Beginning Of Irrigation Research Articles

Исследование динамики влажности почвы при капельном поливе

Purpose: to study the dynamics of moisture in soils on the drainage layer during drip irrigation to save water resources and ensure uniform watering of crops using moisture contours. Materials and methods. The study is based on the theory of moisture transfer under the influence of drip irrigation on soil. Moisture contours were studied in laboratory conditions using a soil lysimeter, which was used to model the geological cross-section of the irrigated area, represented by alluvial meadow soils formed on pebbles. The pebble layer thickness was assumed to be up to 3 m. A regression analysis of moisture movement was carried out, and a mathematical model describing the nature of its movement on the drainage layer was obtained. The estimated volume of wet soil was defined on the basis of moisture contours as a result of calculating the volume of the formed lathe object using cartograms for each hour of irrigation. Results. Data on the moisture distribution in soil profile according to irrigation hours, presented on cartograms constructed using a personal computer, were obtained. The contours with the same humidity – isolines on which the humidity was displayed: 5; 10; 40 % are highlighted on the cartograms. It has been determined that water at an emitter discharge of 2.5 l/h reaches the drainage layer 4 hours after the beginning of irrigation. The graph for moisture distribution in soil volume by hour, reflecting the dynamics of water distribution supplied from an emitter with a constant discharge over 10 hours of irrigation has been constructed. Conclusion. The dynamics of moisture distribution during drip irrigation in soils located on a drainage bed was studied. Under experimental conditions, when crop irrigation lasts for more than 8 hours, an ineffective excess of irrigation rate and an increase in the design capacity of the drip irrigation system are observed.

Morfofisiologia e trocas gasosas da romãzeira sob estresse salino e aplicação foliar de nitrogênio

ABSTRACT Salinity is one of the abiotic stresses that affect gas exchange and growth of pomegranate. In this context, the application of nitrogen fertilizer through the leaves can minimize these effects. Thus, the objective of present study was to evaluate the effect of foliar nitrogen fertilization on pomegranate seedlings irrigated with brackish water. The design used was randomized blocks, in an incomplete factorial scheme (Central Composite Design) with five electrical conductivities of irrigation water - ECw (0.50, 1.15, 2.75, 4.35, and 5.00 dS m-1) and five doses of foliar nitrogen fertilization - FNF (0, 0.33, 1.15, 1.97, and 2.30 g L-1), with four replicates and two plants per experimental plot. Plant height, number of leaves, stem diameter, and gas exchange (stomatal conductance, net photosynthesis, intercellular CO2 concentration, transpiration rate, instantaneous carboxylation efficiency, instantaneous water use efficiency, and intrinsic water use efficiency) were evaluated at 60 days after the beginning of irrigation with saline water. Salinity of irrigation water negatively affects the gas exchange of pomegranate seedlings. Foliar nitrogen fertilization up to 1.31 g L-1 improves plant height and number of leaves in pomegranate seedlings under salt stress. Foliar nitrogen fertilization up to 1.59 g L-1 increases the net photosynthesis of pomegranate seedlings.

Modeling of soil moisture movement and wetting behavior under point-source trickle irrigation

The design and selection of ideal emitter discharge rates can be aided by accurate information regarding the wetted soil pattern under surface drip irrigation. The current field investigation was conducted in an apple orchard in SKUAST- Kashmir, Jammu and Kashmir, a Union Territory of India, during 2017–2019. The objective of the experiment was to examine the movement of moisture over time and assess the extent of wetting in both horizontal and vertical directions under point source drip irrigation with discharge rates of 2, 4, and 8 L h−1. At 30, 60, and 120 min since the beginning of irrigation, a soil pit was dug across the length of the wetted area on the surface in order to measure the wetting pattern. For measuring the soil moisture movement and wetted soil width and depth, three replicas of soil samples were collected according to the treatment and the average value were considered. As a result, 54 different experiments were conducted, resulting in the digging of pits [3 emitter discharge rates × 3 application times × 3 replications × 2 (after application and 24 after application)]. This study utilized the Drip-Irriwater model to evaluate and validate the accuracy of predictions of wetting fronts and soil moisture dynamics in both orientations. Results showed that the modeled values were very close to the actual field values, with a mean absolute error of 0.018, a mean bias error of 0.0005, a mean absolute percentage error of 7.3, a root mean square error of 0.023, a Pearson coefficient of 0.951, a coefficient of correlation of 0.918, and a Nash–Sutcliffe model efficiency coefficient of 0.887. The wetted width just after irrigation was measured at 14.65, 16.65, and 20.62 cm; 16.20, 20.25, and 23.90 cm; and 20.00, 24.50, and 28.81 cm in 2, 4, and 8 L h−1, at 30, 60, and 120 min, respectively, while the wetted depth was observed 13.10, 16.20, and 20.44 cm; 15.10, 21.50, and 26.00 cm; 19.40, 25.00, and 31.00 cm, respectively. As the flow rate from the emitter increased, the amount of moisture dissemination grew (both immediately and 24 h after irrigation). The soil moisture contents were observed 0.4300, 0.3808, 0.2298, 0.1604, and 0.1600 cm3 cm−3 just after irrigation in 2 L h−1 while 0.4300, 0.3841, 0.2385, 0.1607, and 0.1600 cm3 cm−3 were in 4 L h−1 and 0.4300, 0.3852, 0.2417, 0.1608, and 0.1600 cm3 cm−3 were in 8 L h−1 at 5, 10, 15, 20, and 25 cm soil depth in 30 min of application time. Similar distinct increments were found in 60, and 120 min of irrigation. The findings suggest that this simple model, which only requires soil, irrigation, and simulation parameters, is a valuable and practical tool for irrigation design. It provides information on soil wetting patterns and soil moisture distribution under a single emitter, which is important for effectively planning and designing a drip irrigation system. Investigating soil wetting patterns and moisture redistribution in the soil profile under point source drip irrigation helps promote efficient planning and design of a drip irrigation system.

Development Economics of Irrigated Agriculture in Ukraine

The development of irrigated agriculture is a strategic direction of sustainable development of the agrarian sector of economy, ensuring national food security, increasing export potential and efficient use of land and resource potential. The purpose of the article is to systematically analyze the economic framework for the development of irrigated agriculture in Ukraine. The methodological basis of the study is a systematic approach, within which the following general scientific and special methods have been used: analysis, synthesis, generalization, abstraction, historical and comparative analysis, monographic and systemic analysis, formalization, and graphing. The historical and economic background of the development of irrigated agriculture in Ukraine has been analyzed, with five stages of its genesis identified: 1840–1917 (the beginning of irrigation and justification of its feasibility on the ground); 1918–1941 (construction of the first irrigation systems, collective and state farm amelioration networks); 1946–1960 (post-war reconstruction of irrigation systems and construction of large hydroelectric power plants and reservoirs); 1961–1990 (construction of large state and inter-farm irrigation systems, active development of irrigated agriculture); 1991–2021 (gradual decline of the state irrigation network; development of drip irrigation). The size and structure of sown areas on irrigated lands in Ukraine, the structure of sown areas under drip irrigation, and the comparative yield of major crops in agricultural enterprises of Ukraine under irrigation conditions have been systematically studied. It has been shown that economic efficiency in irrigated agriculture is formed under the influence of cost and price mechanisms, and investment decisions are based on the programmability of the yields obtained and the payback of costs by increasing production, and the development of micro-irrigation is economically feasible in small areas of high-intensity crops

Salinidade da água e ácido salicílico no crescimento de plantas de tomate

The tomato is one of the most important vegetables in Brazilian market. The production of this vegetable can be limited by the excess of salts in the water used for irrigation. The use of phytohormones, such as salicylic acid (SA), is used to minimize the negative effects of excess salts on plants. The objective of this paper was to evaluate the attenuating effect of salicylic acid on tomato plants growth irrigated with saline water. The experimental design was the randomized blocks in an incomplete factorial scheme 5 (SA doses: 0.0, 0.29, 1.0, 1.71 and 2.0 mM) x 5 (electrical conductivities of irrigation water - ECw: 0.5, 1.3, 3.25, 5.2 and 6 dS m-1), combined according to the experimental matrix Central Compound of Box, with four replicates and two plants per experimental plot. Growth evaluations were performed 45 days after the beginning of irrigation with saline water. Plant height, number of leaves, stem diameter, absolute and relative growth rate for plant height, root dry mass, shoot dry mass, total dry mass, Dickson's quality index, leaf area, specific leaf area and specific leaf weight were evaluated. The tomato plants growth was reduced by the increase in ECw. Salicylic acid, applied exogenously up to 2.0 mM, did not promote attenuating effect of salinity on tomato plants.

Management of the Water Slide Brought and Saline Flow in Irrigated Onion (<i>Allium cepa</i> L.) Cultivation in the Senegal River Delta

The find for the optimal slide of water to bring to the plot during the irrigated onion crop was important in order to limit the recharge of the water table close to the soil surface. The quantities of water supplied during onion irrigation were estimated from measurements made with a metal crest to the plot positioned at the tertiary canal. The flow rates at the tertiary canal directly irrigating the plot were recorded during irrigation. From this flow rate, the quantity of water supplied to each plot was determined. From then, the performance of the irrigated system in onion cultivation should pass on the management of this water slide at the level of the hydroagricultural facilities. The integrated soil water mass, salinity and water table dynamics monitoring system was used to assess the water requirements of onion following the irrigation. The daily water requirement of onion in the holland soil of the delta was estimated to average 0.45 g/m3. These requirements were varied according to the development stage of the crop. The water level between the ridges was between 6 and 9 mm during irrigation. This was not permanent, it infiltrated between 12 and 18 hours. This type to the stingray irrigation did not favour the arrival of the water table on the surface. The only fluctuations in the water table were observed during the bulb maturation phase. During this phase, the soil water masses were important. The electrical conductivity recorded varied during the campaign. At the beginning of irrigation, it was 3.62 mS/cm on a 30 cm profile, it decreased towards the end of the irrigations to reach 2.06 mS/cm. The quantities of salt recorded on a 30 cm profile varied from one month to the next; they were 0.468 t/ha at the beginning of irrigation (January) and 0.275 t/ha at the end of the campaign (April). From these results we can say that land degradation in the Senegal river delta would be linked to the arrival of salty groundwater on the surface.

Effect of Pulse Drip Irrigation Duration on Water Distribution Uniformity

Developing an appropriate irrigation schedule is essential in order to save water while at the same time maintaining high crop yields. The standard procedures of the field evaluation of distribution uniformity do not take into account the effects of the filling and emptying phases of the irrigation system. We hypothesized that, in sloping sandy soils, when short drip irrigation pulses are applied it is important to take into account the total water applied from the beginning of irrigation until the emptying of the irrigation system. To compute distribution uniformity, we sought to characterize the filling, stable pressure, and emptying phases of a standard strawberry irrigation system. We found that the shorter the time of the irrigation pulse, the worse the distribution uniformity and the potential application efficiency or zero deficit are. This effect occurs because as the volume of water applied during filling and emptying phases increases, the values of the irrigation performance indicators decrease. Including filling and emptying phases as causes of non-uniformity has practical implications for the management of drip irrigation systems in sloping sandy soils.

Effects of alternate moistube-irrigation on soil water infiltration

Alternate moistube-irrigation is a new type of water-saving irrigation, and research on water infiltration with alternate moistube-irrigation is important for the design of irrigation schemes and helpful to understand and apply this technology. The effects of the pressure head (1.0 m and 1.5 m) and tube spacing (10 cm, 20 cm, and 30 cm between two moistubes respectively) on soil water infiltration in alternate moistube-irrigation were studied in laboratory experiments, and the cumulative infiltration, discharge of the moistube, and shape and water distribution of the cross-section of the wetting front were determined. The cumulative infiltration increased quickly and linearly with the infiltration time at 0-96 h (R2>0.99), and changed smoothly at 96-192 h with a basically steady infiltration rate. The discharge of the moistube increased rapidly at the beginning of irrigation, then decreased before stabilizing. The cumulative infiltrations and discharges of moistube under the 1.5 m pressure head were more than those under the 1.0 m pressure head. The shape of the cross-section of the wetting front for a single moistube was similar to a concentric circle. With the increase of tube spacing, the interaction between water infiltrations of two moistubes decreased. The soil water distributions around two moistubes were similar to each other under the 1.0 m pressure head and large tube spacing. When the tube spacing was 20 cm, the soil water distribution was more uniform around two moistubes. Keywords: alternate irrigation, moistube-irrigation, soil water infiltration, water use efficiency, water-saving irrigation DOI: 10.25165/j.ijabe.20201304.5297 Citation: Shen L X, Zhang Y M, Yang M, Liu R H. Effects of alternate moistube-irrigation on soil water infiltration. Int J Agric & Biol Eng, 2020; 13(4): 151–158.

THE CHANGES OF COTTON SEED-LINT YIELD IN PARTS OF FURROW LENGTH UNDER DIFFERENT IRRIGATION SCHEDULING

The paper indicates the results of furrow irrigation technology along parts of furrow and its impact on seed-lint yield and boll weight of upland cotton varieties (Gossypium hirsutum L.) Sultan, UzPITI-103, C-8295 and Kelajak. The research was conducted in the condition of old irrigated typical sierozem soils with mechanical composition of silt loam in Tashkent province, at the Central Experimental Station of Uzbekistan’s Cotton Breeding, Seed Production and Agrotechnologies Research Institute in 2015 to 2019. In research, cutoff flow furrow irrigation was applied where irrigating with inflow rate of 0.40 to 0.42 l s-1 in the beginning of irrigation in three in four part of furrow, then decreasing it till 0.20 to 0.22 l s-1, the inflow rate decreased twice 0.12 to 0.15 l s -1 by reaching water the end of furrow which ensured wetting the root zone layer of soil smoothly along the furrow length. Irrigation scheduling 70-75-65% Fc was optimal for cotton varieties of Sultan and C-8295, where the irrigation scheduling 70-70-60% Fc for UzPITI-103 variety and irrigation scheduling 65-65-60% Fc for Kelajak variety was optimal. In all abovementioned varieties the highest seed-lint yield and boll weight were obtained in the furrow length of 30 to 70 m. The highest seed-lint yield of cotton (4.71 t ha-1 Sultan variety, 4.48 t ha-1 UzPITI-103 variety, 4.27 t ha-1 C-8295 variety, 3.93 t ha-1 Kelajak variety) was obtained in the part of furrow length 30 to 70 m in comparison with the furrow length 0 to 30 m and 70 to 100 m the seed-lint yield was decreased by 0.17 t ha-1 and 0.39 t ha-1 in Sultan, 0.13 t ha-1 and 0.16 t ha-1 in UzPITI-103, 0.10 t ha-1 and 0.16 t ha-1 in C-8295, 0.14 t ha-1 and 0.21 t ha-1 in Kelajak varieties. According to research results, the furrow length must not exceed 70 m.

Effects of alternate moistube-irrigation on soil water infiltration

Alternate moistube-irrigation is a new type of water-saving irrigation, and research on water infiltration with alternate moistube-irrigation is important for the design of irrigation schemes and helpful to understand and apply this technology. The effects of the pressure head (1.0 m and 1.5 m) and tube spacing (10 cm, 20 cm, and 30 cm between two moistubes respectively) on soil water infiltration in alternate moistube-irrigation were studied in laboratory experiments, and the cumulative infiltration, discharge of the moistube, and shape and water distribution of the cross-section of the wetting front were determined. The cumulative infiltration increased quickly and linearly with the infiltration time at 0-96 h (R2>0.99), and changed smoothly at 96-192 h with a basically steady infiltration rate. The discharge of the moistube increased rapidly at the beginning of irrigation, then decreased before stabilizing. The cumulative infiltrations and discharges of moistube under the 1.5 m pressure head were more than those under the 1.0 m pressure head. The shape of the cross-section of the wetting front for a single moistube was similar to a concentric circle. With the increase of tube spacing, the interaction between water infiltrations of two moistubes decreased. The soil water distributions around two moistubes were similar to each other under the 1.0 m pressure head and large tube spacing. When the tube spacing was 20 cm, the soil water distribution was more uniform around two moistubes. Keywords: alternate irrigation, moistube-irrigation, soil water infiltration, water use efficiency, water-saving irrigation DOI: 10.25165/j.ijabe.20201304.5297 Citation: Shen L X, Zhang Y M, Yang M, Liu R H. Effects of alternate moistube-irrigation on soil water infiltration. Int J Agric & Biol Eng, 2020; 13(4): 151–158.

Evaluation of fertigation management impacts of surface drip irrigation on reducing nitrate leaching using numerical modeling.

The objective of this study was to investigate the impacts of fertigation strategies on nitrate leaching and its uptake into maize plants. Field experimental data were employed to calibrate a numerical model (HYDRUS 2D/3D) for a surface drip irrigation system in a sandy clay loam soil. The calibrated model was used to simulate nitrate plant uptake and its leaching in different fertigation scenarios based on various fertigation durations and different start times of fertigation. Finally, nitrogen plant uptake was compared with maize N requirement during growth stages in two fertigation frequency scenarios. These simulations were also performed in sandy loam soil. The results show that, if fertigation is done at the end of irrigation, nitrate leaching in shorter fertigation duration will be less than the leaching in longer fertigation duration. However, in the case of fertigation at the beginning of irrigation, the nitrate leaching is higher if the fertigation duration is short, and vice versa. Furthermore, reducing the number of fertigation events in the sandy clay loam soil increases the nitrate plant uptake. However, in the sandy loam soil, a lesser number of fertigation events reduce nitrate uptake.

Influence of cover cropping on water uptake dynamics in an irrigated Mediterranean vineyard

AbstractAs a result of its physiological characteristics, vine's yield and quality responses are greatly affected by water availability in the soil. Knowledge about water uptake of grapevines in pedoclimatic conditions of high water availability is essential when considering the increasing use of irrigation in a previously rainfed crop. We studied the water uptake of irrigated grapevines under different soil covers. The study was carried out over 2 years in southern Portugal, a Mediterranean climate region, in ‘Aragonez’ grapevines planted in Vertisols. A cover crop was sown in half the area while maintaining the permanent resident vegetation in the remaining area. Five levels of annual irrigation supply were applied: 200, 150, 100 and 50 mm, and no irrigation. Soil moisture was monitored every 2 or 3 weeks, and weekly after the start of irrigation. Results show that water uptake in the interrows did not cease after the beginning of irrigation. Water uptake by the vines occurred to depths of approximately 3 m, hence 7.5 times greater than the cover crop root system depth. Results suggest that over time, the presence of the cover crop forces the vine root system, mainly its thinner roots, to seek water in increasingly deeper soil compartments. Copyright © 2017 John Wiley & Sons, Ltd.

MANAGING FURROW IRRIGATION METHOD IN CORN SMALL HOLDINGS

A field study on corn using furrow irrigation was carried out in northern Egypt on a clay loam soil with 1.2 g cm-3, average soil bulk during 2015 season in Shibin El-Kom area, Egypt. The main aim of this work is to study the changing of irrigation rate (10.71 and 5.35 m3 h-1) and fertilizer application (in complete irrigation time and half wave) on two different slopes (0.05 and 0.1%) of corn field in order to improve furrow irrigation method in small holdings. Corn seeds (Hi-Tech 2031) were planted on May 13, 2015 and received eight irrigations during the growing season. Application efficiency (Ea) was highly achieved by applying 10.71 m3 h-1 and improved by all treatments in second irrigation due to increasing initial soil moisture content compared to first irrigation. Storage efficiency (Es) was properly achieved by applying all treatments except 10.71 m3 h-1 inflow rate under 0.05% furrow slope because 7% deficit was occurred. The results showed that, average of corn yield, green forage yield, 100-grain weight, number of rows per ear and number of grains per row increased by decreasing furrow slope, decreasing inlet flow rate, and nitrogen application after offering half wave. Nitrogen application after offering half wave was achieved high nitrogen (N) concentration in corn root zone. The results indicated that corn yield increased by 8.90, 0.39 and 5.74% by applying furrow slope 0.05% relative to 0.1%, 5.35 m3 h-1 inlet flow rate relative to 10.71 m3 h-1 and nitrogen application after offering half wave along furrow relative to nitrogen application with the beginning of irrigation, respectively.

DPSIR analysis of land and soil degradation in response to changes in land use .

In this paper we analyze the causal chain, from the driving forces to the state, impacts and system responses, for several present and past human activities related to land use and land degradation. The DPSIR framework approach is used for analysing and assessing land degradation problems within a comprehensive view of interactions between human society and the environment. With this approach, land use, land and soil degradation in several parts of the world (Mexico, Spain and Togo) are analyzed in relation to different land use types: the beginning of irrigation in the 1860’s in a semiarid zone with calcareous soils in North-eastern Spain; influence of the land utilization type (LUT) on land degradation in Mexico; soil erosion and reservoir siltation as a global problem (Spain and Mexico); and the protective effects against degradation when soil is considered as a sacred area in Togo. These analyses allow us to learn from the past and could help us to develop strategies to prevent land and soil degradation. This approach provides a useful insight for a systematic analysis when trying to understand the causes of land and soil degradation in response to changes in land use.

Isotopomer analysis of production, consumption and soil-to-atmosphere emission processes of N2O at the beginning of paddy field irrigation

In irrigated rice paddies, episodic release of nitrous oxide (N2O) from the soil to the atmosphere has been observed during the first flood irrigation, but the biogeochemical mechanisms underlying these emissions remain unclear. To elucidate both microbial pathways of N2O production, consumption and emission processes of N2O from soil surfaces, we analyzed isotopomer ratios (bulk nitrogen and oxygen isotope ratios, δ15Nbulk and δ18O, and intramolecular 15N site preference, SP) of surface-emitted N2O and N2O in soil gas from paddy fields in Japan at the beginning of irrigation. Results indicate that surface-emitted N2O is produced at shallow depths above the rising groundwater table, and that it is emitted by diffusive transport through air-filled soil pores. Immediately after soil surfaces are submerged, N2O accumulates in the soil because of the low diffusivity and high solubility of N2O in water. Isotopomer analysis revealed that high N2O emissions during the flooding process resulted mainly from N2O production by bacterial denitrification (nitrate reduction). Moreover, as soil submergence progressed, declining soil NO3− concentration promoted the use of N2O as an electron acceptor. Thereby, most of the N2O was reduced to N2. N2O emissions were increased by nitrogen fertilizer application before irrigation. The applied nitrogen fertilizer might enhance N2O production.

Optimization of the furrow irrigation efficiency

Furrow irrigation is used for row crops. S.C.S., based on a great number of field experiments, under different circumstances and soil families, has developed design equations for furrow irrigation. These equations have been used for steady flow rate or for flow rate with one reduction when the water reaches the end of the furrow. They can also be used for a small period of time (time step) when the flow rate can assumed to be steady. Many scientists, who dealt with furrow irrigation, try to improve the application efficiency by investigation the importance of the parameters that influence the furrow irrigation. Slope, furrow length, intake family have extensively been studied. Flow rate has been studied as steady or with a cutback of flow when water has advanced to furrow end. This article studies the influence of altering flow rate at furrow irrigation to application efficiency. The steepest descent method is implemented for the optimisation at each time step flow rate. Steepest descent method evaluates the derivative of the function, which has to be optimized (application efficiency), to the parameter that is changing (flow rate). The derivative of the application efficiency to flow rate is calculated analytically. The optimized application efficiency is achieved when the derivative is zero, thus the value of flow rate is raised if the derivative is positive or is decreased if the derivative is negative. When the flow rate at each time step is optimised, the process begins again because the optimisation for the flow rate of the initial steps didn’t take into account the optimized flow rates of the later time steps. This process converges and estimates the optimised flow rate at each time step. The results of the optimisation for two samples are alike. The maximum application efficiency is achieved by increasing the flow rate at the beginning of irrigation and before the water reaches furrow end the flow rate must be decreased to the minimum value of flow rate that fulfils instant infiltration.

Irrigation enhances precipitation at the mountains downwind

Abstract. Atmospheric circulation models predict an irrigation-rainfall feedback. However, actual field evidences for local evaporation recycling (moisture feedback) are weak. We present strong field evidence for an increase in rainfall at the mountains located downwind of irrigated zones. We chose two regions, located in semiarid southern Spain, where irrigation started at a well defined date, and we analyzed rainfall statistics before and after the beginning of irrigation. Analyzed statistics include the variation of (1) mean rainfall Δ P, (2) ratio of monthly precipitation to annual precipitation Δ r, and (3) number of months with noticeable rainfall episodes Δ Pmin after a shifting from unirrigated to irrigated conditions. All of them show statistically significant increases. Δ P and Δ r show larger and more statistically significant variations in June and July than in August. They also tend to increase with the annual volume of water applied in the neighbouring upwind irrigation lands. Increases in Δ Pmin are statistically significant during the whole summer. That is, the number of noticeable rainfall events displays a relevant increase after irrigation. In fact, it is this number, rather than sporadic large rainfall episodes what makes the summers wetter. The increase in rainfall, while statistically significant, is distributed over a broad region, so that it is of little relevance from a water resources perspective, although it may enhance vegetation yield.

Effects of drip irrigation with saline water on waxy maize (Zea mays L. var. ceratina Kulesh) in North China Plain

In order to study the effects of drip irrigation with saline water on waxy maize, three years of field experiments were carried out in 2007–2009 in North China Plain. Five treatments with average salinity of irrigation water, 1.7, 4.0, 6.3, 8.6, and 10.9 dS/m were designed. Results indicated that the irrigation water with salinity <10.9 dS/m did not affect the emergence of waxy maize. As salinity of irrigation water increased, seedling biomass decreased, and the plant height, fresh and dry weight of waxy maize in the thinning time decreased by 2% for every 1 dS/m increase in salinity of irrigated water. The decreasing rate of the fresh ear yield for every 1 dS/m increase in salinity of irrigation water was about 0.4–3.3%. Irrigation water use efficiency (IWUE) increased with the increase in salinity of irrigation water when salinity was <10.9 dS/m. Precipitation during the growing period significantly lightened the negative impacts of irrigation-water salinity on the growth and yield. Soil salinity in depth of 0–120 cm increased in the beginning of irrigation with saline water, while it was relatively stable in the subsequent year when salinity of irrigation water was not higher than 4.0 dS/m and the soil matric potential (SMP) at 0.2 m directly underneath the drip emitter was controlled above −20 kPa. © 2010 Elsevier B.V. All rights reserved.

Comparative Study of Neck Pain in Relation to Increase of Cervical Epidural Pressure During Percutaneous Endoscopic Lumbar Discectomy

A prospective study. By monitoring cervical epidural pressure (EP) changes throughout the procedure, we intend to discover the effect of percutaneous endoscopic lumbar discectomy (PELD) on cervical epidural pressure and whether there is a correlation between posterior neck pain and increased cervical EP, which is known to have a linear correlation with intracranial pressure (ICP). Patients sometimes complain of posterior neck pain during PELD. Due to the massive irrigation fluid used during the procedure, the possibility of increased ICP as the cause is quite strong. Twenty-eight patients undergoing PELD with ASA physical status 1 or 2 were enrolled in this study. In all patients, a cervical epidural catheter was placed at the C6-C7 level before the procedure and was connected to a pressure transducer. Cervical EPs were monitored continuously throughout the procedure. Initial stabilized EP (EP), EP at the time of neck pain, maximal EP during the procedure, and EP at the end of the procedure were checked. Neck pain onset time from the beginning of irrigation and total irrigation time were also checked. Of 28 patients, 8 patients complained of neck pain. Neck pain onset time from the beginning of irrigation was 35.6 +/- 11.3 (mean +/- SD) minutes. The EP at the time of neck pain (52.9 +/- 9.2 mm Hg) was significantly higher than the maximal EP in patients without neck pain (34.8 +/- 14.7 mm Hg). In all patients who complained of neck pain, the cervical EP at the time of neck pain showed pressures above 37 mm Hg. The maximal EP in those with neck pain (73.6 +/- 25.8 mm Hg) was also significantly higher than the EP in those without neck pain (34.8 +/- 14.7 mm Hg). In a correlation study, patients with higher maximal EPs had higher probabilities of having neck pain. In 6 of 8 patients, an abrupt increase in EP was observed after the onset of neck pain, while in the other 2 patients, the procedure ended just after neck pain appeared. Neck pain occurring during PELD is associated with a highly increased cervical EP generated by continuous infusion.

トマトの養液栽培における水分ストレスに応じた給液制御システムの開発 （４） 布センサを用いた培地水分量に基づく給液制御

A simple irrigation control system with a fabric sensor was developed for high-Brix tomato production in the restricted root-zone hydroponics. The fabric sensor is composed of a L-shape acrylic unit (LAU) with a non-woven fabric (NWF, thickness: 2 mm, width: 20 mm) and an electrode unit (EU) . The vertical part of NWF in LAU is in contact with a pair of electrodes of EU, and the horizontal part of the NWF is placed under the rooting substrate in the bed. In this irrigation control system, electrification between the electrodes of fabric sensor is detected by a float-less level switch (FLS) . When water content in the substrate is high, the electrodes are charged with electricity because the NWF absorbs ionic water by capillarity. An irrigation pump starts working when the substrate becomes too dry to maintain the electric current in the electrodes. Water content in the substrate at the beginning of irrigation (IP) increased with increasing the height of placement of EU (HEU) and variable resistance (VR) between the electrodes as well as with decreasing the electric conductivity of nutrient solution (ECn) . Using the irrigation control system, the amount of irrigation changed automatically in response to substrate water content, which was affected by solar radiation and plant growing stage. Tomato fruits with Brix values higher than 9% were produced by using this irrigation control system under appropriate conditions of HEU, VR and ECn to optimize the water stress level of the plants.