and a relatively stable correlation across different growth stages. Peak b of the histogram changed with the increase in leaf N content during the reviving stage of wheat. The histogram of the canopy image color parameters had a good correlation with leaf N content and yield. Through the neural network training and estimation model, the root mean square error (RMSE) and the mean absolute percentage error (MAPE) of the estimated and measured values of leaf N content and yield were smaller for the index histogram (0.465, 9.65%, and 465.12, 5.5% respectively) than the index mean value of the canopy images (0.526, 12.53% and 593.52, 7.83% respectively), suggesting a good fit for the index histogram image color and robustness in estimating N content and yield. Hence, the use of the histogram model with a smartphone has great potential application in N diagnosis and prediction for wheat and other cereal crops.

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Some kinematics of halo coronal mass ejections

Open Astronomy ◽

10.1515/astro-2020-0010 ◽

2020 ◽

Vol 29 (1) ◽

pp. 81-88

Author(s):

Virendra Kumar Verma ◽

Nishant Mittal ◽

Ramesh Chandra

Keyword(s):

Coronal Mass Ejections ◽

Solar Flares ◽

Coronal Holes ◽

Geomagnetic Disturbances ◽

Class A ◽

Heliospheric Physics ◽

Class B ◽

The Mean ◽

Class C

AbstractWe present an investigation of halo coronal mass ejections (HCMEs) kinematics and other facts about the HCMEs. The study of HCMEs is very important because HCMEs are regarded as the main causes of heliospheric and geomagnetic disturbances. In this study, we have investigated 313 HCMEs observed during 1996-2012 by LASCO, coronal holes, and solar flares. We find that HCMEs are of two types: accelerated HCMEs and decelerated HCMEs. The mean space speed of HCMEs is 1283 km/s while the mean speed of decelerated HCMEs and accelerated HCMEs is 1349 km/s and 1174 km/s, respectively. The investigation shows that 1 (0.3%) HCME was associated with class A SXR, 14 (4.7%) HCMEs were associated with class B SXR-flares, 87 (29.4%) HCMEs were associated with class C SXR-flares, 125 (42.2%) HCMEs were associated with class M SXR-flares and 69 (23.3%) HCMEs were associated with class X SXR-flares. The speed of HCMEs increases with the importance of solar SXR-flares. The various results obtained in the present analysis are discussed in the light of the existing scenario of heliospheric physics.

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Combining Process Modelling and LAI Observations to Diagnose Winter Wheat Nitrogen Status and Forecast Yield

Agronomy ◽

10.3390/agronomy11020314 ◽

2021 ◽

Vol 11 (2) ◽

pp. 314

Author(s):

Andrew Revill ◽

Vasileios Myrgiotis ◽

Anna Florence ◽

Stephen Hoad ◽

Robert Rees ◽

...

Keyword(s):

Field Experiments ◽

Process Models ◽

Agricultural Technologies ◽

N Application ◽

Area Index ◽

Complex Process ◽

C Cycle ◽

The Mean ◽

Leaf N Content ◽

Leaf N

Climate, nitrogen (N) and leaf area index (LAI) are key determinants of crop yield. N additions can enhance yield but must be managed efficiently to reduce pollution. Complex process models estimate N status by simulating soil-crop N interactions, but such models require extensive inputs that are seldom available. Through model-data fusion (MDF), we combine climate and LAI time-series with an intermediate-complexity model to infer leaf N and yield. The DALEC-Crop model was calibrated for wheat leaf N and yields across field experiments covering N applications ranging from 0 to 200 kg N ha−1 in Scotland, UK. Requiring daily meteorological inputs, this model simulates crop C cycle responses to LAI, N and climate. The model, which includes a leaf N-dilution function, was calibrated across N treatments based on LAI observations, and tested at validation plots. We showed that a single parameterization varying only in leaf N could simulate LAI development and yield across all treatments—the mean normalized root-mean-square-error (NRMSE) for yield was 10%. Leaf N was accurately retrieved by the model (NRMSE = 6%). Yield could also be reasonably estimated (NRMSE = 14%) if LAI data are available for assimilation during periods of typical N application (April and May). Our MDF approach generated robust leaf N content estimates and timely yield predictions that could complement existing agricultural technologies. Moreover, EO-derived LAI products at high spatial and temporal resolutions provides a means to apply our approach regionally. Testing yield predictions from this approach over agricultural fields is a critical next step to determine broader utility.

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Annual Actual Evapotranspiration Estimation via GIS Models of Three Empirical Methods Employing Remotely Sensed Data for the Peloponnese, Greece, and Comparison with Annual MODIS ET and Pan Evaporation Measurements

ISPRS International Journal of Geo-Information ◽

10.3390/ijgi10080522 ◽

2021 ◽

Vol 10 (8) ◽

pp. 522

Author(s):

Stavroula Dimitriadou ◽

Konstantinos G. Nikolakopoulos

Keyword(s):

Time Scale ◽

Gradual Decrease ◽

Actual Evapotranspiration ◽

Pan Evaporation ◽

Empirical Methods ◽

Remotely Sensed Data ◽

Upward Trend ◽

Class A ◽

Evapotranspiration Estimation ◽

Class A Pan

Actual evapotranspiration (ETa) has been insufficiently investigated in Greece. This study aimed to estimate annual ETa by empirical methods (Turc, modified Turc, and Coutagne) for the Peloponnese, Greece, a Mediterranean testbed, between 2016–2019, four of the warmest years since the preindustrial era, and compare them to MODIS ET. Furthermore, measurements of annual pan evaporation (Epan) were performed for two Class A pan stations in the Peloponnese with different reliefs and conditions. The empirical methods and statistical formulae (RMSD, MB, and NMB) were developed as models in ArcMap. The outcomes of the Turc method resembled MODIS ET ranges for all years, followed by those of Coutagne. The estimates by the modified Turc method were almost identical to MODIS ET. Therefore, the modified Turc method can be used as an alternative to MODIS ET (and vice versa) for the Peloponnese for 2016–2019. Moreover, the Epan at Patras University station (semiurban, low elevation) exhibited an upward trend resembling the trends of the empirical methods over the study years, whereas the Epan at Ladonas station (higher elevation, lakeside) required investigation on a monthly time scale. Additionally, the gradual decrease of pan-water icing at Ladonas in December (from 20 d in 2016 to 0 d in 2019) could imply an undergoing decrease in snowpack storage retention across the mountains of the Peloponnese.

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Sweet pepper production in substrate in response to salinity, nutrient solution management and training system

Horticultura Brasileira ◽

10.1590/s0102-05362011000300003 ◽

2011 ◽

Vol 29 (3) ◽

pp. 275-281 ◽

Cited By ~ 6

Author(s):

José S Rubio ◽

Walter E Pereira ◽

Francisco Garcia-Sanchez ◽

Luis Murillo ◽

Antonio L García ◽

...

Keyword(s):

Nutrient Solution ◽

Fruit Quality ◽

Block Design ◽

Sweet Pepper ◽

Training System ◽

Fruit Yield ◽

Salt Treatment ◽

Hoagland Solution ◽

Half Strength ◽

Marketable Fruit

The objective of the present study was to evaluate the marketable fruit yield of sweet pepper plants (Capsicum annuum cv. Orlando) in function of the management of nutrient solution with training system. Plants were grown on coconut coir dust under greenhouse conditions in the southeast of Spain. A randomized block design in split-split plot with four blocks was used to test the effect of the nutrient solution strength (full or half-strength Hoagland nutrient solution), training system (two and three stems per plant) and water salinity (saline and non-saline) on total and marketable yield, fruit quality, and fruit mineral concentration. Salt treatment decreased fruit yield by decreasing the fruit fresh weight but not the number of fruits per plant. Under saline and non-saline conditions, the higher yield of fruits was obtained in plants watered with half-strength Hoagland solution, and grown with three stems per plant. Blossom end rot incidence increased under saline conditions or using full-strength Hoagland solution, but decreased with the combination of half-strength Hoagland solution and three-stem training system. Salt treatment also decreased fruit quality in all the treatments due to a decrease in PO2-, SO4(2-), Fe2+;3+, Cu1+;2+ and Mn2+ concentrations, and fruit shape index. Likewise, plants exposed to salinity and watered with half-strength Hoagland solution and trained with three stems showed a reduction in juice glucose and fructose concentration. Based on these results, an increase of the marketable fruit yield could be obtained under non or moderate saline conditions with the implementation of suitable culture practices.

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