Browsing by Autor "Demis Andrade Foronda"

Now showing 1 - 9 of 9

Aplicación de yeso agrícola y enmiendas orgánicas para la remediación de suelos salino-sódicos
(2020) Ivan Quispe Zenteno; Edgar Gutiérrez Rodríguez; Demis Andrade Foronda
Combined Application of Organic Amendments and Gypsum to Reclaim Saline–Alkali Soil
(Multidisciplinary Digital Publishing Institute, 2022) Demis Andrade Foronda; Gilles Colinet
Saline–alkali soils have high sodicity, high pH, and high levels of soluble salts, as well as carbonates. This study aimed to evaluate the effect of cattle manure and chicken manure combined with gypsum at three levels on reclaiming a saline–alkali soil, through a soil column experiment. Combined treatments were more effective than those of sole gypsum in reducing the initial exchangeable sodium percentage (ESP) below 5%. Electrical conductivity (ECe) was lowered below 1.6 dS m−1 by all treatments, except the control. The higher effectiveness of manures combined with gypsum can be explained by their synergistic effect on Na+ displacement and subsequent soil structure improvement, leading to an enhancement in the leaching process, and then the salinity/sodicity reduction. Soluble salts and Na+ were considerably reduced in all treatments at the first leaching. Soil ESP and ECe threshold values from the US Salinity Lab classification were reached by any treatment, except the control. The addition of cattle manure or chicken manure might enhance the reclamation effect of gypsum with leaching for some saline–alkali soils.
Enmiendas orgánicas para la remediación de suelos salino-sódicos del Valle Alto de Cochabamba
(2020) Daniel Castellon Romero; Demis Andrade Foronda
Estimación del Porcentaje de Sodio Intercambiable en función de la Relación de Adsorción de Sodio para suelos afectados por sales en el Valle Alto de Cochabamba
(2020) Demis Andrade Foronda; Edgar Gutiérrez Rodríguez
Estimation of the Exchangeable Sodium Percentage from&#160;the Sodium Adsorption Ratio for salt-affected soils in Bolivia
(2021) Demis Andrade Foronda
&lt;p&gt;In order to obtain a more cost-time efficient way to determine the sodicity of salt-affected soils, this study aims to generate a regression model to predict the Exchangeable Sodium Percentage (ESP) from the Sodium Adsorption Ratio (SAR&lt;sub&gt;e&lt;/sub&gt;). Based on a database with 84 soil samples from the High Valley of Cochabamba (Bolivia), two linear models were generated: &lt;em&gt;ESP= 0.9725 SAR + 1.5766 &lt;/em&gt;(R&lt;sup&gt;2&lt;/sup&gt;=0.85, RSE=4.47) and &lt;em&gt;ESP= 0.9197 SAR + 0.3813 &lt;/em&gt;(R&lt;sup&gt;2&lt;/sup&gt;=0.71, RSE=0.91)&lt;em&gt; &lt;/em&gt;with square root transformation. Subsequently, through a set of 18 testing samples and a T-test of paired samples between the predicted ESP and measured ESP values, the efficiency of the generated models was verified with a value of p= 0.063 and 0.209, respectively, in contrast to p= 0.285 from the US Salinity Lab referential model. To improve the performance of the generated models, could be necessary a stratification according to soil sodicity levels and additional samples for the calibration dataset.&lt;/p&gt;
Evaluación de la capacidad de fitodesalinización de cuatro halófitas en un suelo salino-sódico
(2020) José Mamani Flores; Omar Arzabe Maure; Demis Andrade Foronda
Prediction of Soil Salinity/Sodicity and Salt-Affected Soil Classes from Soluble Salt Ions Using Machine Learning Algorithms
(Multidisciplinary Digital Publishing Institute, 2023) Demis Andrade Foronda; Gilles Colinet
Salt-affected soils are related to salinity (high content of soluble salts) and/or sodicity (excess of sodium), which are major leading causes of agricultural land degradation. This study aimed to evaluate the performances of three machine learning (ML) algorithms in predicting the soil exchangeable sodium percentage (ESP), electrical conductivity (ECe), and salt-affected soil classes, from soluble salt ions. The assessed ML models were Partial Least-Squares (PLS), Support Vector Machines (SVM), and Random Forests (RF). Soil samples were collected from the High Valley of Cochabamba (Bolivia). The explanatory variables were the major soluble ions (Na+, K+, Ca2+, Mg2+, HCO3−, Cl−, CO32−, SO42−). The variables to be explained comprised soil ECe and ESP, and a categorical variable classified through the US Salinity Lab criteria. According to the model validation, the SVM and RF regressions performed the best for estimating the soil ECe, as well as the RF model for the soil ESP. The RF algorithm was superior for predicting the salt-affected soil categories. Soluble Na+ was the most relevant variable for all the predictions, followed by Ca2+, Mg2+, Cl−, and HCO3−. The RF and SVM models can be used to predict soil ECe and ESP, as well as the salt-affected soil classes, from soluble ions. Additional explanatory features and soil samples might improve the ML models’ performance. The obtained models may contribute to the monitoring and management of salt-affected soils in the study area.
Random Forests to classify salt-affected soils from soluble salt ions
(2022) Demis Andrade Foronda
&lt;p&gt;Salt-affected soils are characterized by an excess of soluble salts and/or sodium. The widely used US Salinity Lab (USSL) classification considers the exchangeable sodium percentage (ESP), electrical conductivity (EC) and pH. Breiman and Cutler's random forests (RF) algorithm chooses the most voted class over all the trees at training time. The aim was to model and predict the USSL salt-term categories from soluble ions by applying RF model classification. Topsoil samples (110) were collected from the High Valley of Cochabamba (Bolivia) and were analyzed to measure the soluble cations (Na&lt;sup&gt;+&lt;/sup&gt;, K&lt;sup&gt;+&lt;/sup&gt;, Ca&lt;sup&gt;2+&lt;/sup&gt;, Mg&lt;sup&gt;2+&lt;/sup&gt;) and anions (HCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;&amp;#8211;&lt;/sup&gt;, Cl&lt;sup&gt;&amp;#8211;&lt;/sup&gt;, CO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;2&amp;#8211;&lt;/sup&gt;, SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2&amp;#8211;&lt;/sup&gt;), in addition to the required salinity parameters to classify the samples according to the thresholds: ESP of 5%, EC&lt;sub&gt;e&lt;/sub&gt; of 4 dSm&lt;sup&gt;-1&lt;/sup&gt; and pH of 8.2. No samples matched in the saline category. The overall out-of-bag error was 17.4% and according to the confusion matrix, the class errors for normal, saline-sodic and sodic soil were 0.12, 0.00 and 0.36, respectively. The variables with higher estimated importance and also selected by RF backward elimination were: Na&lt;sup&gt;+&lt;/sup&gt;, Cl&lt;sup&gt;&amp;#8211;&lt;/sup&gt;, Ca&lt;sup&gt;2+&lt;/sup&gt; and HCO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;&amp;#8211;&lt;/sup&gt;. Additional sampling might be useful in order to reduce the errors and misclassifications, as well as to improve the selection of variables.&lt;/p&gt;
Reclamation of a Saline-Sodic Soil with Organic Amendments and Leaching
(2022) Demis Andrade Foronda
Excessive amounts of Na+ and soluble salts are characteristics of saline-sodic soils. Loss of soil structure and osmotic stress in plants are negative effects of salinity-sodicity. This study evaluated the effect of cattle manure, biochar and tropical peat at 1 and 2% (w/w) with leaching, on the exchangeable sodium percentage (ESP), electrical conductivity (ECe) and pH of a saline-sodic soil from the High Valley of Cochabamba (Bolivia). The soil was placed in simulated soil columns and two lixiviations were applied. The initial values of soil were as follows: ESP of 66.6%, ECe of 20.5 dS m−1, and pH of 8.55. Results after leaching differed significantly (p = 0.05) among the interactions. Cattle manure at 2% was the most effective in reducing soil ESP to 27.6%, followed by the rest of the treatments. The three amendments at any level were efficient in lowering ECe below 4 dS m−1. Peat at 2% decreased the soil pH to 7.76. The superiority of cattle manure can be explained by the improvement of soil aggregation and leaching efficiency, through its OM and Ca2+ + Mg2+ contribution. Overall, cattle manure was superior in reclaiming the soil salinity-sodicity, and only the ECe threshold value from the US Salinity Lab classification was reached by any amendment, indicating that cattle manure, biochar or tropical peat with leaching, can be used to reclaim some saline-sodic soils.