Geomorphic Control on Soil Erosion – a Case Study in the Subarnarekha Basin, India

<p>Geomorphology depicts the qualitative and quantitative characteristics of both terrain and landscape features combined with the processes responsible for its evolution. Soil erosion by water involves processes, which removes soil particles and organic matter from the upper sheet of the soil surface, and then transports the eroded material to distant location under the action of water. Very few studies have been conducted on the nature and dynamics of soil erosion in the different geomorphologic features. In the present investigation, an attempt has been made to assess the control of geomorphologic features on the soil loss. Universal Soil Loss Equation (USLE) was used to determine soil loss from the various geomorphological landforms. Principal component analysis (PCA) was implemented on the USLE parameters to determine the degree of association between the individual principal components and the USLE-derived soil loss. Results obtained from the investigation signify the influence of the various landforms on soil erosion. PC5 is found to be significantly correlated with the USLE-derived soil loss. The results ascertained significant association between the soil loss and geomorphological landforms, and therefore, suitable strategies can be implemented to alleviate soil loss in the individual landforms.</p>

Arsenic in Agricultural Soils of Slovakia

<p>The article presents the current distribution of arsenic in agricultural soils of Slovakia. The current concentration of arsenic (extracted with <em>aqua regia</em>) was measured and evaluated based on 318 monitoring sites of national soil monitoring system in Slovakia. Based on the obtained results, one can state that the average content of arsenic is lower than the valid hygienic limit for arsenic (25 mg.kg-1) for predominated sandy-loamy and loamy soils in Slovakia. Increased values of arsenic were determined only for the Horná – Upper Nitra region (anthropogenic impact) – 24.5 mg.kg-1 and for the Stredný – Central Spiš region (mixed anthrophogenic and geogenic impact) – 129.5 mg.kg-1. These regions belong to the most arsenic-affected regions in Slovakia, where the content of bioavailable forms of arsenic is also increased in the range of 0.013–0.997 mg.kg-1. The hygienic limit for bioavailable arsenic in soils of Slovakia is 0.4 mg.kg-1. Finally, there is a serious risk of arsenic transport from soil into the plants and food chain especially in case of acid soils. A higher risk of As presence seems to be in anthropogenically affected soils.</p>

Digital Terrain Model Derivatives Analysis with the Aim of Identifying Specific Soil Types in Young Post-Glacial Topography with a Vector Approach

<p>This article discusses a study conducted in order to analyse selected Digital Terrain Model (DTM) derivates in diverse young post-glacial topographic profiles with the aim of identifying terrain features that could be related to the soils that formed there. The area under investigation is within the reach of the youngest Vistulian Glaciation, in the north-east of Poland. The main goal of the study was to reveal indirect relationships between a lithological soil type and terrain forms, which transpire from DTM derivatives. This can directly help to assign the type of soil in the area to one of the three soil types: a) made of sand, b) made of loam, c) wet-soils. <span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;">The starting point for<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> the research undertaken was the landscape approach to soil modelling and the article deals with<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> medium scales. </span></span></span>Derivatives were analysed using vector data notation, focusing on selected derivative values and their spatial location in relation to one another. The results obtained indicate the possibility of using this approach as an auxiliary approach in soil mapping of areas for which the quality of source materials (such as precipitation geometry) is low. Thus, they can be of assistance in improving the existing soil maps of selected scales. The trend revealed in the obtained results of DTM analysis can be considered as a contribution to realisation of assumptions of a study in digital soil mapping with the use of selected methods of AI.</p>

Applicability of Fuzzy and Fuzzy Analytic Hierarchy Process (Fuzzy AHP) Methods to Determine the Optimum Soil Depth in Land Suitability Evaluation for Irrigated Rice

<p>The conventional Boolean logic models of land suitability assessment disregard the continuity concepts of the soil and landscape which might cause inaccurate evaluation and classification. To overcome this uncertainty and consequent constraints, the fuzzy set theories were introduced. Therefore, the current study was undertaken to estimate the optimum soil depth that is used in land suitability evaluation for irrigated rice through the fuzzy sets theory and analytic hierarchy process (fuzzy AHP) in Guilan Province, Iran. The square root and quantitative land suitability evaluation methods were employed to calculate traditional land suitability indices (for depths, 0-25, 0-50, 0-75, and 0-100 cm). Also, fuzzy and fuzzy AHP methods were used to explore new land indices. The Sarma similarity indices were used to compare the results of traditional and fuzzy methods for different soil depths. The results showed that the compatibility percentage between the representative pedons (0-100 cm) and the findings of this research (0-50 and 0-75 cm) were remarkable. Furthermore, the highest compatibility percentage of land suitability class was related to the comparison of these two former depths and 0 to 100 cm depths in each of the two used fuzzy methods. Besides, except for 0-25 cm depths, actual yield revealed a significant and positive correlation with the rest three soil pedon depths. These findings show that considering 0 to 50 cm soil depth might be a relevant alternative as the optimal depth to evaluate land suitability for rice in paddy fields in the Guilan rice-growing area. </p>

Soil Fertility in Response to Long-Term Fertilization under the Tobacco Monoculture System on Rendzic Leptosol in Bulgaria

<p>The effect of long-term mineral and organic-mineral fertilization on selected soil properties (pH, total humus and N, available phosphorus, potassium, calcium, magnesium, iron and manganese content) was studied in a stationary trail with tobacco monocropping system. The trial was established on Rendzic Leptosols in 1966. Five treatments were selected for this study, including control without fertilization (Check), nitrogen + phosphorus (NP), nitrogen + potassium (NK), nitrogen + phosphorus + potassium (NPK) and nitrogen + phosphorus + potassium + manure (NPK + manure). Soil samples at a depth of 0–25 cm were collected from all studied plots every year (2014, 2015 and 2016). The results indicated that maintaining humus content at the initial level is not possible through yearly mineral fertilizer application. Long-term mineral phosphorus fertilization increased 5.5–5.7 times available <span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;">P<span style="font-family: TimesNewRomanPSMT; font-size: 5pt; color: #231f20; font-style: normal; font-variant: normal;">2<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;">O<span style="font-family: TimesNewRomanPSMT; font-size: 5pt; color: #231f20; font-style: normal; font-variant: normal;">5</span></span></span></span> in the soil compared to the initial level. The soil available <span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;">K<span style="font-family: TimesNewRomanPSMT; font-size: 5pt; color: #231f20; font-style: normal; font-variant: normal;">2<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;">O</span></span></span> content in NK and NPK treatments increased, respectively, by 41.1% and 44.9% over the initial level. A remarkable increase in available phosphorus (25.5 times) and potassium (2.5 times) content in the soil compared with the initial level was found due to longterm NPK + manure fertilization. The NPK + manure treatment was found to be the most efficient management system in accumulating of total humus and N, available <span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;">P<span style="font-family: TimesNewRomanPSMT; font-size: 5pt; color: #231f20; font-style: normal; font-variant: normal;">2<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;">O<span style="font-family: TimesNewRomanPSMT; font-size: 5pt; color: #231f20; font-style: normal; font-variant: normal;">5</span></span></span></span>, <span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;">K<span style="font-family: TimesNewRomanPSMT; font-size: 5pt; color: #231f20; font-style: normal; font-variant: normal;">2<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;">O</span></span></span>, Fe and Mn in a long-term fertilized Rendzic Leposol, under a tobacco monocropping system.</p>

Effect of Liquid Organic Fertilizers and Soil Moisture Status on Some Biological and Physical Properties of Soil

<p>This study was conducted to evaluate the effects of liquid organic fertilizers (LOFs) and soil moisture status on some biological and physical properties of postharvest soil of maize cultivation. For this purpose, a factorial greenhouse experiment was performed based on the completely randomized design with three replications. Treatments consisted of five levels of LOFs (control, vermicompost tea, vermiwash, plant growth-promoting rhizobacteria [PGPR] enriched vermicompost tea and PGPR enriched vermiwash) and three levels of soil moisture status (field capacity [FC], 0.8 FC and 0.6 FC). The results showed LOFs caused an increase of soil biological properties (soil microbial respiration, soil microbial biomass, dehydrogenase activity and the number of aerobic heterotrophic bacteria) and the improvement of soil physical condition. LOFs increased aggregate stability, hydrophobicity and total porosity, while decreased bulk density and soil penetration resistance. Increasing water stress levels reduced soil biological activity and made soil physical properties more unfavorable. In general, LOFs improved soil conditions by enhancing soil physical and biological properties and decreased the negative effects of water stress. In addition, results showed that LOFs enriched with PGPR could be more effective than non-enriched ones.</p>

Positive and Negative Effects of Addition of Organic Carbon and Nitrogen for Management of Sulfuric Soil Material Acidity under General Soil Use Conditions

<p>This paper reports the findings of two studies conducted to investigate the effects on pH, Eh and sulfate content of sulfuric soil material of acid sulfate soil following the addition of organic carbon and nitrogen. The first study compared the responses to simple carbon sources (glucose, sodium acetate and molasses) with complex organic matter in the form of chopped<em> Phragmites</em>. The second experiment considered the effect of nitrogen by testing organic matter with varying nitrogen content. <span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;">The results of the first study showed that the</span> changes in Eh and sulfate contents induced by these treatments mirrored the changes in pH, <span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;">the highest change being<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> only 5.6 units induced by sodium acetate</span></span>. These results showed that organic carbon alone was ineffective in treating sulfuric soil material acidity, and that nitrogen was needed. Lucerne hay which had the highest nitrogen content produced the largest increase in pH by 4.2 units, and the changes of pea straw and wheat straw was 3.2 units. It was proposed that the alkalinising effect of the treatments was mediated by anaerobic microbial metabolism which required sources of nitrogen as well as organic carbon. The changes in soil redox conditions by -150 mV measured indicated that sulfur-reducing bacteria induced the changes in Eh, which caused pH to increase and sulfate content to decrease in comparison with nitrate-reducing bacteria.<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> The findings of these<span style="font-family: TimesNewRomanPSMT; font-size: 9pt; color: #231f20; font-style: normal; font-variant: normal;"> studies have implications for management of sulfuric soil material acidity.</span><br style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" /><br class="Apple-interchange-newline" /><br /></span></p>

Changes in some chemical properties of saline-sodic soils over time as affected by organic residues: An incubation study

<p>Salinization and sodification of agricultural lands in arid and semi-arid regions of the world are two limiting factors in the crop production. This study was conducted to evaluate the effect of readily available agricultural residues on changing some chemical properties of saline-sodic soils. Wheat, potato, sunflower, and canola residues were separately added into three saline-sodic soils at a rate of 2% by weight and thoroughly mixed with soils. Control and treated soils were incubated for 168 days at a constant moisture and temperature. The pH, electrical conductivity (EC), soluble cations, available nitrate (NO3-) and phosphorous (P), cation exchange capacity (CEC), and exchangeable sodium percentage (ESP) were measured during the incubation. The EC increased in the response to the incorporation of plant residues, whereas the pH was reduced. The application of organic components in soils increased CEC and decreased ESP. The results showed that the maximum reduction in ESP was observed in the potato treatment because of the highest Ca2+ concentration. The average reduction in ESP of treated soil samples at the end of incubation followed this order: 16.1% (potato residue-treated soil) &gt;12.7% (canola residue-treated soil) &gt;11.1% (wheat residue-treated soil) &gt;9.6% (sunflwer residue-treated soil). The potato residue was the most effective amendment in changing the chemical properties of saline-sodic soils in comparison with other organic residues. The results indicated that the application of organic residues had a positive impact on reducing the soil sodicity and improving the soil fertility depending on their chemical composition.</p>

Soil phosphorus fractionation in calcareous soil as affected by organic amendments application

<p>Understanding of P transformations following organic amendments addition to highly calcareous soils is necessary for developing better management practices that can help enhance P fertilizer use efficiency. Phosphorus solubility and availability for plant uptake under the conditions of arid calcareous soil is very low, making P nutrient supply a critical issue under these conditions. The aim of this study was to evaluate the impact of various types of organic amendments (chicken compost, cow compost and a mixture of humic-fulvic acid) applied alone at different rates of KH2PO4 fertilizer on P fractions in calcareous soil using the sequential chemical extraction method. Amended calcareous soil was incubated under laboratory conditions and soil samples were collected at 0, 4, 8 and 16 weeks of the incubation periods. Soil was sequentially extracted and analyzed for P different fractions. The results indicated that the addition of chicken and cow compost increased soluble and exchangeable-P and Ca-P fractions in calcareous soil and the increases depend on application rates. The results indicated that combination of chicken and cow compost with different KH2PO4 fertilizer application rates increased the concentration of soluble and exchangeable-P in the soil compared to organic amendments or KH2PO4 fertilizer applied alone. The P associated with Ca was the dominant P fractions in soil, ranging between 51 to 59% regardless of the different treatment and the period of incubations. The Al- and Fe-associated P fractions varied between 2 and 9%, with the maximum value being observed at the eighth week of incubation. The residual-P fraction ranged between 5 and 22% at different incubation periods.</p>

The influence of pistachio shell biochar and barley residues on soil properties

<p>This research was conducted to evaluate the effects of biochar and barley residues on some physicochemical properties of silty loam soil and water erosion using water erosion simulator. Biochar was produced from pistachio shells under slow pyrolysis at 500°C under anaerobic condition. Biochar and barley residues were mixed to soils at three rates of 0, 0.5 and 1% (by weight), and 6.5 kg of soil was filled in trays with length, wide and height of 35 × 20 × 10 cm, respectively. The experiments were performed in 3 repetitions for 4 months as a completely randomized design. The results showed that application of 1% of biochar significantly increased P (phosphorus), K (potassium) and OC (organic carbon) of the soil in comparison with control. Also, application at both levels (0.5 and 1%) of barley residues significantly increased P, K, TN (total nitrogen), and OC. Application of biochar and barley residues significantly increased the mean weight diameter of aggregates, plant available water content, and saturated moisture content and significantly decreased water dispersible clay (p &lt; 0.05). Consequently, the amount of water erosion decreased at the rainfall intensity of 60 mm·h-1 during 20 minutes. Generally, the effect of barley residues to improve soil properties was higher than the biochar.</p>