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There are significant and on-going issues faced by the U.S. Army Corps of Engineers and other federal agencies in regulating and affording protections to arid non-perennial stream resources in western arid regions of the U.S. (i.e., Arid West). The significance of these issues is magnified by the large portion of dryland areas situated within the U.S., as well as worldwide, where non-perennial streams also comprise most of the stream types. It is essential for politicians, decision makers, and those assessing and managing aquatic resources to be aware of the current body of understanding available on these important resources. An in-depth literature and geospatial analysis was conducted on arid non-perennial stream functions as they relate to key climate ecosystem controls, influential environmental parameter controls, and hydrology (e.g., streamflow regime) forcing functions at various landscape scales and settings. Out of the overall stream function categories of Biogeochemical, Habitat, Hydrology, Sediment, Biodiversity, Energy Dissipation, and Connectivity examined within global and U.S. literature, only Biogeochemical, Habitat, Hydrology, Sediment emerged as the primary function categories of study focus. Global and U.S. data followed similar overall trends with generally a higher coverage of Habitat functions above all other function categories, which was unexpected given the higher importance of Hydrology and Sediment within the overall hierarchy of influences among stream function categories. Other similar overall trends within global and U.S. data included higher occurrences within cold steppe subclimes, steppe precipitation areas, and ephemeral streams. Of the three environmental parameters (watershed position, stream planform type, and riverine corridor sampling location type) analyzed, these patterns tended to be more consistent when compared across watershed positions, with generally more deviation when viewed through the lenses of stream planform types and sampling type locations. Arid non-perennial streams provide critical watershed functions in various arid environs, yet further focused research is needed to augment Biodiversity, Energy dissipation, Hydrology, and Connectivity functions across both ephemeral and intermittent arid streams. Future global and U.S. research is also recommended within cold desert subclimes, across a greater diversity of channel forms and small-scale sampling location types, and with intermittent streams for providing information essential to regional stream assessment, management and regulation of arid non-perennial streams.

Harvesting water from the atmosphere is an important process to solve the extreme lack of water resources in arid regions. Adsorption-based atmospheric water harvesting (AWH) takes advantage of solar thermal energy to harvest water from air. This technique is particularly suitable for arid regions characterized by low humidity and an abundance of sunshine. Nonetheless, under low humidity conditions, AWH is highly dependent on water-adsorbing materials exhibiting excellent performance. In this work, a metal–organic framework (MOF), namely [Zn2(bpy) (btec)(H2O)2]·2H2O, also denoted as MWH-1, was investigated for application in water harvesting under low humidity conditions ( 200 cm3∙cm−3; RH = 10%, uptake: >250 cm3∙cm−3). This ensured effective water harvesting at high temperatures during the day. In situ powder X-ray diffraction and Fourier-transform infrared analyses confirmed the sensitive water adsorption process of MWH-1a. The X-ray single-crystal study further demonstrated that single-crystal structures could be completely restored following water harvesting. MWH-1 showed good structural stability and enabled water harvesting under low humidity and high temperature conditions. Thus, it has the potential for application in round-the-clock water harvesting in extremely arid regions.

The ADRIMED campaign provides measurements of all key parameters regarding atmospheric composition in the Mediterranean area during the summer 2013. This is an opportunity to quantify the ability of current models to adequately represent the atmospheric composition in this complex region, which is influenced by anthropogenic emissions from Europe, Africa, the Middle-East and from shipping activities as well as mineral dust emissions mostly from the arid areas in Africa, sea-salt emissions, biomass burning emissions and biogenic emissions from the vegetation. The CHIMERE model in its present version is a chemistry-transport model which takes into account all these processes. We show here by simulating the period from 5 June to 15 July 2013 with the CHIMERE model and comparing the results to both routine and specific ADRIMED measurements that this model allows an adequate representation the atmospheric composition over the western Mediterranean, in terms of ozone concentration, particulate matter (PM) and aerosol optical depth (AOD). It is also shown that the concentrations of PM on all the considered area is dominated by mineral dust, even though local dust emissions in Europe are certainly overestimated by the model. A comparison with sulphate concentrations at Cape Corsica exhibits some discrepancies related to the regridding of shipping emissions.

Agriculture is an important sector in Algeria, it is the second economic component of the country, however the country suffers from water shortage and high soil permeability, especially in the Sahara region The Sahara area in Algeria accounts for about 85% of its total area, the Algeria's Sahara considered as the most arid region in the world and has a high soil permeability, Leading to consume a large quantities of water for irrigation. In order to solve these problems, hydrogels are the effective solution proposed. Hydrogel s have the capacity of holding a large amount of water and keep it c lose to the plant's roots . The purpose of this study was to estimate the effect of hydrogel on soil permeability by application of three different dosage of Hydrogel in three parcels. The results proved that the addition of hydrogel enabled to yield 50% more production, using almost 50% less water.

A study was undertaken to identify differences in the performance of low-impact development (LID) measures in arid and humid cities. Yinchuan and Guangzhou in China were selected as a representative of each type. A stormwater management model was constructed with the aid of a geographic information system and LID measures of permeable pavements (PP), rain gardens (RG), green roofs (GR) and combinations of these were then designed. The results showed that a combination of PP, RG and GR provided the largest reduction in total runoff, peak runoff and runoff coefficient in both cities. Paired measures also delivered a significantly higher performance than single measures, with PP plus GR better than other paired combinations. The results of this work could guide the construction of sponge cities in both arid and humid areas.

Hydrologic response in a watershed is driven by precipitation. Multi-site rainfall generators can be used to model watersheds using spatially varied rainfall inputs to better analyze how the rainfall variability affects runoff generation. This study adopted both a single-site rainfall generator (CLIGEN) and a multi-site rainfall generator to generate two rainfall data sequences, which were then used to drive the Soil and Water Assessment Tool (SWAT) for runoff simulation. The 148-km2 Walnut Gulch Experimental Watershed and its two sub-watersheds were selected to evaluate the hydrologic response. Runoff calibration was done against measured runoff in the watershed. Statistics showed that the single-site and multi-site rainfall generators gave similar results regarding annual precipitation. However, the multi-site generator performed much better than the single-site generator in both mean summer flow and for the different return period flows. The runoff derived from the single-site generator was significantly over-estimated in all three watersheds. As for the multi-site generator, the derived runoff was satisfactorily predicted in the smaller watersheds but only overestimated in the largest watershed. This indicated that in small to medium sized watersheds, the spatial variability of rainfall could play an important role for hydrologic response because of the heterogeneity of convective rainfall in this semi-arid region, which makes the application of multi-site rainfall generator a better option than the single-site generator.

Rates of soil development provide critical information about the types and rates of geomorphic and landscape evolutionary processes. Soil development in arid and semiarid regions of the southwestern United States is predominantly controlled by influx of eolian dust, yet our ability to quantify the rates of morphologic development and of dust and carbonate incorporation is limited by available age control. We describe 10 pedons in the Socorro area of central New Mexico and analyze their silt, clay, and carbonate contents. These soils have well-established direct or indirect age control that we used to estimate average rates of dust and carbonate accumulation over the past ~0.5–800 ka. We also computed the profile development index (PDI) for these soils using 10 common morphologic properties and compare our resulting PDI chronofunction to those from northern and southern New Mexico. We find that the net silt-and-clay content increases in progressively older soils at rates similar to the profile-mass carbonate contents, presumably sourced primarily from eolian dust. Our chronofunction comparison indicates that soil development occurs more rapidly in higher latitude regions of New Mexico than in the drier warmer climates of the Socorro area and southern New Mexico. We interpret the N–S regional trend of soil development considering a regional climate gradient. We conclude that greater mean annual precipitation and cooler mean annual temperatures and/or slower rates of eolian dust accumulation into the soil profile at higher latitude northern sites cause the observed differences in regional soil development. This would promote greater mobility of available silt and clay, and also increase rates of soil formation, as indicated by the presence of argillans in late-Pleistocene soils of northern New Mexico.

MDFRC item.Freshwater rivers have been substantially altered by development and flow regulation. Altered hydrological regimes have affected a range of biota, but impacts are often most obvious on freshwater fish. Flow largely influences the range of physical habitat available to fish at various life history stages. Biological rhythms are therefore often linked to flow and optimized so that opportunities for spawning, growth and dispersal are synchronized. Assuming that flow therefore becomes the main factor which structures freshwater fish communities, the use of species specific biological information should be able to inform adaptive flow delivery strategies from the river reach to catchment scale. A test of this assertion was performed as a case study of native fish within the Edward-Wakool River system (New South Wales, Australia). Fish within the system were assigned to one of four groups based on biological similarity. Aspects of reproductive and movement ecology were then reviewed to generate optimal flow release strategies for each group. Life expectancy and hydrological constraints were then investigated and used to develop a possible 10-year flow delivery program that could generate ecological outcomes within a strategic adaptive management framework that considered potential impacts on third parties. The approach could be used to develop flow characteristics to benefit biota in any watercourse provided enough data are available to link potential outcomes with flow delivery.

The Yangtze River is a major component of the ‘Asian Water Tower’ and it provides freshwater resources for hundreds of millions of people in East Asia. Hence, climatic and environmental changes in the source region of the Yangtze River (SRYR) are of major significance for understanding changes in the status of its freshwater resources. However, due to the contradictory results shown by the available paleoclimatic records from the SRYR and neighboring regions, it remains unclear how the regional climate and hydrology have evolved since the middle Holocene. Here, we present records of hydrological variations based on multiple proxies (grain size, scanned micro-scale X-ray fluorescence (XRF) element composition, and loss on ignition (LOI)) of the sediments of alpine lake Saiyong Co, with the aim of reconstructing hydrological changes in the SRYR since 5.8 ka. The first principal component (PC1) of the XRF scanned element record is dominated by Ti, Fe and K, representing terrigenous inputs from the catchment. The LOI profile shows an inverse pattern of variation to that of PC1, suggesting that the sedimentary organic matter is primarily derived from aquatic plants. Since 5.8 ka the overall decrease in sample scores on PC1 and the increasing LOI, together with the grain-size based lake-level record, indicate an overall drying trend in SRYR. Furthermore, several major droughts are recorded, at ∼4.0 ka, ∼2.8 ka and ∼1.8 ka. The hydrological variations at Saiyong Co are supported by multiple records from the SRYR, suggesting that millennial-scale environmental variations were regionally synchronous and were influenced by Northern Hemisphere summer insolation and movement of the intertropical convergence zone.

Tremendous benefits of biochar (BC) amendment to soil have been reported, including their role in alleviating the impact of salinity stress in plants. The aim of this study was to evaluate the effects of BC produced at 300 °C (BC300) and 700 °C (BC700) on the germination rate (GR) and selected growth characteristics of corn plants irrigated with salinized water over a growth period of 6 weeks. The experimental treatments included three biochar treatments: BC0 (control, without biochar addition), BC300, and BC700. The treatments also included three salinity levels of irrigation water: 0, 3, and 6 dS·m−1. The biochar was applied at a rate of 3%. The GR decreased with increasing salinity level, which was more evident in the first week. This stress impact was reduced when treated with the BC700 relative to the saline treatments without BC. Both BC treatments demonstrated contrasting effects on corn growth, nutrient uptake, and Na+ and K+ content in plant tissue. The effect of BC700 treatment on plant height and root length was limited, but the impact of salinity stress on chlorophyll meter readings, chlorophyll fluorescence parameter (Fv/Fm), dry matter yield, and N and P uptake were largely mitigated. It also increased K+ and decreased Na+ content in plant tissue. However, the BC300 treatment adversely affected plant growth parameters at each salinity level. Overall, the BC produced at a higher temperature significantly alleviated the impact of salinity stress on plant growth characteristics, which is probably attributed to their higher surface area and porosity, enhancing their salt ion sorption capacity.

Knowing the tolerance of plants grown in the Brazilian semi-arid region to salt stress is of paramount importance for the sustainability of regional agriculture. This study was developed to examine the growth and yield of prickly pear cactus ‘Orelha de Elefante Mexicana’ (Opuntia stricta Haw) irrigated with increasing water salinity levels (0.75, 3.0, 5.25 and 7.50 dS m-1 to 25 ºC) and grown on soils representative of the Brazilian semi-arid region (chromic Luvisol, Solonetz and Fluvisol). Total fresh weight decreased linearly, with a 21.42% reduction when we compare the average fresh weight per plant in the lowest and highest saline level treatments. The chromic Luvisol and Solonetz soils showed the best fresh weight and dry matter yields under the present experimental conditions. Conhecer a tolerância das plantas cultivadas na região semiárida brasileira ao estresse salino, é de fundamental importância para a sustentabilidade da agricultura regional. Este trabalho objetivou avaliar o crescimento e produtividade de palma forrageira ‘Orelha de Elefante Mexicana’ (Opuntia stricta Haw), irrigada com níveis crescentes de salinidade da água (0,75; 3,0; 5,25; e 7,50 dS m-1 a 25 ºC) e cultivada sobre solos representativos da região semiárida brasileira (Luvissolo crômico, Planossolo nátrico e Neossolo flúvico). A massa verde total apresentou efeito linear decrescente havendo uma redução de 21,42 % ao comparar a massa verde média por planta do tratamento de menor nível com o tratamento de maior nível salino. Os solos Luvissolo crômico e Planossolo nátrico apresentaram as melhores produtividades de massa verde e massa seca nas condições deste experimento.

This study presents a paleolimnological and paleoclimatological reconstruction based on diatoms and phytoliths of four Pampean shallow lakes (from south to north, La Salada, Sauce Grande, Los Chilenos, and Puan) strategically located along a climatic gradient from arid (south) to semiarid conditions (north). This research aims to identify the main drivers and mechanisms of long-term ecological change, and the main climatic mechanisms behind the regional hydroclimatic variability. It was found that these lakes were initially temporary, with clear waters, and eventually, became permanent with turbid waters. We propose that this change is due to an increase in precipitation in the last ca 1000 years, which resulted in higher lake levels and an increase in surface area, leading to an increased fetch and subsequent resuspension of sediment. This climatic amelioration occurred after ∼910 cal yr BP, first in what is today the arid Pampean region, then in the semiarid region, and finally in the modern humid region at ∼ -9 cal yr BP (1959 CE). Variations in lake's water level were the main driver of ecological change, followed by salinity (in Puan and La Salada) and nutrient load (in Los Chilenos and Sauce Grande). In general, those lakes on the southwest, located closer to the limit of moisture influence originating in the Pacific and Atlantic oceans (Arid Diagonal) were more sensitive to hydroclimatic changes than those located in the central Pampean region.

As a common measure for grassland restoration, the fence for prohibition of grazing is usually applied to the steppe in northern China. A study in Hulunbuir grassland showed the average litter mass in the steppes that enclosed for ten years can reach 70-550g/m2. The excessive accumulation of litter caused by long-term grazing prohibition can intercept more precipitation, which will reduce the water available to grassland plants and hinder the further recovery of plant communities. Therefore, the establishment of a reasonable litter interception model can help estimating the interception of steppes with different litter accumulation and provide some theoretical support for the formulation of fencing policies. Based on the model of litter interception rate change, we established a dynamic interception model of litter: I = I m ( 1 − e − k t ) ( t : time; I : dynamic interception; I m : maximum interception; k : exponential coefficient of litter interception). After testing by an indoor simulated rainfall experiment, we found that this model has high accuracy ( R 2 : 0.908 – 0.992). The litter mass (LM) determines the maximum interception, and the rainfall intensity (RI) determines the speed of interception which reaches its maximum value. After the conversion of coefficients, we established a prediction model of litter interception based on LM and RI: I = ( 0.003 L M + 0.44 ) [ 1 − e − ( 0.33 R I + 3.76 ) t ] , R 2 = 0.86 , P 0.001 . The easily obtainable characteristics of LM and RI data make this model easy to apply.

Urban parks play an essential role in urban settings; significantly contribute to the health of every age group person. Parks provide opportunities for families to connect with nature and breathe in the fresh air. Due to global climate change and increased urbanisation in the past few decades, extreme heat can be experienced in urban areas. Mental and physical health issues arise primarily due to a sedentary lifestyle in cities. Staying at parks for a longer duration could promote stress reduction and perceived physical health. The present study aims to assess the thermal comfort conditions at an urban park in the hot semi-arid climate(BSh) of Haryana, India. The present study investigated the outdoor thermal comfort range and thermal sensations of visitors at a park during the summer season using the onsite monitoring of the microclimate parameters and questionnaire survey in the hot-semi arid region of India. Thermal comfort indices, Physiological equivalent temperature (PET) and Universal Thermal Climate Index (UTCI) and Wet bulb globe temperature(WBGT) have been applied to investigate the outdoor thermal comfort conditions. The seven-point sensation scale has been used to record the visitors' thermal sensations. The results indicated that:1) WBGT was found to be the most suitable index to investigate the OTC conditions. The neutral UTCI, PET, and WBGT ranged within 28.03 °C to 35.6 °C, 24.04 °C to 37.5 °C, and 23.5 °C to 26.1 °C, respectively. 2) The neutral PET ,UTCI, and WBGT were found to be 30.8 °C, 31.8 °C, and 24.8 °C, respectively.3) Dry bulb temperature is the most significant thermal comfort parameter affecting visitors' thermal sensations, followed by mean radiant temperature.4) Thermal comfort indices were found to be most significantly affected by globe temperature. The study's outcome could provide theoretical design reference to urban designers to develop new parks and existing parks, ultimately promoting public health.

Little attention has been paid to climate change in the marginal regions of the Asian summer monsoon (ASM) domain since Marine Isotope Stage (MIS) 3 (60-27 cal kyr BP). Here, based on the mineralogy and grain size of a 24-m-long sediment core retrieved from Jilantai Salt Lake, we provide a paleolake evolution record from a marginal region of the ASM domain over the past 47 kyr. Our results indicate that the lake was a brackish or saline lake and that the region was relatively humid during 47–43 cal kyr BP. From 43 to 27.5 cal kyr BP, the lake salinity increased and the climate began to deteriorate. From 27.5 to 11.8 cal kyr BP, aeolian activity intensified and the climate was arid. From 11.8 to 5.6 cal kyr BP, the lake salinity continuously increased, and the climate was persistently arid. After 5.6 cal kyr BP, the lake salinity dramatically increased, the lake became a salt lake, and the climate was extremely arid. In general, the climate was semihumid in mid-late MIS 3, arid in MIS 2 (27–11.7 cal kyr BP), and hyperarid in the Holocene. This climate change pattern is apparently different from that in the regions influenced by the Asian monsoon and westerlies, indicating that the enhanced Asian monsoon or westerlies were not the main forcing mechanism driving climate change in the marginal regions of the ASM domain. Enhanced ice-albedo feedback caused by the expanded Northern Hemisphere ice volume during MIS 3 would have resulted in less net incoming solar radiation and relatively low temperatures in the mid-high-latitudes. The relatively low temperatures might have weakened the evaporation capacity of Jilantai Basin and increased south-north temperature gradients, resulting in an increase in local precipitation. Therefore, the climate was semihumid in mid-late MIS 3. The lowest Northern Hemisphere summer insolation (NHSI) combined with significantly increased ice-albedo feedback associated with the largest Northern Hemisphere ice volume would have led to a remarkable reduction in temperature, resulting in the reorganization of major atmospheric and hydrological systems in the Northern Hemisphere and an arid climate in MIS 2. Subsequently, the Northern Hemisphere ice volume nearly vanished, and the rising NHSI enhanced evaporation, thereby generating a hyperarid climate in the Holocene.

Temporal and spatial changes of green water (GW) security due to climate and land-use/land-cover (LULC) changes can be used to make the best decisions for sustainable GW management. In this study, simultaneous effects of climate and LULC changes on water resources in Kashafrood Basin were evaluated using the Soil and Water Assessment Tool (SWAT). A land change modeler was set up to monitor LULC, assess changes and make predictions. The MIROC-ESM model derived from Coupled Model Intercomparison Project Phase 5 under two representative concentration pathway (RCP) emission scenarios RCP2.6 and RCP8.5 was applied to evaluate the effects of climate change. Two indices of GW-Scarcity and GW-Vulnerability, representing GW-Security, were quantified using the GW-Footprint concept in Kashafrood Basin. The results show that the annual average of blue water was predicted to increase by 142–350%, and GW storage and the annual averages of GW flow were predicted to decrease by 12–65 and 8–20%, respectively, depending on emission scenarios and time. The GW-Security estimates in the entire basin suggest a better condition in the future by indicating 24–45 and 16–52% decreases in GW-Scarcity and GW-Vulnerability, respectively, depending on emission scenarios and time. HIGHLIGHTS Land change modeler predicts a decline in agricultural area and a growth in urban and pasture areas.; Blue water rises by 142–350% under the effect of climate and land-use changes.; Green water (GW) storage and GW flow decrease by 12–65 and 8–20%, respectively.; The condition of the basin in terms of GW-Security would improve in the future.; GW-Scarcity and GW-Vulnerability escalate in southern and some western subbasins.

The major tributary of the lower Colorado River, the Gila River, is a critical source of water for human and natural environments in the southwestern United States. Warmer and drier than the upper Colorado River basin, with less snow and a bimodal precipitation regime, the Gila River is controlled by a set of climatic conditions that is different from the controls on upper Colorado River flow. Unlike the Colorado River at Lees Ferry in Arizona, the upper Gila River and major Gila River tributaries, the Salt and Verde Rivers, do not yet reflect significant declines in annual streamflow, despite warming trends. Annual streamflow is dominated by cool-season precipitation, but the monsoon influence is discernable as well, variable across the basin and complicated by an inverse relationship with cool-season precipitation in the Salt and Verde River basins. Major multiyear streamflow droughts in these two basins have frequently been accompanied by wet monsoons, suggesting that monsoon precipitation may partially offset the impacts of a dry cool season. While statistically significant trends in annual streamflow are not evident, decreases in autumn and spring streamflow reflect warming temperatures and some decreases in spring precipitation. Because climatic controls vary with topography and the influence of the monsoon, the impact of warming on streamflow in the three subbasins is somewhat variable. However, given relationships between climate and streamflow, current trends in hydroclimate, and projections for the future, it would be prudent to expect declines in Gila River water supplies in the coming decades. Significance Statement This research investigates the climatic controls on the Gila River and its major tributaries, the Verde and Salt Rivers, to gain insights on how trends in climate may impact future water supply. The Gila River is the major tributary of the lower Colorado River, but, unlike the situation for the upper Colorado River, no significant decreasing trends in annual streamflow are evident despite warming temperatures. Climate–streamflow relationships are more complex in this part of the Colorado River basin, and several factors may be buffering streamflow to the impact of warming. However, given the key climatic controls on streamflow, current and emerging trends in climate, and projections for the future, declines in streamflow should be expected in the future.

This paper presents a new index to determine meteorological drought conditions, the Drought Exceedance Probability Index (DEPI), derived from monthly precipitation time series. Its formulation is simple and undemanding in terms of baseline information requirements. This makes the DEPI suitable for routine application to any climate, similar to the well-known Standardized Precipitation Index (SPI). The index is based on the calculation of cumulative rainfall anomalies and their subsequent standardization, similarly to other indices. The hallmarks of the DEPI, and its main comparative advantages, are the process of accumulating anomalies and their standardization process. The paper compares the DEPI with the SPI in several different climates across the world and in all cases the results show the complementarity of both indices. The DEPI shows an excellent ability to reflect the actual severity and duration of droughts, without requiring application on different time scales, unlike the SPI. It is also valid for all types of climates, including arid and semiarid or Mediterranean, for which the literature has shown that using the SPI is problematic.

Soil salinization caused by natural and anthropogenic factors is an important environmental hazard especially in arid and semi-arid regions of the world. Accumulation of salts in the soil is a major threat to crop production and global agriculture; therefore, rapid and precise detection of salt-affected lands is highly critical for preserving soil sustainability and supporting food production. Advancement in remote sensing techniques and machine-learning algorithms has started to contribute to fast and large-scale monitoring and mapping of soil salinization throughout the world. This paper aims to analyze the performance of three different machine-learning algorithms to map soil salinity using Landsat-8 OLI, Sentinel-2A satellite images, and ground-based electrical conductivity (EC) measurements with the aid of Google Earth Engine (GEE) platform. Classification and regression trees (CART), random forest (RF), and support vector regression (SVR) methods are implemented to create a correlation between ground measurements and satellite-derived environmental variables or spectral indices. After selecting the optimum five variables including wetness band, three soil salinity indices, and one vegetation index, soil salinity maps are generated in three machine-learning algorithms. The output soil salinity map in RF algorithm demonstrated the most reliable spatial distribution of various soil salinity classes in the selected study area. Despite CART provided slightly better prediction of soil salinity with R-squared (R2) of 0.98 for Sentinel-2A data, and 0.96 for Landsat-8 OLI data in comparison with accuracy results of RF technique with R2 of 0.96 for Sentinel-2A data and 0.94 for Landsat-8 OLI data, the output map of RF model estimated more reliable salinity levels in salt crusts, agricultural lands, drainage areas, and swamps. The corresponding result highly matched with visual interpretation. Soil salinity maps derived from SVR algorithms by using various combinations of input variables displayed relatively poor estimation of soil EC values compared to the other two methods.

An unprecedented demand for Food, Energy, and Water (FEW) resources over coming decades and the rising climate concerns require integrated FEW innovations with least environmental footprint. Collocating photovoltaic (PV) technology with agriculture is a promising approach towards dual land productivity that could locally fulfill growing food and energy demands particularly in rural areas. This ‘agrivoltaic’ (AV) solution can be highly suitable for hot and arid climates where an optimized solar panel coverage could prevent excessive thermal stress during harsh weather thereby increasing the crop yield and lowering the water budget. One of the concerns with using standard fixed tilt solar array structure that faces North/South ( N / S ) direction for AV farming is the spatial heterogeneity in the daily sunlight distribution for crops and soil water contents, both of which could affect crop yield. Dynamic tilt control through a tracking system can eliminate this problem but could increase the system cost and complexity. Here we present the investigation of vertically tilted bifacial AV farms which can be especially attractive for climates where PV losses due to dust are high. The relative food-energy performance for the vertical East/West faced bifacial panel ( bi- E / W ) scheme is compared with the standard monofacial tilted panels facing North/South ( mono- N / S ) through integrated models for energy conversion, spatial/temporal shade patterns, and the crop yield that is benchmarked against the reported field experiments for lettuce. We show that both schemes have similar food-energy yields for shade-sensitive crops which require a relatively low array density (i.e. ⩽ 1 / 2 of that for the standard ground mounted PV systems). On the other hand, the two PV schemes have remarkably different food-energy yields for denser PV array configuration for which bi- E / W provides higher crop yield and mono- N / S exhibits higher energy yield. To preserve ⩾ 80% of lettuce yield, the maximum array density is limited from half to twice of the standard PV systems corresponding to the varying shade response for the crop. Similarly, to preserve 80% of the energy yield, the lettuce yield is predicted to vary from 65% (shade-sensitive) to 100% (shade-tolerant). The vertical bi- E / W scheme is although not superior in terms of the combined food-energy performance, it could be attractive for its distinct advantages such as spatial homogeneity for shades and rainfall under panels, convenient architecture for farm machinery mobility, and an inherent resilience to soiling.

Under global warming, according to results obtained from offline drought indices driven by projections of general circulation models (GCMs), future droughts in China will worsen but the results are not consistent. We analyzed changes in droughts covering the entire hydrologic cycle using outputs of GCMs of the 6th Coupled Model Intercomparison Project (CMIP6) for SSP2-4.5 and SSP5-8.5 climate scenarios, and compared the results with that of popular, offline drought indices [the self-calibrating Palmer Drought Severity Index (scPDSI), Standardized Precipitation Evapotranspiration Index (SPEI) and Standardized Precipitation Actual Evapotranspiration Index (SPAEI)]. Among meteorological, agricultural, and hydrological drought indices tested under both SSP scenarios, the results obtained from SPAEI and scPDSI agree better with univariate drought indices than SPEI. scPDSI generally agrees well with agricultural droughts (Standardized Soil Moisture Index with the surface soil moisture content; SSIS). Future droughts estimated using soil moisture analysis are more widespread than that from precipitation and runoff analysis in humid regions of South China by the end of the twenty-first century. In arid northwestern China and Inner Mongolia, drought areas and severity based on scPDSI and SSIS forced with the SSP scenarios show obvious decreasing trends, in contrast to increasing trends projected in South China. Trends projected using SPEI contradict those projected by other drought indices in non-humid regions. Therefore, selecting appropriate drought indices is crucial in project representative future droughts and provides meaningful information needed to achieve effective regional drought mitigation strategies under climate warming impact.

Two global experiments were carried out to investigate the effects of dynamic vegetation processes on numerical climate simulations from 1948 to 2008. The National Centers for Environmental Prediction (NCEP) Global Forecast System (GFS) was coupled with a biophysical model, the Simplified Simple Biosphere model (SSiB) version 2 (GFS/SSiB2), and the same model coupled with a biophysical and dynamic vegetation model, SSiB version 4/Top-down Representation of Interactive Foliage and Flora Including Dynamics (TRIFFID) (GFS/SSiB4/TRIFFID). The effects of dynamic vegetation processes on the simulation of precipitation, near-surface temperature and the surface energy budget were identified on monthly and annual scales by assessing the GFS/SSiB4T/TRIFFID and GFS/SSiB2 results against the satellite-derived leaf area index and albedo and the observed land surface temperature and precipitation. The results show that, compared with the GFS/SSiB2 model, the temporal correlation coefficients between the globally averaged monthly simulated leaf area index and the Global Inventory Monitoring and Modeling System (GIMMS)/Global Land Surface Satellite (GLASS) leaf area index in the GFS/SSiB4/TRIFFID simulation increased from 0.31/0.29 (SSiB2) to 0.47/0.46 (SSiB4). The correlation coefficients between the simulated and observed monthly mean near-surface air temperature increased from 0.50 (Africa), 0.35 (Southeast Asia) and 0.39 (South America) to 0.56, 0.41, and 0.44, respectively. The correlation coefficients between the model-simulated and observed monthly mean precipitation increased from 0.19 (Africa), 0.22 (South Asia), and 0.22 (East Asia) to 0.25, 0.27, and 0.28, respectively. The greatest improvement occurred over arid and semiarid areas. The spatiotemporal variability and changes in vegetation and ground surface albedo modeled by the GFS with a dynamic vegetation model were more consistent with the observations. The dynamic vegetation processes contributed to the surface energy and water balance and, in turn, improved the annual variations in the simulated regional temperature and precipitation. The dynamic vegetation processes had the greatest influence on the spatiotemporal changes in the latent heat flux. This study shows that dynamic vegetation processes in Earth system models significantly improve simulations of the climate mean status.

Soil inorganic carbon (SIC) is an important reservoir of carbon (C) in arid, semi-arid, and semi-humid regions. However, knowledge is incomplete on the dynamics of SIC and its relationship with soil organic C (SOC) under different land use types in the semi-humid region, particularly in coastal zones impacted by soil salinization. We collected 170 soil samples from 34 profiles across various land use types (maize-wheat, cotton, paddy, and reed) in the middle-lower Yellow River Delta (YRD), China. We measured soil pH, electrical conductivity (EC), water-soluble salts, and SOC and SIC contents. Our results showed significant differences in both SOC and SIC among land use types. The dry cropland (maize-wheat and cotton) soils had significantly higher SOC and SIC densities (4.71 and 15.46 kg C m–2, respectively) than the paddy soils (3.28 and 14.09 kg C m–2, respectively) in the 0–100 cm layer. Compared with paddy soils, reed soils contained significantly higher SOC (4.68 kg C m–2) and similar SIC (15.02 kg C m–2) densities. There was a significant positive correlation between SOC and SIC densities over a 0–100 cm soil depth in dry cropland soils, but a negative relationship in the paddy soils. On average, SOC and SIC densities under maize-wheat cropping were 15% and 4% lower, respectively, in the salt-affected soils in the middle-lower YRD than the upper YRD. This study indicated that land use types had great influences on both SOC and SIC and their relationship, and salinization had adverse effect on soil C storage in the YRD.

Water crises in arid and semi-arid regions, particularly in desert areas, are considered a challenge owing to the fact that no functioning solutions have been introduced throughout history to change the whole map from yellow to green. Current desert regions are still deserts from millions of years ago, and all scenarios that have been introduced to occupy desert regions accounts for 1%–2% of the total area. Middle East and North Africa (MENA) countries that are located in such arid and semi-arid zones are disadvantaged by limited water supply because of high temperature, low precipitation, and limited water resources. We have found that, there is no consortium between different fields of interest in the hopes of eventually overcoming the global water crisis. This is practically the case when it comes to using desalination and wastewater treatment technologies and their application for agriculture. Water crises should not only be solved using desalination and wastewater treatment, but other items should be also taken into consideration such as soil, plant, and organic matter use, among others. In the present perspective, we are developing novel solutions to overcome the global water crisis via nonconventional water reuse with minimum constrains to ecosystems using the principles of the Sophisticated Desert Development Project (SDDP) or “Electro-agric technology”. Electro-agric is technique that uses electrical fields throughout agricultural practices. Electro-agric technology comprises five main sections, including water, soil, organic matter, and plants, among others, that may be achieved via the establishment of a consortium between different major establishments like the Faculties of Engineering, Agriculture, and Science. Traditional approaches for cultivating land in arid and semi-arid regions are inappropriate and electro-agric technologies may be considered as the only alternative solution for regions that are located between the latitudes 35°N to 35°S in which the arid and semi-arid weather prevails and in which in seven of the world's major deserts are located. We believe that the map of MENA countries produced will transform from yellow to green, indicating reclamation of this resource; however this can only be accomplished if we comply with electro-agric technologies. Moreover, national incomes will be increased, and new communities will be stabilized.

The need for sustainable agricultural practices to meet the food, feed, and fuel demands of a growing global population while reducing detrimental environmental impacts has driven research in multi‐faceted approaches to agricultural sustainability. Perennial cropping systems and microbial biofertilizer supplements are two emerging strategies to increase agricultural sustainability that are studied in tandem for the first time in this study. During the establishment phase of a perennial switchgrass stand in SW Montana, USA, we supplemented synthetic fertilization with a nitrogen‐fixing cyanobacterial biofertilizer (CBF) and were able to maintain aboveground crop productivity in comparison to a synthetic only (urea) fertilizer treatment. Soil chemical analysis conducted at the end of the growing season revealed that late‐season nitrogen availability in CBF‐supplemented field plots increased relative to urea‐only plots. High‐throughput sequencing of bacterial/archaeal and fungal communities suggested fine‐scale responses of the microbial community and sensitivity to fertilization among arbuscular mycorrhizal fungi, Planctomycetes, Proteobacteria, and Actinobacteria. Given their critical role in plant productivity and soil nutrient cycling, soil microbiome monitoring is vital to understand the impacts of implementation of alternative agricultural practices on soil health.

Quality irrigation water is precious in agriculture under arid conditions. The value addition in agricultural product makes a new commodity outside the traditional frame to achieve higher returns with improved shelf-life and minimizes post-harvest losses. The aim of this study is to evaluate and quantify the improvements possible in water productivity through value addition in date cultivated under arid conditions in Oman. The primary and secondary data were collected through questionnaire surveys from farmers, sellers, factories and ministry extensions. The comparisons were made between the marketing of raw product against those with value-added, which were produced using the same quantity of resources; particularly irrigation water. The productivity was estimated by the ratio of agricultural benefits in kg to the irrigation water use in m3. The net-profit based productivity ratio improvements in Khalas and Fardh dates were 540% and 360% respectively for value-added dates packed with nuts. The lowest productivity ratio was observed in Khalas dates with saffron and other flavors (111%), and Fardh date paste (129%). In Khalas, the best improvement by the value-addition in average water productivity from the base-values of 0.57 kg/m3, or 0.63 OMR/m3 of the raw date were 2.06 kg/m3 or 2.28 OMR/m3 in date with nuts respectively while in Fardh, the same were 1.55 kg/m3 or 1.71 OMR/m3 respectively. The observed potential improvements in equivalent water productivity indicates the benefit of value addition would be vital for achieving agricultural sustainability goals under arid agriculture.

Soil structure plays a critical role in agroecosystems because it controls soil air and water capacity, nutrient availability, and crop root growth. A field experiment was conducted to evaluate the effect of bentonite on soil relative water content, soil cone penetration resistance, soil bulk density, aggregate size distribution, and millet crop yield components in a semi-arid region in northern China from 2011 to 2015. Treatments consisted of six bentonite rates (0, 6, 12, 18, 24, and 30 Mg·ha−1) applied only in the initial year. Addition of bentonite significantly increased soil relative water throughout the profile (0–60 cm) and aggregates in 0.25–2 mm class in 0–40 cm depth; it significantly decreased soil bulk density, soil cone penetration resistance, and aggregates in 0.053–0.25 mm class in the 0–40 cm depth. All of the bentonite treatments significantly increased 1000-kernel weight and panicle number up to 16% and 33%, respectively, but did not affect kernels per spike. Treatment with 24 Mg·ha−1 bentonite achieved the greatest effect on all the soil physical parameters and crop yield components averaged over all years; the highest application rate (30 Mg·ha−1) had an increasing effect over time. This study indicates that application of bentonite improves soil health in sandy-loam soil in a semi-arid region, and thus it would help promote sustainable agriculture development in regions with similar soil and climate.

The degradation and desertification of grasslands pose a daunting challenge to China's arid and semiarid areas owing to the increasing demand for them in light of the rise of animal husbandry. Monitoring grasslands by using big data has emerged as a popular area of research in recent years. As grassland degradation is a slow and gradual process, the accurate identification of grassland cover is key to monitoring it. Vegetation coverage is currently monitored mainly by combining inversion-based methods with field surveys, which requires significant human effort and other resources and is thus unsuitable for use at a large scale. We proposed to use time series from the enhanced vegetation index (EVI) in capsule network-based methods to identify grasslands. The process classified grassland coverage into four levels, high, medium, low, and other, based on Landsat images from 2019. The accuracy in classifying the grasslands at each level was higher than 90%, with an overall accuracy of 96.32% and a kappa coefficient of 0.9508. The proposed method outperformed the SVM, RF, and LSTM algorithms in terms of classification accuracy.

Rainwater harvesting (RWH) is an alternative technique to potentially overcome the increasing need for water. However, identifying suitable sites for RWH remains a complex task. The present study o...

Soil water deficit is a major production-limiting factor in the predominantly rainfed agriculture of the Ruzizi plain, eastern Democratic Republic of Congo (DRC). Appropriate soil and water conservation (SWC) practices would be a valuable option for maximizing water uptake by plants in the context of water demand and supply unbalance. This study assessed the efficiency of selected SWC practices in improving water and nutrient (nitrogen and phosphorus) balances along the slope gradients in Ruzizi plain using a three-season field experiment. The SWC practices, tied ridges and Zai pits, improved the cumulative soil water balance by 148.7 and 21.1%, respectively, compared to conventional tillage. In the same order, the maize (Zea mays L.) yield performance significantly varied with SWC practices: tied ridges (2.16 t ha-1) out performed the Zai pits (1.48 t ha-1) and conventional tillage (1.58 t ha-1). Besides, the tied ridges reduced the total nitrogen losses by 34.4–49.8%, compared to conventional tillage. However, SWC practices were only reliable when daily rainfall amounts were at reasonable threshold (>10 mm) and on low slope gradients (

Returning straw to the field has become the most important straw utilization method in China. The aim of this research was to study the appropriate amount of nitrogen fertilizer applied when returning the straw of three major crops (wheat, rice, and corn) to the field in areas under low to high yield levels based on the demand of nitrogen for microbial decomposition of straw. Under the condition of returning 100% straw to the field, we developed the formula for calculating the nitrogen application rate and estimated the urea application rate for the three major grain crops. The results showed that returning straws of wheat, early-season rice, middle-season rice and late-season rice, and corn to the field with urea application at the rate of about 150 kg/ha, 120～135 kg/ha, 75 kg/ha, and 75～90 kg/ha, respectively, can provide sufficient nitrogen for microbial decomposition. The urea application rate for returning 100% wheat straw to the field in Huang-Huai-Hai region, Middle-Lower Yangtze region, Loess plateau region, and Northwest arid region was 135–230 kg/ha, 110–190 kg/ha, 85–145 kg/ha, and 95–165 kg/ha, respectively. 52.5–98.5 kg/ha of urea was used for 100% early rice straw returning to the field in Middle-Lower Yangtze region and South China. In addition, the urea application rate for 100% middle-late rice straw returning to the field was 95–180 kg/ha, 100–185 kg/ha, 95–175 kg/ha, and 75–140 kg/ha, respectively. The rate of urea application for 100% corn straw returning to the field in Northeast China, Huang-Huai-Hai, Northwest arid region, and Southwest China was 60–135 kg/ha, 50–115 kg/ha, 60–135 kg/ha, and 45–105 kg/ha, respectively. The amount of nitrogen fertilizer required for the total return of crop straw is not only affected by crop straw C : N, yield per unit area, and ratio of grass to grain but also affected by straw returning mode, regional nitrogen application level, and other factors. Therefore, the amount of nitrogen fertilizer should be adjusted according to the type of cropping system, soil, and climatic conditions of the specific location. This substantial N input for stimulating straw decomposition may favor N losses with nitrate leaching and nitrous oxide emissions and hold a potential for soil N eutrophication in the long term if the level is not carefully adjusted to the N requirement of the subsequent crops and changes in soil organic matter levels.

© 2021 John Wiley & Sons, Ltd.Basins with hydrological modifications pose challenges in hydrological modelling, especially when there are limited data about basin characteristics. Models, however, are vital if we are to identify undisturbed hydrological conditions and evaluate the extent of modifications. In this study, we used SWAT to model the hydrological processes in a semi-arid closed basin, where basin hydrology was heavily modified with reservoirs and irrigation canals and drains. Modelling was also challenging due to limited data about basin characteristics and irrigation management. We modelled the hydrological processes using topographic, land use/cover, soil and climate data. The auto-irrigation tool in SWAT, which determines the timing and amount of irrigation based on the plant water stress factor, was used to represent irrigation. We successfully calibrated/validated the model for streamflow and reservoir storage and confirmed it further by analysing simulated water volumes in wetlands collecting drainage flows. We used the model to simulate the undisturbed hydrologic state and the effects of intensified irrigation. This study showed that SWAT can provide reasonable predictions of hydrological processes in agricultural basins where the natural flow regime is altered by man-made structures. Simulations with the model revealed that the construction of reservoirs followed by land use changes and intensified irrigation have affected streamflows and downstream ecosystems significantly.

Drylands are arid and semi-arid areas whose main feature is their low level of precipitation. They cover nearly half of Earth’s land surface and are distributed worldwide, constituting the planet’s largest biome. Dryland soils have low fertility, are greatly affected by climate variability, and are vulnerable to wind and water erosion. The phosphorus-rich soil dust traveling by aeolian processes from drylands is the main source of P for the global primary productivity in P-limited areas, a fact that highlights the importance of arid and semiarid areas in the global nutrient budget. This review discusses the development of dryland soils, the sources of P in drylands, the C, N, P, relation in dryland soils, the fractionation and bioavailability of P, and biotic and abiotic factors affecting the P in drylands. Finally, the dynamic of P in biological soil crusts and resource islands is discussed. Combined, they contribute to the surface organic matter pools, alter the soil fertility, and are determinant factors in P’s availability in dryland soils. We conclude the review by highlighting the gaps in knowledge that should be addressed in future research regarding biological and abiotic processes that determine the dynamics of P in drylands.

En ambientes áridos y semiáridos la disponibilidad de agua es el factor principal que controla los procesos biológicos. En un pastizal de la Estepa Magallánica Seca, sur de Santa Cruz, se instaló un ensayo de intercepción de lluvias con el fin de evaluar los cambios en la disponibilidad hídrica en la superficie del suelo. Se realizaron tres tratamientos: sequía con intercepción del 50% (simula año seco), testigo y un tratamiento con riego (50% más de lluvia en el verano). Cada tratamiento tuvo tres repeticiones y en todos los casos se excluyó el pastoreo. El experimento contó con sensores de potencial hídrico mátrico (MPS-6) y temperatura de suelo (un sensor Decagon ECT por parcela a 10 cm de profundidad), y un pluviómetro (Decagon device ECRN – 100), todos conectados a un logger Decagon EM50 con frecuencia de registro horaria. La hipótesis de este trabajo fue que el riego durante el verano evitaría que el suelo se seque y que la intercepción de lluvia generaría un período seco más intenso y prolongado durante esta estación. En general, el suelo estuvo húmedo en el tratamiento irrigado, aunque se generaron breves períodos secos en los casos de lluvias escasas entre riegos. Las parcelas de intercepción tuvieron un período seco más intenso y más prolongado en el tiempo tal como se supuso, pero esto ocurrió solamente en el otoño. A principios de invierno el suelo alcanzó valores de capacidad de campo y permaneció así durante la primavera. Los períodos secos en la superficie del suelo fueron breves, ocurrieron en la estación cálida y dependieron de las lluvias estivales.

Soil salinization is a limiting factor for irrigated agriculture, and inappropriate irrigation and fertigation continues to worsen the problem, especially in arid regions. Determination of threshold soil salinity is of great environmental importance for salinity control in irrigation areas. A two consecutive year’s cotton field experiment was conducted to develop the dynamic threshold soil salinity (Sth) and quantitatively evaluate the effects of applying nitrogen on salinity stress alleviation. Four irrigation amounts (75%, 100%, 125%, and 150% of crop water requirement) and four nitrogen application rates (195, 255, 315, and 375 kg ha−1) were applied with groundwater and brackish water irrigation to produce the dynamic soil salinity (EC1:5) and mineral nitrogen (N) content pools with a wide range of values. Results showed that the EC1:5 and soil N pools were built-up in a range of 0.16−1.68 dS m−1 and 0.3–17.9 mg kg−1. The Sth for cotton at the seedling, squaring, flower boll, and mature stages were 0.69, 0.74, 1.02, and 1.02 dS m−1, respectively. Cotton crops presented the highest nitrogen uptake at optimal soil mineral nitrogen values of 12.7 and 16.2 mg kg−1 during the reproductive growth stage, and an appropriate nitrogen application rate increased the Sth by 19−126%. In addition, the linear equations of salt–nitrogen relation were determined and used to calculate the soil N under higher soil salinity (above the Sth) for maintaining cotton production. These findings produced a new perspective to determine threshold soil salinity and mitigate soil salt suppression by nitrogen management.

Leachate originating from municipal solid waste landfills poses a serious contamination threat to public health. The study performed a bio-physicochemical characterization of leachate from two landfills in Oman, i.e., Multaqa landfill leachate (MLL) and Barka landfill leachate (BLL) before and after rainfall. Samples were characterized for 92 parameters. Additionally, the leachate pollution index (LPI) was estimated to assess the expected contamination levels and potential environmental health risks. The study found a high value of the leachate parameters without any rainfall incidents. Pearson correlations (±ve) are seen at more than 90% in all cases, which is a strong association (r>0.75) for the measured parameters in both MLL and BLL. Rainfall significantly reduced the concentrations of organic contaminants and solids in leachate due to dilution. The study revealed about 18%–29% and 14%–28% reductions in the LPI sub-index for organic and inorganic contaminants, respectively, after rainfall. The overall LPI values were higher compared with similar findings from the literature. Such deviations could be attributed to the unsegregated nature of solid waste, resulting in the formation of contaminants or from the disposal of a high volume of solid waste in a smaller area. Therefore, the study recommends efficient management strategies for landfills to reduce potential leachate groundwater contamination.

Although playing an important role in shaping the environment, the mechanisms responsible for runoff initiation and yield in arid and semiarid regions are not yet fully explored. With infiltration-excess overland flow, known also as Hortonian overland flow (HOF) taking place in these areas, the uppermost surface ‘skin’ plays a cardinal role in runoff initiation and yield. Over large areas, this skin is composed of biocrusts, a variety of autotrophs (principally cyanobacteria, green algae, lichens, mosses) accompanied by heterotrophs (such as fungi, bacteria, archaea), which may largely dictate the infiltration capability of the surface. With most biocrust organisms being capable of excreting extracellular polymeric substances (EPS or exopolymers), and growing evidence pointing to the capability of certain EPS to partially seal the surface, EPS may play a cardinal role in hindering infiltration and triggering HOF. Yet, despite this logic thread, great controversy still exists regarding the main mechanisms responsible for runoff generation (runoff initiation and yield). Elucidation of the possible role played by EPS in runoff generation is the focus of the current review.

The main objective of this research paper was to find out the major governing factors controlling fluoride enrichment in groundwater resources in the Jaipur region of India. Chemical analysis of co...

The rainfall, one of the most important natural input resource for dryland agricultural production system, is erratic and temporal in nature. An attempt has been made to analyze thirty years (1990-2019) of meteorological data for prediction of probable week of onset and withdrawal of monsoon and to end with crop planning in North Gujarat region (India).The highest and lowest amount of weekly rainfall was observed in 27th and 39th SMW, respectively. The probability distribution functions viz. generalized extreme value, Gumbel maximum, Gamma and Weibull were found best-fit for prediction of weekly rainfall. The analysis revealed 26th SMW (25 Jun – 01 Jul) and onwards as the most suited sowing time of kharif crops. There are also chances of occurrence of moisture stress during 34th and 35th SMW. The results would be useful for agricultural scientists, researchers, decision makers and policy planners in the field of agricultural crop planning and irrigation management for semi arid regions.

Context Shifting agricultural operations to more sustainable management practices is needed in the face of a changing climate. Aims In this study, the short-term effects of three tillage systems (no tillage, minimum tillage and conventional tillage) on a wide selection of soil properties in a semi-arid agrosystem of eastern Tunisia were assessed. Methods The studied soil properties included saturation percentage, bulk density, penetration resistance, mean weight diameter, electric conductivity, soil reaction, soil organic matter, carbonates, available phosphorus and exchangeable potassium. The impacts of tillage systems on soil quality indices (SQI) developed based on the total set of properties (SQI-T), or a minimum set (SQI-M) selected through principal component analysis, were also investigated. Key results Relative to conventional tillage, no tillage increased bulk density, penetration resistance and electrical conductivity, whereas minimum tillage affected only saturation percentage and pH. No tillage and minimum tillage did not enhance soil quality relative to conventional tillage. The SQI-T and SQI-M were highly correlated (r = 0.93) to each other suggesting that the outcomes of the two indices are comparable. Principal component analysis efficiently selected the most influential indicators of the effects of tillage systems on soil quality. Conclusions and implications Farmers in the study region are encouraged to consider minimum tillage during the early years of transition from standard to no tillage systems to avoid rapid decline in soil quality and consequent yield loss.

A field experiment was conducted during rabi 2016-17 and 2017-18, at the Research Farm of Department of Agronomy, Punjab Agricultural University, Ludhiana, to study the phenological behaviour of gobhi sarson (Brassicanapus L.) and thermal indices as influenced by drip irrigation (60, 80 and 100% of cumulative pan-evaporation, CPE) and fertigation schedules (60, 80 and 100 % recommended dose of fertilizers, RDF) in comparison with conventional flood irrigation and manual application of fertilizers i.e. absolute control. The pooled data revealed that Brassica irrigated through drip at 100 % of CPE took maximum number of days to attain 50% flowering, 50% siliqua formation and physiological maturity, followed by 80 and 60% of CPE. Higher fertigation levels also delayed the number of days taken to attain various phenological stages. Maximum seed yield was observed at 100% of CPE with 100% RDF which was statistically at par with 100% of CPE with 80% RDF and 80% of CPE with 80 or 100% RDF, but significantly higher than absolute control. Maximum accumulation of heat units along with heat use efficiency (1.49 kg grains ha-1 °C day hour-1) was also obtained at 100% of CPE with 100% RDF.

Brazil’s leadership in soybean and maize production depends on predictable rainfall in the Amazon-Cerrado agricultural frontier. Here we assess whether agricultural expansion and intensification in the region are approaching a climatic limit to rainfed production. We show that yields decline in years with unusually low rainfall or high aridity during the early stages of crop development—a pattern observed in rainfed and irrigated areas alike. Although agricultural expansion and intensification have increased over time, dry–hot weather during drought events has slowed their rate of growth. Recent regional warming and drying already have pushed 28% of current agricultural lands out of their optimum climate space. We project that 51% of the region’s agriculture will move out of that climate space by 2030 and 74% by 2060. Although agronomic adaptation strategies may relieve some of these impacts, maintaining native vegetation is a critical part of the solution for stabilizing the regional climate. Soybean and maize yields in the Amazon-Cerrado region of Brazil are dependent on water from rain. Warming and drying will make the climate less suitable for agricultural production; changes have already moved 28% of croplands out of their optimum climate space.

Previous studies on tidal flood mapping are mostly through continental- and/or global-scale approaches. Moreover, the few works on local-scale perception are concentrated in Europe, Asia, and North America. Here, we present a case study approaching a tidal flood risk mapping application in the face of climate change scenarios in a region with a strong environmental and social appeal. The study site is an estuarine cut in the Brazilian semi-arid region, covering part of two state conservation units, which has been suffering severe consequences from tidal flooding in recent years. In this case study, we used high-geodetic-precision data (lidar DEM), together with robust tidal return period statistics and data from current sea level rise scenarios. We found that approximately 327.60 km2 of the estuary is under tidal flood risk and in need of mitigation measures. This case study can serve as a basis for future management actions, as well as a model for applying risk mapping in other coastal areas.