- University of Puerto Rico, Mayaguez Campus
Department of Crops and Agro-environmental Sciences
Faculty of Agriculture
Rebecca Tirado-Corbala
University of Puerto Rico Mayaguez, Agroenvironmental Sciences, Department Member
- University of Puerto Rico Mayaguez, Crops and Agroenvironmental Sciences, Department Memberadd
- Computer Science, Forestry, Soil Science, Agronomy, Environmental Geology, Organic agriculture, and 20 moreAgroecology, Environmental GIS, Soil Mechanics, Wetlands, Archaeological Soil Micromorphology, Agroforestry, Soil ecology, Soil Chemistry, Urban Forestry, Soil Dynamics, Ecological restoration, Urban Wetlands, Pedology (Soil), Soil Mineralogy, Climate Change, Remote Sensing, Biogeochemistry, Groundwater, Biofuels, and Energyedit
ABSTRACT Understanding the quality condition and it's variation pattern play an important role in future planning and appropriate management of water resources and this requires availability of data related to location, amount and... more
ABSTRACT Understanding the quality condition and it's variation pattern play an important role in future planning and appropriate management of water resources and this requires availability of data related to location, amount and distribution of chemical factors of water in a given geographical region; thus processing and analysis of such data should be implemented by considering their spatial location related to each other, and therefore geostatistics is used as a technique for this purpose. The aim of this research is to determine the most suitable interpolation method in order to assessment and spatial analysis of parameters Cl, Na and TH in groundwater in Shahr-e Babak (located at western part of Kerman province). For this purpose, the common geostatistical methods such as ordinary kriging, universal kriging and deterministic methods including IDW, GPI, LPI and RBF were used. Results showed that from deterministic methods, RBF due to having lower RMSE and MAE is more suitable to develop the variation map of parameters Cl, Na and TH. Also, from common geostatistical methods, ordinary kriging is the best one. Finally, by comparing various interpolation methods it was concluded that, simple kriging method was superior to other deterministic and common geostatistical methods and it was selected as the suitable method to develop final map of variation of parameters Cl, Na and TH in Shahr-e Babak plain.
Research Interests:
Degree Doctor of Philosophy, Ohio State University, Soil Science, 2010 . Abstract In Ohio, approximately 55% of agricultural land needs drainage to overcome occasional water ponding, reduce soil erosion, improve fields to support farm... more
Degree Doctor of Philosophy, Ohio State University, Soil Science, 2010 . Abstract In Ohio, approximately 55% of agricultural land needs drainage to overcome occasional water ponding, reduce soil erosion, improve fields to support farm equipment and reduce crop yield variability. In ...
Research Interests:
Sweet oranges in Puerto Rico and other citrus-producing areas in the world have been greatly affected by the Huanglongbing disease (HLB). Historically, most of Puerto Rico’s citrus production has been located from 0–600 m above sea level,... more
Sweet oranges in Puerto Rico and other citrus-producing areas in the world have been greatly affected by the Huanglongbing disease (HLB). Historically, most of Puerto Rico’s citrus production has been located from 0–600 m above sea level, where fruit acquire a desirable color and flavor due to climatic conditions. However, higher populations of the disease vector Diaphorina citri Kuwayama have been reported at these elevations in Puerto Rico. Although only 6.4% of the land area is located above 600 m, it is composed mainly of environmentally sensitive or non-arable land where Inceptisols are the dominant soil order. For that reason, ‘Marr’s Early’ and ‘Pera’ sweet orange (Citrus sinensis) scions grafted on ‘Carrizo’, ‘HRS 802’, and ‘HRS 812’ rootstocks were planted in Alonso clay series Inceptisol (Oxic Humudepts) at 649 m in 2010. Tree growth parameters (height, diameter, canopy volume) and yield efficiency were measured. Fruit quality was determined from juice content (%), total s...
Research Interests:
Research Interests:
Standardized reference evapotranspiration (ET) and ecosystem-specific vegetation coefficients are frequently used to estimate actual ET. However, equations for calculating reference ET have not been well validated in tropical... more
Standardized reference evapotranspiration (ET) and ecosystem-specific vegetation coefficients are frequently used to estimate actual ET. However, equations for calculating reference ET have not been well validated in tropical environments. We measured ET (ET<sub>EC</sub>) using Eddy Covariance (EC) towers at two irrigated sugarcane fields on the leeward (dry) side of Maui, Hawaii, USA in contrasting climates. We calculated reference ET at the fields using the short (ET<sub>0</sub>) and tall (ET<sub>r</sub>) vegetation versions of the American Society for Civil Engineers (ASCE) equation. The ASCE equations were compared to the Priestley–Taylor ET (ET<sub>PT</sub>) and ET<sub>EC</sub>. Reference ET from the ASCE approaches exceeded ET<sub>EC</sub> during the mid-period (when vegetation coefficients suggest ET<sub>EC</sub> should exceed reference ET). At the windier tower site, cumulative ET<sub>r...
Research Interests:
Research Interests:
Research Interests:
Pineapple [Ananas comosus (L.) Mere] is an important fruit crop cultivated in many tropical countries. This fruit crop requires large amounts of nitrogen (N) and potassium (K) to maximize yield. Although pineapple has low water... more
Pineapple [Ananas comosus (L.) Mere] is an important fruit crop cultivated in many tropical countries. This fruit crop requires large amounts of nitrogen (N) and potassium (K) to maximize yield. Although pineapple has low water requirements, extended drought can affect yield. Two experiments were conducted to study the effects of fertilizer application methods and drip irrigation management on pineapple yields. Pineapple cultivars MD-2 and Cabezona were planted at Isabela and Lajas, Puerto Rico, respectively. Fertilizer and irrigation treatments included: i) Controlapplication of 896 kg/ha of a granular fertilizer (12-6-10-3) at two, five and nine months after planting; ii) FS-R- application of 150-150-120-45 kg/ha at planting plus 20 foliar applications of urea and potassium sulfate (50 kg/ha) every three weeks, rainfed; iii) FS-DI- application of 150-150-120-45 kg/ha at planting plus 20 foliar applications of urea and potassium sulfate (50 kg/ha), drip irrigation applied every three weeks; iv) FERT- application of 150-150-120-45 kg/ha at planting, but urea and potassium sulfate (50 kg/ha) were applied throughout fertigation; and v) CRF- same amount of nutrients as FS-R but N was applied as a controlled release fertilizer every six months. At Isabela, treatment FS-R produced the highest fruit weight (2.5 kg per fruit) and 1.5% of N in tissue, but did not differ significantly from FS-DI and CRF. Plants under CRF registered the highest Brix (15.8°). Although foliar fertilizer tended to produce higher yields, controlled release fertilizer is recommended because it eliminates the need for frequent foliar application without compromising yield.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests: Horticulture and Biology
Research Interests:
Research Interests:
Irrigation scheduling (IS) and fertilization are among the most important practices in the production of horticultural crops because they affect fruit quality and quantity directly. Thus, a 15-year-old avocado orchard (cv. ‘Simmonds’) was... more
Irrigation scheduling (IS) and fertilization are among the most important practices in the production of horticultural crops because they affect fruit quality and quantity directly. Thus, a 15-year-old avocado orchard (cv. ‘Simmonds’) was used to determine precise IS, based on monitoring soil moisture content (SMC), remote sensing technologies [Unmanned Aerial Vehicle (UAV)] under two fertilization levels using granular formulation 15-3-19. In October 2015, all trees were pruned (topped and hedged) to 3.05 m height and 2.44 m diameter. In December 2015, soil moisture (SM) sensors were installed at five (10, 30, 50, 70 and 90 cm) soil depths in six locations. Trees received two fertilizer treatments: F1-9.06 kg and F2-12.07 kg of 15-3-19/tree/year every three months. Precipitation and SM data were recorded daily for 21 months; SM data was corrected with a quadratic equation (y = -4.1881x2 + 3.6886x - 0.3083) generated specifically for the Coto soil series (Typic Hapludox). The SM val...
Research Interests:
Research Interests:
Research Interests:
Since Huanglongbing (HLB) disease was detected in 2009 in Puerto Rico, a steady drop in citrus production has been experienced, forcing farmers to abandon their land or switch to other crops. Between 2015 and 2016, we used grafted trees... more
Since Huanglongbing (HLB) disease was detected in 2009 in Puerto Rico, a steady drop in citrus production has been experienced, forcing farmers to abandon their land or switch to other crops. Between 2015 and 2016, we used grafted trees from two experimental orchards (Tahiti lime and Nova mandarin), each on five rootstocks, to collect soil and plant tissue samples from each scion‒rootstock combination to determine soil fertility, tissue nutrient content, and yield. The tree growth parameters (height, diameter, and canopy volume) and efficiency of the two orchards were also measured. These orchards, growing in Coto series (Typic Hapludox), were planted in 2009 and reported as heavily infested with HLB by 2011. Our results showed that soil and tissue samples from the Tahiti lime orchard exhibited benefits for tree growth parameters when grafted on Carrizo and Cleopatra rootstocks. Lower tree mortality (13%) was observed for Tahiti lime grafted on Carrizo, HRS 812, Carrizo and Rough le...
Research Interests:
Knowledge about seasonal and litter bag soil position effects on litter decomposition (k value), mineralization and nitrification rate of annual legumes in Puerto Rico is limited. This study determined dry matter yield (DMY), k value of... more
Knowledge about seasonal and litter bag soil position effects on litter decomposition (k value), mineralization and nitrification rate of annual legumes in Puerto Rico is limited. This study determined dry matter yield (DMY), k value of litter bags placed below and above the soil surface, mineralization and nitrification rates of Lablab purpureus cv. “Rongai” and Mucuna pruriens (Velvet bean) seeded in the wet and dry season in Oxisol soils (Typic Eustrustox). There was an interaction (p < 0.05) for season and legumes on DMY, k value and N content. “Rongai” DMY was higher for the dry than wet season while Velvet bean had an opposite seasonal response. Higher k value occurred in the wet season for legumes, but “Rongai” had higher k than Velvet bean. For both legumes, N content was higher on litter bag placed below-ground in both seasons. However, in the wet season, there was less N in the above ground litter position. Higher inorganic N was observed at 90 days of soil incubation (...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Field fires can modify soil nutrient cycling and alter soil microbial communities (SMC), although the latter is not well understood. In the southern region of Puerto Rico, field fires have become a significant problem during the dry... more
Field fires can modify soil nutrient cycling and alter soil microbial communities (SMC), although the latter is not well understood. In the southern region of Puerto Rico, field fires have become a significant problem during the dry season. To mimic the effects of a field fire, we performed prescribed fires on a hillside at the Juana Díaz Agricultural Experiment substation in October 2015 and March 2017. A complete randomized block design was established in Yauco soil (Typic calciustolls) that included the following treatments: negative control (unburned), positive control (burned plots, no remediation), mulching treatment (burned plots remediated with Leucaena spp. mulch), and surfactant treatment (burned plots remediated with a surfactant). In the first burning (2015), soil samples were collected before burning and at 30, 180, and 420 days after burning (DAB). In the second burning (2017), soil samples were collected at 30, 90, and 270 DAb. soil physicochemical properties and micr...
Research Interests:
Research Interests:
Knowledge of carbon (C) and nitrogen (N) dynamics under different irrigation practices in pomegranate orchards is novel and essential to develop sustainable production systems. The aim of this research was to determine the effect of... more
Knowledge of carbon (C) and nitrogen (N) dynamics under different irrigation practices in pomegranate orchards is novel and essential to develop sustainable production systems. The aim of this research was to determine the effect of high-frequency drip irrigation and different rates of N fertilizer on C and N distribution in the soil and N uptake by pomegranate fruit and leaves. The main treatments were surface drip irrigation (DI) and subsurface drip irrigation (SDI), and the sub-treatments used were three initial N rates (N1, N2, and N3). As trees grew larger, the N application rate increased. From 2013–2015, trees received the following rates of N: 62–113 (N1), 166–263 (N2), or 244–342 kg/ha (N3). Soil and leaf total C (TC) and N (TN), soil dissolved organic C (DOC), soil nitrate (NO3−), and total N uptake by fruit were evaluated between 2012 and 2015. Soil samples were collected to 120 cm depth at 15 cm increments. DI resulted in higher concentrations of TN, TC, NO3−, and DOC in...
Research Interests:
The experiment consisted of two dates of planting [in September (D1) and February (D2)] of maize (Zea mays L.) DKC 67-60, to evaluate the effect of four N fertilization levels (0, 56, 112 and 185 kg/ha) and three ages at harvest [70, 77... more
The experiment consisted of two dates of planting [in September (D1) and February (D2)] of maize (Zea mays L.) DKC 67-60, to evaluate the effect of four N fertilization levels (0, 56, 112 and 185 kg/ha) and three ages at harvest [70, 77 and 84 days after planting (DAP)] on dry matter yield (DMY) of the leaves, stem, ear and of the entire plant; and as indicators of nutritive value [crude protein (CP) and neutral detergent fiber (NDF)] of harvested material prior to ensiling. In both plantings, the levels of N affected (P<0.05) DMY of leaves, stems, ears and entire plant, exhibiting both a linear and a quadratic response, and suggesting that the optimum N application rate is between 112 and 185 kg/ha. Age at harvest date affected (P<0.05) DMY of stems, ears and entire plant, but not that of the leaves. Greater DMY was observed at 84 DAP for all components. The CP concentration was greater in the forage of the first planting (D1). Increasing N application rates increased CP, but...
Research Interests:
Phosphorus (P) and Zinc (Zn) stand out for their interactions, however, little is known about the interaction of these elements in organic substrates used in the development of plants. The objective of this work was to evaluate the... more
Phosphorus (P) and Zinc (Zn) stand out for their interactions, however, little is known about the interaction of these elements in organic substrates used in the development of plants. The objective of this work was to evaluate the extractable and total P and Zn of the enriched coconut powder substrate and the development of tomato seedlings grown on the same substrate. The work consisted of 10 treatments and 4 replicates with different doses of P and Zn. The substrate used was coconut powder enriched with nutrient solutions in a ratio of 10:1 (v/m). Then, the experiment was conducted using the enriched substrate to observe the effect of P and Zn doses on the development of tomato seedlings in trays. The height, number of leaves and the dry matter of the plants were evaluated. For the water and Mehlich-1 extractors the highest values of P and Zn were for treatments with the highest doses and only the quadratic positive effect of P did not differ statistically in the enriched coconut...
Research Interests:
Tree seedlings planted in containers along sidewalks in urban environments show restricted growth and development over time. This is the result of limited soil volume and soil compaction that hampers nutrient availability and water... more
Tree seedlings planted in containers along sidewalks in urban environments show restricted growth and development over time. This is the result of limited soil volume and soil compaction that hampers nutrient availability and water movement. Using tree species commonly used in urban forestry in Puerto Rico, this study was conducted to determine their growth response when planted in compacted soils. Seedlings of three ornamental tropical tree species, trumpet bush [Tecoma stans (L.) Juss. ex Kunth], bottle brush [Callistemon citrinus (Curtis) Skeels], and pink trumpet (Tabebuia rosea dc.) were transplanted into pots of sandy clay loam or clay soils at three levels of compaction: control (no compaction), 1.2 g/cm3 and 1.4 g/cm3 bulk density, respectively. Plant height, shoot diameter, leaf number and color, foliar area, and root, shoot, and leaf dry weights were measured on two plants every two months for six months. All species exhibited better growth in sandy clay loam at 1.2 g/cm3;...
Research Interests:
Abstract Synthetic gypsum, a by-product of electricity generation, is used as a soil amendment to overcome water ponding, improve soil and water quality, improve field conditions to support farm equipment, and reduce the variability of... more
Abstract Synthetic gypsum, a by-product of electricity generation, is used as a soil amendment to overcome water ponding, improve soil and water quality, improve field conditions to support farm equipment, and reduce the variability of crop yield in no-till fields by improving hydrology. Gypsum is a source of soluble calcium (Ca) that improves physical properties of the soil by promoting clay aggregation, thereby increasing water infiltration rates and movement through the soil profile. Undisturbed soil samples from Brookston and Celina soils in Ohio, USA were collected to a depth of 75 cm in agricultural fields treated with gypsum for 0, 4, and 12 years to determine changes in chemical and physical properties. Gypsum applications increased exchangeable Ca and Ca: Mg ratios, and promoted clay flocculation and improved soil structure. Mean weight diameter of aggregates increased with gypsum treatment at most depths in both soils. Micromorphological analysis showed variations in porosity (ɸ), pore size distribution, pore shape and aggregate size related to gypsum treatment, soil, and soil depth. There were no consistent responses to years of gypsum application. Gypsum treated soils had higher porosity than untreated soils in all depths
Research Interests:
A continuous spatio-temporal database of accurate soil moisture (SM) measurements is an important asset for agricultural activities, hydrologic studies, and environmental monitoring. The Advanced Microwave Scanning Radiometer 2 (AMSR2),... more
A continuous spatio-temporal database of accurate soil moisture (SM) measurements is an important asset for agricultural activities, hydrologic studies, and environmental monitoring. The Advanced Microwave Scanning Radiometer 2 (AMSR2), launched in May 2012, has been providing SM data globally with a revisit period of two days. It is imperative to assess the quality of this data before performing any application. Since resources of accurate SM measurements are very limited in Puerto Rico, this research will assess the quality of the AMSR2 data by comparing with ground-based measurements and perform a downscaling technique to provide a better description of how the sensor perceives the surface soil moisture as it passes over the island. The comparison consisted of the evaluation of the mean error, root mean squared error, and the correlation coefficient. Two downscaling techniques were used and their performances were studied. The results revealed that AMSR2 products tend to underest...
Research Interests:
Gypsum is an excellent source of Ca and S, both of which are required for crop growth. Large amounts of by-product gypsum [Flue gas desulfurization gypsum-(FGDG)] are produced from coal combustion in the United States, but only 4% is used... more
Gypsum is an excellent source of Ca and S, both of which are required for crop growth. Large amounts of by-product gypsum [Flue gas desulfurization gypsum-(FGDG)] are produced from coal combustion in the United States, but only 4% is used for agricultural purposes. The objective of this study was to evaluate the effects of (1) untreated, (2) short-term (4-year annual applications of gypsum totaling 6720 kg ha(-1)), and (3) long-term (12-year annual applications of gypsum totaling 20,200 kg ha(-1)) on alfalfa (Medicago sativa L.) growth and nutrient uptake, and gypsum movement through soil. The study was conducted in a greenhouse using undisturbed soil columns of two non-sodic soils (Celina silt loam and Brookston loam). Aboveground growth of alfalfa was not affected by gypsum treatments when compared with untreated (p > 0.05). Total root biomass (0-75 cm) for both soils series was significantly increased by gypsum application (p = 0.04), however, increased root growth was restric...
Research Interests:
Abstract The conventional procedures for soil Cation Exchange Capacity ( CEC ) measurement are time consuming and laborious. It is also difficult to maintain stability for long-term experiments and projects. Therefore, this study aimed at... more
Abstract The conventional procedures for soil Cation Exchange Capacity ( CEC ) measurement are time consuming and laborious. It is also difficult to maintain stability for long-term experiments and projects. Therefore, this study aimed at comparing Adaptive Neuro-Fuzzy Inference System (ANFIS)-based subtractive clustering algorithm with different inputs combinations as well as sequential regression models for simulation of variations in soil CEC . Results showed that the corresponding values of root mean squared error ( RMSE ) and coefficient of determination ( R 2 ) between the measured and simulated CEC using the best regression equation and ANFIS models were 2.05 and 0.733, 1.35 and 0.806, respectively. Nevertheless, sensitivity analysis was conducted to determine the most and the least influential variables affecting soil CEC . Results of the present investigation showed that the ANFIS model had the ability to estimate soil CEC by computing easily measurable variables with guarantee of authenticity, reliability and reproducibility.
Research Interests:
Research Interests:
Standardized reference evapotranspiration (ET) and ecosystem-specific vegetation coefficients are frequently used to estimate actual ET. However, equations for calculating reference ET have not been well validated in tropical... more
Standardized reference evapotranspiration (ET) and ecosystem-specific vegetation coefficients are frequently used to estimate actual ET. However, equations for calculating reference ET have not been well validated in tropical environments. We measured ET (ET<sub>EC</sub>) using eddy covariance (EC) towers at two irrigated sugarcane fields on the leeward (dry) side of Maui, Hawaii, USA in contrasting climates. We calculated reference ET at the fields using the short (ET<sub>0</sub>) and tall (ET<sub>r</sub>) vegetation versions of the American Society for Civil Engineers (ASCE) equation. The ASCE equations were compared to the Priestley–Taylor ET (ET<sub>PT</sub>) and ET<sub>EC</sub>. Reference ET from the ASCE approaches exceeded ET<sub>EC</sub> during the mid-period (when vegetation coefficients suggest ET<sub>EC</sub> should exceed reference ET). At the windier tower site, cumulative ET<sub>r...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Tree seedlings planted in containers along sidewalks in urban environments show restricted growth and development over time. This is the result of limited soil volume and soil compaction that hampers nutrient availability and water... more
Tree seedlings planted in containers along sidewalks in urban environments show restricted growth and development over time. This is the result of limited soil volume and soil compaction that hampers nutrient availability and water movement. Using tree species commonly used in urban forestry in Puerto Rico, this study was conducted to determine their growth response when planted in compacted soils. Seedlings of three ornamental tropical tree species, trumpet bush [Tecoma stans (L.) Juss. ex Kunth], bottle brush [Callistemon citrinus (Curtis) Skeels], and pink trumpet (Tabebuia rosea dc.) were transplanted into pots of sandy clay loam or clay soils at three levels of compaction: control (no compaction), 1.2 g/cm and 1.4 g/ cm bulk density, respectively. Plant height, shoot diameter, leaf number and color, foliar area, and root, shoot, and leaf dry weights were measured on two plants every two months for six months. All species exhibited better growth in sandy clay loam at 1.2 g/cm; a...
ABSTRACT Increased availability of flue gas desulfurization gypsum (FGDG) and the recognition of its potential to improve soil–water relationships have stimulated studies of its use on poorly drained soils with high seasonal rainfall,... more
ABSTRACT Increased availability of flue gas desulfurization gypsum (FGDG) and the recognition of its potential to improve soil–water relationships have stimulated studies of its use on poorly drained soils with high seasonal rainfall, especially on no-tillage (NT) soils. Previous studies have focused on the effects of gypsum on hydrological properties at the soil surface (e.g. infiltration and soil crusting) but little information is available concerning the effects of surface-applied gypsum in profiles of non-sodic NT soils with contrasting drainage classes. To address this lack of information, undisturbed columns from two non-sodic NT soil profiles, characterized as being either moderately well drained or poorly drained, were collected from agricultural fields with historic information regarding number of years of gypsum application (i.e. 0, 4, and 12 yr). Alfalfa was planted in the columns and then plant growth, and soil chemical and hydrologic properties were measured. Higher Ca concentrations were found in both gypsum treated soils compared with control (CT) soils (P &lt; 0.10). A greenhouse water balance study revealed significantly (P &lt; 0.10) greater cumulative drainage (∼60%) associated with the Brookston long-term (LT) gypsum and the Celina short-term (ST) gypsum soil treatments than for the control treatments. This greater drainage response was attributed to Ca redistribution to lower depths and improved soil structure. However, restricted drainage in Celina LT columns was attributed to secondary Ca carbonate precipitation in pores at 60–75 cm depth. Leachate samples collected from the columns indicated no element deficiencies that would negatively affect alfalfa growth. Nutrients and trace element concentrations also were within accepted limits for good plant growth and water quality.
Research Interests:
Synthetic gypsum, a by-product of electricity generation, is used as a soil amendment to overcome water ponding, improve soil and water quality, improve field conditions to support farm equipment, and reduce the variability of crop yield... more
Synthetic gypsum, a by-product of electricity generation, is used as a soil amendment to overcome water ponding, improve soil and water quality, improve field conditions to support farm equipment, and reduce the variability of crop yield in no-till fields by improving hydrology. Gypsum is a source of soluble calcium (Ca) that improves physical properties of the soil by promoting clay aggregation, thereby increasing water infiltration rates and movement through the soil profile. Undisturbed soil samples from Brookston and Celina soils in Ohio, USA were collected to a depth of 75 cm in agricultural fields treated with gypsum for 0, 4, and 12 years to determine changes in chemical and physical properties. Gypsum applications increased exchangeable Ca and Ca: Mg ratios, and promoted clay flocculation and improved soil structure. Mean weight diameter of aggregates increased with gypsum treatment at most depths in both soils. Micromorphological analysis showed variations in porosity (ɸ), pore size distribution, pore shape and aggregate size related to gypsum treatment, soil, and soil depth. There were no consistent responses to years of gypsum application. Gypsum treated soils had higher po-rosity than untreated soils in all depths b75 cm and a higher percentage of micropores and mesopores compared to the control. Also, gypsum treated soils had larger aggregates than the control for all soil depths examined. Aggregates b100 μm predominated in the Brookston control soils, and b 200 μm aggregates dominated the Celina control soils. However, there was no prevailing aggregate size for gypsum treated soils. In conclusion, our study found positive effects of gypsum on most properties measured; although, not consistently related to years of gypsum applications to both soils.
Research Interests:
The experiment consisted of two dates of planting [in September (D1) and February (D2)] of maize (Zea mays L.) DKC 67-60, to evaluate the effect of four N fertilization levels (0, 56, 112 and 185 kg/ha) and three ages at harvest [70, 77... more
The experiment consisted of two dates of planting [in September (D1) and February (D2)] of maize (Zea mays L.) DKC 67-60, to evaluate the effect of four N fertilization levels (0, 56, 112 and 185 kg/ha) and three ages at harvest [70, 77 and 84 days after planting (DAP)] on dry matter yield (DMY) of the leaves, stem, ear and of the entire plant; and as indicators of nutritive value [crude protein (CP) and neutral detergent fiber (NDF)] of harvested material prior to ensiling. In both plantings, the levels of N affected (P<0.05) DMY of leaves, stems, ears and entire plant, exhibiting both a linear and a quadratic response, and suggesting that the optimum N application rate is between 112 and 185 kg/ha. Age at harvest date affected (P<0.05) DMY of stems, ears and entire plant, but not that of the leaves. Greater DMY was observed at 84 DAP for all components. The CP concentration was greater in the forage of the first planting (D1). Increasing N application rates increased CP, but had no effect on NDF concentration. Age at harvest had no effect on CP, but progressively increased NDF. Both pH and organic acid concentrations in the silages were similar with the four N levels; all of the silages showed good fermentation characteristics.
Research Interests:
A continuous spatio-temporal database of accurate soil moisture (SM) measurements is an important asset for agricultural activities, hydrologic studies, and environmental monitoring. The Advanced Microwave Scanning Radiometer 2 (AMSR2),... more
A continuous spatio-temporal database of accurate soil moisture (SM) measurements is
an important asset for agricultural activities, hydrologic studies, and environmental monitoring.
The Advanced Microwave Scanning Radiometer 2 (AMSR2), which was launched in May 2012, has
been providing SM data globally with a revisit period of two days. It is imperative to assess the
quality of this data before performing any application. Since resources of accurate SM measurements
are very limited in Puerto Rico, this research will assess the quality of the AMSR2 data by comparing
it with ground-based measurements, as well as perform a downscaling technique to provide a better
description of how the sensor perceives the surface soil moisture as it passes over the island. The
comparison consisted of the evaluation of the mean error, root mean squared error, and the correlation
coefficient. Two downscaling techniques were used, and their performances were studied. The results
revealed that AMSR2 products tend to underestimate soil moisture. This is due to the extreme
heterogeneous distributions of elevations, vegetation densities, soil types, and weather events on the
island. This research provides a comprehensive study on the accuracy and potential of the AMSR2
products over Puerto Rico. Further studies are recommended to improve the AMSR2 products.
an important asset for agricultural activities, hydrologic studies, and environmental monitoring.
The Advanced Microwave Scanning Radiometer 2 (AMSR2), which was launched in May 2012, has
been providing SM data globally with a revisit period of two days. It is imperative to assess the
quality of this data before performing any application. Since resources of accurate SM measurements
are very limited in Puerto Rico, this research will assess the quality of the AMSR2 data by comparing
it with ground-based measurements, as well as perform a downscaling technique to provide a better
description of how the sensor perceives the surface soil moisture as it passes over the island. The
comparison consisted of the evaluation of the mean error, root mean squared error, and the correlation
coefficient. Two downscaling techniques were used, and their performances were studied. The results
revealed that AMSR2 products tend to underestimate soil moisture. This is due to the extreme
heterogeneous distributions of elevations, vegetation densities, soil types, and weather events on the
island. This research provides a comprehensive study on the accuracy and potential of the AMSR2
products over Puerto Rico. Further studies are recommended to improve the AMSR2 products.