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Budiman Minasny - One of the best experts on this subject based on the ideXlab platform.
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Limited effect of organic matter on soil Available Water Capacity
European Journal of Soil Science, 2017Co-Authors: Budiman Minasny, Alex B. McbratneyAbstract: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.
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Predicting and mapping the soil Available Water Capacity of Australian wheatbelt
Geoderma Regional, 2014Co-Authors: José Padarian, Budiman Minasny, Alex B. Mcbratney, N. DalglieshAbstract:Abstract Soil Available Water Capacity (AWC) is the main source of Water for vegetation and it is the potential amount of Water Available for atmospheric exchange. Studying its spatial distribution is crucial for agricultural planning and management and for use in biophysical modelling. The aim of this work is to obtain a continuous spatial prediction of AWC over Australia's wheatbelt (about 1.75 million km 2 ), using digital soil mapping techniques. We used a data set of 806 soil profiles which have field measurements of drainage upper limit (DUL) and crop lower limit (CLL). We mapped AWC at five depth intervals (0–5, 5–15, 15–30, 30–60, and 60–100 cm) with the help of different combinations of environmental information (topographic, climatic, soils, landsat imagery, gamma-ray spectrometry) as covariates. The modelling techniques used were symbolic regression (GP), Cubist, and support vector machines (SVM). We also tried two averaging methods to generate an ensemble model. We observed decreasing RMSE values with the addition of extra covariates and also an expected decreasing soil depth. In general, SVM produced the best accuracy. We were able to improve the predictions using one of the ensemble techniques, based on a weighted average of GP, Cubist and SVM model. The map generated with the optimal ensemble model was an unrealistic representation of AWC therefore we decided to present a sub-optimal model as the final map. We stress the need to not only focus on the numerical performance in order to obtain a flexible and stable model, but also a coherent visual representation without anomalies.
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Predicting and mapping soil Available Water Capacity in Korea
PeerJ, 2013Co-Authors: Suk Young Hong, Budiman Minasny, Kyung-hwa Han, Yi-hyun Kim, Kyung-do LeeAbstract:The knowledge on the spatial distribution of soil Available Water Capacity at a regional or national extent is essential, as soil Water Capacity is a component of the Water and energy balances in the terrestrial ecosystem. It controls the evapotranspiration rate, and has a major impact on climate. This paper demonstrates a protocol for mapping soil Available Water Capacity in South Korea at a fine scale using data Available from surveys. The procedures combined digital soil mapping technology with the Available soil map of 1:25,000. We used the modal profile data from the Taxonomical Classification of Korean Soils. The data consist of profile description along with physical and chemical analysis for the modal profiles of the 380 soil series. However not all soil samples have measured bulk density and Water content at −10 and −1500 kPa. Thus they need to be predicted using pedotransfer functions. Furthermore, Water content at −10 kPa was measured using ground samples. Thus a correction factor is derived to take into account the effect of bulk density. Results showed that Andisols has the highest mean Water storage Capacity, followed by Entisols and Inceptisols which have loamy texture. The lowest Water retention is Entisols which are dominated by sandy materials. Profile Available Water Capacity to a depth of 1 m was calculated and mapped for Korea. The western part of the country shows higher Available Water Capacity than the eastern part which is mountainous and has shallower soils. The highest Water storage Capacity soils are the Ultisols and Alfisols (mean of 206 and 205 mm, respectively). Validation of the maps showed promising results. The map produced can be used as an indication of soil physical quality of Korean soils.
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Inverse meta-modelling to estimate soil Available Water Capacity at high spatial resolution across a farm
Precision Agriculture, 2010Co-Authors: M. J. Florin, Alex B. Mcbratney, Brett Whelan, Budiman MinasnyAbstract:Geo-referenced information on crop production that is both spatially- and temporally-dense would be useful for management in precision agriculture (PA). Crop yield monitors provide spatially but not temporally dense information. Crop growth sim- ulation modelling can provide temporal density, but traditionally fail on the spatial issue. The research described was motivated by the challenge of satisfying both the spatial and temporal data needs of PA. The methods presented depart from current crop modelling within PA by introducing meta-modelling in combination with inverse modelling to esti- mate site-specific soil properties. The soil properties are used to predict spatially- and temporally-dense crop yields. An inverse meta-model was derived from the agricultural production simulator (APSIM) using neural networks to estimate soil Available Water Capacity (AWC) from Available yield data. Maps of AWC with a resolution of 10 m were produced across a dryland grain farm in Australia. For certain years and fields, the esti- mates were useful for yield prediction with APSIM and multiple regression, whereas for others the results were disappointing. The estimates contain 'implicit information' about climate interactions with soil, crop and landscape that needs to be identified. Improvement of the meta-model with more AWC scenarios, more years of yield data, inclusion of additional variables and accounting for uncertainty are discussed. We concluded that it is worthwhile to pursue this approach as an efficient way of extracting soil physical infor- mation that exists within crop yield maps to create spatially- and temporally-dense datasets.
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Digital soil mapping using legacy soil data in Korea.
2010Co-Authors: Suk Young Hong, R. J. Gilkes, Budiman Minasny, Zhang Yongseon, Kim Yihyun, Jung Kangho, N. PrakongkepAbstract:Soil carbon storage and Available Water Capacity are important properties for land management, plant production and environment and ecosystem management. This paper will apply the digital soil mapping concept for mapping these two properties in South Korea. A Korean soil database was compiled, which includes chemical and physical properties such as particle size, moisture retention, organic matter, cation exchange Capacity, and a limited number of bulk density data based on 380 soil series. The first step is to estimate bulk density for estimation of both C storage and Available Water Capacity. Bulk density at different depths of soils was predicted by deriving a pedotransfer function model with sand, depth, and organic matter, based on Adams’ model (1973). Organic C distribution with depth was first derived by converting from mass basis C (kg/kg) to volume basis C (kg/m 3 ). C storage (kg/m 2 ) was first calculated by multiplying C on the volume basis to the thickness of each soil layer (m), and finally integrated to a depth of 1 m for each soil series. Mapping Available Water Capacity was more challenging as only half of the database contains measurement of Water retention at -33 and -1500 kPa. Field Capacity was calculated from clay content and predicted bulk density and adjusted by taking into account porosity. Wilting point was calculated from clay content and adjusted for any discrepancy with predicted field Capacity and porosity. Available Water Capacity (mm) to a depth of 1 m was estimated by multiplying the amount of Water stored between field Capacity and wilting point and the thickness of the layer. The carbon storage and Available Water Capacity from surface to a depth of 1 m for the south part of whole Korean peninsula were mapped using the estimated parameters in a soil series map unit (1:25,000). Mean value of carbon density of Korea is approximately 5 kg/m 2 and Available Water Capacity is approximately 154 mm. Total soil carbon storage of agricultural land in Korea is approximately 174 Gg.
Ian Macadam - One of the best experts on this subject based on the ideXlab platform.
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Modelling wheat yield change under CO2 increase, heat and Water stress in relation to plant Available Water Capacity in eastern Australia
European Journal of Agronomy, 2017Co-Authors: Bin Wang, De Li Liu, Senthold Asseng, Ian MacadamAbstract:Abstract 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.
Alex B. Mcbratney - One of the best experts on this subject based on the ideXlab platform.
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Limited effect of organic matter on soil Available Water Capacity
European Journal of Soil Science, 2017Co-Authors: Budiman Minasny, Alex B. McbratneyAbstract: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.
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Predicting and mapping the soil Available Water Capacity of Australian wheatbelt
Geoderma Regional, 2014Co-Authors: José Padarian, Budiman Minasny, Alex B. Mcbratney, N. DalglieshAbstract:Abstract Soil Available Water Capacity (AWC) is the main source of Water for vegetation and it is the potential amount of Water Available for atmospheric exchange. Studying its spatial distribution is crucial for agricultural planning and management and for use in biophysical modelling. The aim of this work is to obtain a continuous spatial prediction of AWC over Australia's wheatbelt (about 1.75 million km 2 ), using digital soil mapping techniques. We used a data set of 806 soil profiles which have field measurements of drainage upper limit (DUL) and crop lower limit (CLL). We mapped AWC at five depth intervals (0–5, 5–15, 15–30, 30–60, and 60–100 cm) with the help of different combinations of environmental information (topographic, climatic, soils, landsat imagery, gamma-ray spectrometry) as covariates. The modelling techniques used were symbolic regression (GP), Cubist, and support vector machines (SVM). We also tried two averaging methods to generate an ensemble model. We observed decreasing RMSE values with the addition of extra covariates and also an expected decreasing soil depth. In general, SVM produced the best accuracy. We were able to improve the predictions using one of the ensemble techniques, based on a weighted average of GP, Cubist and SVM model. The map generated with the optimal ensemble model was an unrealistic representation of AWC therefore we decided to present a sub-optimal model as the final map. We stress the need to not only focus on the numerical performance in order to obtain a flexible and stable model, but also a coherent visual representation without anomalies.
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Inverse meta-modelling to estimate soil Available Water Capacity at high spatial resolution across a farm
Precision Agriculture, 2010Co-Authors: M. J. Florin, Alex B. Mcbratney, Brett Whelan, Budiman MinasnyAbstract:Geo-referenced information on crop production that is both spatially- and temporally-dense would be useful for management in precision agriculture (PA). Crop yield monitors provide spatially but not temporally dense information. Crop growth sim- ulation modelling can provide temporal density, but traditionally fail on the spatial issue. The research described was motivated by the challenge of satisfying both the spatial and temporal data needs of PA. The methods presented depart from current crop modelling within PA by introducing meta-modelling in combination with inverse modelling to esti- mate site-specific soil properties. The soil properties are used to predict spatially- and temporally-dense crop yields. An inverse meta-model was derived from the agricultural production simulator (APSIM) using neural networks to estimate soil Available Water Capacity (AWC) from Available yield data. Maps of AWC with a resolution of 10 m were produced across a dryland grain farm in Australia. For certain years and fields, the esti- mates were useful for yield prediction with APSIM and multiple regression, whereas for others the results were disappointing. The estimates contain 'implicit information' about climate interactions with soil, crop and landscape that needs to be identified. Improvement of the meta-model with more AWC scenarios, more years of yield data, inclusion of additional variables and accounting for uncertainty are discussed. We concluded that it is worthwhile to pursue this approach as an efficient way of extracting soil physical infor- mation that exists within crop yield maps to create spatially- and temporally-dense datasets.
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mapping continuous depth functions of soil carbon storage and Available Water Capacity
Geoderma, 2009Co-Authors: Brendan P Malone, Budiman Minasny, Alex B. Mcbratney, Geoff M LaslettAbstract:Abstract There is a need for accurate, quantitative soil information for natural resource planning and management. This information shapes the way decisions are made as to how soil resources are assessed and managed. This paper proposes a novel method for whole-soil profile predictions (to 1 m) across user-defined study areas where limited soil information exists. Using the Edgeroi district in north-western NSW as the test site, we combined equal-area spline depth functions with digital soil mapping techniques to predict the vertical and lateral variations of carbon storage and Available Water Capacity (AWC) across the 1500 km2 area. Neural network models were constructed for both soil attributes to model their relationship with a suite of environmental factors derived from a digital elevation model, radiometric data and Landsat imagery. Subsequent fits of the models resulted in an R2 of 44% for both carbon and AWC. For validation at selected model depths, R2 values ranged between 20 and 27% for carbon prediction (RMSE: 0.30–0.52 log (kg/m3)) and between 8 and 29% for AWC prediction (RMSE: 0.01 m/m). Visually, reconstruction of splines at selected validation data points indicated an average fit with raw data values. In order to improve upon our model and validation results there is a need to address some of the structural and metrical uncertainties identified in this study. Nevertheless, the resulting geo-database of quantitative soil information describing its spatial and vertical variations is an example of what can be generated with this proposed methodology. We also demonstrate the functionality of this geo-database in terms of data enquiry for user-defined queries.
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Integral energy as a measure of soil-Water availability
Plant and Soil, 2003Co-Authors: Budiman Minasny, Alex B. McbratneyAbstract:The Available Water Capacity is the most commonly used parameter to quantify the amount of Water readily Available to plants. However, it does not directly describe the energy requirements of the plant to remove a unit amount of Water from the soil at various moisture contents within the Available range. We present the integral energy concept as an attempt to quantify this. It is calculated from the integral of a soil's Water-retention curve. We demonstrate the calculation for different types of soil. The integral energy provides useful information regarding the amount of energy, and hence the availability of Water to plants. The value appears to be more correlated with basic soil physical properties, such as clay and sand content, compared with the conventional Available Water Capacity.
S. Dogliotti - One of the best experts on this subject based on the ideXlab platform.
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Changes in soil quality and plant Available Water Capacity following systems re-design on commercial vegetable farms
European Journal of Agronomy, 2013Co-Authors: F. Alliaume, Walter A.h. Rossing, M. Garcia, Ken E. Giller, S. DogliottiAbstract:Abstract Loss of ecological functions due to soil degradation impacts viability of crop production systems world-wide, particularly in vegetable cropping systems commonly located in the most productive areas and characterized by intensive soil cultivation. This paper reports soil degradation caused by intensive vegetable farming, and its reversibility after two to five years of drastic changes in soil management on 16 commercial vegetable farms in south Uruguay. Changes in soil management included addition of green manures and pastures in rotations of vegetable crops, use of animal manure, and erosion control support measures (terracing, reducing slope length, re-orientation of ridges). Soil degradation caused by vegetable farming was assessed by comparing soil properties in 69 vegetable fields with values at reference sites located close to the cropped fields. Effects of the changes in soil management in the 69 fields were assessed by comparing soil properties at the start and to those at the end of the project. Compared to the on-farm reference sites, the vegetable fields contained 36% less SOC, 19% less exchangeable potassium, Water stable aggregates with an 18% smaller geometric mean diameter, and 11% lower plant-Available soil Water Capacity. Phosphorus availability was 5 times higher under vegetable cropping compared to the on-farm reference. Phaeozems (Abruptic) revealed greater degradation (44% less soil organic carbon (SOC)) than Vertisols (24% less SOC) and Phaeozems (Pachic) (21% less SOC). After two to five years of improved soil management, SOC concentration in the upper 20 cm increased by on average 1.53 g kg −1 (12%) in the Phaeozems (Abruptic) and 1.42 g kg −1 (9%) in the Phaeozems (Pachic). SOC in Vertisols increased only by 0.87 g kg −1 , most likely due to their greater initial SOC concentration. Topsoil carbon sequestration was on average 3.4 Mg ha −1 in the Phaeozems. Multiple linear regression showed the quantity of incorporated amendments, the initial amount of SOC and the clay content to explain 77% of the variability in yearly changes of SOC. Available Water Capacity increased significantly with SOC particularly due to more Water retention at field Capacity, resulting in an increase in Available Water Capacity in the first 20 cm of soil of 8.4 mm for every 10 g kg −1 of SOC increase. Results are discussed in relation to perspectives of soil degradation reversal in the long term.
Bin Wang - One of the best experts on this subject based on the ideXlab platform.
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Modelling wheat yield change under CO2 increase, heat and Water stress in relation to plant Available Water Capacity in eastern Australia
European Journal of Agronomy, 2017Co-Authors: Bin Wang, De Li Liu, Senthold Asseng, Ian MacadamAbstract:Abstract 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.