Influencia del tipo de cultivo en algunas propiedades físicas y químicas de un inceptisol de la provincia de el oro

Abstract

The soil is considered an essential natural environment for life, according to research carried out by several scientists, various crops can be developed with adequate productivity standards. The current problems of world agricultural production are due to the fact that the functions of the soil are under constant threat, due to erosion, loss of soil organic carbon, nutrient imbalance, acidification, soil contamination, waterlogging , compaction, soil sealing, salinization and loss of soil biodiversity. The agricultural reality in Ecuador constantly seeks to increase the productivity of crops to obtain greater profits, much of the soil in our country due to mismanagement and the use of inadequate technologies, crops have deteriorated, which has caused a decrease of the productivity of various production systems. In the province of El Oro, the fundamental base of agricultural production is concentrated in the cultivation of bananas, cocoa, coffee, rice, corn, lemon, sugar cane, mango and other short-cycle crops. The objective of this research was to determine the influence of the cultivation of corn and cocoa in some physical and chemical properties of an Inceptisol, through soil analysis. The research was carried out in the experimental area of the Santa Inés farm, belonging to the Faculty of Agricultural Sciences of the Technical University of Machala, located at km 5,5 of the Machala-Pasaje road. The study is observational, cross-sectional, prospective and analytical. The corn and cocoa agroecosystems were selected, where soil samples were randomly taken, which were georeferenced. In both crops, mini pits were made up to 60 cm deep, in which soil samples were taken at depths of 0-15, 15-30 and 30-45 cm; later the samples were homogenized to guarantee their representativeness and then they were sent to the soil, foliar and water laboratory, belonging to the Ecuadorian Agency for the Assurance of Agricultural Quality (AGROCALIDAD), located in the interoceanic highway Km 14½ and Eloy Alfaro, Granja from MAGAP, Tumbaco-Quito; Accredited by the SAE with accreditation No. SAE-LEN-16-006 to perform the corresponding analytical determinations. To know whether or not there are significant statistical differences between the means of the variables real density, clay, silt and sand, pH, organic matter (MO), cation exchange capacity (CIC) and electrical conductivity (CE) as a function of the Maize and cocoa agroecosystems at the aforementioned depths of the soil, a Student's t test was performed for independent groups, after fulfilling the requirements of data normality, independence of observations and homogeneity of variances. When one of these requirements was not met, the non-parametric Mann-Whitney U test was run in order to determine whether or not there were differences between the corn and cocoa agroecosystems. The verification of the assumption of normality of data was carried out with the Shapiro-Wilk test since less than 30 observations are presented in each agroecosystem under study. Verification of the assumption of homogeneity of variances was carried out with the Levene test. The representation of the results was carried out by means of bar graphs that represent the agroecosystems on the X axis and the measured variables on the Y axis. The data processing was carried out with the statistical program SPSS version 25 of test for Windows 10 with a reliability of 95%, that is, a level of significance α = 0.05. The results obtained show that within the physical properties for the sand variable there were significant differences between both agroecosystems, presenting a high content for corn of 34,67% in relation to the value of cocoa that was 16.50%, mainly due to the alluvial action formed by fluvial and marine material from the soil in this area that causes low cohesion, which results in a high separability of the aggregates, which is manifested with more intensity in the maize agroecosystem, as it is a cycle crop short and a high frequency of soil tillage that favors the acceleration of the degradation process and decrease of soil fertility. The clay variable showed a higher value in the cocoa area of 46,50% compared to 24% corn, which confirms the influence of the type of crop in the deterioration of the physical properties of the soil, presenting very high differences precisely due to to the disturbance originated in the soil of the corn area due to excess tillage, in relation to the soil of the cocoa area where tillage is zero. The content of organic matter (MO) presented a higher value in cocoa 3,71%; because in this agroecosystem the soil remains uncultivated and that this crop generates a high amount of plant residues such as litter, branches and stems than being decomposed by microorganisms raise this variable. In the primary elements nitrogen and phosphorus, cocoa cultivation presented higher values due to the fact that in this production system, the soil is not tilled frequently and also this crop generates a large amount of plant biomass which, when decomposed, improves soil fertility; Unlike the cultivation of corn, where the soil is subjected to frequent tillage and intensive exploitation that causes the reduction of these soil nutrients. In relation to magnesium, a significant difference was also found between the two agroecosystems with values of 3,58 and 2,77 cmol / kg of soil in the corn and cocoa crops respectively, in the same way, a highly significant difference was detected in the CIC with values of 13,28 and 30,68 cmol / kg of soil for the cultivation of corn and cocoa, this is due to the fact that this last system presented high percentages of clays and MO that are linked to give high values in this variable. In the case of the variables silt, real density, pH, potassium, calcium and electrical conductivity, no significant differences were evidenced, presenting homogeneity within these parameters.