Effect of changes in moisture profiles of a transitional red-brown earth with surface and slotted gypsum applications on the development and yield of a wheat crop

1987 ◽  
Vol 38 (2) ◽  
pp. 239 ◽  
Author(s):  
NS Jayawardane ◽  
J Blackwell ◽  
M Stapper
Keyword(s):  
Root Zone ◽  
Potential Evapotranspiration ◽  
Soil Depth ◽  
Irrigation Scheduling ◽  
Kernel Weight ◽  
Oxygen Flow ◽  
Wheat Crop ◽  
Moisture Contents ◽  
Subsurface Layers ◽  
Moisture Profiles

The low productivity of transitional red-brown earths for flood irrigated upland cropping is associated with their low infiltration rates and inadequate aeration of the root zone. The effect of the measured changes in the moisture and aeration profiles with surface and slotted gypsum applications on growth and development of a wheat crop was evaluated in a preliminary field study, on non-replicated plots.The patterns of changes in moisture profiles in the gypsum slotted plots were similar to those observed in the previous season, namely, deeper preferential wetting and faster internal drainage through the slots. This resulted in lower volumetric moisture contents in the slots and in the surface and subsurface layers between slots, compared to the non-slotted plots.The critical moisture contents were defined for each soil depth at which an air-filled porosity of 0.08 mm3 mm-3 was reached. For the transitional red-brown earth used in this study, air-filled porosity needs to be larger than 0.08 mm3 mm-3 to provide a soil pathway for oxygen flow to roots. The moisture profiles in the no-gypsum, surface gypsum and slotted gypsum plots measured throughout the cropping season indicated the period of time when oxygen flow through different soil layers was likely to be restricted. The moisture contents were higher than the critical value in the surface and subsurface layers of the non-slotted plots, particularly in the plot with no gypsum applications, during a period in winter with prolonged rainfall and low evapotranspiration rates. This resulted in reductions in the rates of phasic development, tillering, canopy closure and dry matter production and finally lower yields in the non-slotted plots, especially in the plot without gypsum. Differences in grain yields were mainly due to differences in the number of spikes m-2.During the second half of the growing season higher potential evapotranspiration, lower rainfall and accurate irrigation scheduling resulted in the moisture contents being maintained below the critical limits at all depths in all plots. Consequently, the two yield components which were determined during this period, namely, the number of kernels per spike and kernel weight, showed only slight variations between plots.

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.

Simulating the effects of saline and sodic subsoils on wheat crops growing on Vertosols

2007 ◽  
Vol 58 (8) ◽  
pp. 802 ◽  
Author(s):  
Zvi Hochman ◽  
Yash P. Dang ◽  
Graeme D. Schwenke ◽  
Neal P. Dalgliesh ◽  
Richard Routley ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Grain Yield ◽  
Crop Yields ◽  
Soil Depth ◽  
Soil Layer ◽  
Strong Support ◽  
Nutrient Loss ◽  
Wheat Crop ◽  
Subsurface Layers ◽  
Best Estimates

Soils with high levels of chloride and/or sodium in their subsurface layers are often referred to as having subsoil constraints (SSCs). There is growing evidence that SSCs affect wheat yields by increasing the lower limit of a crop’s available soil water (CLL) and thus reducing the soil’s plant-available water capacity (PAWC). This proposal was tested by simulation of 33 farmers’ paddocks in south-western Queensland and north-western New South Wales. The simulated results accounted for 79% of observed variation in grain yield, with a root mean squared deviation (RMSD) of 0.50 t/ha. This result was as close as any achieved from sites without SSCs, thus providing strong support for the proposed mechanism that SSCs affect wheat yields by increasing the CLL and thus reducing the soil’s PAWC. In order to reduce the need to measure CLL of every paddock or management zone, two additional approaches to simulating the effects of SSCs were tested. In the first approach the CLL of soils was predicted from the 0.3–0.5 m soil layer, which was taken as the reference CLL of a soil regardless of its level of SSCs, while the CLL values of soil layers below 0.5 m depth were calculated as a function of these soils’ 0.3–0.5 m CLL values as well as of soil depth plus one of the SSC indices EC, Cl, ESP, or Na. The best estimates of subsoil CLL values were obtained when the effects of SSCs were described by an ESP-dependent function. In the second approach, depth-dependent CLL values were also derived from the CLL values of the 0.3–0.5 m soil layer. However, instead of using SSC indices to further modify CLL, the default values of the water-extraction coefficient (kl) of each depth layer were modified as a function of the SSC indices. The strength of this approach was evaluated on the basis of correlation of observed and simulated grain yields. In this approach the best estimates were obtained when the default kl values were multiplied by a Cl-determined function. The kl approach was also evaluated with respect to simulated soil moisture at anthesis and at grain maturity. Results using this approach were highly correlated with soil moisture results obtained from simulations based on the measured CLL values. This research provides strong evidence that the effects of SSCs on wheat yields are accounted for by the effects of these constraints on wheat CLL values. The study also produced two satisfactory methods for simulating the effects of SSCs on CLL and on grain yield. While Cl and ESP proved to be effective indices of SSCs, EC was not effective due to the confounding effect of the presence of gypsum in some of these soils. This study provides the tools necessary for investigating the effects of SSCs on wheat crop yields and natural resource management (NRM) issues such as runoff, recharge, and nutrient loss through simulation studies. It also facilitates investigation of suggested agronomic adaptations to SSCs.

ESTIMATING YIELD COMPONENTS OF WHEAT FROM CALCULATED SOIL MOISTURE

1967 ◽  
Vol 47 (6) ◽  
pp. 617-630 ◽  
Author(s):  
W. Baier ◽  
Geo. W. Robertson
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Yield Components ◽  
Root Zone ◽  
Unit Area ◽  
Kernel Weight ◽  
Wheat Crop ◽  
Climatic Data ◽  
Grain Yields ◽  
Insight Into

Yield components of a wheat crop, namely number of heads per unit area, number of kernels per head and 1000-kernel weight, were related to soil moisture estimated from a meteorological budgeting procedure using only standard climatic data. Several soil-moisture variables, such as moisture content in the root zone from jointing to heading, significantly affected all three yield components and thereby final grain yields. The calculated yield components did not give better estimates of grain yields than those obtained directly from soil-moisture variables, but they did provide a better insight into the relationships between soil moisture, other climatic variables and grain yields at each of the eight stations across Canada. The practical use of a soil-moisture climatology based on the established relationships between estimated soil moisture and yield components is discussed.

Characterizing water use by irrigated wheat at Griffith, New South Wales

Soil Research ◽  
1987 ◽  
Vol 25 (4) ◽  
pp. 499 ◽  
Author(s):  
WS Meyer ◽  
FX Dunin ◽  
RCG Smith ◽  
GSG Shell ◽  
NS White
Keyword(s):  
Water Use ◽  
Field Experiments ◽  
Root Zone ◽  
Soil Surface ◽  
Irrigation Scheduling ◽  
Balance Model ◽  
Wheat Crop ◽  
Water Tables ◽  
Irrigated Wheat ◽  
Upward Flux

Wheat is being grown increasingly in the irrigated areas of south-east Australia. Its profitability depends on high yields, which in turn, are highly dependent on accurate water management. This combination, together with the increasing need for greater water use efficiency to minimize accessions to rising water-tables, calls for effective irrigation scheduling. To achieve this, accurate estimates of crop water use and upward fluxes of water into the root zone from shallow water-tables are required. A weighing lysimeter, installed in 1984, measured hourly evaporation (Ea) from a wheat crop which enabled the accuracy of water use estimates to be assessed. Daily potential evaporation (Ep) was calculated from a combination equation previously calibrated over lucerne, while previously developed crop coefficients for wheat were used to convert Ep to estimated Ea. Daily Ea was the major component in a water balance model for irrigated wheat. The model was quite efficient (r2 = 0.911, but with a bias of -8.8%, which indicated that Ea values were generally underestimated. The underestimate was due primarily to the wind function used in the calculation of Ep, and alternative functions for both daily and hourly calculations were derived. The 1984 lysimeter data also showed that change in soil water content was accurately measured with the field-calibrated neutron probe. Comparisons of measured and estimated water use from field experiments in 1981 and 1982 indicated that upward flux from a water-table between 1 a5 and 2.1 m below the soil surface may be up to 30% of daily Ea. This upward flux will need to be taken into account if irrigation scheduling is to promote efficient use of irrigation water.

Field Measurements and Simulation of Nitrogen Fate under Citrus Production

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 498c-498
Author(s):  
A. Fares ◽  
A.K. Alva ◽  
S. Paramasivam
Keyword(s):  
Mass Balance ◽  
Best Management Practices ◽  
Rainy Season ◽  
Crop Production ◽  
Management Practices ◽  
Root Zone ◽  
Field Measurements ◽  
Irrigation Scheduling ◽  
N Leaching ◽  
Citrus Production

Water and nitrogen (N) are important inputs for most crop production. The main objectives of nitrogen best management practices (NBMP) are to improve N and water management to maximize the uptake efficiency and minimize the leaching losses. This require a complete understanding of fate of N and water mass balance within and below the root zone of the crop in question. The fate of nitrogen applied for citrus production in sandy soils (>95% sand) was simulated using a mathematical model LEACHM (Leaching Estimation And Chemistry Model). Nitrogen removal in harvested fruits and storage in the tree accounted the major portion of the applied N. Nitrogen volatilization mainly as ammonia and N leaching below the root zone were the next two major components of the N mass balance. A proper irrigation scheduling based on continuous monitoring of the soil water content in the rooting was used as a part of the NBMP. More than 50% of the total annual leached water below the root zone was predicted to occur in the the rainy season. Since this would contribute to nitrate leaching, it is recomended to avoid N application during the rainy season.

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.

A MOISTURE STRESS INDEX FOR WHEAT BY MEANS OF A MODULATED SOIL MOISTURE BUDGET

1968 ◽  
Vol 48 (5) ◽  
pp. 535-544 ◽  
Author(s):  
A. R. Mack ◽  
W. S. Ferguson
Keyword(s):  
Soil Moisture ◽  
Stress Function ◽  
Potential Evapotranspiration ◽  
Moisture Stress ◽  
Moisture Distribution ◽  
Stress Index ◽  
Wheat Crop ◽  
Moisture Budget ◽  
Dough Stage ◽  
Soil Moisture Budget

Actual evapotranspiration (AE), soil moisture distribution, and moisture stress for a wheat crop (PE-AE) were estimated by the modulated soil moisture budget of Holmes and Robertson. The estimated soil moisture was reasonably well correlated with soil moisture measured weekly by means of gypsum blocks. Wheat yields from experimental plots in the corresponding area were related more closely to the moisture stress function (PE-AE: r = − 0.83), than to the seasonal precipitation (r = 0.62), the potential evapotranspiration (PE) or the evapotranspiration ratio (AE/PE). Regression analyses showed that the grain yields were reduced by an average of 156 (±sb = 40) kg/ha per cm of moisture stress from emergence to harvest, or by 311 and 69 kg/ha per cm of stress, from the fifth-leaf to the soft-dough stage and from the soft-dough stage to maturity, respectively. The moisture stress function may be used to characterize the soil–plant–atmosphere environment for the growing season of a crop. Precipitation and evapotranspiration data are presented annually for three standardized growing periods at Brandon from 1921 to 1963.

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 THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF SUGAR CANE (SACCHARUM OFFICINARUM): A REVIEW

2011 ◽  
Vol 47 (1) ◽  
pp. 1-25 ◽  
Author(s):  
M. K. V. CARR ◽  
J. W. KNOX
Keyword(s):  
Water Stress ◽  
Water Relations ◽  
Sugar Cane ◽  
Root Zone ◽  
Water Productivity ◽  
Crop Coefficient ◽  
Saccharum Officinarum ◽  
Irrigation Scheduling ◽  
Background Information ◽  
Technology Choice

SUMMARYThe results of research on the water relations and irrigation needs of sugar cane are collated and summarized in an attempt to link fundamental studies on crop physiology to irrigation practices. Background information on the centres of production of sugar cane is followed by reviews of (1) crop development, including roots; (2) plant water relations; (3) crop water requirements; (4) water productivity; (5) irrigation systems and (6) irrigation scheduling. The majority of the recent research published in the international literature has been conducted in Australia and southern Africa. Leaf/stem extension is a more sensitive indicator of the onset of water stress than stomatal conductance or photosynthesis. Possible mechanisms by which cultivars differ in their responses to drought have been described. Roots extend in depth at rates of 5–18 mm d−1 reaching maximum depths of > 4 m in ca. 300 d providing there are no physical restrictions. The Penman-Monteith equation and the USWB Class A pan both give good estimates of reference crop evapotranspiration (ETo). The corresponding values for the crop coefficient (Kc) are 0.4 (initial stage), 1.25 (peak season) and 0.75 (drying off phase). On an annual basis, the total water-use (ETc) is in the range 1100–1800 mm, with peak daily rates of 6–15 mm d−1. There is a linear relationship between cane/sucrose yields and actual evapotranspiration (ETc) over the season, with slopes of about 100 (cane) and 13 (sugar) kg (ha mm)−1 (but variable). Water stress during tillering need not result in a loss in yield because of compensatory growth on re-watering. Water can be withheld prior to harvest for periods of time up to the equivalent of twice the depth of available water in the root zone. As alternatives to traditional furrow irrigation, drag-line sprinklers and centre pivots have several advantages, such as allowing the application of small quantities of water at frequent intervals. Drip irrigation should only be contemplated when there are well-organized management systems in place. Methods for scheduling irrigation are summarized and the reasons for their limited uptake considered. In conclusion, the ‘drivers for change’, including the need for improved environmental protection, influencing technology choice if irrigated sugar cane production is to be sustainable are summarized.

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