Texture influence on soil phosphorus content and distribution in semiarid Pampean grasslands

Suñer L., J.A. Galantini. 2015. Texture influence on soil phosphorus content and distribution in semiarid Pampean grasslands. InternationalJournal of Plant & Soil Science (ISSN: 2320-7035) Vol.: 7, Issue.: 2 109-120, no.IJPSS.2015.136, PDF

Extended Abstract

Soil texture affects the soil environment and the mineralization of soil organic matter (SOM) in several ways. It has been reported that a rich clay content in the topsoil results in high levels of soil organic matter; at the same time, it enhances nitrogen, phosphorus and sulphur availability (Galantini et al., 2004; Duval et al., 2016). Soil P (phosphorus) equilibrium and availability can be modified by soil texture as a consequence of changes in physicochemical properties, in phosphate adsorption-desorption-diffusion processes, and in SOM mineralization-immobilization processes.

Physical fractionation methods based on SOM particle size have been developed to separate organic fractions with different characteristics and dynamics (Andriulo et al., 1990; Galantini et al., 1997). It is therefore now possible to distinguish between SOM associated with the fine and with the coarse fractions, which have different structures and roles. The fine soil fraction (clay, silt) corresponds to a more humidified or mineral-associated organic matter (MOM), and the coarse fraction (different sizes of sand) to less transformed, labile, light or particulate organic matter (POM). Considering that both fractions are crucial to soil fertility, it is important to determine the organic (Po) and inorganic (Pi) phosphorus contents in each size fraction and to relate them to soil texture. Differences in P content are expected to be found in both particle size fractions: the fine fraction is likely to contain the more stable Po (Po-MOM) and the more available Pi (Pi-clay and silt sizes); the coarse fraction, instead, is assumed to contain the more labile Po (Po-POM) and Pi (Pi-sand size) with low availability in the short term.

The hypothesis is that soil texture affects the equilibrium of the different P-forms in soils of the semiarid Pampas region, mainly through stabilization in the resistant organic forms of fine-textured soils and accumulation in the labile organic forms of sandy soils. The aim of the study is to determine the content and distribution of the main P-forms in texturally different soils and to relate them to the available P-index.

Soil samples (0-0.15 m) were collected from 27 sites with different textures in a 25-year-old pasture located in the Experimental Station of Bordenave, Argentina (63°01’20”W; 37°51’55”S). Soil particle size fractions were obtained through wet sieving by separating the fine (0-100 µm) and coarse (100-2000 µm) fractions. Soil organic matter was determined in both fractions, and thus mineral-associated (MOM) and particulate organic matter (POM) were obtained, respectively. Extractable (Pe), organic (Po), inorganic (Pi) and total extractable (Pt) phosphorus were determined. Occluded P (Pocl) was calculated as the difference of [Pt - (Po+Pi)] applied to the whole soil and the particle fractions.

In these soils, texture determines P content and the equilibrium of its different forms. Available P-forms (estimated by Pe) were related to the inorganic form present in the fine fraction of the soil. Phosphorus content in its different forms was closely associated with soil fractions. The level of Po was higher in the coarse fraction of the soils containing more fine fractions. All the studied P-forms were higher in fine-textured soils than in coarse ones. However, P-forms in particle size fractions showed different tendencies. In coarse-textured soils, Po in MOM was lower than in fine-textured ones, whereas P-content was higher in MOM and lower in POM compared with fine-textured soils (Rosell et al., 2000).

Based on these results as well as previous ones, we propose a conceptual model to identify P changes in soils of different textures (Galantini et al.2005, 2007; Rosell et al., 2000; Suñer & Galantini, 2012; Suñer et al., 1998, 2002, 2013, 2014; Zalba & Galantini, 2007).

Soil organic fractions and their P-content within the sand fraction are inside the labile pool, whereas those within the silt and clay fractions are inside the intermediate and passive pools. Inorganic minerals of the coarse fraction can be considered a passive pool of P, while P in the fine fraction represents an active pool. According to this finding, a conceptual model can be proposed where P could be linked to SOM fractionation schemes. The principal flows in this model are a) weathering and physico-chemical processes, which reduce the size of coarse minerals until mineral particles reach a size below 50 µm and are then included in the fine fraction; b) humification, by which organic inputs are transformed into more complex molecules with a lower size; c) mineralization of SOM fractions, which produce nutrient release and make P available for plants; d) physico-chemical equilibrium, e) P-uptake by plants; f) recycled P, by which crop residue returned to the soil can improve Po by a POM increase.

Andriulo A., J.A. Galantini, C. Pecorari, E. Torioni. 1990. Materia orgánica del suelo en la región pampeana. I. Un método de fraccionamiento por tamizado. Agrochimica (Italia) XXXIV (5-6) 475-489.

Duval M.E., J.A. Galantini, J.M. Martinez, F.M. López, L. Wall. 2016. Sensitivity of different soil quality indicators to assess sustainable land management: Influence of site features and seasonality. Soil & Tillage Research 159: 9-22.

Galantini J.A., R.A. Rosell. 1997. Organic fractions, N, P, and S changes in a semiarid Haplustoll of Argentine under different crop sequences. Soil & Tillage Research 42: 221-228. ISSN: 0167-1987  ELSEVIER

Galantini J.A., L. Suñer, H. Krüger. 2005. Dinámica de las formas de P en un Haplustol de la región semiárida pampeana durante 13 años de trigo continuo. Revista Investigaciones Agropecuarias (RIA – INTA) 34 (2): 13-31.

Galantini J.A., L. Suñer, J.O. Iglesias. 2007. Sistemas de labranza en el sudoeste bonaerense: efectos de largo plazo sobre las formas de fósforo en el suelo. Revista Investigaciones Agropecuarias (RIA – INTA) 36 (1): 63-81.

Galantini J.A., N. Senesi, G. Brunetti, R. Rosell. 2004. Influence of texture on the nitrogen and sulphur status and organic matter quality and distribution in semiarid Pampean grassland soils. Geoderma 123: 143-152  PDF

Rosell R.A., J.A. Galantini, L.G. Suñer. 2000. Long-term crop rotation effects on organic carbon, nitrogen and phosphorus in Haplustoll soil fractions. Arid Soil Research and Rehabilitation 14 (4) 309-316.

Suñer L., J.A. Galantini, G. Minoldo. 2014. Soil phosphorus dynamics of wheat-based cropping systems in the semi-arid region of Argentina. Applied and Environmental Soil Science Volume 2014 (2014), 6 págs. Article ID 532807, http://www.hindawi.com/journals/aess/2014/532807/  PDF

Suñer L., J.A. Galantini. 2013. Dinámica de las formas del P en suelos de la región sudoeste pampeana: Estudio de la incubación con fertilizante fosfatado. Ciencia del Suelo 31: 33-44.

Suñer L.G., J.A. Galantini, R.A. Rosell, M.D. Chamadoira. 2002. Cambios en el contenido de las formas de fósforo en suelos de la región semiárida pampeana cultivados con trigo (Triticum aestivum). Rev. Fac. Agron., La Plata 104(2): 105-111.

Suñer L.G., J.A. Galantini, R.A. Rosell. 1998. Comparación de métodos para la determinación de fósforo orgánico de suelos de la Región Semiárida Pampeana Argentina. Información Tecnológica (Chile) 9 (6) 51-54.

Suñer L.G., J.A. Galantini. 2012. Fertilización fosforada en suelos cultivados con trigo de la región pampeana. Ciencia del Suelo 30(1) 57-66.

Zalba P., J.A. Galantini. 2007. Improved soil tests methods for available phosphorus in acid, neutral and alkaline soils. Communications in Soil Science and Plant Analysis 38: 1579-1587.

Soil organic matter quality, quantity and distribution under different tillage systems

Galantini, J.A.; M. Duval; J.M. Martinez; V. Mora; R. Baigorri & J.M. García-Mina. 2016. Quality and quantity of organic fractions as affected by soil depth in an argiudoll under till and no-till systems. International Journal of Plant & Soil Science 10 (5) - doi:10.9734/IJPSS/2016/25205

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Crop rotation and fertilization in Argentine semiarid region: Wheat productivity (quality and yield)

Galantini J.A., J.O. Iglesias, A.M. Miglierina, R.A. Rosell, A. Glave. 1992. Rotación y fertilización en sistemas de producción de la región semiárida argentina. I. Productividad (calidad y rendimiento) del trigo. Rev. Fac. Agronomía (U.B.A.) 13 (1) 67-75. (in Spanish)

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In the semi-arid region of the Buenos Aires province the effect of 12 years of different crop rotations with wheat (Triticum aestivum) on crop productivity was studied. The rotations were: TV, wheat-winter and summer grasses; TI, wheat-winter grasses; TPa wheat-alfalfa (Medicago sativa) pasture; TPc, wheat-mixed pasture. All divided into treatments without (nf) and with (f) fertilizer (N and P every year) application. Wheat-grazing, the typical of the region included rotation. production of total dry matter aerial (MSTA), grain, straw, protein and N content in grain and straw were evaluated. The inclusion of annual grasses into crop rotation produced a initial positive effect on crop performance and increased grain yield, however, grain quality were not modified. Fertilization increased wheat grain yields,  but in TV only quality was improved. Pasture in rotation with grain yield was similar, but the response to fertilization was significant only in TPc. Alfalfa as predecessor improved wheat dry matter quality, however, grain yield was not increased.

Key words: Crop-rotation, wheat productivity, semi-arid region

Soil cover under no till systems in Southwestern Buenos Aires Province

Abstract

No tillage (NT) is generally associated with high levels of crop residues on soil surface, which has positive effects on physical and chemical fertility, soil biology and erosion control. However, the absence of soil cover may have a worse effect on soil quality in the long term than conventional tillage. In this study we determined the presence of surface residues and soil cover in fields for winter crops in the years 2011, 2012 and 2013.The study area included the southwest of Buenos Aires province (SOB), Argentina, where over 120 fields under NT were sampled. Our objectives were: i) to establish a simple methodology for surface residues sampling; ii) to determine the current status of surface residues and soil cover in cropped fields under NT in the SOB; iii) to establish the relationship between amount of surface residues and soil cover for the predominant crops of the SOB.A large proportion of fields in the subhumid-semiarid region of SOB had lower soil cover than the required by the literature to be considered conservation agriculture, which would provide adequate protection against erosion. In the studied area, most of winter crops (56%) left adequate soil cover while, in average, summer crops did not leave the minimum of 30% soil cover. The analyzed data show the difficulty in the region for the production of dry matter and its permanence as soil cover, even in agricultural fields with continuous no-tillage.

López F.M., M.E. Duval, J.M. Martínez, J.A. Galantini. 2015. Cobertura en el Sudoeste Bonaerense en suelos bajo siembra directa. Ciencia del Suelo 32 (2) 273-281.

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Use of cover crops in soybean monoculture: effects on water and carbon balance

Abstract

The cover crops (CC) is a good alternative to improve the lack of coverage and carbon balance in soils under no tillage with soybean (Glycine max L. Merr.) monoculture, predominant in the Pampean Region. In this study (2006-2011) the effect of winter cover crops -wheat (T), oats (A), vetch (V) and oats+vetch (A+V)- on water consumption, dry matter production and its impact on the of soil organic carbon contents (TOC) was evaluated. Biomass production of the CC was closely related to rainfall recorded between the months of June and October. In general, T and A treatments contributed greater amount of soil cover, on average, these grasses biomass were 24 and 91% higher compared with A+V and V. The water cost of including CC was 13-93 mm compared to traditional fallow (Ct). At the time of sowing of soybean, in general, Ct presented the highest water content. However, this treatment showed a loss of moisture by evaporation without biomass production, which is used by the CC to fix carbon between 18 and 303 kg C ha^-1 depending on the year conditions. The use of CC -T, A and A+V- increased the TOC at 0-20 cm depth at rates of 597 to 98 kg C ha^-1yr^-1, while it decreased at 824 and 289 kg C ha^-1 yr^-1 without CC or using legumes (V), respectively. For conservation or increase the TOC, use of CC such as A, A+V and T would be a feasible option given that exceeds the minimum source C input of4,5 Mg C ha^-1 necessary to maintain the TOC in soils south of Santa Fe.

Key words: Argiudoll; winter cover crops; available water; organic carbon

Duval M.E., J.E. Capurro, J.A. Galantini, J.M. Andriani. 2015. Utilización de cultivos de cobertura en monocultivo de soja: Efectos sobre el balance de carbono. Ciencia del Suelo 32 (2) 247-261.

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Foliar nitrogen fertilization of wheat in the Southwestern Pampas

Abstract

In the semiarid and subhumid Pampean region, foliar nitrogen (N) application to wheat at anthesis stage coincides with an erratic rainfall period, which defines yield and quality. The objectives of the study were to evaluate the effect of foliar N application at anthesis on wheat grain yield and quality in the Southwestern of Buenos Aires Province, an area characterized by variations in climate and soil fertility, and to apply the principal component analysis (ACP) in all variables. A total of 30 experiments were conducted from 2004 to 2012 in the Southwestern. Nitrogen rates of 0, 25, 50 and 100 kg N ha^-1 were applied at sowing and 25 kg ha^-1 at anthesis. Water availability to the crop was variable in the study period, which caused significant yield variations. The ANOVA for all the experiments, showed no significant differences for N at sowing or at anthesis, but it indicated a protein increase in 25 of the 30 experiments. In all trials yield from the control treatment ranged from 1784 to 2600 kg ha^-1 and N foliar application response from 145 to 1273 kg ha^-1. The grain protein content, which averaged 132 g kg^-1, increased 11% with N fertilization at anthesis. Low and poorly distributed rainfall limited yield and foliar N response. Nitrogen rates at sowing that produced the maximum response to foliar application ranged from 0 to 100 kg N ha^-1. The most influential variables in ACP were the rainfall of September, October and November, dry matter at Z60,soil water content at sowing and N availability. The yield was estimated with 72% confidence and protein with 59%. In these environments, foliar N application resulted in variable grain yield buy it proved to be a useful practice for enhancing protein content. 

Landriscini M.R., J.M. Martínez, J.A. Galantini. 2015. Fertilización foliar en trigo en el sudoeste bonaerense. Ciencia del Suelo 32 (2) 183-196. ISSN 0326-3169 (versión impresa)  ISSN 1850-2067 (versión electrónica)

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Evaluation of the physical quality of soils in the pampas region: effect of management practices

Abstract

The adoption of no tillage (SD) has increased worldwide in recent decades and particularly in Argentina, although sometimes doubts have been raised about its effect on soil physical properties. The objective of this work was to evaluate changes due to management systems on some soil parameters associated with porosity and water storage. They were compared to those proposed as "ideal" or "critical", according to the literature, and with reference levels obtained under pristine conditions. The study sites are located in Bengolea, Monte Buey, Pergamino and Viale. At each site, two agricultural situations with different intensities of management (Good Practices and Poor Practices), and a natural situation (Natural Environment) were evaluated. Bulk density, total porosity, volume of different pore sizes (macropores, mesopores and micropores), and total organic carbon and its fractions were determined in soil samples (0-10 cm). The lower levels of total organic carbon due to agricultural practices caused a decrease in total porosity, mainly reflected by the lower volume of macropores, which decreased up to 23%. Agricultural use resulted in soil compaction, although not critical, due to a decrease of the macropores. Bulk density values were within the optimal range, although problems of compaction can occur when the values of index of structural stability are below 6.13. Total organic carbon and the index of structural stability were the only variables with values lower than optimal in agricultural soils, allowing to differentiate, at some sites, between good and poor practices.

Duval M.E., J.A. Galantini, J.M. Martínez. F.M. López, L.G. Wall. 2015. Evaluación de la calidad física de los suelos de la región pampeana: efecto de las prácticas de manejo. Ciencias Agronómicas RIFCA-UNR 25: 33-43.         ISSN Impreso: 1853-4333  ISSN On-Line: 2250-8872

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Nitrogen use efficiency for wheat in semiarid region of Buenos Aires (Argentina): effects of the dose and timing application

Abstract

In semiarid regions optimal fertilization is difficult due to erratic rainfall. The aim of this study was to analyze the influence of climate variability on the response to different rates and timing of fertilization on wheat productivity and on efficiencies in the use of nitrogen in a site of the semiarid region of the province of Buenos Aires, Argentina. For five years, fertilization trials were conducted in wheat combining N rates (0, 25, 50 y 100 kg ha^-1) and times of fertilization: Seeding (Ns) and tillering (Nm). Agronomic efficiency (EUF) for dry matter (MS) and grain, and apparent recovery of nitrogen (RAN) were evaluated. Interactions between variables (year, rates and times) and efficiencies were found. In Nm, significant correlations of all parameters were found with October rainfall. Protein for Ns and Nm was significantly and inversely correlated with full cycle rainfall. Significant correlations were found in EUF of MS and grain in this order; Full cycle rainfall> Spring rainfall> Oct rainfall> Set rainfall. Interannual climate variability showed the greatest influence on the nitrogen use efficiencies, regardless the application timing.

Key words Fertilization timing; tillering application; erratic rainfalls

Martínez J.M., J.A. Galantini, M.R. Landriscini. 2015. Eficiencia en el uso del nitrógeno del trigo en la región semiárida de la provincia de Buenos Aires (Argentina): efectos del momento de aplicación. Agriscientia 32 (1) 15-27.

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Assessing nitrogen requirements of wheat crops with a chlorophyll meter in the Southwestern Pampas

Abstract

A chlorophyll meter is a promising tool for monitoring the status of N through the green index (IV). The hypothesis was that estimates from the use of a chlorophyll meter would be more closely linked to the N harvested from dry matter than to wheat (Triticum aestivum L.) grain yield, which is affected by climate variability. The objective was i) to determine IV sensitivity to predict total dry matter (MST) and grain yield, protein content and N-uptake, and ii) to evaluate N-availability at planting to establish reference plots without N deficiencies by using a chlorophyll meter at different stages of wheat cultivation and comparing field tests with a pot experiment. In 2010, a nitrogen fertilization trial was conducted in pots, while in 2011 and 2012 the trials were conducted on two sites in SOB under no-tillage. In two (Z22 y Z40) and three (Z22, Z40 y Z70) stages of the crop, chlorophyll meter readings were taken for the field and pot trials, respectively. The field prediction of MST and grain yield , protein content and N uptake with chlorophyll meter readings showed significant regressions with low settings (R² = 0.11 to 0.29). In the pot experiment, the prediction of N-uptake for the three sampled stages increased, without differences in slopes and with a high setting (R²=0.79). The chlorophyll meter would be a promising indicator of N-uptake by the crop; in sub-humid regions, however, it would not be an accurate tool to predict grain yield or protein content in wheat crops. Also, a chlorophyll meter would be useful to estimate the available N needed by the wheat crop and to determine the nutritional status of the plant.

Key words Green index; ACA 303; Sub-humid Region

Martínez J.M., J.A. Galantini, M.R. Landriscini. 2015. Diagnóstico de fertilidad nitrogenada en trigo con la utilización de un clorofilómetro en el Sudoeste Bonaerense. Ciencia del Suelo 33(1) 31-43.

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Texture influence on soil phosphorus content and distribution in semiarid Pampean grasslands

Suñer L., J.A. Galantini. 2015. Texture influence on soil phosphorus content and distribution in semiarid Pampean grasslands. International Journal of Plant & Soil Science (ISSN: 2320-7035) Vol.: 7, Issue.: 2 109-120, no.IJPSS.2015.136

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Soil texture can modify the content, equilibrium and dynamic of soil phosphorus (P) in very different ways. The objective of this work was to study the P form contents associated to physical fractionation of SOM in soils with different texture. Soil samples (0-0.15 m) were obtained from 27 sites with different texture in a twenty five years old pasture located in the Experimental Station of Bordenave, Argentina (63°01’20”W; 37°51’55”S). Soil particle size fractions were obtained by wet sieving separating the fine (0-100 µm) and coarse (100-2000 µm) fractions. Soil organic matter was determined in each fraction, mineral associated organic matter (MOM) and particulate organic matter (POM), respectively. Extractable (Pe), organic (Po), inorganic (Pi) and total extractable (Pt) phosphorus was determined and occluded P (Pocl) was calculated as the difference [Pt - (Po+Pi)] in the whole soil and the particles fractions. In these soils, texture determines P reserves and the equilibrium of its different forms. Available P forms (estimated by Pe) was related to the inorganic form present the fine fraction of the soil. Phosphorus content in its different forms is closely associated with soil fractions. The level of Po was higher in the coarse fraction of soils with a higher content of fine fractions. All the studied P forms were higher in fine textured soils than in coarse ones, however, P forms in particle size fractions showed different tendencies. In coarse textured soils, Po in the MOM was lower than fin textured ones, however, The P content in MOM was richer and POM was poorly than fine textured soils.

Relationship between P availability and P content in Particulate Organic Carbon

Soil organic matter (SOM) or carbon (SOC) consists of a number of fractions (which can be separated by granulometric wet sieving) having different properties among them. Information on fraction nutrient distribution and long-term crop rotations is lacking for semiarid environments. The objective of this research was to study the agronomic effects on soil OC, N, and P fractions. The humified OC was the largest and least variable fraction of the SOC. Soil under continuous mixed pasture had higher OC contents than under annually tilled treatments. Similarly, soil total nitrogen under the cropped treatments decreased from 1.7 g N kg-¹ in noncultivated soils (reference plots) to 1.0, 0.7 an 0.7 g N kg-¹ under mixed pasture, pasture-crop, and wheat-crop respectively, in the fine soil fraction. The reference plots also showed significantly lower levels of organic phosphorus (P o ) in comparison to the other treatment (from 67.1 w g P o g-¹ to greater than 100 w g P o g-¹ in the fine fraction of the treatments and years). The noncultivated soil showed larger values of P o and inorganic P in the large-size granulometric fraction (0.1-2 mm) than in the soil fine fraction (0-01 mm). However, the rotation treatments had greater concentrations of P in the fine fraction. The Po from the coarse fraction appears to be the most labile and sensitive fraction to tillage and environmental conditions, and may be closely related to P availability.

Rosell R.A., J.A. Galantini, L.G. Suñer. 2000. Long-term crop rotation effects on organic carbon, nitrogen and phosphorus in Haplustoll soil fractions. Arid SoilResearch and Rehabilitation 14 (4) 309-316.