ANATOMICAL CHANGES IN Urochloa plantaginea AND Urochloa platyphylla UNDER DIFFERENT SOIL MOISTURE CONDITIONS

Urochloa plantaginea and Urochloa platyphylla are common weeds in the highland area. However, in recent years, they have been found in wetlands and poorly drained soils, but the biology and behavior of the species in these conditions are not known. Thus, the objective was to assess anatomical changes in plants of Urochloa plantaginea and Urochloa platyphylla grown under different soil moisture conditions, as well as the adaptive structures generated as a result of each environment. A completely randomized experimental design in the form of a 2x2 factorial design was used, with factor A being two species of Urochloa (U. plantaginea and U. platyphylla), and species B being three soil moisture conditions (50 and 100% FC and 5 cm water depth), with four repetitions. The assessments were performed by means of anatomical cuts, observing the number and diameter (micrometers - μm) of aerenchymas in stems, roots and leaves; total diameter and the central root cylinder (μm); diameter of the fistula medulla and cortex (μm) in stems; mesophyll thickness and leaf midrib (μm). It was found that, for the two species of Urochloa, the water depth condition induced an increase in the number and diameter of aerenchymas in roots and leaves and provided a larger diameter of the fistulous pith in stems. The diameter of the central cylinder and the thickness of the leaf mesophyll midrib were more compact at 50% FC, also, for both species. Therefore, the adaptive structures generated vary as a result of the field capacity of the soil.

Functional Performance of Parallel Drain Subsurface System in Waterlogged Paddy Field

Waterlogging induced salinity is a common problem in many command areas of irrigation projects. Subsurface drainage improves the productivity of poorly drained soils by decreasing the water table, providing greater soil aeration, improving root zone soil salinity and enhancing the crop yield. A pilot study has been conducted to explore the functional performance of the parallel drain subsurface system in waterlogged paddy field by considering the lateral drain spacing and drain depth are the factors influences the soil properties. This experiment was carried out in farmers’ field at Sembari village, Lalgudi, Tamil Nadu, India in waterlogged paddy field during October 2020 to February 2021. Treatments of this study consisted the combination of three lateral drains spacing of 7.5 m, 10.0 m and 12.5 m and two drain depths of 60 cm and 80 cm and a control plot. This study investigated the changes in soil properties, depth to water table, drainage coefficient and crop behaviors after installation of the system. Reduction in Soil pH, removal of slats in drain water, lowering the depth to water table and higher drainage coefficient recorded for narrow lateral drain spacing and deeper drain depth treatment has improved the root zone environment for crop growth. Paddy has been established very well in terms of plant height and number of tillers per plant in S1D2 (7.5 m drain spacing and 80 cm drain depth) treatment which was also reflected in grain yield and straw yield over undrained paddy field yield. Based on the results, it is recommended to install parallel drain subsurface system at 7.5 m drain spacing and 80 cm drain depth in the study area.

Implications of A Priori Parameters on Calibration in Conditions of Varying Terrain Characteristics: Case Study of the SAC-SMA Model in Eastern United States

This study seeks to advance the knowledge about the effect of the Sacramento Soil Moisture counting Model (SAC-SMA) a priori parameters on calibration. We investigated the catchment characteristics where calibration is most affected by the limitations in the a priori parameters and we studied the effect on the modeled processes. The a priori SAC-SMA model parameters were determined from soil-derived physical expressions that make use of the soil’s physical properties. The study employed 63 catchments from the eastern United States (US). The model calibration employed the Shuffle-Complex algorithm (SCE-UA) and used the a priori parameters as default allowing for ±35% as a range of deviation. The model efficiency after calibration was sensitive to the catchment landscape properties, particularly the soil texture and topography. The highest efficiency was obtained in conditions of well-drained soils and flat topography where the saturation excess overland flow is predominant. Most of the catchments with smaller efficiency had poorly drained soils where mountainous and forested catchments of predominant subsurface stormflow had the lowest efficiency. The current regional study shows that improvements of SAC-SMA a priori parameters are crucial to foster their operational use for calibration and prediction at ungauged catchments.

Characterising soil moisture regimes on poorly drained soils in Ireland using optical satellite derived vegetation indices and the OPTRAM model

<p>Soil drainage capacity is the degree and frequency at which the soil is free of saturation. It influences land use and management, soil nutrient cycling and greenhouse gas fluxes. Accurate information on drainage conditions is crucial for crop production and management and fundamental in developing strategies to adhere to environmental sustainability goals. This is particularly important in Ireland where approximately 50% of the soils are classified as “marginal”. These are mainly poorly drained soils which negatively impact plant growth and productivity.</p><p>Soil moisture acts as a proxy for drainage capacity. Timely and accurate information on soil moisture allows for precision management strategies. It aids in designing effective interventions on farms for artificial drainage works which are often assessed by information on soil moisture, soil type and hydrology. Such data are conventionally acquired by in-situ point sampling techniques which are costly and time consuming. Remote sensing has the potential to provide a solution by allowing simultaneous coverage of large geographic areas, quickly and in a cost effective manner.</p><p>This study uses optical remote sensing data from Sentinel 2 to derive information on soil moisture conditions on selected sites in Ireland.  We develop the OPTRAM model of Sadeghi et al (2017) by exploring the use of remote sensing based vegetation indices such as the Normalised Difference Vegetation index, Enhanced Vegetation Index and Normalised Difference Red Edge Index for the years 2015-2020 along with short wave transformed infrared reflectance to estimate soil moisture variations for our study areas. We show that  non-linear estimates of the wet and dry edge curves in the model are better suited for Ireland, which is dominated by wet conditions for most of the year and also identify the best vegetation indices for studying soil moisture variations.</p>

Statistical Soil Characterization of an Underground Corroded Pipeline Using In-Line Inspections

Underground pipelines have a space-dependent condition that arises from various soil properties surrounding the pipeline (e.g., moisture content, pH, aeration) and the efficiency of protection measures. Corrosion is one of the main threats for pipelines and is commonly monitored with in-line inspections (ILI) every 2 to 6 years. Preliminary characterizations of the surrounding soil allow pipeline operators to propose adequate protective measures to prevent any loss of containment (LOC) of the fluid being transported. This characterization usually requires detailed soil measurements, which could be unavailable or very costly. This paper implements categorical measurements of soil properties and defect depth measurements obtained from ILI to characterize the soil in the surroundings of a pipeline. This approach implements an independence test, a multiple correspondence analysis, and a clustering method with K-modes. The approach was applied to a real case study, showing that more severe defects are likely located in poorly drained soils with high acidity.

Diversity and evolution of stem structure in Eleocharis (Cyperaceae)

Eleocharis (Cyperaceae) includes more than 300 species of perennial or annual herbs, frequently found on poorly drained soils. The species are morphologicaly similar, and the taxonomy is difficult because their vegetative and reproductive structures are very reduced. Previous study on the stem architecture in the subgenus Limnochloa showed that anatomical features help in the interpretation of the evolution, taxonomy and ecological aspects of the group. Our objectives were to add new characters from the stem (= culm) structure, to explore the characters in a greater number of Eleocharis species, representatives of the other subgenera, and add these data in a new phylogenetic analysis with molecular data. The study covered 68 species obtained from herbaria and fixed material. In addition to the stem architecture, the internal organization of the tissues, the cross-section format, the presence or absence of stretched cells in aerenchyma air gaps and the plant size were included in the morphological analysis. Our data confirm that spongy aerenchyma pattern is the ancestral condition while the mixed and septate patterns occurred independent and punctually. Only the cross-section format was variable among specimens while the other characters were uniform and relevant for taxonomic use.

Paspalum fasciculatum (bull grass).

Paspalum fasciculatum, commonly known as Bamboo Grass, is native to the Americas, from south Mexico to Argentina (Randall, 2012). It is a serious pasture weed in areas of fertile, poorly drained soils in the tropical Americas. It can influence abiotic ecosystem processes and significantly alter ecological community composition. In Trinidad, although only partially distributed across the region, it negatively impacts over 50% of the biodiversity where it is found, and its invasiveness has been ranked as 'medium'. It is a common weed in banana plantations and oil palm in Costa Rica and along borders of streams, and swamps at low altitudes from southern Mexico to Ecuador and Argentina.

Bacopa monnieri (water hyssop).

Bacopa monnieri is an aquatic herb that has been used as an ornamental in ponds and aquaria and as a medicinal herb. It grows gregariously and often forms dense mats in marshy places, mangroves, riverbanks, coastal areas and along streams and ditches. It can tolerate brackish water and has adapted to grow under varying soil and climatic conditions, performing exceptionally well on poorly drained soils and waterlogged areas. It is native to the Americas, Asia and Africa and listed as invasive in Japan, Singapore, Spain, Portugal and the Cayman Islands. In aquatic habitats it has deleterious effects on native plants and animals, water quality, water flow and sedimentation. In terrestrial situations it degrades riverbanks, margins of ponds, lakes and coastal areas.

Capturing Spatiotemporal Patterns in Presence-Absence Data to Inform Monitoring and Sampling Designs for the Threatened Dakota Skipper (Lepidoptera: Hesperiidae) in the Great Plains of the United States

Declines among species of insect pollinators, especially butterflies, has garnered attention from scientists and managers. Often these declines have spurred governments to declare some species as threatened or endangered. We used existing presence–absence data from surveys for the threatened Dakota skipper Hesperia dacotae (Skinner) to build statistical maps of species presence that could be used to inform future monitoring designs. We developed a hierarchical Bayesian modeling approach to estimate the spatial distribution and temporal trend in Dakota skipper probability of presence. Our model included a spatial random effect and fixed effects for the proportion of two grassland habitat types: those on well-drained soils and those on poorly drained soils; as well as the topographic slope. The results from this model were then used to assess sampling strategies with two different monitoring objectives: locating new Dakota skipper colonies or monitoring the proportion of historically (pre-2000) extant colonies. Our modeling results suggested that the distribution of Dakota skippers followed the distribution of remnant grasslands and that probabilities of presence tended to be higher in topographically diverse grasslands with well-drained soils. Our analysis also showed that the probability of presence declined throughout the northern Great Plains range. Our simulations of the different sampling designs suggested that new detections were expected when sampling where Dakota skippers likely occurred historically, but this may lead to a tradeoff with monitoring existing sites. Prior information about the extant sites may help to ameliorate this tradeoff.

Evolution of the Materials and Methods Used for Subsurface Drainage of Agricultural Lands from Antiquity to the Present

Agricultural drainage plays an important role worldwide in food production and conservation of soil resources, while safeguarding investments in agricultural production and irrigation projects. It can improve crop yields and land productivity, especially on poorly drained soils and in cases of prolonged waterlogging. Both the subsurface drainage materials and the installation techniques used have a long history dating to prehistoric times. Over time, new subsurface drainage materials, installation techniques and modernized equipment were being developed continuously to take advantage of technological advances provided through research and development, while the planning and organization of the implementation process were improved. Today’s new materials and improved installation methods can offer solutions to problems still unsolved, while sometimes creating new ones. This paper considers the evolution of basic subsurface drainage materials and their installation techniques as they developed and adapted over time as well as possible future trends in drainage system design and application.