Water Infiltration

The effects on two earthworm species of a gradient of metal contamination in soil collected close to a 50-year-old lead recycling factory were investigated in mesocosms filled with soil sampled at three distances from the factory (10, 30 and 60 m). After 5 weeks of exposure, earthworm litter consumption and weight change were measured. Burrow systems were analysed using Xray tomography, and water infiltration was measured. No significant differences in earthworm weight or activity were observed between mesocosms filled with soil from 30 and 60 m. In contrast, both earthworm species significantly lost weight and burrowed less in the soil sampled at 10 m. In the cores filled with the soil collected at 10-m distance, Aporrectodea caliginosa avoided the highly contaminated first layer (0-5 cm) and burrowed deeper whereas Lumbricus terrestris burrowed relatively more in this layer. We assume that these different reactions are associated with their ecological types. Epi-anecic earthworms forage litter at the soil surface, whereas endogeic earthworms are geophagous and thus are able to forage deeper. This was further corroborated by the bioaccumulation factors measured for each species: for L. terrestris, BAF values for Pb and Cd only decreased slightly in the 10-m soil correlating with their overall reduced activity. However, BAF values for A. caliginosa were 20-fold lower compared to those observed in soil from 30 and 60 m. These modifications in burrowing behaviour in the 10-m mesocosms resulted in a significant and marked decrease in water infiltration rates but only for L. terrestris.

Spatial variability in IR can be assessed quantitatively and qualitatively using semivariograms calculated from Measuring infiltration within a landscape is important because it is the spatial data on IR. Moreover, a close relationship one of the key processes controlling water budgets for the agricultural between infiltration and easily measured soil variables production and transport processes in the soil profile. Estimation of may be exploited to estimate infiltration with a reasonthis process at an acceptable level of accuracy is important, especially in the case when it exhibits high variability, since its measurement is able accuracy at unobserved sites in the field. Ordinary a time-and labor-consuming procedure. This study was conducted to kriging (or simply kriging) and cokriging can sometimes evaluate and compare kriging and cokriging to estimate infiltration be used for this purpose. While kriging uses the spatial rate (IR) using limited available data on an 8.5-ha alluvial field (loamy information on infiltration, cokriging uses spatial informixed mesic Ustifluvent). Infiltration tests were conducted using doumation on infiltration along with spatial correlation beble-ring infiltrometers until steady-state IRs were obtained at nodes tween infiltration and an auxiliary variable to make of an irregular grid consisting of 24 columns and four rows. Values of estimations on unobserved sites (Vieira et al., 1981; field-measured IR ranged from 1.92 to 8.88 cm h Ϫ1 , with a mean of Vauclin et al., 1983; Isaaks and Srivastava, 1989). 5.11 cm h Ϫ1. Bulk density of subsoil was significantly related to IR Vieira et al. (1981) characterized spatial variability of and, therefore, helped estimation of IR values at unobserved locations. 1280 field measurements of infiltration rate on Yolo Both kriging and cokriging adequately estimated IR when 50 observed Loam (fine-silty, mixed, nonacid, thermic, Typic Xeror-IR values were used with both estimators (mean reduced error was 4.15 ϫ 10 Ϫ3 for kriging and 4.10 ϫ 10 Ϫ3 for cokriging). To determine tents) by applying geostatistical concepts. They found the minimum number of observed IR values needed to estimate IR that the observations separated by 50 m or less were without losing significant spatial information, kriging and cokriging dependent on each other as indicated by the range of the were repeated with 45, 40, 35, and 30 observed IR values. Forty-five semivariogram, and concluded that 128 field-measured measured IR values with kriging, and 40 values with cokriging were values were sufficient to obtain essentially the same adequate to estimate IR. Therefore, cokriging was found superior to information as with 1280 values. Vauclin et al. (1983) kriging in estimating IR in the case of limited available data.

Background: Tilt table test (TTT) is commonly used for dizziness work-up, that includes use of nitroglycerine(NTG) during provocation phase. Paradoxical hypertensive reaction to NTG is extremely rare. Pheochromocytoma rarely presents as dizziness and hypertensive emergency can rarely occur during TTT with NTG provocation in these patients. Case: A 51year-old woman with controlled hypertension underwent TTT for dizziness with sublingual NTG for provocation phase. Within 14 minutes, she developed hypertensive emergency, pulmonary edema and cardio-pulmonary instability with room air SpO 2 71%, heart rate 103 bpm and BP 273/158mmHg, cold, clammy and greyish skin. Possible anaphylaxis to NTG with hypertensive emergency was suspected and treated with hydralazine, metoprolol, intravenous methylprednisolone sodium succinate and diphenhydramine. Initially, epinephrine was withheld due to severe hypertension. Despite treatment, patient decompensated with further respiratory distress and developed hypotension. Epinephrine was given with respiratory support to stabilize her. She recovered uneventfully and was discharged home. Decision-Making: Possible anaphylaxis to NTG was suspected given the rapidity of the patient's adverse reaction. Skin test with NTG was recommended, but posed risk of life threatening adverse reaction. Hyperadrenergic surge from undiagnosed pheochromocytoma was considered as alternate diagnosis. Laboratory studies showed elevated 24-hour urine metanephrine 4266 mcg/24hr (normal range, 140 to 785) and 24-hour urine normetanephrine 4175 mcg/24hr (normal range, 75 to 375). MRI of abdomen revealed right suprarenal mass consistent with diagnosis of pheochromocytoma. Conclusions: NTG, an antihypertensive, with paradoxical hypertensive response should evoke suspicion for pheochromocytoma. Focused laboratory and imaging studies prevented a potentially life threatening skin test with nitroglycerine in this patient.

The objectives of this study were to develop an equation for the ponding time, t p , and determine the number of on-off cycles using the infiltration equations introduced by Horton and Kostiakov and to compare the observed and predicted ponding times t p. To achieve these objectives, a sprinkler infiltration test was conducted on the Harran soil series at the Sanhurfa-Koruklu, Tubitak Agricultural Research and Development Station on the Harran plain. The soil characteristic parameters of the Horton and Kostiakov equations were determined from the results of sprinkler infiltration tests. The ponding time equations were developed by choosing a sprinkler application rate of i s = 13.61 mm h À1 that is higher than the steady-state infiltrability rate of i ss = 7.1 mm h À1. The number of on-off cycles was then determined from repeated cycles. The ponding times t p for the experiment, the Horton equation, and the Kostiakov equation were 4.17, 4.09 and 2.69 h, respectively. The numbers of on-off cycles for all three methods were estimated to be two. Under the same management conditions, it was concluded that irrigation at a rate i s > i ss could be completed in 44% less time without the occurrence of runoff and erosion.

Rainfall infiltration and suction variation in unsaturated soils must be taken into consideration in the analysis of most slope stability problems, particularly in the tropical regions where the annual precipitation is high. The process of rainfall infiltration into unsaturated soils is an extremely complex problem attributed to the non-linearity of the hydraulic property functions of the unsaturated soils. This paper describes in detail two instrumented laboratory models, i.e. one-dimensional soil column, and two-dimensional slope model used to provide experimental evidences for the transient suction variations in the unsaturated soils under certain rainfall conditions. The performances of the laboratory models were tested on four typical types of residual soils, i.e. sand-gravel, silty gravel, sandy silt, and silt (kaolin), and a two-layered soil system, i.e. sandy silt underlain by silty gravel. The results showed that the suction distributions for the single-layered homogeneous soils obtained from the simpler onedimensional soil column were almost identical to that of two-dimensional slope model. However, the two-dimensional slope model should be employed for the two-layered soil system because of the dominant effect of the lateral flow mechanism. The capillary barrier effect was observed when a less permeable soil layer was underlain by a more permeable soil layer. The minimum suction value in soil is governed by the rainfall intensity, rainfall duration, and the saturated permeability of soil. The in?ltration rate of the ?ne-grained soils that subjected to shrink and crack was independent of the soil permeability, but was significantly governed by the preferential flows developed in the soils.

Water infiltration is an important hydrological process that influences runoff and soil loss patterns in mountain ecosystems. In this paper, we present results on spatial variation in infiltration in croplands on the volcanic soils of Mt. Elgon, in Eastern Uganda. Twelve experimental sites with slope gradients ranging from 12 to 32% were established. Infiltration tests were carried out with a double ring infiltrometer and three measurements were taken at the upper, middle and lower sections of each experimental site to assess the local variability of infiltration. In addition soil information was collected on each experimental site. The soil infiltration data were then evaluated to fit to four commonly used water infiltration models: (1) Philip (1957), (2) Green-Ampt (1911), (3) Horton (1940) and (4) Kostiakov (1932). The twelve experimental sites cover two cropping systems: annual (6 sites) and perennial (6 sites) crops. Based on the results, we examine the spatial variability of infiltration, the relationship of infiltration to landscape position, and the influence of soil composition on infiltration rates on the slopes. The factors affecting spatial variability of soil infiltration were analysed using correlation and regression techniques. Steady state infiltration rates generally increased with the slope gradient and were crop type independent (P < 0.05). The performance of the four applied water infiltration models was generally good with mean R 2 values ranging from 0.79 to 0.87, although all the models tended to over-predict the steady state infiltration rates at most sites. Overall, the Philip's and Kostiakov gave better results than the Horton and Green-Ampt models in reproducing the infiltration process on Mt. Elgon.

In this paper, we present and analyze a global database of soil infiltration measurements, the Soil Water Infiltration Global (SWIG) database, for the first time. In total, infiltration curves were collected across all continents in the SWIG database. These data were either provided and quality checked by the scientists who performed the experiments or they were digitized from published articles. Data from 54 different countries were included in the database with major contributions from Iran, China, and USA. In addition to its global spatial coverage, the collected infiltration curves cover a time span of research from 1976 to late 2017. Basic information on measurement location and method, soil properties, and land use were gathered along with the infiltration data, which makes the database valuable for the development of pedo-transfer functions for estimating soil hydraulic properties, for the evaluation of infiltration measurement methods, and for developing and validating infiltration models. Soil textural information (clay, silt, and sand content) is available for 3842 out of 5023 infiltration measurements (~76%) covering nearly all soil USDA textural classes except for the sandy clay and silt classes. Information on the land use is available for 76 % of experimental sites with agricultural land use as the dominant type (~40%). We are convinced that the SWIG database will allow for a better parameterization of the infiltration process in land surface models and for testing infiltration models. All collected data and related soil characteristics are provided online in *.xlsx and *.csv formats for reference, and we add a disclaimer that the database is for use by public domain only and can be copied freely by referencing it.

RUSLE is a model used to estimate mean annual soil loss. The model is a predictive tool used to evaluate land use and land cover options. Soil Erodibility (K) Factor is a measure of the predisposition of soil particles to detachment and conveyance by rainfall and surface runoff. The study sought to model soil erodibility (K) factor for river Nzoia basin, western Kenya. Geographical Information System (GIS) techniques were used to generate spatial representation of soil erodibility in the basin. The soil erodibility in river Nzoia basin was classified into: Low (0-0.09); Moderate (0.09-0.13); High (0.13-0.19) and Severe (0.19-0.13) levels. The upper and parts of the middle river Nzoia basin with low and moderate erodibility levels are mainly defined by forestland. These areas experience minimal soil erosion due to dense vegetation cover. Areas with high and severe erodibility levels are defined by land use that is primarily characterized by agricultural activities that tend to leave the soil surface bare. These areas experience high soil erosion due to rainfall and surface runoff. Therefore, to attain environmental restoration of river Nzoia basin, there is need to employ resources for conservation programmes in the areas with high and severe erodibility levels.

Water infiltration is an important hydrological process that influences runoff and soil loss patterns in mountain ecosystems. In this paper, we present results on spatial variation in infiltration in croplands on the volcanic soils of Mt. Elgon, in Eastern Uganda. Twelve experimental sites with slope gradients ranging from 12 to 32% were established. Infiltration tests were carried out with a double ring infiltrometer and three measurements were taken at the upper, middle and lower sections of each experimental site to assess the local variability of infiltration. In addition soil information was collected on each experimental site. The soil infiltration data were then evaluated to fit to four commonly used water infiltration models: (1) Philip (1957), (2) Green-Ampt (1911), (3) Horton (1940) and (4) Kostiakov (1932). The twelve experimental sites cover two cropping systems: annual (6 sites) and perennial (6 sites) crops. Based on the results, we examine the spatial variability of infiltration, the relationship of infiltration to landscape position, and the influence of soil composition on infiltration rates on the slopes. The factors affecting spatial variability of soil infiltration were analysed using correlation and regression techniques. Steady state infiltration rates generally increased with the slope gradient and were crop type independent (P < 0.05). The performance of the four applied water infiltration models was generally good with mean R 2 values ranging from 0.79 to 0.87, although all the models tended to over-predict the steady state infiltration rates at most sites. Overall, the Philip's and Kostiakov gave better results than the Horton and Green-Ampt models in reproducing the infiltration process on Mt. Elgon.

IntroductionIn rainfed agricultural systems, sustainable and efficient water management practices are key to improved agricultural productivity and natural resource management. The agricultural system in sub-Saharan Africa (SSA) relies heavily on the availability of rainfall. With the erratic and unreliable rainfall pattern associated with poor and fragile soils, agricultural productivity has remained very low over the years. Much of the SSA agricultural land has been degraded with low fertility as a result of ongoing cultivation and wind and water erosion. This has resulted in an increased food shortage due to the ever-increasing population and land degradation. Better agricultural and nutritional security are further hampered by the lack of reliable access to the available water resources in the subsurface hydrological system.MethodsThis study used socio-economic data from 112 farm households and Boolean and Fuzzy methods to understand farmers&#39; perceptions and identify suitabl...

In rainfed agricultural systems, sustainable and efficient water management practices are key to improved agricultural productivity and natural resource management. The agricultural system in sub-Saharan Africa (SSA) relies heavily on the availability of rainfall. Agricultural productivity has remained very low due to the erratic and unreliable rainfall pattern associated with poor and fragile soils. Much of the SSA agricultural land has been degraded with low fertility due to ongoing cultivation and wind and water erosion. This has resulted in an increased food shortage due to the ever-increasing population and land degradation. The lack of reliable access to the available water resources in the subsurface hydrological system further hampers better agricultural and nutritional security.
This study used socio-economic data from 112 farm households and
Boolean and Fuzzy methods to understand farmers’ perceptions and identify suitable areas to implement Solar Based Irrigation Systems (SBISs) in the agroecologies of Bougouni and Koutiala districts of southern Mali. Results revealed that the usage of SBISs has been
recent (4.5 years), majorly (77%) constructed by donor-funded projects mainly for domestic water use and livestock (88%). Regarding irrigation, vegetable production was the dominant water use (60%) enabling rural farm households to gain over 40% of extra household income during the dry season. Results further showed that 4,274 km2 (22%) of the total land area for the Bougouni district, and 1,722 km2 (18%) of the Koutiala district are suitable for solar-based irrigation.

Soil surface roughness affects surface depression storage, water infiltration, overland flow velocity as well as overland flow organisation. This paper attempts to give an overview of our knowledge of the effects of roughness on surface runoff and to indicate areas where further research is most needed. The relationship between soil surface roughness and depression storage is relatively well understood. On the other hand, few studies exist on the relationship between roughness and the infiltration characteristics of a tilled surface, although this may be more important. Insights, which have been developed over the past few years, may in the near future lead to a better prediction of the hydraulic resistance of interrill and concentrated overland flow. Recent studies have also provided important information on the effects of roughness on runoff patterns. soil roughness / depression storage / infiltration / hydraulic resistance / runoff pattern Résumé-Rugosité du sol et écoulement sur le terrain. La rugosité de la surface du sol affecte le stockage de l'eau dans les dépressions de la surface, son infiltration et la vitesse ainsi que l'organisation de l'écoulement sur le terrain. Cet article tente de donner une vue d'ensemble de nos connaissances actuelles sur les effets de la rugosité sur le ruissellement de surface et indique les domaines dans lesquels de nouvelles recherches sont les plus nécessaires. La relation entre la rugosité de la surface et le stockage de l'eau dans les dépressions est relativement bien connue. En revanche, il existe peu d'études sur la relation entre la rugosité d'une surface labourée et ses caractéristiques d'infiltration, bien que ce phénomène soit plus important. Les tentatives d'approche développées au cours des dernières années devraient conduire, dans un proche avenir, à une meilleure prédiction de la résistance hydraulique des zones de ruissellement diffus et concentré. Des études récentes ont fourni également des informations importantes sur les effets de la rugosité sur l'organisation spatiale de ruissellement. Rugosité du sol / stockage dans les dépressions / infiltration / résistance hydraulique / organisation spatiale de ruissellement

Water infiltration is an important hydrological process that influences runoff and soil loss patterns in mountain ecosystems. In this paper, we present results on spatial variation in infiltration in croplands on the volcanic soils of Mt. Elgon, in Eastern Uganda. Twelve experimental sites with slope gradients ranging from 12 to 32% were established. Infiltration tests were carried out with a double ring infiltrometer and three measurements were taken at the upper, middle and lower sections of each experimental site to assess the local variability of infiltration. In addition soil information was collected on each experimental site. The soil infiltration data were then evaluated to fit to four commonly used water infiltration models: (1) Philip (1957), (2) Green-Ampt (1911), (3) Horton (1940) and (4) Kostiakov (1932). The twelve experimental sites cover two cropping systems: annual (6 sites) and perennial (6 sites) crops. Based on the results, we examine the spatial variability of infiltration, the relationship of infiltration to landscape position, and the influence of soil composition on infiltration rates on the slopes. The factors affecting spatial variability of soil infiltration were analysed using correlation and regression techniques. Steady state infiltration rates generally increased with the slope gradient and were crop type independent (P < 0.05). The performance of the four applied water infiltration models was generally good with mean R2 values ranging from 0.79 to 0.87, although all the models tended to over-predict the steady state infiltration rates at most sites. Overall, the Philip's and Kostiakov gave better results than the Horton and Green-Ampt models in reproducing the infiltration process on Mt. Elgon.

Inadve rt e nt s oil compac tion at th e urb a n lot s ca le is a pro ces s t hat redu ces infilt ra tion rates, whi ch ca n lead to inc reased stormwater runoff. Th is is parti cularly importan t in low im pact development strategies wh ere stormwater is intended to infiltrate rath er th an flo w throu gh a tradition a l s torm wate r ne twor k to a dete ntion basin. The effec t of compac tion on infiltration ra tes on sandy soils in No rth Ce ntral Florida was measured with a double ring infiltrometer on urban con stru ction sites and ac ro ss va rious levels of compaction. Average non-compacted infiltrati on rates ra nged from 377 to 634 mm hr•' (14.8 to 25.0 in hr') for natura l fo rest, from 637 to 652 mm hr•' (25. 1 to 25 .7 in hr •') fo r pl a nte d forest, and 225 mm hr•' (8.9 in hr•') for pastu re sites. Average infiltration rates on compacted soils ranged 8-175 mm hr•' (0.3•6.9 in hr-'), 160 to 188 mm hr ' (6.3 to 7-4 in hr•'), and 23 mm hr ' (0.9 in hr•') for th e sa me res pective sites. Although th ere was wide variability in infiltration rates across both compacted and non-co mpacted sites, co nstruction ac tivity or compac tion treatments redu ced infi ltration rates 70 to 99 percent. Maximu m compaction as measured with a cone penetrom eter occu rred in the 20 to 30 em (7.9 to 11.8 in) depth range. When studying the effect of different levels of compaction due to light and heavy con stru ction equi pme nt, it was not as important how heavy the equipm ent was but wh eth er compaction occurred at all. Infi ltration rates on compacted soils were generally mu ch lower th an the design storm infiltration rate of 254 mm hr' (10.0 inches hr') for th e 1oo-yr, 24-hr storm used in the region. This implies th at construction activity in th is region increases th e potential for runoff and the need for large stormwate r conveyance networks not on ly due to the increase in imperviou s area associated with develo pment but also because the compacted pervious area effectively approaches the infiltra tion behavior of an imperviou s surfac e.

Rainfall infiltration and suction variation in unsaturated soils must be taken into consideration in the analysis of most slope stability problems, particularly in the tropical regions where the annual precipitation is high. The process of rainfall infiltration into unsaturated soils is an extremely complex problem attributed to the non-linearity of the hydraulic property functions of the unsaturated soils. This paper describes in detail two instrumented laboratory models, i.e. one-dimensional soil column, and two-dimensional slope model used to provide experimental evidences for the transient suction variations in the unsaturated soils under certain rainfall conditions. The performances of the laboratory models were tested on four typical types of residual soils, i.e. sand-gravel, silty gravel, sandy silt, and silt (kaolin), and a two-layered soil system, i.e. sandy silt underlain by silty gravel. The results showed that the suction distributions for the single-layered homogeneous soils obtained from the simpler onedimensional soil column were almost identical to that of two-dimensional slope model. However, the two-dimensional slope model should be employed for the two-layered soil system because of the dominant effect of the lateral flow mechanism. The capillary barrier effect was observed when a less permeable soil layer was underlain by a more permeable soil layer. The minimum suction value in soil is governed by the rainfall intensity, rainfall duration, and the saturated permeability of soil. The in?ltration rate of the ?ne-grained soils that subjected to shrink and crack was independent of the soil permeability, but was significantly governed by the preferential flows developed in the soils.

A computer model for the analysis and design of grass swale perforated pipe systems is presented. The model, which was calibrated and validated using experimental as well as field data, performs detailed computations for flow through the system on a lot by lot basis ͑i.e., from one catchbasin to another͒. Several parameters affecting the system performance are considered in the modeling approach. These especially included lot size and imperviousness, grass swale dimensions and its infiltration capacity, pipe length, number of orifices and their configuration, trench dimensions, and native soil infiltration capacity. The model was used to simulate the minimum trench depth required to capture runoff from a 25 mm storm for different native soils and different lot imperviousness ratios. Trench depths varied from 0.3 to 1.4 mm depending on native soil infiltration capacity and lot imperviousness.

The California Department of Transportation requires that all new flexible pavements include a 75-mm layer of asphalt-treated permeable base (ATPB) between the asphalt concrete and aggregate base layers. The purpose of the ATPB layer is to intercept water entering the pavement, either through cracks in the asphalt concrete or through high-permeability asphalt concrete, and to transport it out of the pavement before it reaches the unbound materials. Results are presented of a study using heavy vehicle simulator (HVS) trafficking to evaluate the performance of drained and undrained flexible pavements under wet conditions. A drained structure is a pavement section that contains an ATPB layer between the asphalt concrete and aggregate base. An undrained structure is a pavement section that does not contain an ATPB layer. Wet conditions intend to simulate approximate surface infiltration rates that would occur along the northwest coast of California during a wet month for a badly cracked...

Through action research and development partnerships, Africa RISING is creating opportunities for smallholder farm households to move out of hunger and poverty through sustainably intensified farming systems that improve food, nutrition, and income security, particularly for women and children, and conserve or enhance the natural resource base.

This study addresses infiltration from furrows or narrow channels. The basic approach is to develop the two-dimensional infiltration as a combination of the corresponding one-dimensional vertical and an edge effect. The idea is borrowed from previous applications for infiltration from disc and strip sources. The assumption is tested directly with numerical experiments using four representative soils and three furrow shapes ͑triangular, rectangular, and parabolic͒. The edge effect is the difference between the cumulative infiltration per unit of adjusted wetting perimeter and the corresponding one-dimensional infiltration. A general conclusion is that the edge effect is linearly related to time. In addition, it was observed that the two empirical parameters in the function used to relate the edge effect with time have narrow ranges and are related to soil hydraulic parameters, furrow shape, the boundary and initial conditions and additional geometric factors. The approach leads to a physically based infiltration function for irrigation furrows ͑or narrow channels͒ without the need to perform a fully two-dimensional simulation. Also, a simplified expression was found for the limiting steady-state case, which is analogous to Wooding's equation for infiltration from a shallow pond.

Preferential use of creeping bentgrass [Agrostis stoloniferous L. Applying light, frequent amounts of water (syringing) var. palustris (Huds.)] on golf putting greens has expanded into the is a management practice often utilized on bentgrass hotter, more environmentally stressful regions of the southeastern putting greens under heat stress conditions. This prac-United States where turfgrass decline is problematic during summer months. Methods of reducing temperatures in the putting green micro-tice is based on the concept of evaporative cooling. Syringclimate would enhance bentgrass survival under heat stress conditions. ing creeping bentgrass has been shown to produce modest The objectives of this study were to evaluate the bentgrass putting (1 to 2ЊC) turf mat temperature reductions (Duff and green microclimate under combined misting and/or subsurface fan Beard, 1966) or no reduction unless the turf had already systems with surface fans. Field studies were conducted in the summers wilted (DiPaola, 1984). No information is available on of 2001 and 2002 on a 'Crenshaw' creeping bentgrass putting green the use of water mist in a fan's air stream to reduce located in Clemson, SC. Treatments consisted of surface fan only, canopy and soil temperatures. surface fan plus misting, surface fan plus subsurface fan, and surface Forcing air into a USGA (United States Golf Associafan plus misting and subsurface fan. Fan treatments were applied tion) green rootzone through subsurface drain lines has from 1100 to 1500 h on days when temperatures were Ն29.5؇C, there been shown to reduce soil temperatures. A preliminary was no visible cloud cover, and wind speed Ͻ 1.0 m s Ϫ1. Surface fan study noted forcing air into the rootzone reduced soil plus misting treatments reduced putting green canopy, soil surface, and soil temperatures by as much as 9, 7, and 6؇C, respectively, while temperatures 2 to 3ЊC at a depth of 5 cm in the afternoon increasing canopy relative humidity and soil moisture content. Bene-(Dodd et al., 1999). Similar experiments also reported fits were generally observed over a range of 5 m from the fan. These soil temperature reductions as great as 2.5ЊC at 10-cm treatments demonstrate great potential for improving canopy and soil depth in USGA bentgrass greens (Bigelow et al., 2001). microclimate conditions influencing bentgrass survival in a heat stress Using misting and/or subsurface fans with surface fans environment. Surprisingly, the use of subsurface fans did not enhance may provide effective means of reducing plant and soil the cooling effect provided by surface fans. Fan/mist systems should be temperatures of bentgrass putting greens in the southern investigated further to determine possible disease occurrence during United States. The objective of this study was to evaluextended use periods. ate, under heat stress conditions, the effects of misting and/or subsurface air movement on the bentgrass putting green microclimate when used in combination with

Earthworm burrow systems are generally described based on postulated behaviours associated with the three ecological types. In this study, we used X-ray tomography to obtain 3D information on the burrowing behaviour of six very common anecic (Aporrectodea nocturna and Lumbricus terrestris) and endogeic (Aporrectodea rosea, Allolobophora chlorotica, Aporrectodea caliginosa, Aporrectodea icterica) earthworm species, introduced into repacked soil cores for 6 weeks. A simple water infiltration test, the Beerkan method, was also used to assess some functional properties of these burrow systems. Endogeic worms make larger burrow systems, which are more highly branched, less continuous and of smaller diameter, than those of anecic worms. Among the anecic species, L. terrestris burrow systems are shorter (9.2 vs 21.2 m) with a higher number (14.5 vs 23.5) of less branched burrows (12.2 vs 20.2 branches m −1), which are also wider (7.78 vs 5.16 mm) than those of A. nocturna. In comparison, the burrow systems made by endogeic species appeared similar to each other. However, A. rosea burrows were short and narrow, whereas A. icterica had a longer burrow system (15.7 m), more intense bioturbation intensity (refilled macropores or soil lateral compaction around them) and thus a greater number of burrows. Regarding water infiltration, anecic burrow systems were far more efficient due to open burrows linking the top and bottom of the cores. For endogeic species, we observed a linear relationship between burrow length and the water infiltration rate (R 2 =0.49, p<0.01). Overall, the three main characteristics significantly influencing water infiltration were burrow length, burrow number and bioturbation volume. This last characteristic highlighted the effect of burrow refilling by casts.

Preferential use of creeping bentgrass [Agrostis stoloniferous L. Applying light, frequent amounts of water (syringing) var. palustris (Huds.)] on golf putting greens has expanded into the is a management practice often utilized on bentgrass hotter, more environmentally stressful regions of the southeastern putting greens under heat stress conditions. This prac-United States where turfgrass decline is problematic during summer months. Methods of reducing temperatures in the putting green micro-tice is based on the concept of evaporative cooling. Syringclimate would enhance bentgrass survival under heat stress conditions. ing creeping bentgrass has been shown to produce modest The objectives of this study were to evaluate the bentgrass putting (1 to 2ЊC) turf mat temperature reductions (Duff and green microclimate under combined misting and/or subsurface fan Beard, 1966) or no reduction unless the turf had already systems with surface fans. Field studies were conducted in the summers wilted (DiPaola, 1984). No information is available on of 2001 and 2002 on a 'Crenshaw' creeping bentgrass putting green the use of water mist in a fan's air stream to reduce located in Clemson, SC. Treatments consisted of surface fan only, canopy and soil temperatures. surface fan plus misting, surface fan plus subsurface fan, and surface Forcing air into a USGA (United States Golf Associafan plus misting and subsurface fan. Fan treatments were applied tion) green rootzone through subsurface drain lines has from 1100 to 1500 h on days when temperatures were Ն29.5؇C, there been shown to reduce soil temperatures. A preliminary was no visible cloud cover, and wind speed Ͻ 1.0 m s Ϫ1. Surface fan study noted forcing air into the rootzone reduced soil plus misting treatments reduced putting green canopy, soil surface, and soil temperatures by as much as 9, 7, and 6؇C, respectively, while temperatures 2 to 3ЊC at a depth of 5 cm in the afternoon increasing canopy relative humidity and soil moisture content. Bene-(Dodd et al., 1999). Similar experiments also reported fits were generally observed over a range of 5 m from the fan. These soil temperature reductions as great as 2.5ЊC at 10-cm treatments demonstrate great potential for improving canopy and soil depth in USGA bentgrass greens (Bigelow et al., 2001). microclimate conditions influencing bentgrass survival in a heat stress Using misting and/or subsurface fans with surface fans environment. Surprisingly, the use of subsurface fans did not enhance may provide effective means of reducing plant and soil the cooling effect provided by surface fans. Fan/mist systems should be temperatures of bentgrass putting greens in the southern investigated further to determine possible disease occurrence during United States. The objective of this study was to evaluextended use periods. ate, under heat stress conditions, the effects of misting and/or subsurface air movement on the bentgrass putting green microclimate when used in combination with

The ratio of cutback time to advance time has been investigated vis siixulating sloping borders with free out-flow. Also, the ratio of cutback inflow to initial inflow has been investigated. The sirnulation was accomplished utilizing a zero inertia model that describes the rnovernent of water aiong the borders. The flow was cutback when the maximum application efficiency for a given irrigation parameter was obtained. The irrigation parameters considered were four infiltration families, three slopes, three roughness coefficients, three depths, and two field lengths. The results reveaied that there was no unique relationship between the times of cutback and advance. lt however was found that the ratio of the cutback tiine to the advance time was mostly less than one. From a frequency analysis, 8CI % of the values of the cutback to the advance ratio are less than 1.0. The ratio of cutback-initial infloiv ranges generally from 0.2 to 0.8. The frequency analysis implies that 60 % of the values of the cutback-initial inflow ratio fali in a dornain of akrout 0.4-0.6" Key wards: border ircigation, cutbsck-advance time, cutback-initicl iruflotr. l. t\TRout cTIo\ Automation of irrigatioit svstetns bect-rriles irrcreasinsl_r and-11-Bull. Fac. .{gric., Cairo Aniv., 54 (2!!il;41-s4. RATIOS OF CUT'BACK.ADVANCE TIME AND CUTBACK. INITIAL INFLOW FOR BORDER. IRRIGATION

Los suelos del bosque de Calden reciben aportes de residuos variables en cantidad y calidad segun la vegetacion dominante. El objetivo fue analizar si esta influye sobre algunas propiedades edaficas. Un Haplustol Entico se muestreo en parches con predominio de especies forrajeras (F), no forrajeras bajo calden (NF) y arbustivas (A). Se determinaron fracciones de carbono organico, nitrogeno total, fosforo disponible, cationes intercambiables, parametros de hidrofobicidad e infiltracion. El suelo de NF presento mayor contenido de carbono organico total y de sus fracciones, de nitrogeno total y de fosforo disponible. En el suelo de F la densidad aparente fue mayor y el contenido de calcio intercambiable menor. La superficie del suelo del parche F se clasifico como ligeramente repelente al agua, mientras que la de los otros dos suelos como fuertemente repelente. La tasa de infiltracion media fue menor en NF y mayor en A, este ultimo presento la mayor tasa de infiltracion final. Estudios...

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This paper addresses the global outer synchronization problem between two fractional-order complex networks coupled in a drive-response configuration. In particular, for a given fractional-order complex network composed of Lur'e systems, an observer-type response network with non-fragile output feedback controllers is constructed. Both additive and multiplicative uncertainties that perturb the control gain matrices are considered. Then, using the stability theory of fractional-order systems and eigenvalue distribution of the Kronecker sum of matrices, we establish some sufficient conditions for global outer synchronization. Interestingly, the developed results are cast in the format of linear matrix inequalities (LMIs), which can be efficiently solved via the MATLAB LMI Control Toolbox. Finally, numerical simulations on fractional-order networks with nearest-neighbor and small-world topologies are given to support the theoretical analysis.

In preparation for golf course tournaments, turfgrass managers often seek increased ball roll distances on putting greens. The objective of this study was to determine the effect mowing height and frequency had on ball roll distance during simulated tournament conditions. Two 14-d field experiments were conducted in 2015 and 2016 at the Joseph Valentine Turfgrass Research Center located in University Park, PA. Each study was conducted on a 'Penn A-4' creeping bentgrass (Agrostis stolonifera L.; CBG) and annual bluegrass (Poa annua L.; ABG) putting green. Plots measured 1.5 m by 3.0 m and were arranged in a randomized complete block design with a 3 × 3 factorial treatment structure. For the main effect of height of cut (HOC), mowers were set to a bench height of 2.1 mm, 2.5 mm, and 2.9 mm. For mowing frequency (MF), plots were mowed once, twice, or four times per day. Single cut (SC) and double cut (DC) treatments were performed in the morning whereas double-double cut (DD) treatments consisted of a DC in the morning and again in the afternoon. Ball roll distance (BRD) and turfgrass quality were assessed. Although a few interactions were present in the ABG study, the main effects of HOC and MF were significant on 79% and 82% rating dates, respectively. On CBG, the main effect of HOC and MF were significant on 89% and 86% of rating dates. For both species, turfgrass quality was reduced during the trial as HOC was reduced and MF was increased. 1 INTRODUCTION Putting greens are the most intensely managed playing surfaces on golf courses. Ball roll distance (BRD), often referred to as "green speed" by golfers, and trueness of the ball's roll across a green have a major impact on the playability of putting surfaces. For golfers, green speed is directly associ

Anomalous influxes of water into unfilled collection bags can greatly overestimate volume and flow rate data from seepage meters. From static tank trials, initially empty collection bags (4,500 mL capacity) attached to seepage meters gained significantly more water relative to bags prefilled to 1,000 mL. Data from a study of groundwater flow at redds of brook trout Salvelinusfontinalis in Scott Lake, Ontario, indicate that the use of unfilled bags biases seepage meter data. At these redds, the anomalous influx of water into unfilled bags was significant (intercept of regression equation, y = 275 mL); however, this influx was sufficiently reduced when prefilled bags were used (y = 34 mL). Our data suggest that even at high flow rates (22-169 mL-irr 2-min '), seepage measures can be inflated by an order of magnitude when initially empty bags are used. Because of this anomaly, previous measures of groundwater flow at brook trout redds with unfilled bags are probably not representative of natural flow rates. Our estimates of groundwater flow at brook (rout redds in Scott Lake (6-296 mL-nrr 2-min~!) are very similar to the range in groundwater flow found in lake and stream redds (4-340 mL-m'-min' 1) by other methods. We suggest the use of prefilled collection bags (filled to 1,000 mL) and conformity in measurement units (mL-m~2-min~') when groundwaler flow is measured with seepage meters.

A phenomenon called 'piping' often occurs in hydraulics works, involving the formation and evolution of a continuous tunnel between the upstream and the downstream sides. The hole erosion test is commonly used to quantify the rate of piping erosion. However, few attempts have been made to model these tests. From the equations for diphasic flow with diffusion, and the equations of jump with erosion, a piping model is developed. A characteristic time of internal erosion process is proposed. Comparison with experimental data validates our results. To cite this article: S.

Through action research and development partnerships, Africa RISING is creating opportunities for smallholder farm households to move out of hunger and poverty through sustainably intensified farming systems that improve food, nutrition, and income security, particularly for women and children, and conserve or enhance the natural resource base.

A non-linear numerical finite element method (FEM) model of a thermo-electric focal plane array (FPA) detector is presented here. Laser induced thermo-voltage profiles tend to spread out for small lock-in frequencies as the thermal diffusion length is inversely proportional to the square-root of the lock-in frequency. This leads to a frequency and spatial dependent thermal cross-talk level. In this paper we investigate the thermal cross-talk level quantitatively in function of spatial coordinates and lock-in frequency. Experimental data are provided at an optical power level of 1W. The impact of non-linear thermal parameters as the temperature dependence of the absorption coefficient, the thermal conductivity, the heat transfer coefficient and the Seebeck coefficient on the thermal profile and cross-talk level generated inside the detector material are studied in detail. Heat losses that are included in the model are conduction and laminar free convection. The relative importance of the above mentioned non-linear thermal parameters in terms of thermal cross-talk for steady-state solutions are discussed as well.

Some two dozen methods for estimating infiltration and roughness parameters from field measurements of test irrigations are reviewed in this paper. They differ in their assumptions, ease of analysis, quantity of field data required, and accuracy. They are divided into two broad categories, depending upon the basic approach to determine infiltration. One features direct application of mass conservation, expressed in terms of the infiltration parameters and then inverted in some way in order to extract those parameters. The other involves repeated simulation with a sequence of values of the infiltration parameters, coupled to some kind of search procedure-an optimization-to minimize differences between simulation and measurement. A new one-point technique is proposed, along with suggestions for extending existing methods.

The saturated hydraulic conductivity (K sat) is a key soil hydraulic property governing agricultural production. However, the influence of conversion from conventional tillage (CT) to conservation tillage (CS) (including no tillage (NT) and reduced tillage (RT)) on K sat of soils is not well understood and still debated. In this study, we applied a global meta-analysis method to synthesize 201 paired observations for soil K sat from 59 published studies, and investigated factors influencing the effects of conversion to CS on K sat. Results showed that the K sat measured by hood infiltrometer, tension disc infiltrometer, and Guelph permeameter produced a similar pattern under CS practices, with non-significant (p > 0.05) increase of 6.6%, 3.6% and 4.9%, respectively. However, conversion to CS significantly (p < 0.05) increased K sat by 32.0% for ring infiltrometer, while it decreased K sat by 3.2% for constant/falling head (p > 0.05). Soil layer, CS type and soil texture had no significant (p > 0.05) effects on the influence of conversion to CS on the K sat , but the K sat under CS showed a greater increase for a longer conversion period (time since conversion). In addition, mean annual temperature (MAT) was found to be an important driver controlling the response of K sat to tillage conversion at the large scale. These findings suggested that quantifying the effects of tillage conversion on soil K sat needed to consider experimental conditions, especially the measurement technique and conversion period.

Field properties-topography, hydraulic resistance, and infiltration-play an important role in the performance of surface irrigation systems, and appropriate characterizations of these are required as data input to simulation or design software. The EWRIIASCE Task Committee on Soil and Crop Hydraulic Properties has been charged with preparing a guide for practitioners faced with such data entry. The result is this special section of the Journal of Irrigation and Drainage Engineering in which this paper is the first in the series presented. It describes the characteristics of these field properties and notes a series of caveats to be considered when dealing with them in the course of analyses or designs of surface irrigation systems.