Effects of Different Organic Materials on Crop Production under a Rice–Corn Cropping Sequence

Soil organic matter (SOM) is an important index of soil quality because of its relationship with crop yield. The application of organic matter to soil is a significant method for increasing SOM. Different organic materials have varying effects in increasing SOM. This study investigates the effects of combining different sources of organic matter (i.e., compost, leguminous green manure, and peat) with a chemical nitrogen (N) fertilizer on the growth and N accumulation in corn and rice plants. This study examines seven treatments, including a no-fertilization check and a conventional chemical fertilizer treatment. Shoots of corn and rice were sampled at the tasseling (panicle initiation for rice) and maturity stages. The biomass yield was measured and the total N was analyzed. At the maturity stage, the soil samples were collected to determine the chemical properties. The results showed that a small percentage of the N in the compost and peat, after their application, was available to the crop during the growth season; the production of biomass and N absorption among rice and corn plants was minimal compared to that treated with chemical N fertilizer. The application of compost and peat resulted in SOM accumulation, particularly with peat. However, the application of compost combined with chemical fertilizer not only produced sufficient nutrients for crop growth but also resulted in an accumulation of SOM, which is vital for enhancing the soil quality. Most of the N in green manure (GM) was mineralized shortly after application, causing excessive growth of rice and corn plants during the early stage, but reducing their reproductive growth and grain yield.     

Effects of river infrastructures on the floodplain sedimentary environment in the Rhône River

Journal of Soils and Sediments - River infrastructures such as dikes, groynes, and dams are ubiquitous on most large rivers, and although their consequences on the riverbed morphology have often...     

Effects of a bentonite–water mixture on soil-saturated hydraulic conductivity

To reduce water loss in light-textured soils, hydraulic conductivity should be reduced by mixing the soils with some soil conditioners, e.g. sodium-bentonite. The objectives of this study were to investigate the effects of irrigation water with different bentonite concentrations (0, 0.05, 0.1, 0.15 and 0.2%) on hydraulic gradient (i) and relative saturated hydraulic conductivity (K _rs) in a laboratory soil column with a loamy sand soil. Addition of sodium-bentonite to the soil increased i throughout each experiment. Furthermore, addition of bentonite reduced K _rs, and a 0.2% bentonite–water concentration after infiltration of 48 mm of bentonite–water mixture (BWM), reduced the K _rs value to 56% of K _s. K _rs was reduced as the concentrations of bentonite increased and its value reached ～0.5 to 0.6 as the infiltration of BWM increased. The lowest value of K _rs and the greatest reduction rate occurred at a bentonite concentration of 0.2%. It is concluded that BWM can be used as a channel liner. Using a 0.2% bentonite concentration resulted in a reduction in the seepage ratio from 1.0 to 0.08.     

Effects of Continuous Use of Chemical Fertilizers and Manure on Soil Fertility and Productivity of Maize–Wheat under Rainfed Conditions of the Western Himalayas

Long-term effects of continuous use of chemical fertilizers and manure on soil fertility and productivity of a maize–wheat system were investigated in the ongoing long-term fertilizer experiment, during rabi (2007–2008) and kharif (2008) seasons at the research farm of Chaudhary Sarwan Kumar Himachal Pradesh Agricultural University–Hill Agricultural Research and Extension Centre, Dhaulakuan. After 16 cropping cycles, bulk density decreased in plots where farmyard manure (FYM) was applied, whereas pH decreased in all the treatments. The organic carbon content of the soil increased in all the treatments except 100% nitrogen (N). Cation exchange capacity (CEC) increased in all the treatments over the initial status of the soil. Available N showed buildup over the initial status in most of the treatments. Available phosphorus (P) declined from initial status in treatments where only N was applied alone or with FYM. There was reduction in available potassium (K) status in all the treatments except 100% NPK. Continuous addition of FYM with balanced application of inorganic fertilizers improved content of exchangeable calcium (Ca) and magnesium (Mg) over initial status compared to imbalanced application of fertilizers. Continuous use of imbalanced inorganic fertilizers resulted in lesser crop yields and nutrient uptake compared to that with the application of balanced dose of inorganic fertilizers with FYM.     

Effects of climate factors and soil properties on soil nutrients and elemental stoichiometry across the Huang–Huai–Hai River Basin,China

Purpose

Soil nutrients, elemental stoichiometry, and their associated environmental control play important roles in nutrient cycling. The objectives of this study were (1) to investigate soil nutrients and elemental stoichiometry, especially potassium and its associative elemental stoichiometry with other nutrients under different land uses in terrestrial ecosystems; (2) to discuss the impacts of climate factors, soil texture, and soil physicochemical properties; and (3) to identify the key factors on soil nutrient levels and elemental stoichiometry.

Materials and methods

Soil data, including pH, bulk density (BD), cation exchange capacity (CEC), volumetric water content (VMC), clay, silt and sand contents, total carbon (TC), nitrogen (TN), phosphorous (TP) and potassium (TK), available nitrogen (AN), phosphorus (AP), potassium (AK), and soil organic matter (SOM) under different land-use types, were collected, and their elemental stoichiometry ratios were calculated. Climate data including temperature, precipitation, relative humidity, wind speed, and evapotranspiration were collected. The least significant difference test and one-way analysis of variance were applied to investigate the variability of soil nutrients and elemental stoichiometry among land-use types; the ordinary least squares method and the general linear model were used to illustrate the correlations between soil nutrients, elemental stoichiometry, and soil properties or climate factors and to identify the key influencing factors.

Results and discussion

Woodlands had the highest SOM, TN, AN, and AK contents, followed by grasslands, croplands, and shrublands, while the TP and TK contents only varied slightly among land-use types. SOM, TN, AN, N/P, and N/K were strongly negatively correlated to soil pH (p <?0.05) and were strongly positively correlated to soil CEC (p <?0.05). For soil texture, only C/N was moderately negatively correlated to silt content but moderately positively correlated to sand content (p <?0.05). For climate factors, SOM, TN, AN, N/P, and N/K were significantly negatively correlated to evapotranspiration and temperature (p <?0.05), and the correlations were usually moderate. Soil pH explained most of the total variation in soil nutrients, and climate factors explained 5.64–28.16% of soil nutrients and elemental stoichiometry (except for AP (0.0%) and TK (68.35%)).

Conclusions

The results suggest that climate factors and soil properties both affect soil nutrients and elemental stoichiometry, and soil properties generally contribute more than climate factors to soil nutrient levels. The findings will help to improve our knowledge of nutrient flux responses to climate change while also assisting in developing management measures related to soil nutrients under conditions of climate change.

     

Comparison of the Effects of Salt Stress and Salt–Alkaline Mixed Stress on the Mineral Nutrition of Sunflower

Sunflowers (Helianthus annuus L.) were treated with salt stress and salt–alkaline mixed stress, which were established by mixing proportions of sodium chloride (NaCl), sodium sulfate (Na₂SO₄), sodium bicarbonate (NaHCO₃), and sodium carbonate (Na₂CO₃). The physiological indices of seedlings, including photosynthesis, growth, and mineral element contents, were determined to compare differences in the physiological responses of sunflower to salt stress and salt–alkaline mixed stress. The results showed that the destructive effects of salt–alkaline mixed stress on growth and photosynthesis were more severe than those of salt stress. The contents of mineral elements in the plants stressed were significantly less under salt–alkaline mixed stress than under salt stress. Data analysis indicated that both stresses caused ionic activity and free concentrations of some mineral elements to decline and even caused precipitation. This was coupled with a reduction of absorption capacity of roots. In conclusion, the mineral nutrition in sunflowers was affected under both salt and salt–alkaline mixed stresses, but the effects were more severe under salt–alkaline mixed stress than salt stress.     

Examining the Effects of the Destroying Ammunition,Mines, and Explosive Devices on the Presence of Heavy Metals in Soil of Open Detonation Pit: Part 1—Pseudo-total Concentration

This paper presents the results of determining the pseudo-total concentration of five heavy metals in the soil on which the destruction of ammunition, mines, and explosive devices is carried out by the method of open detonation. In the analyzed area, the concentrations of cadmium, lead, nickel, copper, and zinc were determined, while from the physical properties of the soil were determined the granulometric composition and the pH. The aim of the study is to determine the origin and total load on heavy metals and, based on that, to assess the dangers and impact of the site in terms of the soil pollution by heavy metals. In accordance with the regulations of Bosnia and Herzegovina, the results of the soil testing showed a significant load of copper (up to seven times) and cadmium (up to six times), and exceeding the allowed values for nickel and zinc in some places. Lead was the only metal whose concentration was within the maximum allowed and according to that the soil was classified as unpolluted. A sample of soil from the edge of the pit is the only sample in which all heavy metals, except Ni, were within the maximum allowable concentration. In regard to the concentration of the examined metals, the soil of the pit is classified as medium polluted from the aspect of copper, cadmium, and nickel and highly contaminated with zinc. The concentrations of copper and zinc in the examination area correspond to contaminated soil that represents ecological risk, which requires soil remediation.     

Effect of Amorphous Silicon Dioxide on Cadmium Behavior in the Soil–Rice Plant System

The effect of amorphous silicon dioxide (SiO₂) on cadmium behavior in the soil–plant system was studied in a field experiment on a flooded paddy soil slightly contaminated by cadmium. The application of amorphous SiO₂ results in a 1.3- to 1.8-fold smaller cadmium accumulation in the aboveground organs of rice and a 1.8- to 2.6-fold decrease in the content of its available compounds, which can be explained by metal sorption on the surface of applied silicon dioxide and by the reaction of monosilicic acid, which forms in the SiO₂ solution, with cadmium. The decrease in cadmium availability is most intensive in the first 2 weeks after SiO₂ application. Amorphous silicon causes a 26.6% increase in rice productivity in the first season and 72.9% in the second. The data obtained testify to the fact that the application rates of traditional mineral fertilizers can be decreased without risk to rice productivity if silicon compounds are used. They should become an integral and important part of implementing the 4R-STRATEGY for fertilizer application and plant nutrition optimization.     

The influence of paleofloods on archaeological settlement patterns during A.D. 1050–1170 along the Colorado River in the Grand Canyon,Arizona, USA

Excavations at four archaeological sites consisting of the material remains of A.D. 1050–1170 era farmers along the Colorado River in Grand Canyon National Park, yield geomorphic information used to address questions related to settlement patterns. Archaeological excavation units, test pits, feature fill, and natural exposures contain sediments used to interpret geomorphic history that can, in turn, shed light on archaeological site selection in a challenging environment. The Grand Canyon experiences dramatic geomorphic events such as catastrophic floods and destructive debris flows that are preserved in the stratigraphic record, and can be used to understand cultural/landscape interactions. By combining new geomorphic, stratigraphic, and archaeological data collected during recent excavations with results from previous geomorphic and sediment transport studies, observed trends can be interpreted regarding the possible influence of paleofloods on past settlement patterns. For example, at each of the four sites, reconstructed paleoflood elevations (from existing HEC-RAS virtual shorelines), flood recurrence intervals, site layout, and site stratigraphy/geomorphic setting suggests a temporal trend in site location. The two early sites (Early Pueblo II period: A.D. 1050–1080) contain habitation features located above the approximately 6–8 year high flood (3500 cubic meters per second [cms]) recurrence interval; larger floods (4800 to 5900 cms) of a longer recurrence interval between 40 and 80 years inundate these features. The two later sites in the sample (Late Pueblo II; A.D. 1080–1170) contain habitation features located well above the 40–80 year recurrence high flows. We suggest that early farmers (Early Pueblo II period: A.D. 1050–1080) may not have had adequate experience with flood magnitudes and frequencies and therefore their habitation structures were located in risk-prone areas relatively close to the river. Later habitations (Late Pueblo II; A.D. 1080–1170) were positioned in more protected areas further from the river, perhaps reflecting an acquired knowledge of river dynamics. These trends, although currently based on a limited data set, provide insights into site selection decisions and settlement patterns of early farmers along the Colorado River through Grand Canyon.     

Effects of alternative management practices on the economics,energy and GHG emissions of a wheat–pea cropping system in the Canadian prairies

In recent years alternative farming practices have received considerable attention from Canadian producers as a means to improve their net return from grain and oilseed production. Enhancing the efficiency of nitrogen fertilizer use, including a pulse crop in the rotation, reducing tillage and pesticide use are seen as viable options to reduce reliance on fossil fuel, lower input costs and decrease the risk of soil, air and water degradation. The objective of this study was to determine the effects of 16 alternative management practices for a 2-year spring wheat (Triticum aestivum L.)–field pea (Pisum sativum L.) rotation on economic returns, non-renewable energy use efficiency, and greenhouse gas emissions. The alternative management methods for wheat consisted of a factorial combination of high vs. low soil disturbance one pass seeding, four nitrogen (N) fertilizer rates (20 kg N ha^?1, 40 kg N ha^?1, 60 kg N ha^?1 and 80 kg N ha^?1), and recommended vs. reduced rates of in-crop herbicide application. Alternative management practices for field pea were high vs. low soil disturbance one pass seeding. The resulting 16 cropping systems were evaluated at the whole farm level based on 4 years (two rotation cycles) of data from field experiments conducted on two Orthic Black Chernozem soils (clay loam and loam textures) in Manitoba, Canada. The highest net returns on the clay loam soil were for the high disturbance system with 60 kg N ha^?1 applied to wheat and the recommended rates of in-crop herbicides. The lowest application rate of N, together with low disturbance seeding, provided the highest economic returns on the loam soil. Energy use efficiency was highest for the lowest rate of N application for both tillage systems. The highest rate of N fertilizer and recommended rates of in-crop herbicide produced little additional yield response, lower net returns, and higher GHG emissions. An increase in N fertilizer application from 20 kg ha^?1 to 80 kg ha^?1 increased whole farm energy requirements by about 40%, while reducing herbicide rates had negligible effects on grain yields and total energy input. Overall, as N fertilizer rate increased, the associated GHG emissions were not offset by an increase in carbon retained in the above-ground crop biomass. Moderate to high soil test NO₃-N levels at experimental sites reduced the potential for positive yield responses to N fertilizer in this study, thus minimizing the economic benefits derived from N fertilizer application.     

Effects of the 1982–1983 El Nino on Humboldt penguin colonies in Peru

The Humboldt penguin Spheniscus humboldti is endemic to the Peruvian Current which flows northward along the coast of Chile and Peru. This species has greatly diminished from its former abundance.The coast of Peru is characterised by high biological productivity which concentrates fish such as the anchovy Engraulis ringens, the main prey item of marine predators including seabirds. In years of the abnormal oceanographic conditions of El Nino, the schools of anchovies become unavailable to the seabirds and they disperse in search of food. Massive mortality, especially of juveniles, results and there is nest desertation and lack of reproduction.This paper describes the effects of the 1982–1983 El Nino on Humboldt penguin colonies in Peru. There has been an overall population decline of 65% and the surviving population in 1984 was estimated to be between 2100 and 3000 adults. Although El Nino is a periodic event and the Humboldt penguin has evolved to adapt to such unpredictable changes, the environment has now been altered by man. Under these circumstances, the 1982–1983 El Nino has contributed to placing this species in a critical position.     

Arsenic,lead, and uranium concentrations on sediments deposited in reservoirs in the Rio Grande Basin,USA–Mexico border

Purpose

The El Granero reservoir is the last reservoir of the Rio Conchos before it joins the Rio Grande at the Mexico–USA border. This reservoir, together with the San Marcos reservoir, is located in the arid region of Chihuahua, Mexico. High, naturally occurring radioactivity levels, as well as high arsenic (As) concentrations, have been found in both reservoirs. The main goal of this research was to establish the spatial and temporal distribution of trace and radioactive elements in surface sediments and cores collected from these reservoirs.

Materials and methods

Sediment cores were dated using ²¹⁰Pb and ¹³⁷Cs measurements and applying the constant rate of supply (CRS) model. Major, trace, and radioactive elements were determined in surface samples and three sediment cores. Radioactive elements were determined by both alpha and gamma spectrometry. Major and trace elements were determined by inductively coupled plasma optical emission spectrometry (ICP-OES) using the EPA 3051a method. Enrichment factors (EF), contamination factors (CF), and pollution load indexes (PLI) were calculated in order to identify the human impact in both reservoirs, whereas the chemical index weathering (CIW) was used to assess differences in the degree of weathering.

Results and discussion

High uranium (U) enrichment (EFs?=?24.9–54.7) was observed in core layers at the San Marcos reservoir, while in surface sediments, this enrichment was lower. The high variability of lead (Pb) and As in sediment cores from the Granero reservoir was attributed to human influence. Arsenic and Pb enrichment differences between entry and exit sediment cores were explained by the filtering capabilities of the elongated shape, the topography, and the presence of plants on the reservoir’s bed. The highest PLI was found at the entrance core of the Granero reservoir.

Conclusions

The natural element concentration levels of As, Pb, and U were established at the Granero reservoir. High EFs for As and Pb suggest an anthropogenic origin of these pollutants at specific time intervals. High U concentrations in the San Marcos area are explained as naturally occurring. The concentrations of As in most of the studied sediments could pose a risk to human health by As ingestion, since they are above the probable effect level (PEL).

     

Effects of hydrostatic pressure on phosphorus transformation at the water–sediment interface of a deep reservoir: novel insights into bacterial community and functional genes

Journal of Soils and Sediments - The release of endogenous phosphorus from sediments leads to the eutrophication of water bodies. Bacteria in sediments play a vital role in phosphorus cycling. A...     

Sulphur nutrition of clover: Effects of plant age on the composition‐yield relationship

Abstract

Five levels of S (as gypsum) were topdressed on to a pasture containing subterranean clover. Yield responses by the clover fraction of the pasture were measured, together with the total S concentration, the sulphate S concentration and the N:S ratio in young clover plants collected in autumn prior to the fertilizer application, and in plants from the control plots collected in winter and in spring.

As there were irregular changes in analytical values from autumn through winter to spring, a more detailed series of samples was taken in the second year. Therein, values for total S and sulphate S in clover plants from each treatment rose during the winter and fell during the spring, so that the critical concentration of sulphur or sulphate varied during the growing period. However, the critical N:S ratio was relatively stable, and in view of previously demonstrated correlations with response to added S, appears to be the more useful index for both diagnosis and prognosis.     

The Impact of a Contaminated Lignite Seam on Groundwater Quality in the Aquifer System of the Bitterfeld Region – Modeling of Groundwater Contamination

Until 1990 the Bitterfeld region (Germany) was heavily polluted by mining, an obsolete chemical industry and the uncontrolled deposition of chemical wastes. The cessation of lignite-mining and open-pit drainage may result in a rise of the groundwater level followed by the mobilization of contaminants, especially halogenated hydrocarbons.At a research area in Bitterfeld, highly mobile chlorinated hydrocarbons were detected in both groundwater and sediments. In particular, the pollutants were found to have penetrated a lignite seam separating the quaternary and the tertiaryaquifers. The consequences of the present situation for the progressive groundwater quality of the quaternary aquifer are assessed by means of hydrodynamic modeling using the groundwater simulation program FEFLOW.Starting from the results of the preliminary investigations and adjusting the relevant hydrogeological parameters for diffusion, dispersion, adsorption and initial pollutant distributions, various scenarios were modeled and discussed. It was shown that the impact of a diffusion-controlledscenario on groundwater quality can be neglected, and that only the reversal of the advective vertical direction of flow from the lower seam border to the surface will result in a significant deterioration of groundwater quality.     

Effects of agricultural practices on the hydrodynamics of a deep tilled hardened volcanic ash–soil (Cangahua) in Ecuador

The rehabilitation of indurate pyroclastic formations of the Ecuadorian Sierra (cangahua) paves the way for the development of new agricultural areas. The material derived from the fragmentation of the hardened volcanic ashes is strongly prone to pluvial erosion, essentially because it has a fine silty–sandy texture, and because contains no organic matter and no clay minerals. Rainfall simulation was implemented before and after three cycles of cultivation to asses the evolution of soil structure and its susceptibility to erosion. The cultivated plots were < 1% slope and the rainfall simulation tests were conducted after the harvest on bare surfaces. Two soil preparations, (coarse and fine) and four different agricultural practices, (organic matter, green manure, mineral fertilization, and zero fertilization) were evaluated; as well reference/control plots (uncultivated bare plots).     

Hydrogeochemistry of the Subaé River Impacted by Lead Smelting Activities,Bahia State,Brazil: Geochemical Characterization and Fluxes of Metals

The Subaé river watershed is considered one of the most critical Pb-impacted environments in Brazil and around the world, due to pollutant dispersion during 33 years of lead ore purification in Santo Amaro da Purification. Severe damages have been reported in biota and population, which depends on the Subaé river watershed quality for agriculture, fishing, and shellfish harvesting. This study aims to understand the geochemical characteristics and dynamics of the river close to the former Pb smelter. The river was sampled at eight sites upstream and eight sites downstream the smelter, near the estuary in the Todos os Santos Bay, six times during a year. Immediate analyses were performed by multiprobe. Major ions were measured by chromatography, dissolved metals by ICP-OES in the filtrated samples (0.45 μm), and particulate metals >?0.45 μm by EDX spectrometry. The ions Na⁺ and HCO₃^? are dominated in the river. Most of the samples (47.6%) were classified as sodic, due to oceanic saline intrusion during tide. Despite the high pollution caused by the smelter from 1960 to 1993, still observed in the surrounding soils, dissolved and particulate metals in the river remained low in all sites during the entire year. Only Cu presented some concentration above the threshold of the Brazilian regulations. The discharge of metals by the river into the Todos os Santos Bay appears to be low for Pb and Zn (2.2 and 14.3 kg km^?1 year^?1, respectively), but higher for Cu comparatively to other worldwide bays.     

Effects of permafrost thawing on vegetation and soil carbon pool losses on the Qinghai–Tibet Plateau,China

Bearing a total organic carbon (TOC) content of 9.3–10.7 kg C/m², alpine grassland soils of the Qinghai–Tibet plateau's permafrost region bear a greater organic carbon pool than do grassland soils in other regions of China or than tropical savannah soils. The easily released light fraction organic carbon (LFOC) accounts for 34–54% of the TOC and is particularly enriched in the topsoil (0–0.10 m). The LFOC in the organic carbon pool of alpine cold meadow and alpine cold steppe soils decreased at exponential and quadratic rates, respectively, as the vegetative cover decreased. When the vegetative cover of alpine cold meadows decreased from > 80 dm²/m² to 60 dm²/m², the topsoil TOC and LFOC dropped by 20.4% and 38.4%, respectively. Similarly, when the vegetative cover of alpine cold meadow decreased from 50 dm²/m² to 30 dm²/m² and < 15 dm²/m², the topsoil LFOC content dropped by 60% and 86.7%, respectively. Under climatic warming, the degradation of permafrost and vegetation have resulted in serious soil organic carbon (SOC) loss from the carbon pool. Land cover changes that occurred between 1986 and 2000 are estimated to have resulted in a 1.8 Gg C (120 Mg C/yr) loss in SOC, and a concomitant 65% decrease in the LFOC, in the 0–0.30 m soil layer in the Qinghai–Tibet plateau's permafrost regions. Since the region's ecosystems are quite sensitive to global climate changes, if global warming persists, alpine cold grassland ecosystems are expected to further degrade. Hence, the influence of global climatic change on soil carbon emissions from alpine grasslands should receive more attention.