Papers by Gabriela Pérez-Castillo
Revista de Biología Tropical, 2007
ables, and the authors' personal criteria. The index includes the following parameters: dissolved... more ables, and the authors' personal criteria. The index includes the following parameters: dissolved oxygen percent saturation, pH, nitrate concentration, total phosphorus concentration, chemical oxygen demand, concentration of suspended solids, electrical conductivity and temperature. The index sets itself to zero if the concentration of some toxic substance exceeds the maximum allowed limit. The adjustment values were based on "weights" defined in the National Sanitation Foundation Water quality Index (ICA-NSF). In this study, the weight of fecal coliforms count was excluded, the values of turbidity and the one for total solids were integrated into one (suspended solids) and a factor of 0.08 was assigned to the conductivity parameter. The sub indices associated to suspended solids were obtained from the quality of Kahler-Royer variation graph; the values for pH and the nitrate concentration from the graphs constructed for ICA-NSF. The percentage of dissolved oxygen saturation, in sites like irrigation channels, was evaluated directly from the quality variation graph constructed for ICA-NSF, whereas the same parameter for the flooding lagoons required an adjustment based on the optimal value for similar non contaminated ecosystems. The conductivity was evaluated from adjustments in the qualification functions commented by Escribano & De Frutos. Chemical oxygen demand, total phosphorus and temperature, were qualified based on the functions developed for the ICA-L.
Frontiers in Sustainable Food Systems
The application of dairy farm effluents (DFE) without previous treatment in paddocks was intensif... more The application of dairy farm effluents (DFE) without previous treatment in paddocks was intensified due to the approval of this practice in Costa Rican legislation since 2012. Applying DFE instead of synthetic N fertilizer in grasslands is an opportunity to reach a circular economy; however, this practice increases the risk of emissions of nitrous oxide (N2O), methane (CH4), and ammonia (NH3), which contribute to global warming. A field experiment was carried out using a permanent grassland (90% Star grass and 10% Kikuyo grass) to simultaneously assess the effect of nitrapyrin on yield-scaled emissions of NH3, CH4, and N2O. The experiment lasted for 5 months in 2017, based on a randomized complete block design, including three treatments of control (CK) without N application, surface application of DFE with nitrapyrin (SNI), and without nitrapyrin (S). Total N applied was 149 ± 12 kg N ha−1 for both S and SNI treatments split into five applications. CH4 emissions from S, SNI, and C...
Revista de biologia tropical, 2008
We propose ICA-L, a wetland physicochemical water quality index (WWQI), to be used as a managemen... more We propose ICA-L, a wetland physicochemical water quality index (WWQI), to be used as a management tool for seasonal-flooding lagoons in Palo Verde National Park, Guanacaste, Costa Rica. The goal is to preserve their natural role for native plants as well as migrants and local animal species. The index was developed in four steps: parameter selection, assignment of parameter weight, transformation of data to their corresponding sub indices and selection of an appropriate aggregation function. In this process, the following criteria were used as a reference: WQI from the National Sanitation Foundation, WQI for the Des Moines River, Escribano and De Frutos WQI, the international legislation on maximum acceptable concentration for different water quality variables, and the authors' personal criteria. The index includes the following parameters: dissolved oxygen percent saturation, pH, nitrate concentration, total phosphorus concentration, chemical oxygen demand, concentration of su...
Pedosphere, 2021
Urea is the most common nitrogen (N) fertilizer used in the tropics but it has the risk of high g... more Urea is the most common nitrogen (N) fertilizer used in the tropics but it has the risk of high gaseous nitrogen (N) losses. Use of nitrification inhibitor has been suggested as a potential mitigation measure for gaseous N losses in N fertilizer-applied fields. In a field trial on a tropical Andosol pastureland in Costa Rica, gaseous emissions of ammonia (NH3) and nitrous oxide (N2O) and grass yield were quantified from plots treated with urea (U; 41.7 kg N ha–1 application–1) and urea plus the nitrification inhibitor nitrapyrin (U + NI; 41.7 kg N ha–1 application–1 and 350 g of nitrapyrin for each 100 kg of N applied) and control plots (without U and NI) over a six-month period (rainy season). Volatilization of NH3 (August to November) in U (7.4% ± 1.3% of N applied) and U + NI (8.1% ± 0.9% of N applied) were not significantly different (P > 0.05). Emissions of N2O in U and U + NI from June to November were significantly different (P
Revista de Ciencia y Tecnología, 2010
The following physicochemical parameters were measured to determine the quality of the drainage w... more The following physicochemical parameters were measured to determine the quality of the drainage water of Tamarindo Irrigation Sector, at the Arenal-Tempisque Irrigation District: temperature, pH, dissolved oxygen saturation percentage, electrical conductivity, chemical oxygen demand, concentration of suspended solids, nitrates and total phosphorous, as well as the concentration of zinc, fats and oils. The measurements were taken when it was estimated that drainage water had received the highest pollution loads from the surrounding paddy fields, during the second half of 2002 and the year 2003. The results were evaluated using the water quality index for the management of floodplain lakes (ICA-L). The water from Tamarindo Irrigation Sector, which entered the Palo Verde National Park (PNPV) through La Bocana lagoon, got an average value of ICA-Lp of 70. Relevant increases in total phosphorous concentration were found. Zinc generated a punctual pollution problem in the area of irrigati...
The objective of this study was assess if the water quality from the Mata Redonda lagoon (MRL) an... more The objective of this study was assess if the water quality from the Mata Redonda lagoon (MRL) and from the rice fields in San Lazaro sector of Nicoya, is appropriate for biodiversity and aquatic life development. The water quality analysis was carried out using the Water quality index for managing flood lagoons (ICA-L), which is based on the following data: temperature, pH, oxygen saturation percentage, electrical conductivity, biochemical oxygen demand, suspended solids, nitrate content and total phosphorus content. The ICA-L average (ICA-Lp) from the water drained form the rice fields in the main channel was 42, which corresponds to a ¨bad¨ category value (unfit for sustaining biodiversity in flood lagoons). In the MRL (ICA-Lp 80) and in the lagoon´s drainage (ICA-Lp 81), water quality was classified as “good”. Nevertheless, increases in total phosphorus and the biological oxygen demand (BOD) may cause negative changes in the composition of the ecosystem. The risk level associate...
Nitrification inhibitors are widely used in agriculture to mitigate nitrous oxide (N2O) emission ... more Nitrification inhibitors are widely used in agriculture to mitigate nitrous oxide (N2O) emission and increase crop yield. However, no concrete information on their mitigation of N2O emission is available under soil and environmental conditions as in Pakistan. A field experiment was established using a silt clay loam soil from Peshawar, Pakistan, to study the effect of urea applied in combination with a nitrification inhibitor, nitrapyrin (2-chloro-6-tri-chloromethyl pyridine), and/or a plant growth regulator, gibberellic acid (GA3), on N2O emission and the nitrogen (N) uptake efficiency of maize. The experimental design was a randomized complete block with five treatments in four replicates: control with no N (CK), urea (200 kg N ha–1) alone, urea in combination with nitrapyrin (700 g ha–1), urea in combination with GA3 (60 g ha–1), and urea in combination with nitrapyrin and GA3. The N2O emission, yield, N response efficiency, and total N uptake were measured during the experimenta...
In the tropics, frequent nitrogen (N) fertilization of grazing areas can potentially increase nit... more In the tropics, frequent nitrogen (N) fertilization of grazing areas can potentially increase nitrous oxide (N2O) emissions. The application of nitrification inhibitors has been reported as an effective management practice for potentially reducing N loss from the soil-plant system and improving N use efficiency (NUE). The aim of this study was to determine the effect of the co-application of nitrapyrin (a nitrification inhibitor, NI) and urea in a tropical Andosol on the behavior of N and the emissions of N2O from autotrophic and heterotrophic nitrification. A greenhouse experiment was performed using a soil (pH 5.9, organic matter content 78 g kg–1, and N 5.6 g kg–1) sown with Cynodon nlemfuensis at 60% water-filled pore space to quantify total N2O emissions, N2O derived from fertilizer, soil ammonium (NH4+) and nitrate (NO3–), and NUE. The study included treatments that received deionized water only (control, CK) and two doses of 15N-enriched urea (65 (UR) and 129 mg N kg–1 (UD)) ...
Agronomia Mesoamericana, Dec 1, 2013
Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto
Revista de biología tropical, 2008
We propose ICA-L, a wetland physicochemical water quality index (WWQI), to be used as a managemen... more We propose ICA-L, a wetland physicochemical water quality index (WWQI), to be used as a management tool for seasonal-flooding lagoons in Palo Verde National Park, Guanacaste, Costa Rica. The goal is to preserve their natural role for native plants as well as migrants and local animal species. The index was developed in four steps: parameter selection, assignment of parameter weight, transformation of data to their corresponding sub indices and selection of an appropriate aggregation function. In this process, the following criteria were used as a reference: WQI from the National Sanitation Foundation, WQI for the Des Moines River, Escribano and De Frutos WQI, the international legislation on maximum acceptable concentration for different water quality variables, and the authors' personal criteria. The index includes the following parameters: dissolved oxygen percent saturation, pH, nitrate concentration, total phosphorus concentration, chemical oxygen demand, concentration of su...
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Papers by Gabriela Pérez-Castillo