scholarly journals Calculation of evapotranspiration from potatoes.

1969 ◽  
Vol 17 (4) ◽  
pp. 283-299
Author(s):  
G. Endrodi ◽  
P.E. Rijtema
Keyword(s):  
Soil Cover ◽  
Root Zone ◽  
Potential Evapotranspiration ◽  
Sprinkler Irrigation ◽  
Growing Season ◽  
Diffusion Resistance ◽  
Derived Relations ◽  
Moisture Extraction ◽  
And Diffusion ◽  
Good Agreement

Data from sprinkler irrigation experiments with potatoes were used to calculate the actual and potential evapotranspiration from the crop during the growing season, using standard meteorologie data. During the experiments the moisture extraction from the effective root zone was determined by soil sampling. The water-use by the crop for the different periods was also derived from the water balance and both values were in good agreement in periods without extreme conditions of precipitation, this showing that the derived relations between crop height and surface roughness, between soil cover, light intensity, crop characteristics, soil characteristics and diffusion resistance, and between maturation and internal plant resistance were reasonably established. F.s.-A.G.G.H. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Effect of controlled sprinkler chemigation on wheat crop in a sandy soil

2011 ◽  
Vol 6 (No. 2) ◽  
pp. 61-72
Author(s):  
M.A. Sayed ◽  
M.N.A. Bedaiwy
Keyword(s):  
Grain Yield ◽  
Irrigation Water ◽  
Root Zone ◽  
Nile Delta ◽  
Potential Evapotranspiration ◽  
Irrigation Treatment ◽  
Sprinkler Irrigation ◽  
Wheat Crop ◽  
Evapotranspiration Rate ◽  
Safe Limits

A two-year experiment was conducted in the desert west of the Nile Delta to study the effect of applying fertilizers and other agronomic chemicals through sprinkler irrigation water (a technique referred to as chemigation) on wheat grain yield. Experiment included three levels of irrigation inputs, namely: I<sub>1</sub> = potential evapotranspiration rate (ET<sub>p</sub>), I<sub>2</sub> = 0.8 ETp and I<sub>3</sub> = 0.6 ET<sub>p</sub>, and included two application method of fertilizers and herbicide (chemication and traditional). Applying chemigation resulted in significant increase in grain yield, ranging between 9.9% and 50.0% with averages of 43.2% and 14.5% over the first and second seasons, respectively. Irrigation treatment I<sub>1</sub> produced higher grain yield than the other two irrigation treatments both under traditional and chemigation methods as a result of better fertilizer distribution in the root zone. Grain yield associated with combined I<sub>1</sub> and chemigation was highest of all treatments and was greater than Egypt's national average by 14% and 9% for seasons 1 and 2, respectively. Chemigation resulted in more uniform distribution of nitrate-nitrogen throughout the root zone with nitrate levels falling within safe limits. Concentrations under traditional application resulted in lower levels in upper soil and greater levels at deeper soil of the root zone exceeding safe limits and subjecting the soil and groundwater to contamination hazards. For both N and K fertilizers, fertilizer use efficiency was greater under chemigation than under traditional application. Efficiencies increased with increasing irrigation water, apparently due to better fertilizer distribution. Applying herbicides with sprinkler irrigation water reduced weed infestation from 48% to 6.5%. As a result of improved yield under chemigation, an increase in revenue per hectare of 112.6% was achieved.

Estimating nitrate loading from an intensively managed agricultural field to a shallow unconfined aquifer

2013 ◽  
Vol 49 (1) ◽  
pp. 10-22 ◽  
Author(s):  
P. J. Kuipers ◽  
M. C. Ryan ◽  
B. J. Zebarth
Keyword(s):  
Water Table ◽  
Root Zone ◽  
Potential Evapotranspiration ◽  
Growing Season ◽  
Nitrogen Budget ◽  
Agricultural Field ◽  
Climate Data ◽  
Nitrogen Surplus ◽  
Nitrogen Budgets ◽  
Intensively Managed

Nitrate loading from an intensively managed commercial red raspberry field to groundwater in the Abbotsford-Sumas Aquifer, British Columbia was estimated over a 1 yr period and compared with the nitrogen surplus calculated using a simple nitrogen budget. Nitrate loading was estimated as the product of recharge (estimated from climate data as total precipitation minus potential evapotranspiration (PET)) and monthly nitrate concentration measured at the water table. Most nitrate loading occurred when nitrate, accumulated in the root zone over the growing season, was leached following heavy autumn rainfall events. Elevated groundwater nitrate concentrations at the water table during the growing season when recharge was assumed to be negligible suggested that the nitrate loading was underestimated. The estimate of annual nitrate loading to the water table was high (174 kg N ha−1) suggesting that the tools currently available to growers to manage N in raspberry production are not adequate to protect groundwater quality. The calculated nitrogen surplus from the nitrogen budget (180 kg N ha−1) was similar to the measured nitrate loading suggesting that simple nitrogen budgets may be relatively effective indices of the risk of nitrate loading to groundwater.

scholarly journals Mechanistic modeling of pesticide uptake with a 3D plant architecture model

2021 ◽  
Author(s):  
Helena Jorda ◽  
Katrin Huber ◽  
Asta Kunkel ◽  
Jan Vanderborght ◽  
Mathieu Javaux ◽  
...  
Keyword(s):  
Root Zone ◽  
Chemical Properties ◽  
Mechanistic Modeling ◽  
The European Union ◽  
Architecture Model ◽  
Single Root ◽  
Solute Uptake ◽  
Physical And Chemical ◽  
And Diffusion ◽  
Good Agreement

Abstract A new root solute uptake model based on a lumped version of the Trapp model (Trapp, 2000) was implemented in a coupled version of R-SWMS-ParTrace models for 3-D water flow and solute transport in soil and roots. Solute uptake was modeled as two individual processes: advection with the transpiration stream and diffusion through the root membrane. We parameterized the model for a FOCUS scenario used in the European Union for pesticide registration. Simulation with a single root showed a good agreement with the results produced by the 1D PEARL model. Simulations with a complex root system predicted larger water uptake from the upper root zone, leading to larger pesticide uptake when pesticides are concentrated in the upper root zone. Dilution of root water concentrations at the top root zone with water with low pesticide concentration taken up from the bottom of the root zone lead to larger uptake of solute when uptake was simulated as a diffusive process. This illustrates the importance of modeling uptake mechanistically and considering root and solute physical and chemical properties, especially when root-zone pesticide concentrations are non uniform.

Virus Removal by Filtration

1982 ◽  
Vol 14 (4-5) ◽  
pp. 253-256
Author(s):  
N Sriramula ◽  
M Chaudhuri
Keyword(s):  
Experimental Data ◽  
Escherichia Coli ◽  
Cationic Polyelectrolyte ◽  
Electrokinetic Phenomena ◽  
Virus Removal ◽  
Bacterial Virus ◽  
Gravity Settling ◽  
And Diffusion ◽  
Model Virus ◽  
Good Agreement

An investigation was undertaken on the removal of a model virus, bacterial virus MS2 against Escherichia coli, by sand filtration using untreated, and alum or cationic polyelectrolyte treated media, and uncoagulated as well as alum coagulated influent. Data on discrete virus removal were satisfactorily accounted for by electrokinetic phenomena and diffusion. For virus in association with turbidity, filter coefficients computed from experimental data were in good agreement with those predicted by mechanical straining and gravity settling which were the dominant mechanisms for removal of the turbidity particles to which the viruses attached.

scholarly journals Relationship between Relative Maturity and Grain Yield of Maize (Zea mays L.) Hybrids in Northwest New Mexico for the 2003–2019 Period

Agriculture ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 290
Author(s):  
Koffi Djaman ◽  
Curtis Owen ◽  
Margaret M. West ◽  
Samuel Allen ◽  
Komlan Koudahe ◽  
...  
Keyword(s):  
New Mexico ◽  
Grain Yield ◽  
Sprinkler Irrigation ◽  
Growing Season ◽  
Climatic Conditions ◽  
Agricultural Science ◽  
Production Optimization ◽  
Science Center ◽  
Early Season ◽  
Climate Conditions

The highly variable weather under changing climate conditions affects the establishment and the cutoff of crop growing season and exposes crops to failure if producers choose non-adapted relative maturity that matches the characteristics of the crop growing season. This study aimed to determine the relationship between maize hybrid relative maturity and the grain yield and determine the relative maturity range that will sustain maize production in northwest New Mexico (NM). Different relative maturity maize hybrids were grown at the Agricultural Science Center at Farmington ((Latitude 36.69° North, Longitude 108.31° West, elevation 1720 m) from 2003 to 2019 under sprinkler irrigation. A total of 343 hybrids were grouped as early and full season hybrids according to their relative maturity that ranged from 93 to 119 and 64 hybrids with unknown relative maturity. The crops were grown under optimal management condition with no stress of any kind. The results showed non-significant increase in grain yield in early season hybrids and non-significant decrease in grain yield with relative maturity in full season hybrids. The relative maturity range of 100–110 obtained reasonable high grain yields and could be considered under the northwestern New Mexico climatic conditions. However, more research should target the evaluation of different planting date coupled with plant population density to determine the planting window for the early season and full season hybrids for the production optimization and sustainability.

scholarly journals Combined simulation and optimization framework for irrigation scheduling in agriculture fields

2021 ◽  
Author(s):  
Mireia Fontanet ◽  
Daniel Fernàndez-Garcia ◽  
Gema Rodrigo ◽  
Francesc Ferrer ◽  
Josep Maria Villar
Keyword(s):  
Crop Yields ◽  
Root Zone ◽  
Growing Season ◽  
Irrigation Scheduling ◽  
Irrigated Agriculture ◽  
Traditional Methods ◽  
Simulation And Optimization ◽  
Optimization Framework ◽  
Net Margin ◽  
Combined Simulation

AbstractIn the context of growing evidence of climate change and the fact that agriculture uses about 70% of all the water available for irrigation in semi-arid areas, there is an increasing probability of water scarcity scenarios. Water irrigation optimization is, therefore, one of the main goals of researchers and stakeholders involved in irrigated agriculture. Irrigation scheduling is often conducted based on simple water requirement calculations without accounting for the strong link between water movement in the root zone, soil–water–crop productivity and irrigation expenses. In this work, we present a combined simulation and optimization framework aimed at estimating irrigation parameters that maximize the crop net margin. The simulation component couples the movement of water in a variably saturated porous media driven by irrigation with crop water uptake and crop yields. The optimization component assures maximum gain with minimum cost of crop production during a growing season. An application of the method demonstrates that an optimal solution exists and substantially differs from traditional methods. In contrast to traditional methods, results show that the optimal irrigation scheduling solution prevents water logging and provides a more constant value of water content during the entire growing season within the root zone. As a result, in this case, the crop net margin cost exhibits a substantial increase with respect to the traditional method. The optimal irrigation scheduling solution is also shown to strongly depend on the particular soil hydraulic properties of the given field site.

scholarly journals A MODEL FOR ESTIMATING ACTUAL EVAPOTRANSPIRATION FROM POTENTIAL EVAPOTRANSPIRATION

1975 ◽  
Vol 6 (3) ◽  
pp. 170-188 ◽  
Author(s):  
K. J. KRISTENSEN ◽  
S. E. JENSEN
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Root Zone ◽  
Potential Evapotranspiration ◽  
Actual Evapotranspiration ◽  
Vegetation Density ◽  
Rainfall Distribution ◽  
Sugar Beets

A model for calculating the daily actual evapotranspiration based on the potential one is presented. The potential evapotranspiration is reduced according to vegetation density, water content in the root zone, and the rainfall distribution. The model is tested by comparing measured (EAm) and calculated (EAc) evapotranspirations from barley, fodder sugar beets, and grass over a four year period. The measured and calculated values agree within 10 %. The model also yields information on soil water content and runoff from the root zone.

scholarly journals Climate Change Patterns of Wild Blueberry Fields in Downeast, Maine over the Past 40 Years

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 594
Author(s):  
Rafa Tasnim ◽  
Francis Drummond ◽  
Yong-Jiang Zhang
Keyword(s):  
Climate Change ◽  
Vegetation Index ◽  
Potential Evapotranspiration ◽  
Growing Season ◽  
Spatial Average ◽  
Climate Variables ◽  
Threshold Values ◽  
The Past ◽  
Wild Blueberry ◽  
Crop Health

Maine, USA is the largest producer of wild blueberries (Vaccinium angustifolium Aiton), an important native North American fruit crop. Blueberry fields are mainly distributed in coastal glacial outwash plains which might not experience the same climate change patterns as the whole region. It is important to analyze the climate change patterns of wild blueberry fields and determine how they affect crop health so fields can be managed more efficiently under climate change. Trends in the maximum (Tmax), minimum (Tmin) and average (Tavg) temperatures, total precipitation (Ptotal), and potential evapotranspiration (PET) were evaluated for 26 wild blueberry fields in Downeast Maine during the growing season (May–September) over the past 40 years. The effects of these climate variables on the Maximum Enhanced Vegetation Index (EVImax) were evaluated using Remote Sensing products and Geographic Information System (GIS) tools. We found differences in the increase in growing season Tmax, Tmin, Tavg, and Ptotal between those fields and the overall spatial average for the region (state of Maine), as well as among the blueberry fields. The maximum, minimum, and average temperatures of the studied 26 wild blueberry fields in Downeast, Maine showed higher rates of increase than those of the entire region during the last 40 years. Fields closer to the coast showed higher rates of warming compared with the fields more distant from the coast. Consequently, PET has been also increasing in wild blueberry fields, with those at higher elevations showing lower increasing rates. Optimum climatic conditions (threshold values) during the growing season were explored based on observed significant quadratic relationships between the climate variables (Tmax and Ptotal), PET, and EVImax for those fields. An optimum Tmax and PET for EVImax at 22.4 °C and 145 mm/month suggest potential negative effects of further warming and increasing PET on crop health and productivity. These climate change patterns and associated physiological relationships, as well as threshold values, could provide important information for the planning and development of optimal management techniques for wild blueberry fields experiencing climate change.

scholarly journals MOLECULAR WEIGHT AND ELECTROPHORESIS OF CRYSTALLINE RIBONUCLEASE

1940 ◽  
Vol 24 (2) ◽  
pp. 203-211 ◽  
Author(s):  
Alexandre Rothen
Keyword(s):  
Molecular Weight ◽  
Isoelectric Point ◽  
Unit Weight ◽  
Diffusion Measurement ◽  
Average Value ◽  
Rate Of Sedimentation ◽  
And Diffusion ◽  
Good Agreement

Electrophoretic studies on purified crystalline ribonuclease showed the absence of any impurities differing in mobility from the bulk of material. The isoelectric point of ribonuclease was found by electrophoresis to be at about pH 7.8. Ultracentrifuge studies indicated fair homogeneity of ribonuclease in solution. Only one moving component has been observed. The molecular weight of ribonuclease was found to be 12,700 from rate of sedimentation (S25 = 1.85 x 10–13 in 0.5 M (NH4)2SO4) and diffusion measurement (D = 1.36 x 10–6 in 0.5 M (NH4)2SO4), in good agreement with the average value of 13,000 found from equilibrium measurements. This low value for the molecular weight of a protein would seem to discredit the value 17,600 as representing a universal unit weight for proteins in general.

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