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Increasing population, pollution of current natural resources, global warming and climate change are increasing pressure on water resources. To maintain the food security of the increasing population, it is essential to increase sustainable agricultural production and to use current limited water resources optimally. In this study, the effect of surface drip (SDI) and subsurface drip (SSDI) irrigation methods on water productivity, yield and quality characteristics of soybeans were evaluated. The study was carried out in Bati Akdeniz Agricultural Research Institute located in Antalya, Turkey. To evaluate the performance of the SDI and to compare it with the SSDI, an experiment was conducted based on a randomized blocks design with two factors: irrigation method (SDI and SSDI) and irrigation levels defined as the percentages of available water capacity of the soil profile (100%, 80%, 60%, and 0%). Applied water varied between 45–488 mm and 171–541 mm in the SSDI, and between 50–573 and 164–640 mm in the SDI, during 2016 and 2017, respectively. The yield ranged from 1.98 to 5.61 t ha−1 for SDI and from 2.29 to 6.33 t ha−1 for SSDI. While the increased amount of irrigation water had a positive relationship with the yield, there was a negative relationship with the oil content and fatty acid composition. The SSDI treatments used approximately 90 mm less water than the SDI without any reduction in yield.

Land capability and suitability maps are useful tools for soil resource conservation. This study aimed to build land capability and suitability maps using a multi-thematic approach by GIS in a salt-affected coastal area of Italy. Topographic, morphological, geological, pedological delineations and land cover maps, remote sensing image and climate data were acquired and the main physical and chemical properties, including electrical conductivity (EC) and available water capacity, were analysed on the soil samples collected in the study area. The acquired information were elaborated through QGIS software to obtain the land capability and suitability maps. The suitability map showed that most of the area (80%) is suitable for cultivation and, therefore, can be addressed for agricultural purposes without risk of degradation. In fact, the land capability map showed that 42% of the investigated area belongs to class I and II indicating that they can be used for a wide range of cultivations. While 44% of the investigated area clustered in class III and IV. In these latter the cultivation should be allowed to a limited range of crops due to the high sand content, which does not allow a good water retention, and due to a strong intrusion of sea water with consequent increase of the soil EC. In our study area, where agricultural productivity and environmental impact are in conflict, to classify the lands on base the land capability and suitability could help to define the best agricultural practices to apply in order to preserve soil functions.

Soil physico-chemical properties, biomass production, and root density are considered key factors indicating soil health in an agroecosystem. The soil physico-chemical changes and plant growth (e.g., shoot biomass production and root density) in a 6-year cultivation of plant species used as green manure in a sandy soil from Tropical ecosystem, North-eastern Brazil, were investigated between July and December 2019. We characterized soil physical and chemical properties, shoot biomass production, and root density under ten plant species used as green manure: Brachiaria decumbens Stapf. cv. Basilisk, Canavalia ensiformis (L.) DC, Crotalaria juncea L., Crotalaria ochroleuca G. Don, Crotalaria spectabilis Roth, Lablab purpureus (L.) Sweet, Mucuna pruriens (L.) DC, Neonotonia wightii (Wight & Arn.) J.A. Lackey, Pennisetum glaucum L., and Stilozobium aterrimum Piper and Tracy. The highest values of soil pH, exchangeable cations, CEC, and soil available water capacity were found on the plots where Poaceae plants were cultivated, whereas for H++Al3+, C.E.C., soil available water, and soil available water capacity were found on the plots where Fabaceae plants were cultivated. On the plots where C. ensiformis and N. wightii were cultivated, we found the highest shoot dry biomass and root density, respectively. The results highlight the importance to consider plant species from both Poaceae and Fabaceae family used as green manure as soil conditioner (by promoting soil fertility, nutrient cycling, and hydraulic properties into plant root zone), and thus creating a positive plant-soil feedback. Our findings suggest that (1) a consecutive green manure practice without any input of fertilizers after 6 years changed positively both soil physical and chemical properties, and improve plant growth (e.g., shoot dry biomass and root density) in tropical savanna climate conditions; and (2) by altering soil fertility, both Poaceae and Fabaceae plants used as green manure may create a sustainable cycle into the soil profile thus promoting soil health.

International audience; The purpose of this work was to: (i) propose a methodology to infer local estimates of the available water capacity (AWC) at a plot from a few measurements in laboratory of AWC carried out on horizons of a pit on the same plot, (ii) examine the effect of measurement errors on spatial estimates of AWC and the associated uncertainties. For each horizon identified in the pit, the water content was determined at field capacity and at the permanent wilting point, and thus AWC. 47 soundings were carried out on a regular grid covering the plot. For each sounding, an AWC value was estimated by matching sounding horizons to the pit horizons. Laboratory measurements of AWC on 14 sites were used to validate the 47 local estimates. Statistics such as correlation coefficient, mean error and root mean square error are promising at 0.84, 4.0 mm and 17.5 mm, respectively. The spatialization of AWC was carried out by ordinary kriging, considering or ignoring the measurement errors on AWC. The precision of AWC estimates allowed making evident that accounting for measurement errors provided estimates that were more precise. This result, confirmed by the prediction interval coverage probability statistic, underlined that taking into account measurement errors in spatial modeling is an effective way to reduce the confidence interval of any estimate. These results suggest that it would be better to fix the nugget based on a preliminary test on the measurement error rather than to fix it based on the experimental variogram.

The determination of site productivity in forest ecosystems plays a crucial role in resource management. This study was carried out to identify relationships between site characteristics and height growth of Corsican maritime pine (Pinus pinaster Ait.) plantations in Turkey. Sixty-nine sample plots > 20 years of age were selected from locations with different inclinations, aspects, elevations, slope positions and site class. Soil samples were taken at various depths. Height and age were measured on a dominant tree after felling in each plot. Physical and chemical properties of the soil were determined. Relationships between site index (SI25) and physiographic factors, climatic attributes as well as soil properties were evaluated using correlation analysis and multiple regression analysis. Site index was significantly related with annual precipitation, mean spring rainfall, rainfall June to September, rainfall of the driest month, length of the dry period, mean maximum temperature, mean temperature of the warmest month, stoniness of the soil, sand, silt, clay, pH, electrical conductivity, and available water capacity. Multiple regression accounted for 57.9% of variations in height growth. The models obtained can be used to determine the site index of potential areas in Turkey for maritime pine. It can be said that the productivity of maritime pine may decline in the future due to global climate change.

Soil health (SH) is important to the economics and environmental impacts of crop production, including coffee (Coffea spp.) culture. This study was conducted to gain insights into farmers9 perceptions related to SH concepts and their realities on Colombian coffee farms. A total of 223 soil samples were collected from 145 coffee farms in Cauca, Colombia, that vary by municipality, their membership status with a coffee co-op (member or non-member), and farmer gender. Samples were analyzed for 13 SH indicators, including wet aggregate stability (WAS), available water capacity (AWC), respiration rate, pH, active carbon (AC), organic matter (OM), protein, phosphorus (P), potassium (K), magnesium (Mg), iron (Fe), manganese (Mn), and zinc (Zn). Farmer co-op membership and municipality, but not farmer gender, were significant factors for SH status on farms. Farmer co-op members were asked to identify on their farms the plot that they perceived to have the highest soil fertility and the plot with the lowest soil fertility, which allowed for the evaluation of (1) the correctness of farmers9 SH perception, i.e., whether their perception was aligned with or similar to scientific measurements of SH, and (2) which SH indicators strongly influence farmer perception of SH. Farmers9 perceptions were found to be in line with the scientific laboratory measurements of SH, and their perceptions were significantly positively influenced by the soil9s organic matter and protein contents but negatively influenced by soil respiration. Finally, SH perception correctness was not correlated with farmer gender, locality, or SH conditions.

Aim of study: Evaluating the variability of physical and chemical soil properties under different soil uses in an experimental farmland of the southwestern Colombian Andes.Area of study: This research was conducted at the Botana Experimental Farm in the mountainous area of Nariño, at the south-western Colombia.Material and methods: nine soil variables were measured under six soil uses which included traditional agriculture, agroforestry systems, and a 67-year-old secondary forest that was used as a reference for comparisons with other soil uses. Data was analyzed through Principal Component Analysis and Duncan’s tests.Main results: organic carbon, cation exchange capacity, clay contents and base saturation were the variables with higher variability among soil uses. The secondary forest and an agroforestry system with alley-cropped wax laurel showed the best soil conditions, whilst pastures and monoculture potato crop plots showed the least desirable conditions for all variables.Research highlights: We found that soils under alley-crop with wax laurel presented the characteristics most similar to the secondary forest. Conversely, soils under alley-crop with alder resembled the soils under intensive management (pasture and potato monocrop); which is related to the inadequate management of this agroforestry systems, provoking that the woody component does not accomplish its goal when implemented.Keywords: soil; agroforestry systems; Andes; forest.Abbreviations used: ACAL, Alley cropping of Alder Trees, ACWL; Alley cropping of Wax Laurel; AFS, agroforestry systems; AWC, available water capacity; BD, Bulk Density; BS, Base saturation; CEC, Cation Exchange Capacity; CLA, Clay; CI, Confidence Intervals, INF, Infiltration; ANOVA, Analysis of Variance; OC, Soil Organic Carbon; PAST, Pasture; PCA, Principal Component Analysis; PC, Principal Component; POCR, Potato Crop; POR, Soil Porosity; SCAL, Scattered Alder Trees; SEFO, Secondary Forest; SU, soil uses; AU, Animal unit.

International audience; Soil available water capacity (SAWC) is a key soil indicator that plays a major role in many ecosystem services, such as food production, irrigation management, soil drought, flood control, and climate and gas regulation. Digital soil mapping (DSM) can be used to obtain needed SAWC maps. However, SAWC differs from the usual soil properties considered in DSM in that it involves several soil properties determined at several soil layers. Therefore, a specific approach is required to obtain SAWC maps and the associated uncertainty predictions.The objective of this study was to build a SAWC mapping approach that could predict SAWC values at three maximum rooting depths (60, 100 and 200 cm) and their associated prediction uncertainties.The approach was tested in the Languedoc-Roussillon region (southern France). Elementary available water capacities of each layers (in cm.cm−1) and soil layer thicknesses were first mapped separately at 0–30, 30–60, 60–100 and 100–200 cm and then aggregated to estimate the SAWCs at the three mentioned maximum rooting depths. SAWC uncertainty was estimated with an error propagation model that used a first-order Taylor analysis. This analysis considered the mapping errors of each involved property, which were estimated by the quantile regression forest algorithm. We tested different error propagation models that differently considered the correlations between these mapping errors: no correlation considered, correlations between soil layer thicknesses and elementary water capacities per soil layer only, correlations between soil layers only, or all correlations considered.The performances of both SAWC predictions and their uncertainties were assessed with a 10-fold cross validation that was iterated 20 times. The SAWC predictions showed poor accuracies (percentages of explained variance ranged from 0.12 to 0.13). The uncertainties of SAWC predictions were best estimated when the correlations between the soil layer errors were considered in the error propagation model whereas the uncertainties of SAWC predictions were severely underestimated when these correlations were neglected.In spite of the poor performance in predicting SAWC at the punctual level due to the low density of soil observations (1/19 km2), the SAWC approach appeared promising since it produced maps that agreed with the available pedological knowledge and precisely estimated the uncertainties.

International audience; Conservation agriculture has been developed as a means to improve the sustainability of agricultural systems and reduce drawbacks of conventional agricultural practices. Cropping practices can have a large influence on soil properties such as water retention. Proper tools are needed to assess and model effects of conservation agriculture on soil properties. As measuring soil water retention is expensive and time consuming, pedotransfer functions (PTFs) are now commonly used to predict them. The objectives of this study were to (i) present a new dataset of conservation agriculture data, (ii) assess performances of existing PTFs in predicting soil water retention of soils under conservation agriculture and (iii) develop new specific PTFs to predict water retention in conservation agriculture more accurately. We used data collected only in fields under conservation agriculture in France to evaluate several published PTFs with three evaluation criteria (RMSE, prediction bias (ME) and Nash-Sutcliffe Efficiency (EF)). We then developed new PTFs using three methods - multiple linear regression, regression tree and random forest - to predict soil water content at matric heads of -100 (theta(100), field capacity for sandy soils), -330 (theta(330), field capacity for other soils) and -15 000 cm (theta(15) 000, wilting point). Soil tillage, presence of a cover crop, rotation length and previous reduced/no tillage were used as predictors in addition to basic soil properties for regression trees and random forests. The quality of prediction (RMSE, ME and EF) was calculated for each new PTF using a cross-validation procedure. Generally, predictions of wilting point had lower absolute error than those of sandy-soil field capacity (RMSE = 0.044 and 0.066 cm(3)/cm(3), respectively). EF was usually negative for all water contents. The cross-validation performance of the new PTFs was similar for multiple linear regression (RMSE: 0.028, ME: 0.000, EF: 0.34 for theta(100)) and random forest (RMSE: 0.027, ME: 0.000, EF: 0.36 for theta(100)), and generally worse for regression tree (especially EF). Multiple linear regression that did not consider cropping practices performed as well as random forest and thus did not identify any major influence of agricultural management on predicted water content. Future research on developing PTFs should focus on identifying more relevant predictors.

Better understanding the variabilities in crop yield and production is critical to assessing the vulnerability and resilience of food production systems. Both environmental (climatic and edaphic) conditions and management factors affect the variabilities of crop yield. In this study, we conducted a comprehensive data-driven analysis in the U.S. Corn Belt to understand and model how rainfed corn yield is affected by climate variability and extremes, soil properties (soil available water capacity, soil organic matter), and management practices (planting date and fertilizer applications). Exploratory data analyses revealed that corn yield responds non-linearly to temperature, while the negative vapor pressure deficit (VPD) effect on corn yield is monotonic and more prominent. Higher mean yield and inter-annual yield variability are found associated with high soil available water capacity, while lower inter-annual yield variability is associated with high soil organic matter (SOM). We also identified region-dependent relationships between planting date and yield and a strong correlation between planting date and the April weather condition (temperature and rainfall). Next, we built machine learning models using the random forest and LASSO algorithms, respectively, to predict corn yield with all climatic, soil properties, and management factors. The random forest model achieved a high prediction accuracy for annual yield at county level as early as in July (R2 = 0.781) and outperformed LASSO. The gained insights from this study lead to improved understanding of how corn yield responds to climate variability and projected change in the U.S. Corn Belt and globally.

The spatial distribution and density of different weed species were monitored during a long-term survey over a period of 9 years on a 5.8 ha arable field and related to soil properties. Weed seedlings were determined every year in spring on a regular grid with 429 observation points (15 × 7.5 m; net study area = 4 ha). Dominant weed species were Chenopodium album, Polygonum aviculare, Viola arvensis and different grass weeds, clearly dominated by Alopecurus myosuroides. A non-invasive electromagnetic induction survey was conducted to evaluate available water capacity directly in the field at high spatial resolution. Further soil properties were evaluated following the minimum-invasive approach with soil sampling and subsequent mid-infrared spectroscopy. Plant available nutrients were analysed with conventional lab methods. Redundancy analysis served to describe the effect of soil properties, different years and field crops on weed species variability. Seven soil properties together explained 30.7% of the spatial weed species variability, whereas 28.2% was explained by soil texture, available water capacity and soil organic carbon. Maps for site-specific weed management were created based on soil maps. These maps permit several benefits for precision crop protection, such as a better understanding of soil–weed inter-relations, improved sampling strategies and reduction in herbicide use.

This study mainly focused on the impacts of vermicompost (VC) treatments on physicochemical characteristics of sandy-clay-loam soil and lettuce (Lactuca sativa var. crispa) yield in a green...

Soil physical and chemical properties can be amended by application of organic residues, such as spent coffee grounds (SCG). In this work we examined SCG effects on the modification of some soil physical-hydraulic properties, such as soil water retention and aeration, investigating beneficial uses for this waste product. Soil properties were evaluated using pots filled with a mixture of a sandy loam soil with the contents of 0, 5, 10, 15 and 20% of SCG. The most relevant soil properties to the purposes were the moisture at container capacity (θcc), readily available water capacity (RAWC) and drainable porosity (ϕD). Additionally, under the hypothesis that SCG can be used as soil conditioner, lettuce crop, cultivar “Mimosa Roxa Roxanne”, was transplanted to the pots where the leaf area index and the cumulative biomass throughout the growing cycle were examined. Comparing to the absence of SCG (0%), soil SCG contents of 5, 10, 15 and 20% presented larger values of θcc and consequently larger RAWC and smaller ϕD. Although the increase of soil water storage from 43.2 (0%) to 53.3 (20%) mm, crop development was prejudiced by the reduction on ϕD from 0.1595 (0%) to 0.0827 (20%) m3 m−3, which affected soil aeration. This greater water availability, obtained with the increase of θcc, was promoted by the residue addition pointing out for a possible use of SCG to increase water retention for other crops.

Soil plays a pivotal role in enhancing global water and food security. Irrigation water constitutes more than 70% of the global water demand. The anticipated demographic increase and changing climate will impose more pressures on the global water and food systems. Therefore, and to achieve the target of “more crop per drop per area”, water management plans must be based on more accurate quantitative and dynamic approaches. It is increasingly obvious that the unique aggregates structure of the soil medium regulates water and nutrient circulations, and consequently defines soil and water health, productivity, and water use efficiency. However, the soil aggregates structure is not currently well considered in the quantification of soil–water holding properties. The authors applied a thermodynamic and soil structure-based approach to quantify soil–water holding properties. Specifically, the paper aims at providing a methodology, based on the pedostructure concept, to quantify field capacity (FC), permanent wilting point (PWP), and plant available water (AW). Pedostructure is a representative aggregates unit of a soil horizon that describes the structural organization of the soil medium. Four types of soil were analyzed considering various soil texture and aggregates structure: loamy fine sand, silt loam, clay loam, and silty clay loam. The calculated values for FC and PWP, based on the proposed pedostructure method, were compared with the recommended values by the standard FAO method and soil suction method. Results showed good agreement between the calculated values of the two methods. The proposed pedostructure method introduces a shift in quantifying the plant available water from a texture-based estimation to a soil aggregates structure-based calculation. Such a shift will enable capturing the changes in soil aggregates structure due to agro-environmental practices and the associated impact of these changes on soil–water holding properties.

Quantifying soil water storage is important for plant growth and agricultural production. This is particularly important in sandy soils because they are widely cultivated and prone to drought. We investigated the effect of soil organic carbon (SOC), soil texture and gravel content on soil moisture characteristics in sandy soils. Soil moisture characteristics were analysed using standard soil physical characterization as well as visible–near infrared (vis–NIR) spectroscopy and pedotransfer functions (PTFs). Volumetric water content (−10, −33, −1500 kPa) and available water capacity (AWC) increased by 0.01 to 0.02 m³m⁻³ with a 2% increase in silt plus clay content. Available water capacity increased by about 0.05 m³m⁻³ with a 1% increase in SOC. A 5% increase in gravel in the subsoil decreased the volumetric water content of the soil by 0.01 m³m⁻³. Predictions of volumetric water contents and AWC by vis–NIR were the best when using a random forest model. Pedotransfer functions for AWC predictions performed best when sand, silt, clay, bulk density and SOC were included. Soil moisture storage ranged from 44 to 65 mm in the top 50 cm. At mean evapotranspiration (4.2 mm day⁻¹), irrigation requirements were reduced by 6 days in the sandy soils that have larger SOC and silt contents in the topsoil. These soils are sandy throughout but have subtle differences in particle‐size distribution, SOC concentrations and gravel content. These differences affect soil moisture storage considerably. Soil management practices that increase the SOC contents in these sandy soils favour moisture storage and tend to reduce irrigation requirements. HIGHLIGHTS: SOC, soil texture and gravel affect soil moisture characteristics in sandy soils. With vis–NIR and PTFs, soil water storage, water characteristics and AWC in soils with >80% sand can be quantified and predicted. Available water capacity increased by about 0.05 m³m⁻³ with a 1% increase in SOC. Subtle differences in particle‐size distribution affect soil moisture storage and reduce irrigation requirements.

Accurate knowledge of the soil water retention curve (WRC) is essential for various hydrological and plant-physiological studies. Currently, there is a lack of a uniform protocol for measuring the wilting point water content (WP) with the dewpoint method (DP), despite its ecological relevance and frequent use to calculate available water capacity. We present a new protocol for measuring the WP with the dewpoint method. In contrast to existing methods which add or remove specific amounts of water to moist, air-dry, or oven-dry soil, we propose to apply the dewpoint method after the evaporation method in which tensiometers measure the pressure head of the soil. We suggest to stop the evaporation experiment when the air-entry of one tensiometer cup is reached, to slice the soil core into slabs, and to apply the dewpoint method to subsamples of the slabs. We test the method by numerical simulations and laboratory experiments on five soils covering a broad range of texture. We investigate the accuracy, robustness, and practicability of the new method and compare it to the existing protocols for the dewpoint method and the pressure plate technique. We find that the proposed method allows a precise determination of the WP and the WRC across the full moisture range. It is easy to perform, robust, accurate, and does not require any a priori guess about the amount of water to be added or removed. By fitting a retention curve to the measured data, any water content, including the WP, can be obtained with great confidence.

The type of stratum in dryland ephemeral channel beds (wadis) determines its hydrological characteristics, which impact vegetation productivity. The objective of this study was to assess some key properties of a cemented, fine-grained bed stratum, previously characterized as a fluvio-pedogenic unit (FPU), as well as those of the overlying non-cohesive gravel bed stratum, known as a fluvially active unit (FAU). While the latter is an outcome of regular fluvial processes of recurring scour and fill, the former is characterized by horizonation, calcium carbonate deposition, oxidation, and accumulation of fine-grained material, defining it more as a soil or pseudo soil than as a sediment. The study was conducted in the hyper-arid southern Negev and Arava Valley of Israel, where the FAU and the underlying FPU were investigated, focusing on geo-ecological functioning. The results revealed considerable differences between the two types of strata. The contents of hygroscopic moisture, total organic carbon, and calcium carbonate were fourfold, 57%, and 36% greater, respectively, in the FPU than these in the FAU. Above all, the fine particle contents, including the clay and silt fractions, were almost eightfold and almost sixfold greater, respectively, for the FPU than those for the FAU, characterizing the former as loamy fine sand and the latter as fine sand. Altogether, these properties determine the stratum's field capacity and permanent wilting point, which were 73% and 50% greater, respectively, in the FPU than those in the FAU. In turn, the last two properties determine the available water capacity, which was almost twofold greater under the FPU than that under the FAU. Considering the (i) FPU's mean thickness of 0.6 m; (ii) FPU's horizonation into A, B, and C horizons; and (iii) a 70–90% decrease in available water capacity between FPU's A and B horizons, as well as between its B and C horizons, then the total available water capacity throughout this stratum's thickness is 20–87% greater under the FPU than that under the FAU. In addition, the FPU's cemented nature seems to provide a safe stratum that remains stable during floods, sustaining the establishment and growth of deep-rooted perennial vegetation. It is concluded that the FUP's properties have positive implications for vegetation growth and survival under the harsh climatic conditions across the region.

A key determinant of water-limited yield potential in dryland agriculture is the soil's plant available water capacity (PAWC), the difference between drained upper limit and crop lower limit over the rooting depth. To simulate water-limited yield potential (Yw), a crop model must be parameterised for the local edaphic conditions, which require a quantitative description of drained upper limit, crop lower limit and rooting depth. Often, these soil properties have to be estimated from existing soil surveys, which creates uncertainty for drained upper limit, crop lower limit or rooting depth. The impact of uncertainty in these soil properties on the estimation of Yw has not previously been reported. Using the Agricultural Production Systems sIMulator (APSIM), a sensitivity analysis was performed to identify the effect of uncertainties in drained upper limit, crop lower limit and rooting depth on wheat Yw for two contrasting rainfall sites (high and low) with two typical soil types (shallow sandy duplex and clay) in Western Australia. Simulation results demonstrated that the resultant change in PAWC was the dominant driver of a change in the estimate of Yw, irrespective of whether such a change was caused by drained upper limit, crop lower limit or rooting depth. Estimated errors that underestimated or overestimated PAWC by up to 20 mm only had a marginal impact on Yw (less than 200 kg ha−1) in all environments (soil type × location). But when this error was more than 20 mm, an underestimation would cause more severe deviation of Yw of wheat than an overestimation. On average, 40 mm underestimation of PAWC resulted into 530 kg ha−1 of Yw, while this amount of overestimation caused overestimation of Yw about 290 kg ha−1. The bias of underestimated wheat Yw due to underestimation of PAWC was generally increased with rainfall up to 350 mm. We conclude that it is better to estimate soil hydrological parameters towards overestimating PAWC than to underestimate PAWC. However, where possible, all three soil hydrological parameters should be estimated as accurately as possible.

The quality of a soil is its ability to deliver functions providing ecosystem services, human health and well-being. Soil physical quality (SPQ) values use different parts of the soil water retention curve (SWRC) to calculate SPQ. For example, the plant available water capacity (PAWC) method is the difference in water content between permanent wilting point and field capacity. The S-index uses the slope of the SWRC at its inflection point and the relative air-water energy (AWr) is the integral of “dry” divided by the “wet” area of the SWRC. Increasing demand for soil monitoring policies calls for reliable and sensitive soil quality indicators (SQIs). The objectives of the study were to assess the sensitivity and applicability of SPQ indicators using direct and indirect data inputs. The indirect approach provided sufficient data complexity for the PAWC and S-index values, but the more complex AWr required the direct approach. PAWC and S-index values were identified as static SPQ indicators. The values obtained from these approaches should be used to form baseline static datasets and therefore have an indicative role only. The AWr value was identified as a dynamic SPQ indicator and provided required sensitivity to pick up temporal changes in SPQ. This indicator could be used at multiple scales and could even guide grassland management in terms of SPQ. Higher SWRC data resolution will require more complex hydraulic models to fit and will ultimately improve the accuracy of soil hydraulic data and improve the sensitivity of AWr as a SPQ indicator.

Wastewater reuse is a practice that has been gaining attention for the past few decades as the world's population rises and water resources become scarce. Wastewater application on soil can affect soil health, and the manner and extent to which this occurs depends heavily on soil type and water quality. This study compared the long-term (15+ years) effects and suitability of using secondary-level treated municipal wastewater and brackish groundwater for irrigation on the water holding capacity of a clayey, calcareous soil on a cotton farm near San Angelo, Texas. The soil-water holding properties were determined from the extracted hydrostructural parameters of the two characteristic curves: water retention curve and soil shrinkage curve based on the pedostructure concept. In the pedostructure concept, these hydrostructural parameters are characteristic properties of the soil aggregates structure and its thermodynamic interactions with water. Results indicate that use of secondary treated wastewater increased available water capacity in the top horizon (0–15 cm) and decreased the available water holding capacity of this particular soil in the sub-horizons (15–72 cm). The brackish groundwater irrigation resulted in no effect on available water capacity in the top horizon, but significantly decreased it in the sub-horizons as well. The rainfed soil was the healthiest soil in terms of water holding capacity, but rainfall conditions do not produce profitable cotton yields. Whereas, treated wastewater irrigated soil is producing the highest yields for the farmer. Thus, this treated wastewater source and irrigation system can serve as a suitable irrigation alternative to using brackish groundwater, enhancing the water resource sustainability of this region.

International audience; Although considerable work has been conducted in recent decades to build soil databases, the legacy data from a lot of former soil survey campaigns still remain unused. The objective of this study was to determine the interest in harvesting such legacy data for mapping the soil available water capacities (SAWCs) at different rooting depths (30 cm, 60 cm, 100 cm) and to the maximal observation depth, over the commune of Bouillargues (16 km2, Occitanie region, southern France).An increasing number of available auger hole observations with SAWC estimations – from 0 to 2781 observations – were added to the existing soil profiles to calibrate quantile regression forests (QRFs) using the Euclidean buffer distances from the sites as soil covariates. The SAWC was first mapped separately for different soil layers, and the mapping outputs were pooled to estimate the required SAWC. The uncertainty of the SAWC prediction was estimated from the estimated mapping uncertainties of the individual soil layers by an error propagation model using a first-order Taylor analysis.The performances of the SAWC predictions and their uncertainties were evaluated with a 10-fold cross validation that was iterated 20 times. The results showed that the use of a quantile regression forest that was fed with auger hole observations and that used the Euclidean buffer distances as soil covariates considerably augmented the performances of the SAWC predictions (percentages of explained variance from 0.39 to 0.70) compared to the performance of a classical DSM approach, i.e., a QRF that solely used soil profiles and only environmental covariates (percentages of explained variance from 0.04 to 0.51). The analysis of the results revealed that the performances were also dependent on the spatial patterns of the different examined SAWCs and was limited by the observational uncertainties of the SAWCs determined from auger holes. The best performance tended to also provide the best view of the uncertainty patterns with an overestimation of uncertainty.Despite these gains in performance, the cost-efficiency analysis showed that the augmentation of soil observations was not cost efficient because of the highly time-consuming manual data harvesting protocol. However, this result did not account for the observed gain in map details. Furthermore, the cost efficiency could be further improved by automation.

Vineyard soils show an increased risk of degradation due to being intensively cultivated. The preservation of soil integrity and fertility is a key concept of organic and biodynamic farming. However, both systems are also subject to criticism due to their higher amount of plant protection products used and their increased traffic intensity compared to integrated viticulture, both detrimental to soil quality. The aim of this study was therefore to assess long-term effects of these three management systems on chemical and physical soil quality parameters. For this purpose, topsoil samples were taken in a long-term field trial vineyard at different positions and examined for bulk density, available water capacity (AWC), soil organic carbon (SOC), N, pH, and for total and bioavailable copper (Cu) concentrations. Biodynamic plots had a lower bulk density and higher SOC concentration than the integrated ones, which is probably due to the species-rich cover crop mixture used in the inter-row. However, organic and biodynamic farming showed an accumulation of copper in the under-vine area and in the tractor track, which is problematic for soil fertility in the long-term. Therefore, alternatives for copper in plant protection are necessary to ensure sustainable soil quality through organic and biodynamic viticulture.

Belowground roles of agroforestry in climate change mitigation (C storage) and adaptation (reduced vulnerability to drought) are less obvious than easy-to-measure aspects aboveground. Documentation on these roles is lacking. We quantified the organic C concentration (Corg) and soil physical properties in a mountainous landscape in Sulawesi (Indonesia) for five land cover types: secondary forest (SF), multistrata cocoa&ndash, based agroforestry (CAF) aged 4&ndash, 5 years (CAF4), 10&ndash, 12 years (CAF10), 17&ndash, 34 years (CAF17), and multistrata (mixed fruit and timber) agroforest (MAF45) aged 45&ndash, 68 years. With four replicate plots per cover type, we measured five pools of C-stock according to IPCC guidelines, soil bulk density (BD), macro porosity (MP), hydraulic conductivity (Ks), and available water capacity of the soil (AWC). The highest C-stock, in SF, was around 320 Mg ha&minus, 1, the lowest, 74 Mg ha&minus, 1, was in CAF4, with the older agroforestry systems being intermediate with 120 to 150 Mg ha&minus, 1. Soil compaction after forest conversion led to increased BD and reduced MP, Ks, and AWC. Older agroforestry partly recovered buffering: AWC per m of rooted soil profile increased by 5.7 mm per unit (g kg&minus, 1) increase of Corg. The restored AWC can support about a week&rsquo, s worth of evapotranspiration without rain, assisting in climate change adaptation.

Objetivou-se no presente estudo, avaliar a área foliar, a Clorofila a, b e total e o índice SPAD do girassol cultivada sob diferentes condições de déficit hídrico e, níveis de adubações com NPK de origem mineral e organomineral. O experimento foi conduzido em vasos plásticos preenchidos com Latossolo Vermelho distroférrico, localizado em área experimental do Instituto Federal Goiano, no município de Rio Verde, Goiás. O delineamento experimental utilizado foi o de blocos ao acaso analisado em esquema fatorial 4×4×2, com três repetições. Os tratamentos foram as combinações de quatro reposições hídricas iguais a 50, 75, 100 e 125% da capacidade de água disponível no solo; quatro doses do formulado de NPK referentes a 50, 100, 150 e 200% da recomendação e duas fontes do formulado NPK, mineral e organomineral. As reposições hídricas foram determinadas através de lisímetros de pesagem eletrônica e a água aplicada via sistema de gotejamento superficial. O número de folhas, a área foliar, a clorofila a, clorofila b, a clorofila total e o índice SPAD foram avaliados aos 20, 40, 60 e 80 dias após a semeadura. A reposição hídrica de 125% proporciona o maior número de folhas e área foliar do girassol cv. Aguará 6. O número de folhas, área foliar e índice SPAD do girassol cv. Aguará 6 é maior quando se utiliza o fertilizante mineral.

Conservation agriculture is increasingly accepted by farmers, but the modeling studies on agro-environmental processes that characterize these agricultural systems require accurate information on the temporal variability of the soil&rsquo, s main physical and hydraulic properties. Therefore, specific investigations carried out in long-term experiments can increase our knowledge on the pros and cons of different measurement techniques. In this work, the simplified falling head (SFH) technique and the Beerkan Estimation of Soil Transfer (BEST) procedure were applied to investigate the temporal variability of some main soil physical and hydraulic properties, including bulk density (BD), field saturated hydraulic conductivity (Kfs), macroporosity (Pmac), air capacity (AC), plant available water capacity (PAWC), and relative field capacity (RFC). For this purpose, a long-term experiment was selected, and the experimental information obtained was used to verify the long-term impact (fifteen years) determined by two alternative forms of soil management, minimum tillage (MT) and no tillage (NT), for the cultivation of durum wheat. The main results of the comparison between MT and NT showed: (i) A comparable temporal variability in Kfs values when SFH was considered, given that in 75% of considered cases, the same result (i.e., significant or not significant) was obtained, (ii) a comparable temporal variability in Kfs values under MT (but not under NT) when both SFH and BEST were used, as a result of a possible Kfs,SFH overestimation under NT, (iii) differences in Kfs estimations by a factor of 6 or 7 (Kfs,SFH &gt, Kfs,BEST) when comparable soil conditions (moisture and soil density) were considered, (iv) a comparable temporal variability when other soil indicators (BD, Pmac, AC, PAWC, and RFC) were simultaneously considered. After about fifteen years of field experiments characterized by continuous soil management and conducted with the methodological rigor typical of experimental farms, the SFH- and BEST-derived experimental information showed a substantial equivalence between MT and NT for the fine-textured soil investigated.

The positive effect of soil organic matter (SOM) on crop yield has historically been attributed to the ability of SOM to supply crops with nitrogen and water. Whether management-induced increases in SOM meaningfully supplement water supply has received recent scrutiny, introducing uncertainty to the mechanisms by which SOM benefits crops. Here, we posit that to benefit crops SOM does not need to increase the supply of a growth-limiting resource; it only needs to facilitate root access to extant resource stocks. We highlight evidence for the ability of SOM to alleviate negative impacts of inadequate aeration (mainly waterlogging) and compaction on roots. Waterlogging, even if transient, can permanently downregulate root biosynthesis and call for expensive growth of new roots. Management practices that promote SOM reduce waterlogging by accelerating water infiltration and may promote aeration in non-saturated soils. Compaction as a restriction to root development manifests in drying soils, when mechanical impedance (MI) inflates photosynthate required to extend root tips, leading to short, thick, and shallow roots. SOM reduces MI in dry soils and is associated with root channels to subsoil, granting crops access to deep soil water. Both waterlogging and compaction necessitate additional belowground investment per unit resource uptake. In this framework, crop response to SOM depends on interactions of crop susceptibility to inadequate aeration or compaction, soil moisture, and “baseline” soil aeration and compaction status. By exploring the proposition that SOM catalyzes resource uptake by permitting root development, future research may constrain crop yield improvements expected from SOM management.

International audience; Soil available water capacity (SAWC) is a key soil function for plant growth. Classical SAWC characterization requires time consuming determinations of bulk density and specific soil moisture contents. Consequently, these data are extremely sparse in existing soil databases. Using surrogates of the vegetal response to characterize SAWC across a great number of sites constitutes a promising perspective. The carbon isotope ratio (δ13C) measured in a plant organ is largely known as an indicator of plant water status. The aim of the paper is to test δ13C as an indicator of SAWC in rainfed vineyard.δ13C values of grapes at harvest time were measured at 21 sites on the Languedoc vineyard plain with contrasting SAWC (33 to 308 mm) for four years (2015 to 2018) with contrasting annual precipitation (from 390 to 715 mm). The relationships between δ13C and SAWC determined using a classical approach (soil description, soil sampling and laboratory methods) were satisfactory for all years (RMSEs from cross validation were between 35 and 61 mm). Better relationships were obtained between δ13C and SAWC for years that showed a full winter recharge of SAWC (2015, 2017 and 2018). Averaging the δ13C measurements over such years provided an even better relationship (R2 = 0.85; RMSE 32 mm), which was successfully validated in distant sites on the Languedoc vineyard plain.This work demonstrated that δ13C can be considered as a simple and inexpensive surrogate for estimating SAWC. In addition to considerably increasing the density of SAWC measurements, the use of δ13C would lead to better consideration of the contribution of deep horizons in the case of perennial plants. Application of this isotopic technique to other agro-systems is required to better define the potential areas of use of δ13C.

Highlights • The rate of change in pore size distribution was quantified. • It was faster to degrade than to restore a complex soil structure. • Introducing grassland in degraded soil may induce densification in the short-term., Changes in land use affect the pore size distribution (PSD) of the soil, and hence important soil functions such as gas exchange, water availability and plant growth. The objective of this study was to investigate potentially damaging and restorative soil management practices on soil pore structure. We quantified the rate of change in PSD six years after changes in land use taking advantage of the Highfield land-use change experiment at Rothamsted Research. This experiment includes short-term soil degradation and restoration scenarios established simultaneously within long-term contrasting treatments that had reached steady-state equilibrium. The land-use change scenarios comprised conversion to grassland of previously arable or bare fallow soil, and conversion of grassland to arable and bare fallow soils. In the laboratory, we exposed intact soil cores (100 cm3) to matric potentials ranging from −10 hPa to -1.5 MPa. Based on equivalent soil mass, the plant available water capacity decreased after conversion from grassland, whereas no change was observed after conversion to grassland. Structural void ratio decreased after termination of grassland and introduction of grassland in bare fallow soil, while no change was seen when changing arable to grassland. Consequently, it was faster to degrade than to restore a complex soil structure. The study illustrates that introducing grassland in degraded soil may result in short-term increase in soil density.

International audience; During the last 10 years, several attempts to map soil attributes at the scale of mainland France have been realised. We exemplify them by seven major outputs: maps of organic C stocks, trace elements (TE), microbial density and diversity, soil thickness, available water capacity (AWC), extractable P, and changes in soil pH. We first briefly describe the data and the methods used to produce these maps and summarise their main results. We then focus on their impacts on various categories of the public, i.e. the general public and citizens; farmers; private companies; non-governmental organisations; agricultural development organisations, stakeholders, and national agencies; French governmental bodies; and international organisations. We also analyse the demands that came to the French National Soil Information Centre from 2008 to 2018 and the impact that our activities had in various media. Soil organic C had the largest impact in nearly all categories of end-users, which may be linked to the recent ‘4 per 1000’ initiative launched by the French governmentduring the COP21 and to the fact that farmers are interested in increasing the organic matter content of their soil for increasing the fertility. TE obtained high scores, which may be related to citizens' care about health and to the fact that governmental bodies and national agencies have a major interest in site contamination assessments. The soil P content, pH, and AWC exhibited major impacts on the agricultural sector. Maps of the soil P content and pH were used as geomarketing tools by private companies selling fertilisers and soil amendments, whereas the AWC was already incorporated into decision-making aid tools for irrigation management developed by development organisations for farmers. Microbial diversity generated collaborations with a large network of farmers and had a large media impact. Nevertheless, the visibility of soil information to the general public should be increased. This can be done by using new multimedia and interactive tools. Overall, these selected examples of digital soil mapping of soil attributes at the national scale in France clearly indicate that the soil attributes have substantial impact on various categories of end-users, such as farmers, professional organisations, stakeholders, and policymakers at different levels of decision-making, among others. However, the impacts on the general public and citizens are more difficult to quantify, and increasing the soil awareness of the general public should be of high priority.

International audience; Soil available water capacity (SAWC) is becoming a crucial issue for forest management in the context of climate change. However, the SAWC indicator, which was created for agricultural soils, needs specific adaptations when it is estimated for forest soils. This study aims to determine the best way to apply the SAWC indicator with regard to its significance for explaining variation in tree fertility across a given region. An extensive investigation with spatial sampling of 100 Douglas fir stand plots was conducted in the Haut Languedoc Regional Nature Parc (Southern France). It involved stand fertility assessments, morphological observations of deep soil pits including the saprolite, quantitative estimations of coarse fragments, texture and organic matter laboratory analysis and water retention and density measurements on a limited sample of horizons (35). Different approaches were used to compute SAWC from the collected data. These approaches differed in the methods i) for estimating the fine earth water retention - national vs local pedotransfer function -, ii) for incorporating coarse fragments - assumed to contribute or not to the water retention of soils- and iii) for estimating soil volumes - variable thicknesses and considerations of rooting. The results showed that the estimate of SAWC that explained the greatest variation in tree fertility over the study area (23% of the variance) was obtained by estimating fine earth water retention from a local pedotransfer function, by considering the water retention of the coarse fraction and by exploring the thickest soil volumes (thicknesses of 200 cm, 300 cm and equal to the depth to bedrock) without explicit consideration of rooting observations. The ranking of SAWC component impact on SAWC values was i) soil volume, ii) coarse fraction water retention and iii) fine earth retention. These results indicate that improvements in estimating coarse fraction water retention and soil volume and, to a lesser extent, fine-earth water retention estimated by a forestsoil-adapted pedotransfer function would greatly benefit the application of the SAWC indicator to forest soils.

In Chile, volcanic soils were developed under almost all of the diverse rain and temperature regimes, from the Arid Mediterranean to the Wet Zone of the South. Due to their andic properties, volcanic soils exhibit characteristics that are entirely different from other soil types around the world. The soil physical quality (SPQ) is strongly related to the functions of the soil pore system. Thus, soils characterized by a good SPQ have the ability to store and conduct water, air and nutrients promoting both: maximum crop yield and minimum environmental degradation. Many studies and much scientific progress have been made concerning the storing and conducting of water and air functions in volcanic soils. However, soil physical quality indicators and their temporal changes have been less studied. Thus, the objectives of this study were: i) to assess the impact of land use changes on the physical quality of three main volcanic soil groups in Chile, ii) to quantify the magnitude of their temporal changes and iii) to compare these results with threshold values found in the literature. Three soils derived from volcanic materials formed under different conditions and with different degrees of development were sampled (with different intrinsic properties), on five sampling dates, under three land uses (intensities): native forest (NF), prairie (P) and crops (C). Undisturbed samples were taken at two soil depths: 0–15 cm and 15–30 cm, in 230 cm3 metallic cylinders, and then covered with caps and plastic film to prevent mechanical disturbance and evaporation. We measured and /or calculated from these samples: air capacity (AC), plant available water capacity (PAWC), relative field capacity (RFC), bulk density (dB), air conductivity (kl), pore connectivity indexes (C2 and C3), the coefficient of linear extensibility (COLE) and saturated hydraulic conductivity (Ks). Undisturbed soil blocks were collected to evaluate aggregate stability. To assess differences among land uses and seasons in the SPQ indicators, analyses of variance (ANOVA) were used and an LSD test (p ≤ 0.05) was conducted to separate the means. A principal component analysis (PCA) was performed to associate the SPQ indicators. The results of this study allow us to conclude that the impact on SPQ indicators depended on the soil type, considering their degrees of development, clay content and type, as well as the organic carbon content and the season in which the soil functions were determined. When values of the SPQ indicators were compared with critical and/or threshold values of the mineral soils found in the literature, the indicators of dB and RFC fell completely out of the range considered typical for mineral soils. Thus, several questions remain regarding the real critical values of these soil properties in volcanic soils. More work is necessary to establish the critical value of volcanic soil’s bulk density, since this is a widely used soil property that serves as an estimator of other functional soil quality indicators.

The employment of controlled traffic farming (CTF) can yield improvements to soil quality attributes through the confinement of equipment traffic to tramlines with the field. There is a need to identify how soil property variability and spatial modeling techniques are influenced by the inclusion of controlled traffic regimes at the field scale. Soil properties such as available nitrogen (AN), soil pH, soil total nitrogen (STN), soil organic carbon (SOC), bulk density, macro pore volume, soil quality S-Index, plant available water capacity (PAWC) and unsaturated hydraulic conductivity (Km) were analyzed and compared among different positions within the traffic regime across two annual cropland sites actively employing CTF. The inclusion of tramlines displayed significant worse soil physical conditions when compared to un-trafficked soils while subsequently displaying minimal changes in soil nutrient properties. Furthermore, we contrasted regression models with ordinary geostatistical methods, such as ordinary kriging (OK) as well as the hybrid method of covariate kriging (COK) and regression kriging (ROK) to predict if the spatial distribution of soil properties in the field scale was altered from the traffic regime. The alteration of field scale bulk density, macro pore volume, S-Index and PAWC within the tramline soil caused consistent homogeneity within the area and direction of equipment traffic; however, these linear features were unable to be displayed through our ordinary geostatistical modeling methods and only somewhat captured using the ROK method. Alternately, AN, pH, STN, SOC and Km observed to vary primarily as a function of landscape. This resulted in the addition of light detection and ranging derived terrain covariates with the COK method improving the field scale prediction and reducing uncertainty in the estimation of soil nutrient properties.

Soil water is important for agricultural production, and is a key parameter in hydrologic models and weather prediction models. In this paper we explore the ability of two commonly used paddock scale models for pasture: HowLeaky and DairyMod, to estimate soil water in the topsoil (0–100 mm) and root-zone (0–1000 mm) at daily intervals. We also examined the influence of soil hydraulic properties on estimated amounts of soil water by using soil properties measured at the site, compared with properties from the national database. Soil water estimates were compared with field measurements from four grazing systems in the high-rainfall zone of western Victoria, Australia. Daily soil water amounts in the topsoil and root-zone were well simulated by both Howleaky and DairyMod, with Howleaky performing better overall. Soil water was simulated more accurately for the root-zone than for the topsoil. On average, the error in root-zone water estimations with site-derived soil properties was 18% of plant available water capacity, and ranged from 8 to 24% of their plant available water. When soil properties were instead taken from the national database, the actual values of soil water were predicted poorly, with an average bias of 86 mm. However, relative soil water is the parameter of greater interest, and normalising by the waterholding capacity corrected these biases leading to an average error of 24% of the plant available capacity, with a range across sites from 8 to 31% of the plant available capacity. Nevertheless, with site-derived parameters bias was reduced by more than half in all sites. Errors in model predictions tended to increase during the growing season reaching a maximum at the most critical times of the year for tactical decision-making by farmers (November and December). Superior performance of Howleaky in estimating soil water and other water balance components support the application of Howleaky for soil water simulations in pasture sites at point scale. Improving algorithms for soil water redistribution would be beneficial to increase the model performance.

Water stored in the soil between field capacity and the permanent wilting point, is known as the available water capacity. Its availability to be effectively used by plants depends on the type of soil and its water retention characteristics. The aim of this work was to compile information about water retention curves in Latosols, and to provide a first approximation of values and most likely amplitudes for water storage and available water capacity of these soils. The database was constituted from information collected from articles, theses, dissertations and other publications. Soil water retention curves, as well as available water, were estimated for the order Latosols, and for the suborders Red Latosol (RL), Red-Yellow Latosol (RYL) and Yellow Latosol (YL). RL presented the lowest amplitude of water storage between field capacity and permanent wilting point, resulting in lower available water capacity compared to Yellow and Red-Yellow Latosols. YL presented the highest available water capacity among analyzed soils.

Field experiments were conducted to test different agronomic practices, such as soil cultivation, fertilization, and pest and weed management, in highly controlled plot cultivation. The inter-annual yields and the interpretation of such experiments is highly affected by the variability of climatic conditions and fertilization level. We examined the effect of different climate indices, such as winterkill, late spring frost, early autumn frost, different drought parameters, precipitation-free periods, and heat-related stress, on winter wheat yield. This experiment was conducted in an agricultural area with highly fertile conditions, characterized by a high available water capacity and considerable C and N contents in lower soil depths. Residuals were calculated from long-term yield trends with a validated method (time series autoregressive integrated moving average ARIMA) and these served as base values for the detection of climate-induced, short-term, and inter-annual variations. In a subsequent step, the real yield values were used for their derivations from climate factors. Residuals and real yields were correlated with climate variables in multiple regression of quantitative analyses of the yield sensitivity. The inter-annual variation of yields varied considerably within the observation period. However, the variation was less an effect of the climatic conditions during the main growing time periods, being more of an effect of the prevailing climate conditions in the winter period as well as of the transition periods from winter to the warmer season and vice versa. The high storage capacity of plant available water exerted a remarkable dampening effect on drought-induced effects during the main vegetation periods. Increasing fertilization led to increased susceptibility to drought stress. The results indicate a changed picture of the yield development in these fertile locations.

Teff Eragrostis tef (Zucc.) crop production is essential since it is a major food crop in Ethiopia. This paper presents a teff land suitability evaluation model in Northern semi-arid Ethiopia by using GIS-based multi-criteria decision making analysis (MCDMA) in order to identify areas that best suit sustainable production of the crop. The results showed that 37.59, 56.99 and 5.42% of the area are moderately (S2), marginally (S3) and currently not suitable (N1) for teff crop production. Mean weight diameter, available water capacity, total nitrogen, available phosphorus, exchangeable bases, length of growing period and slope are the major constraints causing serious hurdle for teff production. However, with the application of organic and inorganic fertilizer (especially of nitrogen, phosphorus and potassium fertilizers), tillage, soil and water management practices 2.05, 55.85 and 13.51% changes in suitability from N1 to S3, S3 to S2 and S2 to S1 suitability levels respectively is occurred. This indicates that the area is promising if investments in land and soil managements are made though climate and topographic factors supported by some soil physical and morphological properties are permanently limiting its suitability. GIS-based AHP model is superior for land suitability evaluation of teff crop production in areas with various soil and landscape positions.

Topsoil removal and intensive cultivation of fragile sandy loam soil may reduce water movement into and within the soil and decrease available water capacity. The purpose of this study was to determine if topsoil removal (SSR) and 10-year cultivation have adverse effects on the structural and soil water retention properties. The study was conducted on a fine sandy loam soil in humid tropical coastal plain soils in southern Nigeria. We measured particle size, soil organic matter, pore size through water desorption analysis and infiltration and related water retention properties. Results showed that topsoil removal and cultivation resulted in significant reduction in infiltration, saturated hydraulic conductivity and available water contents and increased the bulk density. Topsoil removal increased fine particle-size fractions and created a shift in pore size distribution to a greater micro porosity. Soil water storage in terms of useful available water (UAW) and easily available water (EAW) were significantly low (p

The long-term performance and benefits of charcoal application on the carbon sequestration and properties of forest soils in temperate or non-tropical regions has not been studied in detail in spite of its important role in global warming. This study was conducted to describe the long-term charcoal-induced changes in organic carbon (OC) content and other soil properties of temperate deciduous forests in Mazandaran province, northern Iran. Three sites were sampled to collect composite soil samples from two depths (0–20 and 20–40 cm) inside and outside of a plot of charcoal-enriched soils surrounding a historical charcoal production site (abandoned for more than 120 years). The presence of charcoal in soils for about 120 years elevated significantly the black carbon, total OC, natural soil OC, total nitrogen, dissolved organic matter, soil OC density, exchangeable bases, saturated hydraulic conductivity, available water capacity and available Fe, Mn and Zn compared to the adjacent reference soils. Cation exchange capacity (CEC) and pH were 15.5 cmolc kg−1 and 0.5 units, respectively, higher than the adjacent reference soils at 0–20 cm soil depth. However, electrical conductivity (EC), bulk density and available Cu were higher in the adjacent reference soil. The aged charcoal had no significant effect on the microbial respiration rate of studied soils. The results of this study provide new insights and strong support for the long-term benefits of biochar application as a management strategy for improving soil productivity as well as sequestering large quantities of durable carbon in soils of the region and mitigating global warming.

Improvements in soil water balance modeling can be beneficial for optimizing irrigation management to account for spatial variability in soil properties and evapotranspiration (ET). A remote-sensing-based ET and water balance model was tested for irrigation management in an experiment at two University of Nebraska-Lincoln research sites located near Mead and Brule, Nebraska. Both fields included a center pivot equipped with variable rate irrigation (VRI). The study included maize in 2015 and 2016 and soybean in 2016 at Mead, and maize in 2016 at Brule, for a total of 210 plot-years. Four irrigation treatments were applied at Mead, including: VRI based on a remote sensing model (VRI-RS); VRI based on neutron probe soil water content measurement (VRI-NP); uniform irrigation based on neutron probe measurement; and rainfed. Only the VRI-RS and uniform treatments were applied at Brule. Landsat 7 and 8 imagery were used for model input. In 2015, the remote sensing model included reflectance-based crop coefficients for ET estimation in the water balance. In 2016, a hybrid component of the model was activated, which included energy-balance-modeled ET as an input. Both 2015 and 2016 had above-average precipitation at Mead; subsequently, irrigation amounts were relatively low. Seasonal irrigation was greatest for the VRI-RS treatment in all cases because of drift in the water balance model. This was likely caused by excessive soil evaporation estimates. Irrigation application for the VRI-NP at Mead was about 0 mm, 6 mm, and –12 mm less in separate analyses than for the uniform treatment. Irrigation for the VRI-RS was about 40 mm, 50 mm, and –98 mm greater in separate analyses than the uniform at Mead and about 18 mm greater at Brule. For maize at Mead, treatment effects were primarily limited to hydrologic responses (e.g., ET), with differences in yield generally attributed to random error. Rainfed soybean yields were greater than VRI-RS yields, which may have been related to yield loss from lodging, perhaps due to over-irrigation. Regarding the magnitude of spatial variability in the fields, soil available water capacity generally ranked above ET, precipitation, and yield. Future research should include increased cloud-free imagery frequency, incorporation of soil water content measurements into the model, and improved wet soil evaporation and drainage estimates.

Land use change, especially conversion of native forests can have large impacts on water resources. Large scale conversion of native forests to agricultural land has occurred in the last few decades in the Mau Forest region. To quantify and understand landscape hydrologic responses, this study aimed at evaluating the effects of land use on soil infiltration, saturated hydraulic conductivity, bulk density, sorptivity, and soil moisture retention. A total of 136 plots representing five different land uses (native forest: n = 39, forest plantations: n = 14, tea plantations: n = 24, croplands: n = 23 and pasture: n = 36) were sampled in three catchments with similar parental material in the Mau Forest region, Western Kenya. Native forest topsoils (0–5 cm) had a bulk density of 1.0 ± 0.2 g cm−3 which was similar to values found for topsoils of forest plantations (1.1 ± 0.2 g cm−3), but significantly lower than topsoils from croplands (1.4 ± 0.2 g cm−3), tea plantation (1.3 ± 0.3 g cm−3) and pastures (1.4 ± 0.2 g cm−3). Similarly, soil infiltration rates were higher in native forest (76.1 ± 50 cm h−1) and in forest plantation (60.2 ± 47.9 cm h−1) than in croplands (40.5 ± 21.5 cm h‐1), tea plantations (43.3 ± 29.2 cm h−1) and pastures (13.8 ± 14.6 cm h−1). Native forest had the highest topsoil organic carbon contents (8.11 ± 2.42%) and field capacity (0.62 ±0.12 cm3 cm−3), while the highest permanent wilting point was recorded for pasture soils (mean of 0.41 ± 0.06 cm cm−3). The highest plant available water capacity was recorded for soils in native forest (mean of 0.27 ± 0.14 cm cm−3). Our study indicates that land use changes result in a significant degradation of soil hydraulic properties, which has likely resulted in changes of the regional water balance. Given the magnitude in which managed land use types have changed infiltration rates in our study area, we conclude that changes in land use types occurring in our study region in the last decades have already affected the hydrological regime of the landscapes and the compositions of flow components. The reduction in infiltration and hydraulic conductivity could result in increased surface run-off, erosion and frequency of flooding events.

Tillage management in agricultural fields has consequences on the dynamics of the soil structure and soil’s pore functions with far reaching effects on the sustainability of cropping system. The purpose of this study is to investigate changes in both capacity and intensity properties of a very clayey Rhodic Hapludox after 37-year of continuous conventional tillage (CT) and no till (NT) management for weed control under coffee plantations. Undisturbed soil samples were collected at four depths and used for hydro-physical characterization. The tillage treatments modified the capacity and intensity parameters differently depending on the sampled depth. Bulk density was similar at the 0–20 cm layer in both CT and NT treatments, but at the 20–40 cm layer, NT significantly increased the bulk density by (6–8%). Also, NT increased the stability of 8–2 mm macroaggregate fraction in water and significantly increased the geometric mean diameter and the mean weight diameter of the water-stable aggregates in most of the layers relative to CT. Moreover, CT increased hydraulic conductivity by 53% in the surface layer. Generally, the magnitude of the differences in soil properties as a consequence of the 2 tillage treatments was greater for hydraulic conductivity (soil intensity parameters) than the bulk density (soil capacity parameters). In the NT plots, more water was retained within the available water range, while CT presented steeper water retention curves and poorly graded pore-size distributions. The pore-size distribution and hydraulic capacity function curves showed that the impact of CT management was more pronounced at the 10–20 cm layer, while that of NT management was most significant at the 0–10 cm layer (soil surface). This study showed that in addition to soil strength indicators, soil intensity parameters (hydraulic conductivity, hydraulic capacity and soil structure) more succinctly explained differential impact of tillage systems on soils, as compared to the capacity parameters (bulk density, pore size distribution, air capacity and available water capacity).

The determination of soil hydraulic properties is laborious and expensive, especially in large-scale applications. One often used substitute for measured hydraulic properties are pedotransfer function (PTFs) estimates. Most PTFs, however, are statistical models that tend to produce biased results for data outside their –often limited– calibration databases. In addition, most PTFs have been established on data derived from temperate regions causing the question whether such models are applicable to soils in tropical regions. This work aimed to evaluate the performance of the Splintex PTF to predict the hydraulic functions for sandy and clayey soils from several tropical and subtropical Brazilian datasets. Splintex is somewhat unique in that it is based on physical principles using a modification of the Arya-Paris method while allowing the estimation of van Genuchten parameters from limited data. In addition, Splintex has an option to include measured soil water retention points, in principle allowing it to produce accurate estimates for a variety of soils. Estimates by Splintex were compared with the empirical Rosetta PTF, which also has an option to use one (or two) retention points. Estimates by both PTFs were compared to observed retention data and field capacity, available water capacity, hydraulic conductivity, and diffusivity using metrics such as Pearson correlation ( r ), mean absolute error (MAE) and root mean square error (RMSE). Both Splintex and Rosetta yielded similar results and sometimes produced significant biases in estimated quantities. In the majority of cases it appears that Splintex produced somewhat better estimates than the 2001 version of Rosetta , indicating that Splintex is a viable, physically-based, alternative to estimating hydraulic properties.

Increasing concern for sustainable water use has the agriculture industry working toward higher efficiency in use of irrigation water. Recent advancements have improved the capabilities of center pivot irrigation systems to vary water application depths across the field, a technology known as variable rate irrigation (VRI). The goal of this study was to provide a geospatial method for potential VRI technology adopters to evaluate control scenarios and potential water savings using freely available datasets. Root zone available water capacity (R) was estimated spatially across two case study fields using the Natural Resources Conservation Service Gridded Soil Survey Geographic Database. The difference in application depth between conventional irrigation (CI) and both sector and zone control VRI was then estimated based on R. Prescription maps were developed to mine undepleted soil water from each irrigation management zone based on a soil water balance approach with a management-allowed depletion of 50%. For CI management, the areal 10th percentile (PCTL) of R for the field was used, while for VRI the 10th PCTL of R for each management zone was used. The highest reduction in irrigation depth was 18 mm where higher values of R were estimated; however, field average reductions ranged from 0 to 12 mm. The greatest improvements in pumpage reduction resulted from converting from sector control to zone control, while increasing the angular resolution only had a minor impact. Energy savings generally increased with higher VRI control resolution. Conclusions support previous notions that VRI may result in small pumping water reductions for some fields; however, improved water distribution may be achieved throughout the field.

The effect of increasing soil organic content (SOC) on the soil water retention and cotton yield productivity of two benchmark U.S. Southern High Plains (SHP) soils was estimated using pedotransfer functions and the CROPGRO-Cotton crop simulation model. Increasing plow layer (0−30 cm) SOC leads to increased wilting point (WP), field capacity (FC), and plant available water capacity (PAW = FC-WP) in both soils. The increase in a clay loam’s available water capacity is modest, with a 1% increase in SOC producing an additional 0.16 cm of PAW in the soil profile’s uppermost 30 cm. The fine sandy loam’s plow layer effect is twice that, with a 1% SOC increase producing a 0.32 cm PAW increase. These effect’s magnitudes were consistent with a recent meta-analysis of SOC on soil water retention, but considerably below those cited by national and regional extension services. As surface SOC levels in both soils were increased above baseline levels the fine sandy loam’s median simulated cotton lint yields were essentially unchanged, while clay loam yields decreased. The clay loam yield effect is attributed to increased soil evaporation rates. Conservation agriculture (CA) practices such as increased residue retention may compensate for these weak soil water retention effects, but cotton’s limited residue production would require winter cover crops or alternate crop rotations. As the success of terminated winter wheat – dryland cotton rotations is unclear in past SHP field studies, a CA sorghum-cotton rotation with periodic tillage is proposed as a SHP dryland production system.

Data sparsity is a major limitation in modelling soil hydraulic properties across large spatial extents, such as the continent of Australia, and can lead to erroneous models being developed. Inverse modelling can be used to make inferences about underlying environmental processes, even when the data is subject to error. Bayesian inverse modelling is one method to quantify uncertainties from multiple sources, including data, model structure, and model parameters. Although, Bayesian inverse modelling approaches have been proven useful in many applications, they are still not commonplace in digital soil mapping (DSM). In this work, we present a Bayesian inverse model for predicting available water capacity (AWC) of soils using sparse data. Specifically, we estimate upper and lower drainage limits (DUL and LL15) using a Bayesian geostatistical model. DUL and LL15 are then differenced to estimate the AWC. This study was carried out using measurements of upper and lower drained limits (DUL & LL15) across NSW, Australia. Two separate Bayesian inverse models were calibrated and validated for the DUL and LL15 soil hydraulic parameters. The calibrated models were then used to spatially predict AWC of soils across a cropping region in New South Wales (NSW), Australia on a 90-m grid. We also present the uncertainty of the parameters and output maps. Our results gave similar estimates of AWC values when compared to those predicted using the Cubist machine learning model. Although the predictions are similar, the Bayesian method allows for the direct quantification of the prediction uncertainties, while the Cubist method cannot.

Plant available water capacity (PAWC), defined as the amount of water held in the soil between the drained upper limit (DUL) and crop lower limit (CLL), is a major determinant for crop yield in dryland cropping areas. However, measured soil profile data quantifying the physical soil parameters that determine PAWC are limited. Choosing a ‘representative’ soil profile in order to parameterise a deterministic model is often subjective and may not be appropriate, leading to biased conclusions. To help support these deterministic crop modelling studies, we analysed soil profile data in Australia available in the APSoil database; a database of field and laboratory measured physical soil properties used to parameterise the Agricultural Production Systems sIMulator (APSIM) model. Specifically, we developed typical soil pattern profiles utilizing wheat for CLL using statistical shape analysis and cluster analysis. Our method allows modellers to reduce the number of soil profile parameter choices using a statistically sound basis. We implement our method by grouping the APSoil soil profiles into five clusters, whereby each cluster is represented by a more general soil profile. The representative soil profiles reflect impact of the soil texture on PAWC. The five clusters and representative soil profiles can then be used in future modelling studies to investigate the impact of soil variation on systems performance. In turn, soil scientists will have a plausible and quantifiable collection of soil profiles to choose from for future studies.

Crop models were originally developed for application at the field scale but are increasingly used to assess the impact of climate and/or agronomic practices on crop growth and yield and water dynamics at larger scales. This raises the question of how data aggregation approaches affect outputs when using crop models at large spatial scales. This study investigates how input and output data aggregation affected simulated rainfed and irrigated potato yield and irrigation water requirement (IWR) across potato production areas in Tasmania, Australia. First, the yield and IWR with aggregated model inputs at 15, 25 and 40 km resolutions (input aggregation) was simulated. Second, simulated model outputs generated with high-resolution input data were aggregated to 15, 25 and 40 km resolutions (output aggregation) and compared to the corresponding yield and IWR with simulations based on input data aggregation. Finally, the differences (D) (DY and DIWR for yield and IWR, respectively) between grids using input and output aggregation were evaluated. The results indicate that the effect of input and output data aggregation on yield depends on water-driven factors including plant available water capacity (PAWC), rainfall and irrigation. Maximum D values were found for rainfed yield (4.4 t ha-1) and IWR (137 mm). DY variations were correlated with the differences of PAWC caused by data aggregation in 82 % of potato production areas. Differences between aggregation methods were reduced when growing season rainfall increased. We conclude that PAWC and the source of water (rainfall or rainfall + irrigation) explained the larger errors associated with the input and output data aggregation on simulated potato yield and IWR. Future studies should consider the data aggregation method in their assessment to minimize errors and therefore produce higher quality advice or farming decisions.

Summary Soil water-holding capacity is an important component of the water and energy balances of the terrestrial biosphere. It controls the rate of evapotranspiration, and is a key to crop production. It is widely accepted that the available water capacity in soil can be improved by increasing organic matter content. However, the increase in amount of water that is available to plants with an increase in organic matter is still uncertain and may be overestimated. To clarify this issue, we carried out a meta-analysis from 60 published studies and analysed large databases (more than 50 000 measurements globally) to seek relations between organic carbon (OC) and water content at saturation, field capacity, wilting point and available water capacity. We show that the increase in organic carbon in soil has a small effect on soil water content. A 1% mass increase in soil OC (or 10 g C kg−1 soil mineral), on average, increases water content at saturation, field capacity, wilting point and available water capacity by: 2.95, 1.61, 0.17 and 1.16 mm H2O 100 mm soil−1, respectively. The increase is larger in sandy soils, followed by loams and is least in clays. Overall the increase in available water capacity is very small; 75% of the studies reported had values between 0.7 and 2 mm 100 mm−1 with an increase of 10 g C kg−1 soil. Compared with reported annual rates of carbon sequestration after the adoption of conservation agricultural systems, the effect on soil available water is negligible. Thus, arguments for sequestering carbon to increase water storage are questionable. Conversely, global warming may cause losses in soil carbon, but the effects on soil water storage and its consequent impact on hydrological cycling might be less than thought previously. Highlights We investigated how available water capacity can be increased with a 1% increase in soil organic carbon. We analysed data from 60 published studies and global databases with more than 50 000 measurements. The increase in organic carbon in soil has a small effect on soil water retention. A 1% mass increase in soil OC on average increased available water capacity by 1.16%, volumetrically.

Increasing heat and water stress are important threats to wheat growth in rain-fed conditions. Using climate scenario-based projections from the Coupled Model Intercomparison Project phase 5 (CMIP5), we analysed changes in the probability of heat stress around wheat flowering and relative yield loss due to water stress at six locations in eastern Australia. As a consequence of warmer average temperatures, wheat flowering occurred earlier, but the probability of heat stress around flowering still increased by about 3.8%–6.2%. Simulated potential yield across six sites increased on average by about 2.5% regardless of the emission scenario. However, simulated water-limited yield tended to decline at wet and cool locations under future climate while increased at warm and dry locations. Soils with higher plant available water capacity (PAWC) showed a lower response of water-limited yield to rainfall changes except at very dry sites, which means soils with high PAWC were less affected by rainfall changes compared with soils with low PAWC. Our results also indicated that a drought stress index decreased with increasing PAWC and then stagnated at high PAWC. Under high emission scenario RCP8.5, drought stress was expected to decline or stay about the same due to elevated CO 2 compensation effect. Therefore, to maintain or increase yield potential in response to the projected climate change, increasing cultivar tolerance to heat stress and improving crop management to reduce impacts of water stress on lower plant available water holding soils should be a priority for the genetic improvement of wheat in eastern Australia.

For biomethane production, the cup plant (Silphium perfoliatum L.) is considered a promising alternative substrate to silage maize (Zea mays L.) due to its high biomass potential and associated ecological and environmental benefits. It has also been suggested to grow cup plant on less productive soils because of its presumed drought tolerance, but robust information on the impact of water shortage on biomass growth and substrate quality of cup plant is rare. Therefore, this study assesses the effects of soil water availability on the chemical composition and specific methane yield (SMY) of cup plant. Furthermore above-ground dry matter yield (DMY) was analysed as a function of intercepted photosynthetic active radiation (PAR) and radiation use efficiency (RUE). Data were collected in a two-year field experiment under rainfed and irrigated conditions with cup plant, maize, and lucerne-grass (Medicago sativa L., Festuca pratensis Huds., Phleum pratense L.). The cup plant revealed a slight decrease of −6% in the SMY in response to water shortage (less than 50% of plant available water capacity). The average SMY of cup plant [306 l (kg volatile solids (VS))−1] was lower than that of maize [362 l (kg VS)−1] and lucerne-grass [334 l (kg VS)−1]. The mean drought-related reduction of the methane hectare yield (MHY) was significantly greater for cup plant (−40%) than for maize (−17%) and lucerne-grass (−13%). The DMY reduction in rainfed cup plant was mainly attributed to a more severe decrease in RUE (−29%) than for maize (−16%) and lucerne-grass (−12%). Under water stress, the mean cup plant RUE (1.3 g MJ−1) was significantly lower than that of maize (2.9 g MJ−1) and lucerne-grass (1.4 g MJ−1). Compared to RUE, the reduced PAR interception was less meaningful for DMY in rainfed crops. Hence, the cup plant is not suitable for growing on drought prone lands due to its high water demand required to produce reasonably high MHYs.