Gerardo Rubio

University of Buenos Aires | UBA · Research Institute of Agricultural and Environmental Biosciences (INBA)

Elucidating how different fertilization treatments affect the resilience of farming systems and the environmental adaptability of agricultural crops is relevant to assess their efficacy as a strategy for minimizing yield fluctuations and supporting global food security. The aim of this work was to compare the effects of fertilization practices and...

The concept of mineral plant nutrient has been the subject of a long debate. Here, we suggest that an updated discussion on this issue requires considering three dimensions. The first one is ontological as it refers to the fundamentals that underlie the category of being a mineral plant nutrient, the second one refers to the practical rules helping...

Purpose The inclusion of winter legumes during fallow periods allows the addition of N to the system through biological N fixation (BNF), which will depend on management practices and crop species (for grain production or a cover crop). The objectives of this study were to evaluate the BNF and biomass and N accumulation in pea and vetch crops growi...

Aims Most studies that quantified the biological N fixation (BNF) and partial N balances of soybean have ignored the belowground structures. Our objectives were to evaluate the contribution of belowground structures to the partial N balance of soybean and to identify the origin (soil or BNF) and source (apparent remobilization or current gain durin...

Food security and economic stability of many developing countries rely on the resilience of major crops to climatic variability and climatic anomalies. Since climate change forecasts predict an increasing frequency and intensity of climatic disturbances, the need to increase our knowledge about the influence of climate variability on crop productiv...

Continuous potassium (K) removal without replenishment is progressively mining Argentinean soils. Our goals were to evaluate the sensitivity of soil-K to K budgets, quantify soil-K changes over time along the soil profile, and identify soil variables that regulate soil-K depletion. Four on-farm trials under two crop rotations including maize, wheat...

AimsComparing different winter legume species by plant traits that determine their contributions to ecosystems as service crops. Since root biomass determines soil organic matter formation and biological nitrogen fixation (BNF) increases soil organic nitrogen stock, those plant traits are more suitable than shoot biomass to select service crops.Met...

Climatic change effects on crop yields are expected to be crop‐ and site specific. Here, Decision Support System for Agrotechnology Transfer models were used to evaluate climatic change effects and mitigation strategies on maize (Zea mays L.) and soybean [Glycine max (L.) Merr.] yields in soils of the subtropical and semi‐arid region of Chaco. Simu...

RESUMEN En una red de ensayos de largo plazo se evaluaron los efectos de 14 años de fertilización continua con N, P y S sobre la concentración de P Bray 1 y Nan, la relación N:P en la fracción lábil y, la relación de las concentraciones de N y P en granos de soja y muestras de suelo. Se analizaron suelos de tres estratos de profundidad (0-5, 5-10 y...

Topsoil hardening is one of the major causes of poor root growth although its effects on subsoil roots are still not well-known. Our aim was to examine the effects of topsoil hardening on the growth and functioning of shallow and deep roots of soybean plants. Two rain shelter experiments were conducted in two consecutive years. Plants were grown in...

Agricultural management practices such as fertilization may affect the overall soil quality and nutrient supply capacity. In this study, we hypothesized that long‐term fertilization promotes (a) an increase in the proportion of easily degradable soil organic C, N, and S fractions and (b) changes in the soil C, N, and S stoichiometric ratios in the...

Commercial phytases are widely used in poultry production, but little is known about their potential use as biofertilizer for agricultural crops as an alternative to reduce the use of synthetic fertilizers. Four purified phytases isolated from Aspergillus niger and Escherichia coli were characterized biochemically and in terms of their adsorption t...

Four purified phytases isolated from Aspergillus niger and Escherichia coli were characterized biochemically and in terms of their adsorption to soils belonging to the Mollisol order. Three different organic P substrates were used to measure enzyme activity in a wide range of pH (2.3 to 9) and temperatures (−10° to 70 °C): p-nitrophenyl-phosphate,...

Pampean landscapes are characterized by the presence of extensive plains originally covered by grasslands. At present, rainfed production of cereal and oil crops is the main economic farming activity of the region and constitutes a high proportion of Argentina exports. The most fertile soils of Argentina are located in this region. They are Molliso...

Soils constitute one of the greatest assets of Argentina. This resource, coupled with the climatic conditions, confers this country the capacity to produce food for more than ten times its current population. Although it is largely known among local scientists that soils constitute the country’s main natural resource, this fact remains largely unkn...

In this chapter, we provide an overview of the main agricultural features of different regions of the country. In the northwest region, climate favors the development of subtropical agriculture, especially in the ample valleys. A great proportion of the expansion of agricultural frontier over the last decades took place in this region and also in t...

Data from long-term crop rotation study sites were combined to evaluate the effect of long-term application (and omission) of P fertilizers. The impact of maintaining either a negative or positive P balances on soil test P at five distinct sites was described by single response functions despite a range of differences in soil properties.

Although the semiarid and subhumid Chaco regions in northern Argentina have been traditionally considered marginal and unsuitable for cultivating grain maize for human and livestock nutrition, this crop is increasingly being adopted by local farmers. The low maize yields observed in the area suggest that climatic constraints limit productivity, whi...

Although the semiarid and subhumid Chaco regions in northern Argentina have been traditionally considered marginal and unsuitable for cultivating grain maize for human and livestock nutrition, this crop is increasingly being adopted by local farmers. The low maize yields observed in the area suggest that climatic constraints limit productivity, whi...

Few reports have compared the P critical level between different crops under equivalent growing conditions and the impact of P balance and P fertilization practices on the long term dynamics of soil available P. The objectives of this study were: i) to determine and compare, under similar field conditions, the P critical values for soybean, maize a...

En los últimos años se ha intensificado el uso agrícola del suelo y con ello la práctica de fertilización de los cultivos de granos. Con el objetivo de evaluar el efecto de los distintos regímenes de fertilización de largo plazo sobre: (a) los contenidos de materia orgánica de suelos (MOS) y nitrógeno potencialmente mineralizable (Nan) en el suelo...

Soil nitrogen (N) dynamics can be modified by cover crops in rotations with cereals. Although, roots are a major source of N, little is known about the dynamics of root decomposition of cash and cover crops. The objective of this study was to assess the effects that cover crop species have on i) the decomposition of spring wheat roots during the gr...

Core Ideas Predictive models of phosphorus sorption were developed for a group of Mollisols. Al ox was the best predictor of short‐term phosphorus sorption indices. Fe ox was the best predictor for those indices that involves longer interaction periods. Phosphorus needs to maximize yield avoiding environmental risks can be estimated with our data....

Nitrogen (N) fertilizers are one of the most expensive inputs in agricultural settings. Additionally, the loss of N increases costs, contributes to soil acidification, and causes off-site pollution of the air, groundwater and waterways. This study reviews current knowledge about technologies for N fertilization with potential to increase N use effi...

Residue decomposition and P release was studied under no tillage field conditions. Cover crop residues releases significant quantities of P for the subsequent cash crop. Phosphorus release from residues is affected by precipitation regime and residue quality. A positive tradeoff was observed between crop residue P dynamics and soil coverage. Under...

Los granos de soja no cambiaron su contenido de N (i.e. proteína) y, por lo tanto, la exportación de N por efectos de fertilización continuada con N, P y S. Sin embargo, los distintos regímenes de fertilización cambiaron la concentración de P y S en el grano y, por lo tanto, su exportación. La concentración de nutriente que mostró mayor sensibilida...

Many of the plant acquisition strategies for immobile nutrients, such as phosphorus (P), are related to the maximization of soil exploration at minimum metabolic cost. Previous studies have suggested that soybean (Glycine max L.), sunflower (Helianthus annuus L.), and maize (Zea mays L.) differ in their P uptake efficiency. In this investigation we...

We evaluated the ability of Brassica napus L. (oilseed rape), Helianthus annus L. (sunflower), and Glycine max L. (soybean) plants grown inoculated with or without bacteria to utilize organic P sources. Plants were supplied with inorganic (dibasic sodium phosphate) and organic P sources (phytate and glucose phosphate) at three concentrations and gr...

Nothofagus antarctica forests in south Patagonia are usually used as silvopastoral systems but how grasses and trees compete for specific resources, such as nitrogen in these systems is unknown. To understand interactions between grasses and N. antarctica trees for N, an experiment with 15N labeled fertilizer was carried out comparing N absorption...

Los suelos constituyen un continuum a través de la superficie terrestre. Cada combinación específica de paisaje, clima, material parental, proceso de meteorización, vegetación y manejo determina diferentes unidades de suelo. En suelos agrícolas, la distinción entre diferentes unidades de suelo suele ser muy compleja y requiere experiencia de campo....

The predictions of two models on biomass allocation were compared on P-stressed and non-stressed crop plants. Allometric coefficients were calculated from paired measurements of root and shoot biomass obtained from field and greenhouse experiments with soybean [Glycine max (L.) Merr.], sunflower (Helianthus annuus L.), and maize (Zea mays L.) plant...

How roots detect and respond to the presence of neighbors is relevant to understand plant belowground interactions. The aim of the present work was to evaluate the effect of the presence of neighboring plants and the limited availability of phosphorus on root architecture. A target plant of Arabidopsis thaliana (Ler or Col) was surrounded by combin...

Soils are a continuum across Earth's surface. Each specific combination of landscape, climate, parent material, weathering process, vegetation and management determines different soil units. In agricultural soils, the distinction among different soil units is often very complex and requires some field experience. In fact, many graduate students and...

It has been reported for many soils that maize (Zea mays L.) has a higher soil-P critical level than soybean (Glycine max L.) and sunflower (Helianthus annuus L). The objective of this work was to compare the rhizosphere P depletion in these three species in order to investigate if they differ in their capacity to acquire soil P. Sequential P fract...

Sulfur (S) deficiencies in grain and forage crops have been detected in many agricultural regions of the world, but soil tests are not commonly used as the basis for sulfur fertilizer recommendation programs. Errors of measurements of soil sulfate were determined to assess whether the variation among and within soil testing laboratories could be a...

The nitrogen (N) from fertilizers has different fate, some of which affect the environment or the human health, e.g. nitrates in groundwater. We determined the fate (plant organs, soil organic matter, remaining nitrates and volatilization) of the N applied to field-grown direct drilling maize. An experiment was carried out in a Typic Argiudoll at C...

Fluorescent compounds have been reported in plant leaves, having an important biological role in the protection towards UV irradiation. It is also known that stress conditions in plants stimulate the production of some of these compounds in their aerial portion. However, less is known about their production by roots or seeds and their presence in t...

Resumen Si bien los bosques de ñire son muy utilizados como sistemas silvopastoriles, existen escasos estudios que evalúen las interacciones existentes entre los estratos arbóreo y herbáceo. El objetivo de este trabajo fue detectar si predominan procesos de facilitación o de competencia entre los componentes vegetales por el recurso nitrógeno (N)....

La región pampeana argentina es una de las áreas agrícolas más productivas del mundo y sus suelos, originalmente bien provistos de potasio (K), son considerados uno de los más ricos en este nutriente. Por tal motivo, históricamente se le prestó poca atención y hasta la actualidad la fertilización potásica ha sido nula. Sin embargo, la intensificaci...

We have observed that low soil phosphorus availability alters the gravitropic response of basal roots in common bean (Phaseolus vulgaris L.), resulting in a shallower root system. In this study we use a geometric model to test the hypotheses that a shallower root system is a positive adaptive response to low soil P availability by (1) concentrating...

It has been reported for many soils that maize (Zea mays L.) has a higher soil-P critical level than soybean (Glycine max L.) and sunflower (Helianthus annuus L). The objective of this work was to compare the rhizosphere P depletion in these three species in order to investigate if they differ in their capacity to acquire soil P. Sequential P fract...

Despite a general consent about the beneficial contribution of arbuscular mycorrhizal fungi (AMF) on natural ecosystems, there is an intense debate about their role in agricultural systems. In this work, soybean (Glycine max L.) and sunflower (Helianthus annuus L.) field plots with different P availabilities were sampled across the Pampean Region o...

Root architecture is of key importance for plant nutrition and performance. It is known that root architecture is determined by genetics and environmental conditions. The aim of the present study was to evaluate if root exudation within a given plant has a role in the development of root architecture. We conducted a series of experiments using Arab...

Los suelos franco-limosos manejados con siembra directa a menudo poseen porosidad estructural baja e inestable. Con el objetivo de determinar la capacidad de los cultivos de cobertura (CC) de mejorar la porosidad y estabilidad estructural de estos suelos se llevaron a cabo experimentos de campo y de invernáculo. Ambos tuvieron tratamientos con y si...

F values, significance levels (between brackets) and LSD mean comparisons for data collected in Experiment 3. Factors were addition of exudates from 0, 3, 6 and 12 plants of A. thaliana ecotype Col and AC [control (−AC) and 5 g L−1 AC added to the growth media

F values, significance levels (between brackets) and LSD mean comparisons for data collected in Experiment 2. Factors were ecotype (A. thaliana ecotypes Ler and Col) and AC [control (−AC) and 5 g L−1 AC added to the growth media

The study of labile and nonlabile forms of P might contribute to advances in soil test procedures and provide insights into management strategies to enhance P bioavailability to crops. Our objective was to evaluate the effect of continuous P fertilization on inorganic (Pi) and organic (Po) P fractions to improve the understanding of soil P dynamics...

In temperate cropping systems, a better understanding of soil C and P transformations is pertinent to evaluate crop management consequences in the medium term. Six-year cropping systems experiments consisting of corn (Zea mays L.)–double-cropped wheat (Triticum aestivum L.)/soybean [Glycine max (L.) Merr.] (two sites) and corn–soybean–double-croppe...

Different relationships between soil-test methods results have been reported in several agricultural regions. Differences in the same soil-test procedure (e.g., soil/solution ratio) exist between soil-testing laboratories from different agricultural regions. Our objectives were to (1) determine the effect of soil/solution ratio on the amount of pho...

A better understanding of the P cycle is necessary to provide insights into management strategies that could enhance P bioavailability for crops. Our objectives were to evaluate the effects of continuous P fertilization on (i) the P budget, (ii) soil-extractable P (Pe) dynamics, and (iii) the relationship between these variables. Two crop rotations...

No- till (NT) silt loam topsoils have often a low and unstable structural porosity. The objective of this study was to determine the capability of cover crops (CC) of improving the structural porosity and stability of silt loam soils under NT. Greenhouse and field experiments were carried out on a silt loam soil (Typic Argiudoll) with and without C...

Data on tree biomass are essential for understanding the forest carbon cycle and plant adaptations to the environment. We determined biomass accumulation and allometric relationships in the partitioning of biomass between aboveground woody biomass, leaves and roots in Nothofagus antarctica. We measured above- and belowground biomass of N. antarctic...

In grasslands composed of C3 and C4 plants, a different pattern of response by the two photosynthetic types to fertilizer may change the floristic composition of the community. In this study, we evaluated the effects of an application of nitrogen (N) and phosphorus (P) fertilizer at two dates in the spring on the aerial growth of C3 and C4 grasses....

A more comprehensive understanding of the mechanisms of phosphorus (P) efficiency is agronomically significant to advance in the design of crop management schemes that increase P efficiency and reduce the need of fertilizers. Phosphorus efficiency is defined as the ability of a plant to acquire P from the soil and/or to utilize it in the production...

In Santa Cruz and Tierra del Fuego provinces, 70% of Nothofagus antarctica forests have been used as silvopastoral systems. For sustainable forest practices it is necessary to take into account main nutrient content and dynamics in the overstory. For this, the aim of this work was to determine the N, P and K contents in N. antarctica stands of two...

Maize production is affected by water and nitrogen (N) deficit either separately or joined, but this fact is not completely defined. The aim was to evaluate the fate of N in maize fertilized and subjected to water stress in controlled conditions. A greenhouse experiment was carried out at the University of Buenos Aires campus. The design was a 2 ×...

The spectroscopic changes in reflectance and fluorescence caused by phosphorus (P) starvation in Brassica napus L. young plants were evaluated. P deficiency produced an important decrease in reflectance values between 500 and 650 nm for both intact leaves and cotyledons. Furthermore, cotyledons under P deficiency showed a Chl-F ratio in the red/far...

Accurate critical levels must be accompanied by predictive models on the amount of P required to increase P availability to a target value to obtain reliable P recommendations. We estimated, based on information on soil properties, the increase in soil available P after the addition of a unit of P (b coefficient) in an area of homogeneous although...

The objective of this work was to evaluate the effect of the chemical nature and application frequency of N fertilizers at different moisture contents on soil N2O emissions and N2O/(N2O+N2) ratio. The research was based on five fertilization treatments: unfertilized control, a single application of 80kg ha−1 N-urea, five split applications of 16kg...

Oilseed rape poses a higher sulfur (S) demand, compared to other crops. This may indicate that the inclusion of this crop in the crop rotation could accelerate soil S depletion. In this work, we compared the allocation of biomass, nitrogen (N), phosphorus (P) and S in oilseed rape mature plants. Two factors were analyzed in a field experiment: nitr...

Nitrous oxide (N2O) contributes to greenhouse effect; however, little information on the consequences of different moisture levels on N2O/(N2O+N2) ratio is available. The aim of this work was to analyze the influence of different soil moisture values and thus of redox conditions on absolute and relative emissions of N2O and N2 at intact soil cores...

The activity of soil pathogens, competition for assimilates, and the changing availability of below-ground resources make root systems subject to a continuous and dynamic process of formation and loss of both fine and coarse roots. As hypocotyl borne roots appear later than other root classes, they may serve to functionally replace basal and primar...

Oilseed rape poses a higher sulfur (S) demand, compared to other crops. This may indicate that the inclusion of this crop in the crop rotation could accelerate soil S depletion. In this work, we compared the allocation of biomass, nitrogen (N), phosphorus (P) and S in oilseed rape mature plants. Two factors were analyzed in a field experiment: nitr...

Root gravitropism determines the relative distribution of plant roots in different soil layers, and therefore, may influence the acquisition of shallow soil resources such as phosphorus (P). Growth pouch and field studies were conducted to evaluate root gravitropism of common bean (Phaseolus vulgaris L.) in response to P deficiency and to detect qu...

Root gravitropism determines the relative distribution of plant roots in different soil layers, and therefore, may influence the acquisition of shallow soil resources such as phosphorus,(P). Growth pouch and field studies were conducted to evaluate root gravitropism of common,bean (Phaseolus vulgaris L.) in response to P deficiency and to detect qu...

A novel technique was developed to spatially map the phosphorus net influx capacity in intact root systems. The method is based on digital autoradiography and permits the quantification of phosphorus influx at high spatial resolution (2 mm). Roots of 18-d-old common bean plants were exposed to 32P-labelled orthophosphate, quickly frozen, excised, l...

Fertilization is an important cause of groundwater contamination with nitrate in agricultural soils. The objectives of the present work were: (i) to quantify the nitrate leaching in two fertilized and irrigated soils of the Pampas Region, Argentina; (ii) to test the ability of the NLEAP model to predict residual and leached nitrate in those soils....

Vehicular and foot traffic increase soil compaction in sport and recreational areas, reducing shoot and root growth and overall quality of turfgrasses. Soil enrichment with sands is a common practice to cope with this problem. Sand-soil mixtures require a high input of fertilizers and water to maintain a high quality surface. These practices may in...