Hard Pan Research Articles

Assessment of soil physical health and productivity of Kharkhoda and Gohana blocks of Sonipat district (Haryana), India

In order to assess soil health of Kharkhoda and Gohana blocks of Sonipat district (a part of western Yamuna canal irrigated region), important parameters namely pH, electrical conductivity (EC), texture, bulk density (BD), saturated hydraulic conductivity (HC), soil organic carbon (OC), available water retension capacity (AWRC) and non capillary pores (NCP) were measured by collecting undisturbed soil samples in nearly 66 villages. Soil physical rating index (PI) method was used to compute PI which was an indicator of soil physical health of thatregion. Results revealed that in Gohana and Kharkhoda blocks, nearly 90% area had pH <8.0 and EC>4 dS m-1, which indicated that soils were saline. Prediction maps of soil BD showed that 75% of the total area in 15-30 cm soil layer had BD above >1.6 mg m-3, which indicated the presence of hard pan in subsurface. HC data of subsurface layer also showed that 60% of the area had values<0.5 cm hr-1 which reconfirmed the presence of hard pan. For both surface as well as subsurface soil layers, mostly AWC was >10% which indicated adequate water retention capacity of these soils. However 85% of subsurface had poor soil aeration capacity as indicated NCP range < 10 %. Prediction map of PI for subsurface layer showed that majority of area had PI<0.4 which indicated that expected yield of the crop cannot be more than 70% of the potential yield even under normal or higher levels of fertilizer and water inputs.

Effect of tillage and soil amendments on soil quality and yield of clusterbean (Cyamopsis tetragonoloba) in shallow hardpan soils of arid Gujarat

A field experiment was conducted at CAZRI, Regional Research Station, Kukma-Bhuj during kharif 2009 to find out the management options for improving soil productivity and quality in shallow hard pan soils in arid Gujarat. There were four tillage treatments, viz no-tillage, minimum tillage, shallow tillage and deep tillage in main plots and four amendments (gypsum at 5 Mg/ha, farmyard manure (FYM) at 5 Mg/ha and both gypsum and FYM at 5 Mg/ha each and control) in sub plots. The results of the experiment showed that deep tillage along with the application of gypsum and FYM at 5 Mg/ha produced maximum yield and maximum net returns. The study found a decreased yield and negative net returns under no-tillage in these shallow hard pan soils. However soil biological and physical properties were better under no-tillage. Long term studies may be necessary to find out the applicability of no-tillage in these soils from a yield perspective.

Hydro-geochemical and Geophysical Study of Groundwater in the Suburb of Osogbo, South Western Nigeria

In an attempt to carry out the assessment of groundwater quality from hand dug wells and streams in Onibu-Eja and Aduramigba communities, suburb of Oshogbo, South Western Nigeria, with a view to determine the impact of a nearby dumpsite on the groundwater quality, twenty (20) water samples were taken randomly at varying depths within the vicinity. The cation and heavy metal analyses were done in accordance to APHA standard using the Atomic Absorption Spectrophotometry (AAS) while the anion analyses were carried out using the ion chromatography and titrimetric methods. Physical parameters were measured on the field. The results observed showed that the water in the study area contains a relatively high amount of calcium, magnesium, and bicarbonate, an indication of temporary hardness. The hydro-geochemical contour maps of the ions shows that cations, anions and heavy metal content where mostly concentrated in the western and eastern parts of the study area. The analyses of the water samples and streams in the study area fall within the acceptable range of World Health Organization (WHO) and the Nigerian Standard of potable drinking water with the exception of the stream despite their proximity to the dumpsite. Vertical Electrical Sounding (VES) carried out on the dumpsite showed that the study area is overlain by a 0.3 to 1.1 m thick lateritic topsoil with resistivity values between 104 ohm m and 437 ohm m which serves as a hard pan over a 7 to 13 m thick predominantly clayey / weathered layer interval with a resistivity value between 35 to 80 ohms meter. Both of these prevent the leachate from percolating into the groundwater in the study area.

PERFORMANCE OF COMBINED SUBSOILER AND MOLDBOARD PLOW IN IMPERVIOUS SOIL AND CORN YIELD

A trial was conducted in a private field at Al-Hartha township, Al-Basrah Governorate, Iraq on autumn season 2012 to investigate the effect of using combined subsoiler with a moldboard plow to make furrows of different depths and spacings immediately after harvest of barley crop for winter season without tillage of the whole field. The study included also plow performance in treating hard subsoil layer and improvement of some physical properties of soil (apparent density, total porosity and soil penetration resistance) and effect on the yield of corn crop var. Bohoth (Researches) 106. The plow used to make furrows represented by combinations of sex double treatments for subsoiler and moldboard plows (S30 M­20 , S40 M­20 , S40 M­30 , S50 M­20 , S50 M­30 and S50 M­40) where S denotes subsoiler and M moldboard plows, while the ancillary number denotes the depth of tine for both plows. Two spacings, i.e. 75 and 100 cm were used between furrows. Control treatment consisted of tillage with moldboard plow at depth of 25 cm using furrow opener to open furrows at 25 cm depth. The field soil was silty clay containing a hard pan of 10 cm thickness at 30-40 cm depth. Randomized complete block design (RCBD)was used with three replicates. Differences between means wre tested by RLSD at p = 0.05. The results indicated the significant superiority of furrow depth treatments using combined subsoiler plow comparing with control treatment in all studied properties. The increase in furrow depth within study ranges resulted in reducing apparent density and soil penetration resistance with increase in soil total porosity, which reflected positively in increased row and seed numbers in corn ear. Plant seed yield improved also, which contributed in significant increases in corn seeds (Mg. h-1). Distances between furrows did not show a significant effect on the studied properties. The treatment S­50 M40 of interaction between furrow depth and 75 cm distance between furrows gave the best results and achieved the highest seed yield of 4.928 Mg. h-1.

The effects of soil freeze—thaw on soil aggregate breakdown and concomitant sediment flow in Prince Edward Island: A review

Edwards, L. M. 2013. The effects of soil freeze-thaw on soil aggregate breakdown and concomitant sediment flow in Prince Edward Island: A review. Can. J. Soil Sci. 93: 459-472. The importance of aggregate size and integrity in soil productivity and crop production is paramount, and aggregate size reduction or increase invariably becomes a primary concern in such soil management practices as tillage and organic matter manipulation. In this regard, therefore, the present review looks particularly at the consequence of freeze-thaw cycling (FTC) on agricultural lands in Prince Edward Island (PEI) where an annual average of 40 cycles induce measurable aggregate breakdown with mixed consequences. On the one extreme, the consequences are manifest in increased soil erosion. On the other extreme, reduced (or reversed) soil compaction and improved seedbed conditions are welcomed consequences where temperature alternation breaks up hard pans or soil clods, or where the predominance of smaller aggregates can be an as...

The effects of soil freeze–thaw on soil aggregate breakdown and concomitant sediment flow in Prince Edward Island: A review

Edwards, L. M. 2013. The effects of soil freeze–thaw on soil aggregate breakdown and concomitant sediment flow in Prince Edward Island: A review. Can. J. Soil Sci. 93: 459–472. The importance of aggregate size and integrity in soil productivity and crop production is paramount, and aggregate size reduction or increase invariably becomes a primary concern in such soil management practices as tillage and organic matter manipulation. In this regard, therefore, the present review looks particularly at the consequence of freeze–thaw cycling (FTC) on agricultural lands in Prince Edward Island (PEI) where an annual average of 40 cycles induce measurable aggregate breakdown with mixed consequences. On the one extreme, the consequences are manifest in increased soil erosion. On the other extreme, reduced (or reversed) soil compaction and improved seedbed conditions are welcomed consequences where temperature alternation breaks up hard pans or soil clods, or where the predominance of smaller aggregates can be an asset in seedbed environments, favouring improved crop emergence and early-spring establishment. In the PEI soils studied, the greatest changes in aggregate size distribution with FTC occurred in the largest and smallest size fractions wherein fractions <0.5 mm showed a 33% average increase while, simultaneously, the 4.75–9.5 mm fractions showed a 28% average decrease. This breakdown is reflected most contrastingly where FTCs to maximum (asymptotic) breakdown averaged up to 3.5 times for a loam as it did for a sandy loam or a fine sandy loam soil. This review also examines FTC in a broader agricultural and environmental context where it can potentially impact agro-sustainability. Where FTC effects on a fine sandy loam were measured in terms of erosion, there was a sediment mass increase of about 90% in interrill flow and about 25% in rill flow. Further, this review emphasizes methodology that has proven to be workable under the circumstances of PEI's dominant agricultural soils and the FTC research objectives that they helped to shape. It was considered important in this review, also, to highlight the need for expanded research (commencing with regional cooperation), particularly on frost depth, to feed into moisture-availability modelling towards improved clarity for end-user benefit.

SOIL FORMATION BY ECOLOGICAL FACTORS: CRITICAL REVIEW

Regolith is the term we give parent material that h as been weathered. The regolith consists of weather ed bedrock near the surface including the soil layer. In the Iranian soil layer we will find: decayed par ent materials, decaying plant material, decaying animal matter (manure) along with vegetation. Results of the present study show us that methods stimulating natu ral fertility in Iran includes composting-adds humu s layer, drip irrigation-balances illuviation and elu viation in arid regions, crop rotation/ intercroppi ng-reflects natural diversity and limits gleization, add lime-r educes gleization, non-cultivation techniques-reduc es hard pan (calcification) caused by compaction and reduce pesticide use-keeps decomposers alive in humus layer.

Wet cultivation in lowland rice causing excess water problems for the subsequent non-rice crops in the Mekong region

Crop diversification is advocated for improvement of income of lowland rice farmers in the Mekong region, including Laos, Cambodia and Thailand. One common problem of adding non-rice crops after wetland rice is excess water caused by reduced drainage associated with the hard pan that is commonly created to store water in the paddy for the rice crop. This paper firstly describes the water balance in the lowland fields particularly on how deep percolation is decreased by the hard pan, and the effect of wet cultivation on soil compaction and water availability in the subsequent crops such as mungbean. Experimental work in Cambodia shows how non-rice crops such as mungbean and peanut often fail completely or partially due to excess water. The common experience is complete failure of the early wet season non-rice crop when rain started earlier and the lowland paddy is saturated with water, but also non-rice crops often do not grow well due to shallow root systems confined to the top soil above the hard pan. Destructing the hard pan may help non-rice crops, but the process is expensive and may have an adverse effect on subsequent rice crops. Experimental work has also demonstrated that where irrigation water is available, irrigation is often not effective as it causes soil saturation in the top soil. Ways to minimize the excess water problem are discussed.

Integrated Suitability Assessment: A Way Forward for Land Use Planning and Sustainable Development in Abu Dhabi, United Arab Emirates

The hyper-arid conditions, low inherent soil fertility, water scarcity, and marginal water quality collectively constrain the local agriculture production in Abu Dhabi, UAE. To achieve this, an integrated suitability assessment was conducted considering soil resources, relief/slope, and water resources and forms the focus of the present study. The soils were classified using Soil Taxonomy (ST). Land suitability for irrigated agriculture has been assessed using standard land suitability method of the FAO Land Evaluation Framework, using the criteria including salinity, hard pan, water table depth, gypsum, and texture. Because of the significance of slope and relief for managing and using soils in the study area, a separate assessment was conducted. The assessment culminated into 2416 ha (0.03%) highly suitable; 309,265 ha (5.4%) moderately suitable; 1550 × 103 ha (27%) marginally suitable; 1753 × 103 ha (31%) temporarily unsuitable; and 2108 × 103 ha permanently unsuitable. Additionally, lack of sufficient fresh water resources is considered as one of the major problems facing agricultural expansion and sustainable development in the study area. Therefore, integration has been made between land suitability results and water availability, expressed by water salinity. For this purpose, an intersection has been carried out between the groundwater salinity map and the land suitability map using ArcGIS to find areas with high potential for agricultural expansion. The overall suitability revealed 220,000 ha with high potential for agricultural expansion considering land suitability and availability of fresh water, giving a chance to add 150,000 ha, to the existing cultivated area of 70,000 ha.

Mechanized Transplanting of Rice (<i>Oryza sativa</i> L.) in Nonpuddled and No-Till Conditions in the Rice-Wheat Cropping System in Haryana, India

The common practice of establishing rice in the rice-wheat system in India is manual transplanting of seedlings in the puddled soil. Besides being costly, cumbersome, and time consuming, puddling results in degradation of soil and the formation of a hard pan, which impedes root growth of subsequent upland crops. In addition, decreased availability and increasing cost of labor have increased the cost of rice cultivation through conventional methods. Because of these concerns, there is a need for mechanized transplanting of rice which is less labor-intensive and can ensure optimum plant population under nonpuddled and/or no-till conditions. A large number of on-farm trials were conducted at farmers’ fields in Haryana, India, from 2006 to 2010 to evaluate the performance of the mechanical transplanted rice (MTR) under nonpuddled and no-till situations as compared to conventional puddled transplant rice (CPTR). Compared with CPTR, nonpuddled MTR produced 3%-11% higher grain yield in different years. Rice cultivars, viz. HKR47, HKR127, PR113, PR114, PB1, PB1121, CSR30, and Arize6129, performed consistently better under nonpuddled MTR as compared to CPTR. Performance of different cultivars (PR113, PR114, HKR47, and Pusa 44) was also better under no-till MTR as compared to CPTR. The “basmati” cultivar CSR30 performed equally in no-till MTR and CPTR systems. The results of our study suggest that rice can be easily grown under nonpuddled and no-till conditions with yield advantages over the CPTR system. Even in the case of similar yield between CPTR and MTR systems, the MTR system will help in reducing labor requirement and ultimately, will increase overall profits to farmers.

Distribution of Metals along Simiyu Wetland of Lake Victoria Basin and its Impact on Agriculture

More than 70% of communities living along Simiyu wetland area are agriculturalists and pastoralists. Physical land degradation and poor nutrient mobility within the soil-plant system have shown a notable impact on agricultural production. Cycling of selected and their impact on agriculture were investigated along Simiyu wetland. Cation Exchange Capacity (CEC) of the soil was studied with respect to soluble cations and selected trace metals. To study the longitudinal and spatial distribution of the selected metals along Simiyu wetland, samples (water, sediments and soil) were taken in three stations along the river namely Bariadi Bridge, Simiyu Bridge and the Simiyu River mouth. Sampling of soil was done at different distances from the river so as to study the flow pattern of the metals and hence to explain the direction of cycling. Sampling was done both inn wet and dry seasons to study the seasonal variation of the metals. Geographical Position System was used to locate the sampling points for soil and water/sediment. Metals Chromium (Cr), Lead (Pb), Zinc (Zn), Coper (Cu), Cadmium (Cd) and Manganese (Mn) analyses were analyzed by atomic absorption spectrophotometer (AAS). High levels of Manganese and Zinc were detected in most samples with different distribution behavior between water and sediments that may reflect difference in solubility of metals in water or possible complex formation of the metals resulting to potentially less solubility of metals, hence retarding their bioavailability to plants low cation exchange capacity. Retarded nutrient mobility in clay soils was observed facilitated by the formation of hard pans resulting to less availability of the nutrients to plants. The study suggests some ways in which farmers can improve soil cation exchange capacity and hence improve agricultural productivity. DOI: http://dx.doi.org/10.3126/jowe.v6i0.5967 J Wet Eco 2012 (6): 31-43

Nitrogen Rates Effects on the Yield, Nutritional Status, Fruit Quality, and Profitability of Tomato Grown in the Spring with Subsurface Irrigation

With increasing environmental concerns, the sharp cost increase of fertilizer and the absence of a soil test to predict nitrogen (N) needs of tomato (Solanum lycopersicon L.) grown on Florida’s sandy soils, a partnership was created with growers, state agencies, and the University of Florida, Institution of Food and Agricultural Sciences (UF/IFAS). The objectives of this study were to identify a range of N rates that would result in highest yields and postharvest quality, and maximum economical return for tomato, grown with subsurface irrigation (management of a perched water table above an impermeable soil layer or hard pan) during the spring season (low probability of leaching rain events). The study was conducted in Spring 2007 and 2008 in Palmetto, FL, with N rates ranging from 22 to 470 kg·ha−1 at pre-plant as ammonium nitrate (NH4NO3). Weather conditions were typical of a dry spring season in central Florida with no leaching rain events recorded in either year; however, rain patterns were different between the 2 years. In the absence of leaching rain and frost protection (either may raise the water table), petiole sap NO3-N decreased over time and the rate of decline depended on the N fertilizer rate. Extra-large and total marketable fruits yields showed a quadratic plateau response to N rates with maximum yields at two harvests (97% of the yields) grown with 172 and 298 kg N/ha in 2007 and 2008, respectively. During subsequent ripening, N rate did not correlate consistently to fruit ripening rate, fruit firmness, nor compositional quality at table-ripe stage. The high value of tomatoes relative to the cost of N fertilizer created a situation in which the profit-maximizing rate of N was not significantly different from the production-maximizing N rate. Whether the profit-maximizing level of N was higher or lower than the UF/IFAS-recommended rate depended on the growing season. With favorable growing conditions (i.e., conditions in 2008), a grower’s net return would have decreased between $1000 and $2000 per hectare by using UF/IFAS-recommended rates depending on market conditions. However, if the UF/IFAS-recommended rate of 224 kg·ha−1 resulted in the highest yield, applying upwards of 300 kg·ha−1 would have increased grower production costs by at least $67/ha. Although fertilizer costs are known before the crop is grown, tomato prices are realized only at the end of the growing season and profit margins can only be calculated after the fact.

Contrasting soil penetration resistance values acquired from dynamic and motor-operated penetrometers

This paper presents a comparison between the static motor-operated and the dynamic cone penetrometers in measuring soil penetration resistance. The static motor-operated penetrometer is driven in the soil at a constant velocity, while the dynamic penetrometer, is driven by repeated hammer blows. Using an energy balance equation, the hammer blows are translated to penetration resistance using the Dutch formula. The motor-operated penetrometer gives a standard soil penetration resistance value, however it is expensive and bulky. On the other hand, the dynamic penetrometer is cheap, easy to use and compact. This paper analysed data collected from three fields, having low, medium, and high values of soil strength, which were surveyed using the two types of penetrometer. Values obtained using the Dutch formula on the dynamic penetrometer are comparable with the values obtained using the motor-operated penetrometer at a site with lower soil strength. However the correlation between the two types of penetrometer decreases with increasing soil strength. Values from the dynamic penetrometer tend to overestimate soil strength due to unaccounted energy loss in terms of friction and vibration. This paper also shows an improvement in the analysis of the data obtained from the dynamic penetrometer. The equal-area spline translates the data into penetration profiles which is useful for discerning hard pans or compacted layers.

Incorporation of Soil Bulk Density in Simulating Root Distribution of Winter Wheat and Maize in Two Contrasting Soils

Root length density (RLD) in a soil profile is an important factor in determining the root uptake of water and nutrients from soil. Accurate descriptions of the RLD distribution are important in developing models to simulate the flux of water and nutrients in fields. However, the normal vertical root length distribution in a soil profile is usually disrupted because of soil heterogeneity. This study used field-measured RLD of winter wheat (Triticum aestivum L.) and maize (Zea mays L.) from two soils in the North China Plain from 2007 to 2010 to examine the effects of soil physical characteristics on the RLD distribution of the double-cropping system. The results showed that RLD distribution pattern was significantly affected by soil bulk density under sufficient water supply. The existence of a hard soil pan under the tillage layer greatly influenced the distribution curve of the RLD. Without bulk density modification, there was an apparent difference between measured and modeled RLD resulting in either overestimating or underestimating root length at certain soil depths. Introducing bulk density into an RLD simulation model significantly reduced the errors of simulated and measured RLD throughout the root zone profile.

Improving maize productivity through tillage and nitrogen management

Continuous cultivation of fields with same implement (cultivator) creates a hard pan in the subsoil which adversely affects crop productivity. In addition to tillage, nitrogen management is a key factor for better crop growth and yield. Impact of different tillage systems and nitrogen management on yield attributes and grain yield of hybrid maize was evaluated by conducting experiments at the Agronomic Research Area, University of Agriculture, Faisalabad during 2008 and 2009. The experiment comprised of three tillage systems viz. conventional tillage, tillage with mould board plough followed by 2-cultivations (with cultivator), tillage with chisel plough followed by 2-cultivations (with cultivator) and three nitrogen levels (100, 150 and 200 kg ha -1 ). Different tillage systems and nitrogen levels significantly influenced the maize yield and yield components. Chisel ploughed plots resulted to heavier cobs, higher 1000-grain weight and grain yield in comparison with other tillage systems. Maize yield with chisel tilled plots was 18 and 9% higher than mould board ploughed and conventionally tilled plots, respectively. Generally, differences between different nitrogen application rates were more pronounced; increasing nitrogen rate resulted in increased yield and yield components of maize. Significantly, highest grains weight per cob, 1000-grain weight and grain yield was recorded with 200 kg ha -1 nitrogen application. Maize yield with 200 kg ha -1 nitrogen application was 17 and 8.50% higher than 100 and 150 kg ha-1 nitrogen application, respectively. Therefore, it may be concluded that maize hybrids should be grown with 200 kg ha -1 nitrogen application by preparing the field with chisel plough followed by cultivator. Key words: Maize productivity, chisel plough, conventional tillage, nitrogen.

Effects of straw mulch on mungbean yield in rice fields with strongly compacted soils

In rice-based lowland areas in the Mekong region, the lack of full irrigation water availability for post-rice legume crops and the poor soil physical and chemical conditions are major constraints for development of sound rice/legume double cropping system. In order to improve legume productivity, use of rice straw mulch and various crop establishment methods were examined in two series of mungbean experiments in Cambodia where soils were coarse and strongly compacted. In one set of experiments conducted at four locations in the first year the effect of straw mulch, planting method (manual vs seed drill) and tillage method (conventional vs no-till) was examined. Another set of experiments were conducted in the second year at three locations with four levels of mulch under two planting densities. On average in year 1, mulching of rice straw at 1.5 t/ha increased mungbean crop establishment from 72 to 83%, reduced weed biomass from 164 to 123 kg/ha and increased yield from 228 to 332 kg/ha. Mulch was effective in conserving soil moisture, and even at maturity the mulched area had on average 1% higher soil moisture content. The amount of mulch between 1 and 2 t/ha did not show consistent effects in year 2, partly because some mulch treatments resulted in excessive soil moisture content and were not effective. Rice straw mulch had a significant effect on mungbean yield in 6 out of the 7 experiments conducted in two years, and mean yield increase was 35%. This yield advantage was attributed to better crop establishment, improved growth and reduced weed pressure, but in some cases only one or two of these factors were effective. On the other hand, planting method, tillage method and planting density had only small effects on mungbean yield in most experiments. Only in one location out of four tested, the no-till treatment produced significantly higher yield than the conventional method. Seed drill produced similar mungbean establishment and grain yield to the manual planting suggesting that the planter can be used to save the labour cost which is increasing rapidly in the Mekong region. Maximum root depth varied little with mulch or planting density, and was shallow (<20 cm) in all three locations where this character was determined. It is concluded that while rice straw mulch increased yield of mungbean following rice, the inability of mungbean roots to penetrate the hard pan is a major constraint for development of a sound rice/mungbean cropping system in the lowlands with compacted soils.

An Evaluation of Two Egg Collection and Two Fertilization Techniques during Landlocked Fall Chinook Salmon Spawning

AbstractIn an attempt to improve embryo survival of landlocked fall Chinook salmon Oncorhynchus tshawytscha, we compared two egg collection techniques and two different egg fertilization (sperm activation) protocols on egg survival to the eyed stage of development. A total of four treatments were used with 13 females: egg collection into a suspended net and fertilization either with or without ovarian fluid and egg collection into a hard plastic pan and subsequent fertilization either with or without ovarian fluid. There was no significant difference in survival to the eyed stage with respect to collection technique. However, the presence of ovarian fluid during sperm activation and fertilization had a small but significantly negative effect on egg survival, decreasing mean eyed egg survival by approximately 4.0%. Overall, eyed egg survival was improved in 10 of the 13 spawns fertilized without ovarian fluid. To maximize embryo survival, removal of ovarian fluid prior to fertilization is recommended for landlocked fall Chinook salmon eggs.

An experimental investigation to characterise soil macroporosity under different land use and land covers of northeast India

Saturated macropore flow is the dominant hydrological process in tropical and subtropical hilly watersheds of northeast India. The process of infiltration into saturated macroporous soils is primarily controlled by size, network, density, connectivity, saturation of surrounding soil matrix, and depthwise distribution of macropores. To understand the effects of local land use, land cover and management practices on soil macroporosity, colour dye infiltration experiments were conducted with ten soil columns (25 × 25 × 50 cm) collected from different watersheds of the region under similar soil and agro-climatic zones. The sampling sites included two undisturbed forested hillslopes, two conventionally cultivated paddy fields, two forest lands abandoned after Jhum cultivation, and two paddy fields, one pineapple plot and one banana plot presently under active cultivation stage of the Jhum cycle. Digital image analyses of the obtained dye patterns showed that the infiltration patterns differed significantly for different sites with varying land use, land cover, and cultivation practices. Undisturbed forest soils showed high degree of soil macroporosity throughout the soil profile, paddy fields revealed sealing of macropores at the topsoil due to hard pan formation, and Jhum cultivated plots showed disconnected subsoil macropores. The important parameters related to soil macropores such as maximum and average size of macropores, number of active macropores, and depthwise distribution of macropores were estimated to characterise the soil macroporosity for the sites. These experimentally derived quantitative data of soil macroporosity can have wide range of applications in the region such as water quality monitoring and groundwater pollution assessment due to preferential leaching of solutes and pesticides, study of soil structural properties and infiltration behaviour of soils, investigation of flash floods in rivers, and hydrological modelling of the watersheds.

Catch and Release. Repeat

Catch and Release. Repeat Will Jennings (bio) Spring Training—Evanston, Illinois, 1964 I walk up close as I can to stare at the mortar between the bricks, close enough to pick at the flakes of an old warehouse advertisement that once covered the entire wall. My father and his brother played a sort of toss-and-bounce-back baseball here, back when this wall was the boundary to their yard, back when this ground even was a yard. I can't imagine grass, really, just hard pan and the split tufts of reedy growth, perhaps a clothesline, a pea gravel path to the alley behind. I am nine, my father's age when this was his family's home during the onset of the Great Depression. Above it all looms this four-story wall. ALLIED COLD STORAGE. A mural that once played to a passing opulence: "Ladies! Summer Storage For Your Fine Furs! Bonded! Fire Proof!" Because it is February, and because where their house once stood is now an asphalt lot for a church's overflow of cars, maybe even because there's a fine misting sleet beginning to sting my ears, I have to pretend really hard to hear the thwap and wumple of a rubber Spaldeen, the high running fastballs of my father dimpling the hem of a lady in mink. My dad has taken me along on a service call, a Sunday afternoon in late winter-early spring when an anytime rain along this southern stretch [End Page 55] of Lake Michigan can turn to ice, and the wind from the east off the water lays down an elegant glaze of misery. It's the time of the year when people try to finick and coax their boilers and gravity furnaces through one more season, one last snap of cold. And this is the sort of busy that keeps my dad's shop flush and our home phone a constant interruption most evenings and weekends. I have just watched him wheedle an apartment's aging behemoth back to the living, with what looked like a nimble whispering from where I stood off shyly in the damp against a shuttered flume for coal. My father has brought me here to show me the house where he once lived. Instead, we are walking around this parking lot beside a church and across Chicago Avenue from the raised tracks where the North Shore Line used to run. As my dad paces off steps from the wall, I am slowly tracing a strike zone on the bricks, one mitten off, and I am thinking, this spot, here, back then and now it is now, and now me. We turn and face each other. My father pantomimes a gangly wind up to a pitch, bluffing a tip off to his high-and-tight heater. I place my wrists together, close my eyes, and pretend to wiggle a bat I do not hold. We go on this day to two more lots, all of them former sites of houses where my father used to live. All of them asphalt or gravel now. By the last, even he doesn't seem surprised and we don't even get out of the car. We sit in the stuttering yellow Falcon, the sound of the sleet revealing the tin economy of its make, the vinyl bench seats turning cold and stiff where our bodies cannot warm them. He smokes his Luckies, and I work on a peppermint I've found in the shelf that serves as a glove box. Decades later, now in my fifties, I imagine hovering high above that small plot of Evanston, circling those vacant lots with penciled lines like the at-bats of a scorecard, a constellation to mark the source and direction of his life, maybe even my own. At each stop on that day's circuit of calls, there were things that could be fixed and things that you just had to imagine. Those boilers and burners were real and took well to wrenches. But my father's childhood, tucked in the rhythms of family and trains, the play-ball cadence of one-pitch-two-strike-three was difficult...

Potential risk of calcium carbonate precipitation in agricultural drain envelopes in arid and semi-arid areas

Soil particle deposition and/or chemical precipitation can reduce the permeability of drain envelopes and filters. The first step in recognizing clogging phenomena is the identification of the nature of the precipitating materials. Calcium carbonate is a substance of low solubility that precipitates rapidly, forming a hard pan layer in the soil and/or clogging drain envelopes. The main objective of the present study is to investigate the precipitation risk of calcium carbonate in agricultural drain envelopes in the Khuzestan province of Iran. In this study, three indicators namely Ryznar, Langelier and Stiff-Davis indices were employed to assess the precipitation risk of calcium carbonate in agricultural drainage water. Results showed that all agricultural drainage systems in the study area give evidence of a potential risk of calcium carbonate precipitation, but the severity of the problem is different. The results also showed that the Ryznar and Stiff-Davis indices provide a better estimation of the potential precipitation risk of calcium carbonate than the Langelier index. Analyses of soil samples and drain envelopes from a drainage system , installed in the Abadan palm grove, showed that the main chemical component was calcium carbonate.