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Peruvian watergrass (Luziola peruviana J.F. Gmel.) is a perennial weed often found in paddy fields in the southern region of Brazil. Its chemical control is performed mainly by herbicides such as glyphosate in burndown, whose efficacy depends on soil moisture. Under excess‐water soil conditions, glyphosate efficacy is reduced, probably due to reduced translocation and the involvement of photoassimilates partition. Furthermore, little is known about the stress tolerance of these plants subjected to water deficit. Based on that, we performed experiments to verify the effect of soil moisture on the biochemical parameters of Peruvian watergrass and glyphosate translocation to the stolon and roots. Total soluble sugars, sucrose, starch, and glyphosate concentrations in leaves, culms, roots, and glyphosate partitioning were quantified. The malondialdehyde content and the lipid peroxidation increased with the drainage. Under drainage conditions, superoxide production was higher in roots than leaves, while peroxide production was lower in roots than leaves. The electrolyte leakage increased with the drainage and glyphosate application. The total soluble sugar content varied in each organ with a significant increase in the culm 14 days after application in the draining treatment. Sucrose varied considerably and reached its maximum concentration at 21 days after herbicide application. The starch accumulation in the culm was 7 days after applying the highest glyphosate dose. The presence of glyphosate in the roots subjected to soil drainage indicates the movement of this herbicide. In conclusion, soil drainage profoundly impacts Peruvian watergrass physiology, increasing the photoassimilates and glyphosate translocation to the stolon and root. This explains why glyphosate efficacy is higher under drainage conditions. [ABSTRACT FROM AUTHOR]

There is an urgent demand to change our intensive crop production systems, replacing them with soil use and management systems that recover, preserve, or improve soil health and are environmentally sustainable, producing healthy and good-quality food. In this work, we compile and present strategies and public policies aimed toward soil and water conservation and food production in Brazil. The results presented may help Brazilian farmers adopt practices to recover, maintain, or improve soil health and politicians to create or modify public policies for healthy soil and food, without the necessity of increasing agricultural areas. Food insecurity was also addressed, with family farming playing an important role in food production and decreasing food insecurity. But these challenges need the combined efforts and engagement of the whole society. [ABSTRACT FROM AUTHOR]

The Brazilian Cerrado biome is known for its high biodiversity, and the role of groundwater recharge and climate regulation. Anthropogenic influence has harmed the biome, emphasizing the need for science to understand its response to climate and reconcile economic exploration with preservation. Our work aimed to evaluate the seasonal and interannual variability of the surface energy balance in a woodland savanna (Cerrado) ecosystem in southeastern Brazil over a period of 19 years, from 2001 to 2019. Using field micrometeorological measurements, we examined the variation in soil moisture and studied its impact on the temporal pattern of energy fluxes to distinguish the effects during rainy years compared to a severe drought spell. The soil moisture measures used two independent instruments, cosmic ray neutron sensor CRNS, and FDR at different depths. The measures were taken at the Pé de Gigante (PEG) site, in a region of well-defined seasonality with the dry season in winter and a hot/humid season in summer. We gap-filled the energy flux measurements with a calibrated biophysical model (SiB2). The long-term averages for air temperature and precipitation were 22.5 °C and 1309 mm/year, respectively. The net radiation (Rn) was 142 W/m2, the evapotranspiration (ET) and sensible heat flux (H) were 3.4 mm/d and 52 W/m2, respectively. Soil moisture was marked by a pronounced negative anomaly in the 2014 year, which caused an increase in the Bowen ratio and a decrease in Evaporative fraction, that lasted until the following year 2015 during the dry season, despite the severe meteorological drought of 2013/2014 already ending, which was corroborated by the two independent measurements. The results showed the remarkable influence of precipitation and soil moisture on the interannual variability of the energy balance in this Cerrado ecosystem, aiding in understanding how it responds to strong climate disturbances. [ABSTRACT FROM AUTHOR]

The uncertainty in soil hydraulic parameters is often not taken into account in process‐based hydrological modeling. Performing runs with 104 stochastic parameter realizations, we evaluated the propagation of uncertainty in the Van Genuchten–Mualem (VGM) parameters into estimates of the threshold values of soil water content used to calculate the total and readily available water, and on the long‐term (30 years) simulations of evaporation, transpiration, bottom flux, and runoff by the SWAP hydrological model. The simulated scenarios included weather data from a location in southeast Brazil and seven soils from the same region cropped with maize, comprising a wide range of texture classes. The results showed that uncertainties in VGM parameters affect the estimates of total and readily available water. Water balance components obtained by a deterministic simulation with average VGM parameters did not always agree with the average or median of stochastic simulations, and stochastic simulations including parameter uncertainties should be preferred. Variations in yearly rainfall characteristics were more important for bottom flux and evaporation, while transpiration and runoff were more strongly influenced by the variations in soil hydraulic properties. Core Ideas: Hydraulic parameter uncertainty and correlations can be used in stochastic simulations with a hydrological model.Parameter uncertainty propagates more strongly into estimates of plant available water than in its threshold water contents.Stochastic averages of simulated water balance components may differ from deterministically obtained values.Bottom flux and evaporation respond to rainfall, while transpiration and runoff depend most on soil properties. [ABSTRACT FROM AUTHOR]

Understanding soil water dynamics and transport of nutrients is challenging in tropical rainforests due to the uniqueness of several properties related to soils, vegetation and seasonality that make relating patterns found in temperate environments to tropical sites difficult. We address the need for better edaphic characterization in tropical environments by investigating soil water percolation rates and chemistry across topographic, soil texture and seasonal gradients in a mature tropical rainforest in Central Amazonia, Brazil. We utilized a passive wick flux meter (e.g., drainage lysimeter) to directly measure real-time percolation fluxes at 60-cm depth, and to sample a suite of chemical species across plateau, slope and valley topographic positions. We found percolation flux volume and chemical exports generally increase with decreasing elevation and clay content, which was lowest in the valley. Daily percolation flux was observed to be 2.39 ± 0.44 in plateau, 3.01 ± 0.50 in slope and 6.16 ± 0.83 mm in valley. Most solutes were present in small amounts of <1 mg L-1, such as PO43-, Fe2+/Fe3+ and Mn2+; however, NO3- concentrations were >20 mg L-1, even exceeding 100 mg L-1 in the valley. Based on additional isotopic analysis, we speculate high NO3- concentrations are partially an artefact of root decomposition following installation of the flux meters. The empirical relationships we show among percolation volume and nutrient exports under varying topographies and soil textures can improve Earth System Model performance by better constraining ecohydrological relationships to nutrient fluxes, which can in-turn better illuminate the important factors that govern their behaviour. [ABSTRACT FROM AUTHOR]

Management practices and soil environmental variables influence microbiological properties and may cause inaccuracies in the interpretation of the results of these bioindicators. This study evaluated the sensitivity of seven microbiological properties to soil management and environmental variables of a Rhodic Ferralsol from a subtropical region of Brazil. The experimental area was cultivated with crotalaria and corn, followed by a fallow period. Samples were collected monthly for a year to determine soil enzyme activities and heterotrophic bacteria and fungi counts. Soil respiration was evaluated directly in the field. Total hydrolytic activity, cellulases, proteases, dehydrogenases and soil respiration were sensitive to management. Moreover, soil respiration was sensitive to fluctuations in soil temperature (r = 0.75) and pre-sampling precipitation (r = 0.54). Dehydrogenase activity was sensitive to soil moisture (r = 0.72) and total microorganisms (r = 0.61). The bacterial (5.69 ± 0.37 log10 CFU g soil−1) and fungal (3.99 ± 0.42 log10 CFU g soil−1) counts showed low sensitivity to soil management and environmental variables. The seven microbiological properties evaluated responded differently to the management and environmental variables. This information must be considered when using soil quality bioindicators to avoid errors in interpreting results. [ABSTRACT FROM AUTHOR]

Soil water infiltration is an important component of the hydrological cycle, and it is best evaluated when the raindrop impacts the ground surface. For this reason, it is affected by changes in land use and land cover and by the characteristics and physical–hydric properties of the soil. This study aimed to evaluate soil water infiltration in areas occupied by annual crops (soybean and corn) and pastures in two watersheds of the Teles Pires River-MT, using simulated rainfall, physical models, and principal component analysis. Infiltration rates were evaluated based on simulated rainfall with an average intensity of 75 mm h−1, with four repetitions per region (upper, middle, and lower) of the hydrographic sub-basins of the Caiabi and Renato rivers, and soil use with cover, without cover, and disturbed. Soil tillage provided higher water infiltration rates into the soil, especially in pasture areas in the two hydrographic sub-basins. There were significant adjustments to the mathematical models based on the infiltration rate data for all land use and land cover conditions. The soil attributes that most interfered with the infiltration rate were microporosity, bulk density, and total porosity in the crop areas of the middle Caiabi and microporosity, clay content, total porosity, and silt content in the areas farming at the source of the Renato River. The Horton and Philip models presented the best adjustments in the hydrographic sub-basins of the Caiabi and Renato Rivers, which are recommended for estimating the water infiltration rate into the soil in different uses, coverages, and regions. [ABSTRACT FROM AUTHOR]

Semi-arid regions are strongly dependent on the rainfall regime. Yet season identification is still ambiguous and clear definitions are lacking regarding which variables and criteria should be used. The objective of this work is to establish a method for hydrological season partitioning in the semi-arid Caatinga biome in northeastern Brazil considering precipitation, soil moisture and vegetation. The following four periods were employed for this purpose: (i) dry–rainy transition, (ii) rainy season, (iii) rainy–dry transition and (iv) dry season. The method was applied to the Aiuaba experimental basin (AEB) from 2003 to 2022. We observed a large inter-annual variability in the duration of seasons and a tendency for the rainy–dry transition season to increase, facts that may indicate changes in the hydrological regime of the region. This novel combination of precipitation, soil moisture, and vegetation data for identification of hydrological seasons within the Caatinga biome allows a detailed seasonal hydrological behaviour analysis. [ABSTRACT FROM AUTHOR]

Soil compaction after initial soil tillage for crop establishment has been a major problem in crop fields because of its deleterious effects on soil functioning and crop performance. Therefore, the study aimed to determine the degree of compaction, soil air capacity, near-surface optimum ratios, and water retention characteristics in a sandy loam. Dystrophic Paleudalf initially under different tillage methods for sugarcane crop but without tillage for two seasons in southern Brazil. Initial soil tillage systems consisted of no-tillage (NT), compacted no-tillage (NTC), conventional tillage, and chiseling of no-tillage (Ch). Disturbed and undisturbed soil was sampled from 0 to 10, 10 to 20, 20 to 40, and 40 to 60 cm layers to determine degree of compaction, air capacity, near-surface optimum ratios, soil water retention characteristics, and soil physical quality index S. Initially, NT treatment had the significantly (p < 0.05) lowest degree of compaction (87%), highest soil air capacity (0.104 cm3 cm−3), air capacity/total porosity ratio (0.261), and better water retention characteristics in the surface layer. Over time, Ch had improved the structure of the subsurface soil layers with the lowest degree of compaction (≈88%) and highest air capacity (≈0.140 cm3 cm−3), while the measured indices were poor in NTC. Irrespective of tillage, the surface layer showed resilience during the years without soil disturbance with low degree of compaction, increased water retention, and air capacity. NT could be a good soil management option for sugarcane production, while mechanical chiseling is advocated for ameliorating compacted soils. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• The use of two rootstocks in common pots favors the increase of all levels of A, E and gs even in full irrigation. • The association between genotypes in the same pot caused different physiological responses. • The use of two rootstocks in common pots is more effective tool for analyses of citrus plants under drought stress conditions. Brazil is a country focused on agribusiness and is the world's largest producer of orange juice. However, citrus production in certain regions of the world is affected by irregular rainfall, which imposes drought stress conditions and causes behavioral changes in plant survival, growth, and productivity. In this context, the objective of this work was to assess a methodology for the selection of citrus rootstocks tolerant to drought when exposed to water deficit regimes. This work was conceived with prior knowledge of the responses to drought tolerance of three rootstocks: Rangpur Lime (RL), Sunki Tropical (ST) and Sunki Maravilha (SM). The study was carried out with Valencia Orange (VO) scion varieties grafted on these three rootstocks. Two plants were conditioned per pot, forcing competition for available water in the soil, and all combinations were exposed to three different water regimes (irrigated, water deficit, and rehydrated). The hydric and physiological relationships were then evaluated. The results showed that in addition to the availability of water, the association between genotypes in the same pot caused different physiological responses. In view of the contrasting strategies of survival/tolerance adopted by these genotypes in response to water deficit, the combination with RL allowed a higher tolerance, showing less water extraction, lower leaf water potential, and relative water content, as well as an increase in the photosynthetic parameters when combined mainly with SM. The methodology used is a promising and more effective tool for analyses of citrus plants under drought stress conditions. [ABSTRACT FROM AUTHOR]

Most lands in the Brazilian semi-arid region are covered with native vegetation (Caatinga) with limited agricultural practices due to chronic water-scarcity issues. However, clearing the native vegetation and using the land for agriculture is becoming a common practice. The objective of this study was to evaluate the effectiveness of forage palm and stone barrier in reducing runoff and erosion compared to native vegetation. The study was conducted in the Jatobá experimental basin, Brazil, using runoff plots with three surface covers: Caatinga, forage palm barrier, and stone barrier. Data collection includes runoff and erosion rates, and soil moisture dynamics at two depths (0–20 and 20–40 cm) in response to rainfall events. Rainfall characteristics were also recorded and analyzed for 30 min for intensity (I30) and erosivity (EI30). Results showed that stone barrier and forage palm treatments were not as effective as the native vegetation Caatinga in reducing soil loss. Stone barrier was the least effective in reducing runoff and soil loss. However, runoff from forage palm was not statistically different from Caatinga. In addition, forage palm improves soil moisture dynamics at two depths. The study findings highlighted the importance of the Caatinga for soil, water and biome conservation in the region. However, the study also suggested that in the places where agricultural practices are conducted, using forage palm as a soil-conservation strategy could be a good alternative. Additional benefits of forage palm include its suitability for intercropping with other crops, and that it can serve as an alternative for animal feed in the region. Information from this study could be used to inform land management and soil- and water-conservation efforts in the semi-arid region of Brazil. [ABSTRACT FROM AUTHOR]

Understanding the trends in land use and land cover (LULC) is crucial for modeling streamflow and sediment yield, particularly in hydrological basins. This study examined the impact of LULC on the dynamics of streamflow and sediment yield within a humid tropical basin of the Atlantic Forest biome in Brazil, focusing on the period from 2000 to 2016. Changes in LULC were analyzed using annual MapBiomas data products for the same period. The Soil and Water Assessment Tool (SWAT) model was deployed to simulate streamflow and sediment yield based on LULC changes. To investigate temporal trends in LULC, a suite of non-parametric statistical tests, including the Mann–Kendall, Pettitt, and Sen's slope estimator tests, was employed. Ecological diversity indices such as Shannon–Weaver, Simpson, and Pielou were applied to assess forest fragmentation, along with the Forest Fragmentation Index. The results revealed a growing trend in urban and sugarcane areas, coupled with a decline in dense vegetation, mangroves, and other forms of dense vegetation. With regard to the correlation between land uses and hydrological variables, the findings indicate minor variations in hydrological balance, attributable to the not-so-significant changes among the studied land-use scenarios, except for sediment yield estimates, which showed more considerable alterations. Notably, the estimates for 2000 and 2013–2016 were the most divergent. In a broader scientific context, this research conclusively establishes that the incorporation of dynamic LULC data into the SWAT model augments the precision and robustness of simulations pertaining to agricultural watersheds, thereby enabling a more comprehensive hydrological characterization of the study area. [ABSTRACT FROM AUTHOR]

The Atlantic Forest exhibits remarkable floristic diversity over short distances, and when combined with altitude, it results in variations in soil biological properties and hydrological dynamics. This study aimed to quantify the distribution pattern of soil biological properties along a small topographic gradient and identify how these properties are related to soil chemical, physical, and topographical attributes in an Atlantic Forest fragment in Brazil. Plots were established along hillslope positions varying from 100 to 180 m of altitude. Soil biological characterization was performed at a depth of 0.0–0.10 m in both summer and winter seasons. The lowland showed higher microbial biomass nitrogen in summer (57.28 ± 5.57 μg g−1 soil) and higher anaerobically mineralizable nitrogen in summer and winter (42.70 ± 2.14 mg kg−1 and 41.06 ± 3.37 mg kg−1, respectively). The midland showed lower microbial biomass carbon, enzymatic activity, and soil moisture in both seasons, and higher metabolic coefficients in summer. Soil chemical properties exerted a greater influence on the variability of biological properties in both seasons. The land slope conditioned lower microbial activity and organic cycling in the midland. Soil biological properties were affected by seasonality. Even a small altitudinal gradient (up to 100 m) in the Sea of Hills regions of the Atlantic Forest can lead to significant changes in soil biological and chemical attributes. [ABSTRACT FROM AUTHOR]

A number of riparian ecosystem functions such as reducing chemicals are associated with high soil moisture conditions. Finding easy-to-measure riparian features that indicate soil moisture regime in riparian ecosystem may of use in environmental management. In this study, we answered the following question: can streambank height, on which these riparian zones are, indicate soil moisture regime? By measuring soil matric potential (0.15–0.9 m depth) and water table depth on a weekly basis at three forested riparian zones on different bank heights (low, moderate and high) and under a similar soil type, we demonstrate that riparian zones on high-to-moderate streambank height (h ≥ 1 m) generally have lower water table compared to riparian zones on low streambanks (h ≤ 0.3 m). This difference on water table depth led to significant differences in soil matric potential as water table depth lowers. However, in order to predict soil moisture regime more accurately, streambank height must be associated with a detailed field description of local factors such as soil type which can help in explaining deviations from the expected pattern of soil moisture as shown in moderate and high. [ABSTRACT FROM AUTHOR]

The main objective of this research is to analyze quantitatively the water situation of the Coremas water system considering the last water crisis that began in 2012, located in the hydrographic basin of the rivers Piancó-Piranhas-Açu, using the ACQUANET simulation model. A series of inflows was also constructed using the rainfall-runoff model Soil Moisture Accounting Procedure. Analyzing the results obtained for the simulated time horizon of the two reservoirs, the efficiency of meeting demands in the simulation of scenario 1, which evaluated the two reservoirs individually, some failures were observed in the sectors of human supply, irrigation, industry and pisciculture, where they presented guarantees above 95%. In the simulation of scenario 2, which was considered in the analysis as a single reservoir, both in the rainy and dry periods, all demands related to the system, such as human supply, animal feeding, irrigation, industry and fish farming, had 100% reliability. Therefore, the Coremas system, despite the water crisis experienced, is considered sustainable and can be used to transfer water to other hydrographic basins during the water crisis period. [ABSTRACT FROM AUTHOR]

The land surface is an important component of numerical weather and climate forecast models due to their effect on energy–water balances and fluxes, and it is essential for forecasts on a seasonal scale. The present study aimed to understand the effects of land surface processes on initialization of seasonal forecasts in the austral spring, in particular soil moisture. We built forecasts with the Brazilian global Atmospheric Model hindcast from 2000 to 2010, with a configuration similar to those used in the operational environment. To improve it, we developed a new initial condition of the land surface using the Land Information System over South America and the Global Land Data Assimilation System for the rest of the globe and used it as the input in the forecast model. The results demonstrated that the model is sensitive to changes in soil moisture and that the new high–resolution soil moisture dataset can be used in model initialization, which resulted in an increase in the correlation of precipitation over part of South America. We also noticed an improvement in the representation of surface fluxes and an increase in soil moisture content and specific humidity at medium and low levels of the atmosphere. The analysis of the coupling between the land surface and the atmosphere showed that, for Central Brazil, the states of the continental surface define the surface fluxes. For the Amazon and La Plata Basins, the model did not correctly represent the coupling because it underestimated the soil moisture content. [ABSTRACT FROM AUTHOR]

Climatic drivers of floods have been widely used to improve nonstationary flood frequency analysis (FFA). However, the forecast ability of nonstationary FFA with out-of-sample prediction has not been comprehensively evaluated. We use 379 flood records from Brazil to assess the ability of process-informed nonstationary models for out-of-sample FFA using the generalized extreme value (GEV) distribution. Five drivers of floods are used as covariates: annual temperature, El Nino Southern Oscillation, annual rainfall, annual maximum rainfall, and annual maximum soil moisture content. Our results reveal that a nonstationary model is preferable when there is a significant correlation between flood and climate covariates in both the training period and full record. The rainfall-based covariates lead to better out-of-sample nonstationary FFA models. These findings highlight that using climate information as covariates in nonstationary FFA is a promising approach for estimating future floods and, hence, better infrastructure design, risk assessment and disaster preparedness. [ABSTRACT FROM AUTHOR]

The Cantareira System is one of the largest water supply systems in the world, supplying about half of the water consumed by 22 million inhabitants in the Metropolitan Region of São Paulo, in southeastern Brazil. In this scenario, in view of climate change, silting is a serious environmental threat and a major challenge to the sustainability of water reservoirs. Therefore, identifying the provenance of sediments is an essential tool to support soil conservation policies, slowing erosion processes and mitigating the deposition of sediments in water reservoirs. Thus, this study aimed to model soil losses—sediment production, by water erosion in the Cantareira System, based on the RUSLE model—Revised Universal Soil Loss Equation, GIS—Geographic Information System and SR—Remote Sensing. The work was conducted on data obtained from online platforms of Brazilian public institutions. The results indicate an average rate of soil loss of 13 Mg ha−1 yr−1, which corresponds to an annual loss of 3 million tons, of which 22% reaches water bodies. The data also show that: (1) in 66 % of the Cantareira System, soil losses are below the soil loss tolerance limits, and, in 34% of the region, water erosion is compromising the sustainability of water and soil resources; (2) the areas with the greatest soil losses are predominantly located in planted forests, agricultural crops and non-vegetated areas; and (3) sectors with high rates of soil loss require the adoption of conservationist practices aimed at reducing sediment production rates and thereby increasing supply and improving water quality. [ABSTRACT FROM AUTHOR]

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Understanding the temporal behaviour of soil moisture in different environments is essential considering its importance in hydrological processes. Few studies have addressed its dynamics in a subtropical climate, in view of temperature variations throughout the year and well-distributed precipitation events which are characteristics that affect the behaviour of soil moisture over time. The temporal stability of soil moisture was investigated in two sets of data collected from a small watershed in southern Brazil. We used multiple linear regression (MLR) to evaluate whether points with greater temporal stability contributed as predictor variables of the models for estimating soil moisture. Soil moisture was monitored in the superficial (0–10 cm) and subsurface (10–20 cm) layers at 39 points with variations in soil characteristics and topography. To assess the temporal stability of soil moisture, two statistical techniques and MLR models were used to identify the topographic, climatological and soil property variables, as well as those that influenced the dynamics of the soil water content. The results showed that the factors of slope, terrain elevation, microporosity and evapotranspiration were determinants for the strong performance of the models, and that the inclusion of points with greater temporal stability helped to improve the estimate in certain datasets. Therefore, the results of this study indicate that the set of results that express topographic factors, land use and cover, along with the soil physical properties should be considered to characterise the temporal stability of soil moisture. [ABSTRACT FROM AUTHOR]

The land–atmosphere interactions play an important role in modulating climate variability at different spatial and temporal scales. In South America, two recognized hot spots of soil moisture–atmosphere coupling are located in southeastern South America (SESA) and eastern Brazil. Soil moisture variability may not only alter the climate locally but may also have nonlocal impacts through changes in the regional circulation. Here we explore how these two local coupling hot spots interact with each other, how soil moisture variability modulates the regional circulation, and what is the consequent nonlocal impact on precipitation. To this end, we analyze numerical experiments, performed with a regional climate model for the period October–March of 1983–2012, that allow us to isolate the influence of the soil moisture interannual variability on the regional climate. When the soil moisture–atmosphere interaction is enabled, we find a nonlocal coupling mechanism that links both hot spots at different temporal scales, favoring precipitation in eastern Brazil to the detriment of the precipitation in SESA through shifts in the regional circulation, when compared with a simulation with constrained soil moisture–atmosphere interaction. In northeastern Argentina, a subregion of SESA located at the exit of the South American low-level jet, it was found that the amount of nighttime precipitation is modulated by the proposed nonlocal coupling mechanism. A better understanding of the variability of precipitation due to the influence of land–atmosphere interaction processes may contribute to improving the predictability of precipitation and the interpretation of climate projections. [ABSTRACT FROM AUTHOR]

Soil erosion in tobacco (Nicotiana tabacum) cultivation has been reported in recent years around the world. Moreover, studies also demonstrated total soil loss during cultivation. In this study, we proposed an assessment of loss of water and soil during the phases of tobacco cultivation. The tobacco cultivation cycle is approximately 180 days in Southern Brazil. We divided this period into 6 phases from planting (September) to the end of the harvest. During the phases, there were variations in soil management, which may indicate different rates of water and soil loss. Gerlach gutters were used to mediate soil and water loss. At each phase of cultivation, we also measured the surface roughness of the soil, water retention, soil exposure, trampling, soil resistance and soil bulk. Our results show that during cultivation the water and soil loss were 10.2% and 62.7 Mg ha−1, respectively. However, the variation of activities during tobacco cultivation indicates different rates of water and soil loss. In the first three phases (90 days after planting), the surface roughness remained high (~19.2%) due to the soil turning, thus reducing the loss of water and soil despite little ground surface coverage. The soil tillage is stopped when the harvest of tobacco begins 120 days after planting. During the harvest, there was an increase in daily activities in the tobacco field, as the leaves were harvested every week, thus reducing soil roughness (~6.8%) and increasing soil density and strength. These conditions increased the rate of soil erosion during harvest. Therefore, the harvest phase is critical to runoff and soil loss. [ABSTRACT FROM AUTHOR]

The Northeastern region of Brazil has long history of drought with impacts on water supply for cities and agriculture. However, the last drought that occurred in the region had unprecedented magnitude and periodicity, making it the longest multiannual drought in Northeastern Brazil. Thus, understanding and characterizing the behavior of this phenomenon is necessary, considering that another episodes may occur. Thus, the objective of this study was to characterize the drought trend in the Northeastern region of Brazil, with the application of the Palmer Drought Severity Index (PDSI). The application of PDSI was carried out with the monthly calculation of the water balance coefficients referring to the soil water balance between the years 2000 and 2019, depending on the relative soil moisture values. The results obtained were submitted to the Mann-Kendall test to identify monthly trends in the index. The annual drought variability in Northeastern Brazil showed moderate to extreme intensity, with the worst drought being observed between the years 2012 and 2019. The monthly drought average shows the Mid-Northern and "Sertão" regions as the most critical, with monthly trend of significant drought severity. The positive trend was observed in the Eastern, Southern and Western coast regions of NEB. [Display omitted] • We evaluated the largest drought in the Northeast of Brazil. • Intensification of the drought in its frequency and magnitude has been proven. • A significant trend was identified for the intensification of drought. • El Niño events and change climate contribute to intensify record drought. [ABSTRACT FROM AUTHOR]

Efforts to restore tropical forests can result in large unpredictability in their trajectories, mainly due to spatial variation in abiotic conditions and plant resource availability. With the construction of a small hydroelectric power plant, a 70-ha forest restoration was conducted in 2008 within the boundaries of seasonal semideciduous forest in southeastern Brazil. This study described the spatial variation of the restored ecosystem after 12 years by simultaneously evaluating the direct influences of distance from the water body (waterline distance) and soil moisture, and the indirect influence of these factors mediated by the forest structure on accumulated litter and soil organic matter (SOM). These effects were estimated in the area under restoration and in forest remnants (considered as reference sites) (Model A), or in the area under restoration alone (Model B). Data on forest structure included density of individuals, total basal area, tree average diameter, average trunk volume index and stratification. Tree density decreased with increasing waterline distance both in the restoration area and in the forest remnants. Consequently, the sites closest to the reservoir formed denser and more stratified forests. Waterline distance and soil moisture content were correlated with each other, but each variable had independent effects of on the amount of litter and SOM. Wetter sites with denser and more stratified forest had greater amounts of accumulated litter and soil organic matter, but only in Model A, which included both the restored area and the forest remnants. In addition, higher basal area values contributed weakly to greater amounts of accumulated litter. Thus, our study suggests that the trajectory and speed of recovery of some ecosystem processes were determined by the waterline distance and soil moisture. Furthermore, the restoration implementation in the period of just 12 years was sufficient to detect the effect of these actions on the litter accumulation and a substantial increase in the amount of soil organic matter. • Waterline distance determined most variation in the forest structure. • Variation in forest structure was due to the new recruited trees in restored area. • Waterline distance had a stronger effect on soil organic matter than soil moisture. • Tree planting recovered about 37% of soil organic matter after 12 years. [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Minimum tillage in rice production is increasing in southern Brazil, reaching 60% of the total planted area. Compared to conventional tillage, in this system there is an increase in the occurrence of perennial weeds, such as Luziola peruviana and Leersia hexandra, which are amphibious plants, as they can occur in both flooded environments and aerobic conditions. These weeds are controlled in burn-down before rice planting by glyphosate applications, the efficacy of which depends on the soil moisture. This study aimed to evaluate the effect of different soil moisture regimes in L. hexandra and L. peruviana growth and photoassimilate partitioning. Both species were assessed under soil moisture regimes of flooded, saturated, 7 kPa, 15 kPa, 40 kPa, and 100 kPa (experiment 1) and flooded, saturated, and 7 kPa (experiment 2). Plants were sampled immediately after drainage (3 months after transplant) and 1 and 2 weeks after drainage. The results showed that as soil moisture levels decreased, growth and development parameters were negatively affected in both species. Photoassimilate partitioning was affected by water regime and differences were observed between species. The total soluble sugars and starch content decreased in the leaves, and sucrose concentration increased in the roots following drainage. Soil drainage affects the growth and alters carbohydrate partitioning of these weeds, increasing the sugar storage in roots. The agronomic impact of these findings is that this behavior may affect herbicide transport in phloem and may affect herbicide efficacy. [ABSTRACT FROM AUTHOR]

The habitat choice of nest sites by founding queens of leaf‐cutting ants varies with abiotic factors such as temperature, soil density, and soil humidity. In this study, we tested the hypothesis that soil density and moisture affect excavation effort (i.e., excavation period, excavated soil amount, initial nest depth, initial chamber volume, and mortality) in queens of the leaf‐cutting ant Atta sexdens (L.) (Hymenoptera: Formicidae). Queens were placed in experimental areas in three natural soils in Brazil with varying density and moisture content. The excavated soil was collected, dried, and weighed, and digging period, nest depth, chamber volume, and queen mortality were evaluated after nest establishment. In artificially shaded habitats (less dense and more humid soil), the establishment of queens was greater, the period of nest foundation was shorter, and excavated soil amount, nest depth, and volume of the initial chamber were greater than in forest and pasture habitats (denser and drier soils). Also, queen mortality was lower in less dense, more humid soil. This indicates a trade‐off between maximizing the depth of the nest, to increase protection against inadequate environmental conditions, and minimizing energy expenditure during excavation, affecting their survival. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Exact Sciences is the property of Master Editora and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Information on evapotranspiration (ET) has the potential to clarify drought's effects on the water balance of natural ecosystems. Here, we use a 6-year dataset to present daily ET trends under different drought conditions in a seasonally dry Atlantic Forest in southeast Brazil as well as environmental and biophysical controls. Generalized linear models (GLMs) were applied to highlight the main controls on ET. Significant differences for ET were not found under different drought conditions (near normal, moderately dry, and severely dry). ET responded positively to net radiation (Rn), bulk surface (gs), and aerodynamic (ga) conductance. Drought severity and soil water storage (SWS) did not significantly affect ET. We attributed the regularization of ET to (i) the stability in the SWS observed in the study site (dystrophic red latosol); (ii) the tree species' adaptations to cope with water stress; (iii) the alternation between droughts and near-normal conditions (which have increased the water in the system on an annual basis); and (iv) the monthly variations in water inputs within the hydrological years. Finally, our study sheds light on the ecosystem characteristics that may represent sources of resilience when facing the droughts predicted in climate change scenarios. [ABSTRACT FROM AUTHOR]

Field tests were carried out to estimate effective unsaturated soil hydraulic properties of layered residual soils in Rio de Janeiro, southeastern Brazil. Data of this type are important for understanding the initiation of rainstorm-induced soil landslides, which often occur in the state of Rio de Janeiro as well as other areas having similar geologic settings and climate conditions. Tests were carried out using a simplified field approach, referred to as the Monitored Infiltration Test, which requires only a tensiometer to measure pressure heads below the wetting front, triggered by flow from a Mariotte bottle which maintains a constant pressure at the top edge of the soil profile. The data can then be analyzed by numerical inversion using the HYDRUS-2D software package. The test is relatively fast since no steady-state flow conditions are needed, and versatile since the test can be carried out quickly on steep slopes with the help of a manual auger. Soil water retention and the unsaturated hydraulic conductivity functions were obtained for a range of young, mature and saprolitic residual soils. The effective hydraulic properties of the distinct residual soil layers can be quite large, reflecting a need to provide a careful analysis of field-scale hydraulic heterogeneity in geotechnical analyses. [ABSTRACT FROM AUTHOR]

In Brazil, small farmers are responsible for a significant amount of agricultural production. These farmers can benefit from deploying meteorological sensors and the analysis of these data to improve decisions regarding their crops. Soil moisture is a particularly important variable. Considering this, the present project developed and implemented an information system using low-cost sensors and free data repositories to generate and publicize information regarding meteorological data. The collected data are combined with public data on rainfall from a meteorological station in the region of the farms, generating soil water balance information which includes indicators of water surplus and deficit, that are shared through a website or an application for mobile devices. The results of the measured variables allow a deeper knowledge of the local microclimate. The farmer, once given the information, can use it as an element for decisions on crop irrigation. Therefore, the participation of farmers in the development of technological solutions is important. The relevance of an interdisciplinary team approach is evident in the creation of technological solutions that help sustainable environmental management. [ABSTRACT FROM AUTHOR]

In a soybean seed production field, the characteristics related to seed quality are not uniform since they were showing variation within the same production area. The work aimed to identify the spatial distribution of yield, quality and storage potential of soybean seeds obtained under tropical lowlands conditions, in the region of Lagoa da Confusão (Tocantins state, North region of Brazil). It used systematic sampling and regular sampling grid with 100x100 m between each point (one point per hectare). At harvest, the plants were threshed with the seeds be cleaned, weighed, dried and stored until the time of physiological and sanitary analyses. They were performed at 50, 100, 150 and 200 days after storage (DAS). Finally, the current soil moisture was also determined when the soybean was harvested. The results had shown that: seed yield varied by 13.03% (195-342 g.m-²); the germination and accelerated aging tests had shown increased variation with storage time, with greater variability (24% to 96%) at 200 DAS; the traits analyzed had shown a strong degree of spatial dependence and with these it possible to identify regions with higher and lower quality of soybean seeds related to vigor and also a greater variation and distinction in the study area according to the period of post-harvest analysis. [ABSTRACT FROM AUTHOR]

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Soil penetration resistance is used as an indicator of mechanical resistance to root growth into the soil matrix. However, penetration resistance measured only under wet soil conditions may not identify the effects of cover crops on soil structure. We aimed to determine the impact of individual and mixes of cover crops on soil penetration resistance as a function of water content and bulk density in an Oxisol under no-tillage in southern Brazil. Six treatments of individual and mixed cover crops were tested: (i) black oat; (ii) ryegrass; (iii) forage radish; (iv) wheat; (v) Fibrous-rooted crop mix: with 80 % fibrous-rooted and 20 % tap-rooted plants; and (vi) Tap-rooted crop mix: 40 % fibrous-rooted and 60 % tap-rooted plants. Soil cores were collected from a depth of 0–0.10 and 0.10–0.20 m and soil penetration resistance was evaluated under four soil water matric potentials (−6, −33, −100, and −500 kPa). Soil penetration resistance (Q) data for each treatment were fitted as a function of bulk density (ρ) and water content (θ) [Q=f(ρ, θ)]. The soil penetration resistance model was a non-linear equation (i.e., a double power function, with a negative exponent for water content and a positive exponent for bulk density). Under a given combination of bulk density and water content values, soil penetration resistance was higher after single crops than crop mixes, indicating a crop-mediated soil strengthening process. The cover crop mixes increased the macroporosity, resulting in an adequate soil physical quality for successional crops such as soybean, although no differences were observed for cover crops at soil water matric potentials of −60 hPa and −330 hPa when soil penetration resistance was used as a static measurement. The modelling of the soil resistance to penetration, as a function of soil bulk density and soil water content, showed that cover crops changed soil cohesion and reduced the impact of drying on soil strength when compared to the single cropping systems, indicating that soil penetration resistance should be modelled under a broad range of water contents, instead of only under a specific soil water content, to quantify the impacts of cover crops on soil strength. • Soil penetration resistance curve gave deeper insight into physical changes than single measure. • Mixed cover crops-maintained soil strength despite changes in moisture and bulk density. • Crop diversity improved soil physical quality, reducing strength for root growth. • The use of a crop with taproot system changes the soil structure and strength model. • Soil penetration resistance should be modelled under a broad range of water contents. [ABSTRACT FROM AUTHOR]

• Recurrent fire leads to degraded rainforest (DRf) and herbaceous-shrubby (HS). • Ksat and 6 years of rainfall-soil suction interactions are analyzed. • HS provide shallow soil saturation even during long dry periods. • Fire decreases Ksat in topsoil and it increases soil suction in depth at HS. • Post-fire soil changes tend to favor rapid suction loss in the unsatured zone. The role of fire in vegetation-soil–water interactions and its implications for soil stability and slope failures is poorly documented in humid tropical regions. This paper focuses on the relationships between vegetation change through recurrent fire and its effects on hydraulic conductivity and soil suction. Two monitoring sites were chosen on steep slopes in the mountainous domain of the Atlantic rainforest: the first is representative of degraded secondary rainforest (DRf) 25–30 years after slash and burn agriculture; the other represents herbaceous-shrubby vegetation (HS) resulting from wildfires in short-time intervals (<5 years). Two fires had previously occurred on the HS slope, one in December 2014 and the other in September 2019. Continuous records of rainfall and soil suction at depths of 10, 20, 50, 100, 150, and 220 cm provided a 6-year data collection from January 2015 to December 2020. Hydraulic conductivity (Ksat) field tests were conducted around the two monitoring sites before and after the September 2019 fire. The main results include: a) soil suction in the topsoil of both vegetation covers follow the rainfall inputs with high values of Ksat (DRf = 195 mm/h; HS = 203 mm/h); b) while quick rainfall-suction responses prevail within the DRf soil profile, soil suction at HS maintains a mean suction value around -27 kPa below 100 cm deep; c) field observations attest to the occurrence of hydrophobicity after the 2019 fire; d) Ksat tests just after this fire indicated a decreasing mean value from 203 mm/h to 46 mm/h; and e) by the end of the dry season after fire, there is a delayed increase in soil suction reaching -143 kPa at a depth of 100 cm and in smaller proportions at 220 cm deep. These results indicate that post-fire soil changes tend to favor the sudden loss of soil stability and slope failure during extreme rainfall events. [ABSTRACT FROM AUTHOR]

During September–November 2020, the meteorological services of Brazil, Argentina, Peru, Paraguay, and Bolivia reported record‐high maximum temperatures in several warm spells during this season. Positive and significant trends in heat wave frequency, intensity, and duration have been recorded since the 1980s, particularly in large cities. In this study, a heat wave is defined as a period in which both daily maximum and minimum air temperatures exceed the corresponding climatological 90th percentile for three or more consecutive days during September–November 2020. In this period, an intense heat wave during the first half of October and two heat waves events in November resulted in record‐breaking daily maximum temperatures in several locations in central South America. Places experienced temperature of about 10°C above normal, and some locations reported maximum temperatures above 40°C for several days in a row. Because its intensity and geographical extension, affecting central South America from southern Peruvian Amazon to southeastern Brazil, the heat wave of September 23–October 15 was selected as a case study. This intense heat wave was due a persistent atmospheric blocking located starting in late September and lasting until middle October 2020, a continuous presence of a warm air mass for several consecutive days contributed to pronounced positive temperature anomalies, possibly reinforced by extremely low soil moisture. This makes it easier for these high‐pressure systems to generate extreme heat waves because more of the sun's energy is going into heating the atmosphere rather than evaporating non‐existent water in the soil. This heat wave aggravated the drought over the Pantanal and other regions in October 2020, increasing fires and impacts on natural and human systems, representing a severe drought‐heat compound event. This vicious cycle of drought and extreme heat is of the kind expected under a warming climate. [ABSTRACT FROM AUTHOR]

A coincidence in the timing of floods and their drivers can be used as a proxy for the causality of flood generation. Here, we investigate the relationship between the seasonality of floods, maximum annual rainfall, and maximum annual soil moisture data of 886 basins in Brazil for 1980–2015 to shed light on process controls of flood generation. Floods tend to occur at the same time of year as soil moisture peaks and lag behind rainfall peaks by 3 weeks. In Amazonia, central and northern Brazil, flood timing is more correlated with the timing of soil moisture peaks than with that of rainfall peaks, which is interpreted as resulting from high subsurface water storage capacities. In southern and southeastern Brazil, on the other hand, flood timing is highly correlated with both soil moisture and rainfall because of low subsurface water storage capacities. These findings can support flood forecasting and climate impact studies. Plain Language Summary: In warm regions, floods are usually generated by a combination of intense rainfall and wet soils. In this paper, we analyze the average timing within the year of floods, extreme rainfall, and soil moisture to elucidate how floods come about in the main Brazilian rivers. We find that in some regions, such as Amazonia and central Brazil, floods tend to occur when soils are wet. In other regions, such as southern Brazil, floods tend to occur when rainfall is most extreme. We believe that these differences are related to differences in the soil water storage capacity. The understanding of the regional importance of each of these components helps increase the efficiency of flood prevention measures and climate change adaptation. Key Points: Flood peaks tend to occur at the same time of year as annual soil moisture peaks and lag behind annual rainfall peaks by 3 weeksFlood seasonality is linked mainly with soil moisture peaks in Amazonia and central Brazil, where soil storage capacity is highFlood timing is highly correlated with rainfall and soil moisture peaks in the south and southeast, where soil storage capacity is low [ABSTRACT FROM AUTHOR]

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Brasileira de Engenharia Agricola e Ambiental - Agriambi is the property of Revista Brasileira de Engenharia Agricola e Ambiental and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Archeological Dark Earths, known in the Brazilian Amazon as Terra Preta de Índio are fertile and structured soils considered as a potential model for sustainable agriculture. In order to recreate these soils a field experiment, named New Dark Earth, was set up in 2003 in the municipality of Tailândia, state of Pará, northern Brazil. The treatments consisted of the application of organic residues (wastes from local industries) in a loamy sand soil: cattle bones, wood charcoal, shredded wood blades, and the control. The objective of this study was to evaluate the effect of these residues on soil physico-hydrological properties. The results showed that the residues did not significantly increase the soil organic carbon content. Only the wood charcoal resulted in some improvements in soil physico-hydrological properties, such as lower soil bulk density and higher total and microporosity, which was mainly attributed to the high porosity of this material. Consequently, it also presented more available water. For now, it was concluded that despite the three residues are widely available in the region, the use of wood charcoal seems to be the best alternative to bring improvements to the soil physical properties, mainly soil water retention. However, more studies need to be carried out. [ABSTRACT FROM AUTHOR]

The expression of HaHB4® transcription factor reduces soybean sensitivity to abiotic stresses, such as water deficit. Studies that quantify the tolerance of HaHB4® soybean to the soil water content in comparison with cultivars currently sown in Brazil are lacking. The objective of this study was to determine the level of drought tolerance of soybean genotypes expressing the HaHB4® transcription factor (TS18-6-610108 and TS18-6-610084) and commercial cultivars (TMG 7063 IPRO and BS IRGA 1642 IPRO) subjected to water deficit during the vegetative phase. We used the fraction of transpirable soil water (FTSW) approach. Parameters related to leaf transpiration, dry matter accumulation, water use efficiency (WUE), and transpiration coefficient (TC) were evaluated in the four soybean genotypes and two treatments (T1--100% replacement of transpired water and T2--without replacement of transpired water). The FTSW threshold for the decline in transpiration was evaluated to identify the onset of water stress in soybean. TS18-6-610108 and BS IRGA 1642 IPRO maintains potential transpiration at low FTSW values. The TS18-6-610108 genotype has 14% higher WUE than the sensitive cultivar under water deficit. Under well-irrigated conditions, the HaHB4® genotypes showed the highest TC values, which indicate well-functioning physiological processes. [ABSTRACT FROM AUTHOR]

Aims: Anthropogenic disturbances due to human economic activities may affect ecosystem services, which are the benefits provided by the ecosystem properties, such as soil water content and soil fertility. Also, these disturbances affect plant community biodiversity and cover, which are also known to affect multiple ecosystem properties. However, the strength of the relative effects of the disturbance itself and of the effect that is mediated by changes in the plant community is still unclear. Questions: We evaluated the relative direct and indirect effects (mediated by changes in the plant community) of the anthropogenic disturbances on ecosystem multifunctionality. Location: Dry forests within the Sustainable Development Reserve Ponta do Tubarão, northeastern Brazil. Methods: We measured standing biomass, litter mass, soil fertility and soil water content in 52 vegetation plots along a gradient of anthropogenic disturbance. Also, we measured woody plant cover and species' functional traits to characterize the plant community functional structure. We measured livestock grazing, selective logging and past clear‐cuts as proxies of anthropogenic disturbance to create an index that characterizes the additive effect of these human activities. By building a theoretical model using the structural equation modelling approach, we investigated how the plant community changes in cover and biodiversity due to anthropogenic disturbances mediate changes in ecosystem properties. Results: Our results show that anthropogenic disturbances had negative effects on ecosystem properties. Plant cover loss caused by anthropogenic disturbances was the major determinant of the negative effect of disturbances. The functional structure of the plant community had a weak effect on these properties. Conclusions: By assessing the effect of human activities on multifunctionality, we found a stronger negative effect of anthropogenic disturbances when compared to its effect on single ecosystem properties. The recovery of plant cover should be a major focus of projects aiming to restore and maintain the multifunctionality of this dryland. [ABSTRACT FROM AUTHOR]

Coffee growing has been highlighted in the organic production system in the Zona da Mata Mineira region. It is intended to analyze and emphasize the actions of Public Rural Extension in the technical development of organic coffee in the municipality of Araponga, State of Minas Gerais, Brazil. The methodological outline of this article corresponds to the use of these tools: bibliographic, documentary and qualitative research. The results point out that the average annual productivity - in the period between 2013 and 2019 - is 20,6 bags/ha. The main claims are based on technological processes for grain processing, phytosanitary products, rural financing, and water and soil conservation. Regarding inputs, the most used is the avian litter. It is concluded that EMATER-MG in Araponga office has a role of institutional relevance through rural extension work. [ABSTRACT FROM AUTHOR]

Copyright of Revista IRRIGA - Brazilian Journal of Irrigation & Drainage is the property of Revista IRRIGA (Brazilian Journal of Irrigation & Drainage) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Anuario do Instituto de Geociencias is the property of Universidade Federal do Rio de Janeiro, Instituto de Geociencias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Cuadernos de Investigación Geográfica is the property of Universidad de la Rioja, Servicio de Publicaciones and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: Potato (Solanum tuberosum L.) is important to the world population's food security. However, potato production is implicated in several environmental problems, particularly soil loss due to crop harvest (SLCH). Moreover, a knowledge bias about this process exists given that most related studies are from Europe. Most studies compare SLCH differences among tuber and root characteristics of distinct crops but not the tuber morphologies, e.g., spherical and elongated ones, within the same crop. Aims: This study aimed to (a) estimate the SLCH in potatoes with contrasting morphologies in a very clayey soil; (b) test whether the potato morphology allied to soil moisture affects the sediment exportation. Methods: A total of 205 potatoes from four plots were collected for morphological and sediment exportation assessments. Several morphological characteristics were measured: weight (g), volume (cm3), axis dimension (mm), concavities (the number and volume), sediment adherence (g), and soil moisture (g kg−1). Results: The spherical potatoes exported 1.28 kg sediment per ton−1 of harvested potato, whereas the elongated ones exported 20% more sediment (1.54 kg). The harvested field with a high soil moisture content (≈ 26%) exported three times more sediment than the field with the lowest moisture content (≈ 16%). Conclusions: The SLCH measured in the study area was lower (0.062 Mg ha−1 harvest−1) than most values reported in the literature. In addition, the potato morphological characteristics affected soil adherence at distinct soil moisture contents. The harvesting technique can be critical to reduce the SLCH. [ABSTRACT FROM AUTHOR]

Brazil is the largest exporter and second largest producer of soybean grains. Most of this production is from plants grown under no-tillage system (NT). This research evaluated the effect of soil compaction, and different amounts of black oat residues on the soil surface on soybean growth and grain yield in lowland under NT. The experiment was conducted in a completely randomized design with seven treatments and four replications, in the 2016/2017 and 2017/2018 crop seasons. The treatments consisted of: 1) winter fallow without soil compaction (WF); 2) winter fallow with soil compaction (WF-C); 3) black oats and complete removal of surface residues, with soil compaction (0R-C); 4) black oats and removal half of surface residues, with soil compaction (0.5R-C); 5) black oats without surface residue removal, with soil compaction (1R-C); 6) black oats without surface residue removal, plus the residues from treatment 3, with soil compaction (2R-C); 7) black oats without surface residue removal, without soil compaction (1R). When the soybean plants were at the phenological stage R2, they were evaluated nodule, root and shoot dry matter, nitrogen contents, plant height, and grain yield. The soil physical properties were evaluated in the 0.0-0.05, 0.10-0.15 and 0.20-0.25 m layers. The soybean aerial dry matter is > 38% in non-compacted soil in year with soil water excess, regardless of the amount of surface oat straw. In year with small water deficit, soil with more surface oat straw produced > 5% shoot dry matter and > 4% of soybean grain, regardless of compaction. The plant growth and grain yield soybean in lowland varied according to the water conditions, and were affected by soil compaction and amounts of black oats residues on soil surface. [ABSTRACT FROM AUTHOR]

Process-based hydrological models are of great importance to understand hydrological processes and support decision making. The LImburg Soil Erosion Model (LISEM) requires information on soil and land-use-related attributes to represent the transformation of rainfall into runoff for isolated rainfall events. This study aimed at evaluating LISEM for estimation of direct surface runoff (DSR) hydrographs in a watershed in Southern Brazil under the predominance of long-duration rainfall events, dominated by Argisols and with availability of a high-density rain gauge network. In addition, this study sought to: (i) suggest and evaluate a procedure for definition of initial soil moisture from antecedent 5-day rainfall depth; (ii) reduce the degree of subjectivity involved in the determination of some vegetation-related parameters by using remote sensing; and (iii) recommend a validation procedure. The saturated soil hydraulic conductivity and the Manning's surface roughness coefficient were calibrated considering 11 rainfall–runoff events, whereas the validation was performed for 4 events from the average calibrated parameters. The Nash–Sutcliffe coefficient was used to assess both calibration and validation, resulting in average values of 0.64 and 0.58, respectively. It can be inferred from the results that the use of remote sensing to derive some LISEM parameters, along with the suggested schemes for definition of initial soil moisture and validation, was effective and provided sound results even for long-duration rainfall events. The results of this study and its methodological procedures can serve as a basis for other professionals who intend to use LISEM for both conducting detailed analyses of DSR hydrographs and supporting water resources management. [ABSTRACT FROM AUTHOR]