Percent Soil Organic Matter Research Articles

Investigating soil health and resilience in small-scale agroecosystems of Mount-Lebanon

ABSTRACT In response to Lebanon’s 2019 economic crisis, agricultural activities intensified to enhance national food security, with implications for soil health. We investigated soil management practices on 26 small-scale farms in a mountainous region, focusing on reconciling static sustainability definitions with dynamic resilience concepts. Surveying farmers revealed varied adoption rates of regenerative practices: intercropping (85%), residue retention (73%), cover crops (61%), organic amendments (46%), integrated organic/mineral amendments (46%), improved irrigation (38%), conservation tillage (30%), crop rotation (19%), and organic/biological pest/disease treatment (11%). Farms were categorized as conventional (C), neutral (N), and regenerative (R) based on practices. Qualitative assessments using seven indicators yielded scores of 4.28 (C), 6.34 (N), and 7.88 (R). Quantitative analyses showed significant differences in soil organic matter percentage (1.86 C, 2.75 N, 3.32 R), soil respiration (156 C, 296 N, 380 R), and earthworm abundance (2.92 C, 4.24 N, 5.72 R). The Soil Quality Index (SQI) indicated varying soil health from 0.05 (C) to 0.49 (R). Our findings highlight the importance of adopting synergistic, sustainable soil management practices to ensure enduring agricultural productivity and safeguard soil resilience, especially in the Mediterranean region.

Improvement of Soil Pore Distribution and Soil Moisture Content using Organic Matter Addition Technology

Background: Coffee plants in Sumbermanjing Wetan are commonly cultivated on dry lands that rely solely on rainfall as the source of water input that eventually makes them susceptible to climate change. The deficiency of organic material and water availability for these plants poses a significant challenge for coffee farmers in Sumbermanjing Wetan. Therefore, a research was conducted to investigate the addition of various organic matter through biopore infiltration holes in coffee plantations with the following objectives: i) to analyze the impact of applying organic matter on the distribution of soil pores and ii) to examine the effect of organic matter application on soil moisture content. Methods: The research was carried out in the Smallholder Coffee Plantation of Argotirto Village, Sumbermanjing Wetan District, Malang Regency. A randomized block design was implemented with five treatment groups, which included the control (P1), two biopore holes + manure (P2), two biopore holes + compost (P3), two biopore holes + green manure (P4) and surface-applied manure (P5), each repeated three times. The observed variables included the percentage of soil organic matter, pore distribution, available water capacity and soil moisture content. Result: The findings indicated that addition of organic matter in biopore infiltration holes enhanced soil organic material content, where treatment P4 (two biopore holes + green manure) exhibiting the highest soil organic material values in the first and third months after the application. The application of organic matter increased soil porosity in all treatments, where treatment P4 (two biopore holes + green manure) showing the highest available water capacity. This suggests that the utilization of organic matter can improve soil aggregation, thus increasing porosity and available water capacity. Consistently, soil water content at a depth of 40-60 cm tended to increase in the third month following biopore infiltration holes application, indicating that the addition of organic matter through biopore infiltration holes can enhance soil moisture at subsoil.

The effect of preservative agriculture technology on some spectral and physical properties of the soil according to the years of application in the Telkif Region

Conservation agriculture is one of the innovative techniques that has proven to be successful in terms of decreasing effort, time, and expenses. The current study used two key criteria to prove some relevant findings for Conservation agriculture in order to test the results of its success, they are the bulk density (which measures soil compaction, de-oxidation and a lack of ventilation) as well as the percentage of soil organic matter. Four regions have been selected for different periods of adoption of conservation agriculture (2, 5, 10) years and other area is a unplowed fallow soil for comparison. The results revealed a great superiority for all conservative agriculture regions in terms of organic matter percentage and soil compaction. Also, the results also indicated that the spectral signatures of the areas that have been used for long-term the conservation agriculture are less than those of fallow soil due the effect of organic matter. This is an encouragement to use this technique of agriculture, where the soil surface appears to be unaffected by the agricultural machines.

Chloride and phosphorus retention and release in soils surrounding a salt-contaminated lake in West Michigan

Salinization in freshwater ecosystems has become an increasingly prevalent issue. Past studies indicate that increased salinity levels in lakes can impact biota, stimulate internal nutrient loading, and prevent seasonal turnover, potentially resulting in impairment to the lake ecosystem. Salt retention in soils and groundwater causes elevated salt concentrations in fresh water long after road salt was applied. We examined salt retention and release in soils collected near the tributaries flowing into and out of a salt-impacted urban lake. We distributed each soil sample into plastic trays and exposed them to three treatments, conducted in series: (1) non salt-contaminated water as a conditioning rinse; (2) salt-contaminated water to mimic salt de-icer runoff; and (3) non salt-contaminated water to determine salt release. We measured retention of chloride from each soil sample based on how much chloride was measured in water draining the soil (effluent). We observed considerable variability among sites presumably because of soil heterogeneity, although overall the soils in our study area retained a modest amount of chloride (mean of ∼29 mg/L) from simulated salt runoff events, even at short exposure times (<30 min). In addition, some soils released chloride following a relatively salt-free rinsing event. There was an overall positive relationship between percent soil organic matter and Cl- retention. We also measured the impact of chloride on bioavailable phosphorus concentration in the effluent, which was relatively modest and variable. Soil total phosphorus had a strong positive correlation with %SOM. Our results suggest that in addition to direct runoff of salt de-icers from roads to lakes, soil retention can also serve as a chloride source that can be released over time, resulting in a delayed impact to aquatic ecosystems.

Correlation between Soil Carbon Potential and Soil Quality Index in Various Types of Dry Land Use in Aceh Besar District

Soil quality is a useful concept when assessing the sustainability of an agricultural business and demonstrating the ability of soil to maintain plant and animal productivity, improve water and air quality, and protect human health. SQI is a soil variable with the following characteristics: 1) well correlated with ecosystem processes; 2) integration of physical, chemical, and biological soil properties; 3) good sensitivity to human-induced soil changes; 4) simple measurement and interpretation; and 5) Reproducibility Soil quality index (SQI) is a diagnostic procedure to evaluate soil function and overall health. This research was carried out on a unit of land in a dry area in Aceh Besar District with a study area of 239,439.63 ha. Analysis of biomass samples and soil samples was carried out at the Laboratory of Soil and Plant Sciences and Soil Physics Laboratory, Faculty of Agriculture, University of Syiah Kuala. The tools used in this study include a set of computers with the Microsoft Windows 10 operating system that are equipped with several software for analysis, writing instruments, and other supporting tools. The main materials used in this study were soil samples, tree diameter measurement data, and land use maps, including geology, climate, slope class, soil, and topography. The results of the correlation analysis test showed a value of 0.6358. This shows that the relationship between soil C potential and soil quality index is a strong correlation. The distribution of carbon in the soil also has a close relationship with the soil quality index and is an effort to maintain carbon stocks in the soil. C - organic content is a very important parameter in compiling soil quality index criteria. Soil quality can be affected by many factors, such as parent material, environmental factors, land use type, and human activities. The percentage of soil organic C is an indicator of the percentage of soil organic matter (BOT), and BOT is able to improve soil structure and aggregates. Soil organic carbon (SOC) concentration is closely related to soil quality and vegetation productivity. This relationship occurs because of the many contributions of soil carbon to soil properties such as the improvement of soil structure and water retention, provision of cation exchange capacity, and supply of plant nutrients through mineralization. This effect is especially important in small-scale tropical farming systems where the use of external inputs is often limited, and SOC concentrations have been positively correlated with yield levels for a variety of tropical soils.

A Nematode Community-Based Integrated Productivity Efficiency (IPE) Model That Identifies Sustainable Soil Health Outcomes: A Case of Compost Application in Carrot Production

Percent soil organic matter (SOM), pH and crop yield are among the biophysicochemical process-driven soil health indicators (SHIs). However, identifying sustainable soil health conditions using these SHIs is limited due to the lack of Integrated Productivity Efficiency (IPE) models. We define IPE as a concept that identifies best-to-worst-case soil health outcomes by assessing the effect of agronomic practices on weighted abundance of functional guilds (WAFG) of beneficial soil organisms and SHIs simultaneously. Expressing WAFG of all beneficial nematodes (x-axis) and SHIs (y-axis) as a percent of untreated control and regression of x and y reveals four quadrants describing worst-to-best-case outcomes for soil health and sustainability. We tested the effects of composted cow manure (AC) and plant litter (PC) applied at 135 (1×), 203 (1.5×), and 270 (2×) kg N/ha on WAFG, SOM, pH, and yield in a sandy clay loam field of a processing carrot cultivar over three growing seasons. Untreated control and urea at 1× served as experimental controls. Data that varied by time and were difficult to make sense of were separated into sustainable, unsustainable, or requiring specific modification to be sustainable categories by the IPE model. Within the sustainable category, all AC treatments and 2× rate of PC treatments had the best integrated efficiency outcomes across the SHIs. The IPE model provides a platform where other biophysicochemical process-driven SHIs could be integrated.

Improvement the Soil Physicochemical Properties and Fenugreek Growth Using Zeolite and Vermicompost under Water Deficit Conditions

The low percentage of soil organic matter, especially in sandy soils in most arid and semiarid regions of the world including Iran, and the increase in the indiscriminate use of chemical fertilizers and the resulting environmental damages make it inevitable to use organic fertilizers and soil amendments for increasing the water and fertilizer efficiency in sustainable agriculture. This study aimed to investigate the physicochemical changes of soil under the organic and mineral treatments of nitrogen and zeolite and alleviation of water stress in fenugreek (Trigonella foenum-graecum). The experimental treatments included five irrigation regimes (without stress, mild water deficit stress, and severe water deficit stress (irrigation after depletion of 20%, 40%, and 60% of available soil water (ASW), respectively), in vegetative and reproductive stages) as the main plot and the factorial combination of three fertilizer treatments (control, vermicompost, and urea) and two zeolite contents (0 and 9 t ha−1) as the subplot. Mild and severe water deficit stress caused at least 34 and 40% reduction in biological yield and 5% and 13% reduction in height in the first and second years, respectively. Applying vermicompost increased the soil organic carbon (OC), and the highest amount of soil nitrogen (N) was observed in the plots treated with zeolite and vermicompost. The available soil phosphorus (P) increased by applying zeolite. The zeolite treatment was more effective than vermicompost in increasing the soil cation exchange capacity (CEC). The treatments with zeolite or vermicompost were able to alleviate water deficit stress. Vermicompost and zeolite improved the biological yield of fenugreek by improving the physicochemical conditions of the soil, especially in the water deficit stress conditions, and reduced the usage of chemical fertilizers in line with the goals of sustainable agriculture.

Physical and Chemical Characteristics of Oil Palm Plantation Soil: A New Lead in Forensic Investigation

Soil sample is one of the important evidence that can be found in crime scene. Unknown soil sample can be analysed and compared with reference sample in order to determine the origin as its physical and chemical components possess unique characteristics. The purpose of this study is to determine the physical and chemical characteristics of soil from oil palm plantations in Perak, Malaysia to assist forensic investigation. Total of 97 topsoil samples were collected from three different oil palm plantations in Perak. Particle size distribution was obtained using dry sieving technique and colour of soil sample was examined under three conditions that are dry, moist and ashed. Soil pH was measured using pH meter and percentage of composition of soil organic matter (SOM) was determined by weighing the sample before and after ignition. Result showed that the composition of particle size &lt;0.18mm was within the range of 5.57-21.11% whereas for particle size between 0.18mm - 0.6mm was within 31.62 - 52.96% and 25.78-66.86% for particle size &gt;0.6mm. The color mode of soil after oven dried, moistened and ashed was greyish brown (10YR 5/2), very dark greyish brown (10YR 3/2) and light yellowish brown (10YR 6/4) respectively. Soil pH was in the range of 5.79 – 6.70. The percentage of SOM was between 3.29 - 20.48%. The physical and chemical characteristics of soil analysed in this study from three different locations of oil palm plantations varied and it is possible to discriminate these locations based on the analysis highlighted in this study.

Long-term grazing exclosure: implications on water erosion and soil physicochemical properties (case study: Bozdaghin rangelands, North Khorasan, Iran)

Grazing exclosure (GE) is used to improve rangelands in the dry area of the world, so it is important to investigate its effects on soil physicochemical and erodibility properties. This study was conducted to evaluate the effect of long-term GE on the physicochemical and erodibility properties of soil and vegetation as compared with open grazing (OG) areas in Bozdaghi region of North Khorasan province, Iran. Soil and vegetation data were sampled from two sites in the grazing exclosure and the open grazing in early autumn in a randomized complete block design with three replications. Therefore, in each area (GE and OG), three transects of 500-m length and 200-m intervals) were set up. Along each transect, five soil samples were taken at the depths of 0-15 and 15-30 cm in a random-systematic method (15 soil samples in each area) and transferred to the laboratory. In the laboratory, some soil physicochemical properties such as saturation percentage, soil texture (clay, silt, and sand), bulk density, porosity, percentage of soil organic matter (SOM), total nitrogen (TN), exchangeable sodium, potassium, pH, and electrical conductivity (EC) were measured and Soil Erodibility Index (SEI) was calculated by using the modified clay ratio relation. After installing the transects (with a length of 50 m) in three blocks in each area, the parameters of species composition and canopy cover were investigated by the linear-contact method. Data analysis was performed by using an independent t test on Statistical Package for Social Sciences (SPSS) v. 23 software. The results indicate that the application of GE in the Bozdaghi area has a significant positive effect on soil physicochemical properties (P < 0.05). Also, the application of GE has increased the amount of SOM and TN in the surface layer of the soil by about twice as much as the OG pastures. Due to these changes, during 20 years in the GE area, the effects of GE can be positively assessed. According to the obtained results, especially the positive changes in vegetation and the soil physicochemical and erodibility properties, it is recommended to execute the GE plan in the study area.

An assessment of the wealth of information given by sponge spicules as a paleoenvironmental tool: The case of two lakes in northeast (Brazil)

This study aimed to test the use of inland sponge spicules as proxy data for a Holocene paleoenvironmental reconstruction of the Trairí River valley, in the state of Rio Grande do Norte, in Northeast Brazil. Spicules were recovered from sediments from two core samples obtained from Lake Fumo and Lake Urtiga, at depths of 0.60 m and 0.96 m, respectively. The following analyses were carried out: phytolith morphotype classification, isotope data (δ13C, δ15N‰), radiocarbon dating (AMS), grain size analysis, sediment morphoscopy, and percentage of soil organic matter. Environmental reconstruction indicated seasons with dry and rainy conditions 1940 years BP. Isotope data pointed to the presence of plants (C3 and C4) and algae. Phytolith classification indicated that Poaceae, Cyperaceae, Arecaceae and/or Bromeliaceae occurred at the location. Spicules from the inland sponges Heterorotula fistula; Ephydatia sp.; Dosilia pydanieli; Corvoheteromeyenia heterosclera; Tubella variabilis; Radiospongilla inesi; and Anheteromeyenia sp. were found in the core samples. Reconstruction based on isotope, phytolith and sedimentology results was compared with the spicule data and only D. pydanieli and H. fistula confirmed the other proxy information.

Adding manure and zeolite to improve soil chemical properties and increase soybean yield

Increasing domestic soybean production is an important part of the effort to reduce reliance on imports. One potential area for improvement is developing soybean crops in Alfisols. Alfisols require intensive effort due to their poor soil chemical properties. Manure and zeolite were proposed as candidate materials that could be used to improve soil chemical properties to support plant growth and increase the productivity of cultivated land. The experiment was designed to study the addition of manure and zeolite on soil chemical properties of Alfisols and soybean yield. The experimental design was arranged in a factorial completely randomized block design with two factors—three rates of zeolite (Z0 = 0 t ha&lt;sup&gt;-1&lt;/sup&gt;, Z1 = 2.5 t ha&lt;sup&gt;-1&lt;/sup&gt; and Z2 = 5 t ha&lt;sup&gt;-1&lt;/sup&gt;) and three manure variables (P0 = no manure, P1 = 5 t ha&lt;sup&gt;-1&lt;/sup&gt; cow manure, and P2 = 5 t ha&lt;sup&gt;-1&lt;/sup&gt; quail manure)—with three replications. The results showed that a combination of 5 t ha&lt;sup&gt;-1&lt;/sup&gt; zeolite and cow manure increased soybean yield. However, zeolite 5 t ha&lt;sup&gt;-1&lt;/sup&gt; resulted in the greatest improvement in soil chemical properties—the highest CEC, soil organic matter percentage, and pH.

Sustainability of soil organic matter at organic mixed vegetable farms in Michigan, USA

Soil samples at thirty (30) USDA organic-certified mixed vegetable farms in Michigan, USA were obtained and analyzed for their percentage of soil organic matter (SOM). The intent was to characterize the changes in SOM content, specifically the overall change since organic certification, the patterns of increase or decline, and whether certain agricultural practices are associated with levels of SOM. A short survey of farmers provided supplemental information about each sampling site, including tillage practices, pesticide use, and cover crops. The results indicate a significant majority (24/30) of organic farms showed increases in the percentage of organic matter content, with one farm exhibiting no change and five farms decreasing. These results were achieved in a variety of soil textures, climatic conditions, and over durations from 1–17 years of organic certification. Organic farms had more than twice the percentage of soil organic matter as the ten (10) conventional farms used as a benchmark. In addition, the soil at the sampled organic farms exhibited high positive correlations between SOM and cation exchange capacity, and between pH and cation exchange capacity. Tillage mean depth at those farms increasing their percentages of organic matter was 70% lower than those farms with decreasing percentages of SOM, which suggests low-till or no till practices may help preserve organic matter. In combination with other management methods, such as cover crop usage and soil amendments, a key indicator of soil health was improved and sustained—a primary objective of organic farming.

Factores que influyen en la erosión hídrica del suelo en un bosque templado

Los ecosistemas forestales son importantes en la aportación de bienes y servicios a la sociedad; sin embargo, pueden estar afectados por erosión hídrica, lo cual representa un problema grave en México. Por lo tanto, el objetivo de este trabajo fue determinar los factores que explican ese tipo de degradación en un bosque templado. Los factores incluidos fueron seleccionados mediante revisión de literatura, a nivel nacional e internacional, con el criterio de uso en programas de manejo y monitoreo. Para evaluar la pérdida por erosión, se utilizó la medición de pedestales. Estadísticamente, se emplearon la correlación de Pearson y el Análisis de Componentes Principales (ACP). Los resultados de la primera evidenciaron que la densidad aparente (r= 0.64), pendiente (r=0.59) y el porcentaje de rocas en la superficie del suelo (r=0.57) tienen correlación positiva con la erosión hídrica; por lo que, al incrementar sus valores, aumenta la presencia de pedestales. Se determinó una correlación negativa con la profundidad (r= -0.48) y el porcentaje de materia orgánica (r= -0.45). A mayor magnitud de estos parámetros, disminuye la presencia de pedestales como expresiones del grado de erosión de los suelos. Mediante el ACP, se obtuvo que, además, incidieron directamente, el espesor del mantillo, la presencia de suelo desnudo y la compactación. También, se identificó una correlación positiva con el porcentaje de suelo desnudo y la compactación. No hubo significancia con la materia orgánica, capacidad de infiltración y profundidad del suelo. Los factores señalados deben considerarse para facilitar los monitoreos futuros.

Trends of litter decomposition and soil organic matter stocks across forested swamp environments of the southeastern US

A common idea in the discussion of soil carbon processes is that litter decomposition rates and soil carbon stocks are inversely related. To test this overall hypothesis, simultaneous studies were conducted of the relationship of environmental gradients to leaf and wood decomposition, buried cloth decomposition and percent soil organic matter in Taxodium distichum swamps across the Mississippi River Alluvial Valley (MRAV) and northern Gulf of Mexico (GOM) of the US. Decomposition of leaf tissue was 6.2 to 10.9 times faster than wood tissue. Both precipitation and flooding gradients were negatively related to leaf and wood litter decomposition rates based on models developed using Stepwise General Model Selection (MRAV vs. GOM, respectively). Cotton cloth should not be used as a proxy for plant litter without prior testing because cloth responded differently than plant litter to regional environmental gradients in T. distichum swamps. The overall hypothesis was supported in the MRAV because environments with higher precipitation (climate normal) had lower rates of decomposition and higher percent soil organic matter. In the MRAV, higher levels of percent soil organic matter were related to increased 30-year climate normals (30 year averages of precipitation and air temperature comprising southward increasing PrinComp1). Soil organic carbon % in inland vs. coastal T. distichum forests of the MRAV were comparable (range = 1.5% to 26.9% vs. 9.8 to 31.5%, respectively). GOM swamps had lower rates of litter decomposition in more flooded environments. Woody T. distichum detritus had a half-life of up to 300 years in the MRAV, which points to its likely role in the maintenance of inland “teal” soil organic carbon. This unique study can contribute to the discussion of approaches to maintain environments conducive to soil carbon stock maximization.

Tillage, Cover Crop and Crop Rotation Effects on Selected Soil Chemical Properties

Research results still vary, especially between locations, on the effects of agricultural practices on soil chemical properties and crop yield, and not all reasons for the variation are fully understood. Thus, this study investigated the influence of tillage, cover crop and crop rotation management practices on selected soil chemical properties. The study was conducted on a silt-loam soil in central Missouri during the 2011 to 2013 growing seasons. The soil was managed by moldboard plow tillage at two levels (tillage [till] vs. no-tillage [NT]). Cover crop management included cereal rye (Secale cereale) at two levels (cover crop [CC] vs. no cover crop [NC]). The main crops that were grown were a corn (Zea mays L.) and soybean (Glycine max L.) rotation. The soil samples were collected each year at 0–10 cm, 10–20 cm, 20–40 cm and 40–60 cm depths for the analysis of soil chemical properties. The results showed that after 3 years of study, the relative increase in percent soil organic matter (OM) was 4% under the no-till management as compared with moldboard plow tillage. In addition, the relative change in the percentage of OM was 8% greater in the CC management compared with NC. Furthermore, the results show a significant improvement (p = 0.0304) in total carbon with a combination of no-till management and a corn/soybean rotation as compared with continuous corn and soybean. The interaction effects of the management practices on the soil chemical properties were difficult to predict throughout the study.

Effects of crop production practices on soil characteristics and metabolic diversity of microbial communities under winter wheat

The aim of this research was to compare the effects of organic (ORG, no mineral fertilisers and pesticides) and conventional (CON, with mineral fertilisation and plant protection chemicals) crop production systems on some soil properties: soil organic matter (SOM) and particulate organic matter (POM) contents, dehydrogenase activity and metabolic microbial diversity (Biolog EcoPlate™). Samples of Haplic Luvisol soil were collected from 23-year-old experimental fields under winter wheat from the depth layers of 0–5, 5–10, 15–20 and 30–35cm. Soil under ORG showed higher contents of SOM, POM and POM expressed as a percentage of SOM by 16.0%, 25.6% and 23.9% respectively, in particular down to 5cm depth, compared with the CON system. Also, dehydrogenase activity was 47.5% higher under the ORG than the CON system. The Biolog EcoPlate revealed higher metabolic microbial diversity in soil under ORG crop production system compared with CON. This result was supported by the average well colour development and Shannon’s diversity index values. Significant correlations between soil quality parameters and winter wheat yield confirmed their effectiveness as indicators of soil disturbance. The results showed that the ORG system much better maintained SOM and soil fertility compared with CON.

Evaluation of Adapt‐N and Realistic Yield Expectation Approaches for Maize Nitrogen Management in North Carolina

Core Ideas The North Carolina nitrogen database made better recommendations than Adapt‐N for plot studies. Different labs produce distinctly different soil organic matter percentages from the same soil. Farmer strip trial results demonstrated approximately 60% of the time that Grower‐25% N yielded similarly to the other treatments. Farmer strip trial results showed overall similar performance for Adapt‐N and Grower‐Consultant rates. Nitrogen decision making for maize (Zea mays L.) is difficult because of seasonal weather fluctuations. New tools have emerged based on dynamic simulation models that account for weather variability. We evaluated the performance of the Adapt‐N tool relative to North Carolina's Realistic Yield Expectation (RYE) framework through six multi‐N rate maize plot trials in three physiographic regions and 38 strip trials on commercial farms in the coastal plain. Yield response and profit were evaluated with quadratic plateau (QP) response curves. The RYE framework generally estimated the agronomic optimum N rate (AONR) well, as did Adapt‐N after modification to account for high soil organic matter (SOM) and C/N ratio mineral‐organic coastal plain soil; there was, however, much greater site variability with Adapt‐N. Adapt‐N was sensitive to SOM content inputs, which varied based on method and laboratory. The RYE provided overall higher dollar return than Adapt‐N; Adapt‐N returns varied based on SOM and yield goal inputs, since they strongly impact N rate recommendations. In the on‐farm strip‐trials, 58% of yields were not statistically different between lower N rates and other treatments including Adapt‐N. On average, Adapt‐N performed similar to grower‐consultant practice with modest tradeoffs between reduced N rates and yield. Adapt‐N recommendations and grower rates yielded higher than RYE and required more N. Overall, the RYE approach performed better than Adapt‐N in N research farm trials; in on‐farm strip trials Adapt‐N performed similarly to grower‐consultant practices and in various cases provided economical yield increases over RYE.

Wetland Soil Properties and Resident Bacterial Communities Are Influenced by Changes in Elevation

Soils from four sites distributed along an elevation gradient from marsh to coastal forest in a wetland bordering the Gulf of Mexico were sampled over a 16-months period. In addition to measuring a suite of environmental conditions, terminal restriction fragment length polymorphism analyses of the resident bacterial communities were performed. Wetland soil bacterial communities varied across both space and time, with all measured variables (temperature, pH, percentage of soil organic matter, salinity, and concentrations of sulfide, NH4+, NO3−, and soluble reactive phosphorus) showing significant site by time interactions. Analyses of bacterial communities showed both marsh zones (Spartina and Cladium) supported similar communities, as did the ecotone and coastal forest. Bacterial communities within coastal forest soils were significantly different than those within marsh soils, and the ecotone communities were significantly different from the Spartina marsh soil. Temperature and pH were the most influential environmental factors impacting bacterial community composition but no predictable patterns were identified, suggesting that community changes are likely the result of intrinsic factors that are affected by local-scale processes. The dynamic nature of the physiochemical variables within wetlands suggests that more work is needed to determine potential interactive effects on bacterial community structure.

Effect of tillage systems and polyacrylamide on soil physical properties and wheat grain yield in arid regions differing in fine soil particles

ABSTRACTA field study was performed for two consecutive seasons to evaluate the effect of polyacrylamide (PAM), tillage systems and particle size on soil physical properties and wheat grain yield. The PAM rates were 0, 10 and 20 kg ha−1 while the tillage treatments included no-tillage (NT), moldboard plowing (CT1), and chisel plowing (CT2). Soil fine particles size of two locations were A (25.2 silt + clay) and B (38.5 silt + clay). Location B reported higher organic matter and total porosity while lower in bulk density. The CT1 and NT treatments denoted better soil organic matter percentage. The CT1 presented maximum infiltration rate compared to other tillage systems. No tillage showed better soil water contents while the minimum was in CT1 of location A and CT2 of location B. Increasing the PAM rate increased total porosity, infiltration rate and soil water content while decreased soil bulk density. Possibly, the presence of compacted layer in location A hindered the effect of PAM. At location B, the CT2 with PAM of 20 kg ha−1 had the highest grain yield compared to other tillage systems. The PAM is beneficial for soil and water conservation and can be used in agriculture.

A Comparison of Five Wetland Communities in a North Dakota Fen Complex

Fens are rare and not well-studied within the Prairie Pothole Region (PPR) of North Dakota. PPR wetlands (including fens) are vulnerable to land use alterations, particularly conversion to agricultural production. In this study, we described a 48-ha natural fen complex with five distinct wetland plant communities (denoted cattail [Typha L. spp.], floating mat [areas at higher elevation with an upward groundwater gradient], herbaceous, tree, and wet meadow). Our goal was to describe the wetland plant communities and determine possible factors driving the formation of several distinct wetland plant communities in close proximity to one another. We identified 148 plant species, six of which are considered priorities for conservation by the North Dakota Natural Heritage Program. We compared the composition of wetland plant communities using multi-response permutation procedure (MRPP) and examined individual attributes (e.g., species richness, evenness, diversity, Floristic Quality Index, percent introduced species, percent soil organic matter, pH, and electrical conductivity) of the wetland plant communities using ANOVA and Tukey's (HSD) test. We found the highest species richness, evenness, and diversity in herbaceous and tree communities and the lowest percent introduced species in floating mat communities. There were no significant differences in the soil properties tested among the five plant communities.