Comparison of neutralization power of amendment based on calcium and magnesium in soils of flat pampas of Santa Fe

El objetivo de este trabajo fue comparar el poder de neutralización de enmiendas calcáreo- magnésicas y evaluar su efecto sobre el complejo de intercambio catiónico en suelos de la pampa llana santafesina. Para ello, se aplicaron tres enmiendas (caliza, dolomita y enmienda mezcla) a dos dosis (neutralización del 100% y 150% del hidrógeno de intercambio). Se evaluó: pH actual, pH potencial, hidrógeno, calcio y magnesio intercambiable luego de 60 días de incubación. El pH actual no mostró diferencias entre dosis, mientras que el incremento de pH de las enmiendas fue caliza > dolomita > mezcla. El pH potencial fue más sensible al tipo de enmienda y dosis. Todos los tratamientos redujeron el nivel de insaturación, aunque ninguno neutralizó la totalidad del hidrógeno intercambiable. En relación con el calcio intercambiable, todos los tratamientos produjeron aumentos y la mayor saturación cálcica se obtuvo con la aplicación de caliza o enmienda mezcla con la dosis necesaria para neutralizar 1,5 veces el hidrógeno intercambiable. En cuanto al magnesio, las enmiendas dolomita y mezcla aumentaron significativamente el contenido independientemente de la dosis. La información aquí presentada es de utilidad para la prescripción de enmiendas calcáreo- magnésica en los suelos de la Pampa llana santafesina.The objective of this study was to compare the neutralization power of amendments based on calcium and magnesium and to assess their effects on the cation exchange complex in soils of flat Pampas of Santa Fe. Three amendments (lime, dolomite and mixture amendment) at rates calculated to neutralize 100% and 150% of exchangeable hydrogen were applied to samples from soils incubated for 60 days. The responses on actual and potential pH, and hydrogen, calcium and magnesium exchangeables were assessed. The increment of actual pH showed differences between amendments and the order of response was lime > dolomite > mixture amendment. No difference between the applied rates were observed. The potential pH was more sensitive to the type and of rates amendment. All treatments reduced the level of unsaturation, although the full neutralization was not achieved with the tested rates. Increments of exchangeable calcium were observed in all treatments and the greatest calcium saturation was obtained when lime or mixture amendment were applied at the highest rate. Dolomite and mixture amendment significantly increased the content of magnesium regardless of the rate. The information presented here is useful for prescribing magnesic-calcareous amendments in soils of the flat Pampas of Santa Fe.Fil: Carrizo, María Eugenia. Universidad Nacional del LitoralFil: Alesso, Carlos Agustín. Universidad Nacional del LitoralFil: Billoud, Hernán. Universidad Nacional del LitoralFil: Pilatti, Miguel Ángel. Universidad Nacional del Litora

Morphological characteristics of soybean root apexes as indicators of soil compaction

Plant soil compaction poses a serious problem to agriculture because it produces different types of changes in plant characteristics. No method has been implemented to date to use root morphological changes as indicators of soil compaction levels. Therefore, the aim of the present study was to evaluate whether or not the morphological changes in root apexes of soybean (Glycine max (L.) Merrill) can be used as indicators of soil compaction levels. To this end, a silt-loamy soil material (from a Typic Argiudoll, Esperanza series), sieved through a 2 mm mesh was used and the following soil bulk density levels were determined: 1.1, 1.3 and 1.5 g cm³ for which the corresponding mechanical resistances were < 0.1, 0.5 and 3.5 MPa, respectively. The distance from the apex to the first tertiary root and the root diameter at 1.5 cm from the apex were measured on the secondary root apexes. A form factor equal to the quotient between these two variables was subsequently calculated. An inverse relationship between soil mechanical impedance and secondary root length and form factor as well as a direct relationship with the secondary root diameter were observed. Changes in rhizodermis cells were also recorded. The following morphological characteristics were found to evidence the highest sensitivity to soil compaction: i) the form factor, ii) rhizodermis papillose cells, iii) apical malformations in root hairs, and iv) root diameter in expansion areas. Taken together, the morphological characteristics of root apexes could be considered to be indicative of soil compaction.A compactação do solo causa severos problemas devido a que gera diferentes mudanças nas características das plantas. Não existem métodos que possibilitem o uso das mudanças da morfologia das raízes como indicadores de níveis de compactação do solo. Avaliaram-se se alterações morfológicas nos ápices de soja podem ser utilizadas como indicadores de graus de compactação do solo. Solo peneirado a 2 mm, classificado como Typic Argiudol (série Esperanza), foi compactado até atingir os seguintes valores de densidade do solo: 1.1, 1.3 e 1.5 g cm³, para os quais corresponderam os valores de resistência mecânica de < 0.1, 0.5 e 3.5 MPa, respectivamente. A distância desde o ápice até a primeira raiz terciária e o diâmetro a 1.5 cm desde o ápice foram medidos nas raízes secundarias. Um fator de forma foi calculado fazendo o quociente entre as duas variáveis medidas. Houve uma relação inversa entre o cumprimento da raiz secundaria e fator de forma com a resistência mecânica, e uma relação direta entre esta ultima e o diâmetro das raízes secundárias. Alterações nas células da rizoderme foram determinadas. As seguintes características morfológicas se mostraram muito sensíveis a compactação do solo: i) o fator de forma, ii) as células papilosas da rizoderme, iii) malformações apicais nos pelos das raízes, e iv) diâmetro das raízes em áreas de expansão. As características morfológicas dos ápices das raízes podem ser consideradas indicadores de compactação dos solos

Comparación del poder de neutralización de enmiendas calcáreo-magnésicas en suelos de la Pampa llana santafesina

The objective of this study was to compare the neutralization power of amendments based on calcium and magnesium and to assess their effects on the cation exchange complex in soils of flat Pampas of Santa Fe. Three amendments (lime, dolomite and mixture amendment) at rates calculated to neutralize 100% and 150% of exchangeable hydrogen were applied to samples from soils incubated for 60 days. The responses on actual and potential pH, and hydrogen, calcium and magnesium exchangeables were assessed. The increment of actual pH showed differences between amendments and the order of response was lime &gt; dolomite &gt; mixture amendment. No difference between the applied rates were observed. The potential pH was more sensitive to the type and of rates amendment. All treatments reduced the level of unsaturation, although the full neutralization was not achieved with the tested rates. Increments of exchangeable calcium were observed in all treatments and the greatest calcium saturation was obtained when lime or mixture amendment were applied at the highest rate. Dolomite and mixture amendment significantly increased the content of magnesium regardless of the rate. The information presented here is useful for prescribing magnesic-calcareous amendments in soils of the flat Pampas of Santa Fe.El objetivo de este trabajo fue comparar el poder de neutralización de enmiendas calcáreo- magnésicas y evaluar su efecto sobre el complejo de intercambio catiónico en suelos de la pampa llana santafesina. Para ello, se aplicaron tres enmiendas (caliza, dolomita y enmienda mezcla) a dos dosis (neutralización del 100% y 150% del hidrógeno de intercambio). Se evaluó: pH actual, pH potencial, hidrógeno, calcio y magnesio intercambiable luego de 60 días de incubación. El pH actual no mostró diferencias entre dosis, mientras que el incremento de pH de las enmiendas fue caliza &gt; dolomita &gt; mezcla. El pH potencial fue más sensible al tipo de enmienda y dosis. Todos los tratamientos redujeron el nivel de insaturación, aunque ninguno neutralizó la totalidad del hidrógeno intercambiable. En relación con el calcio intercambiable, todos los tratamientos produjeron aumentos y la mayor saturación cálcica se obtuvo con la aplicación de caliza o enmienda mezcla con la dosis necesaria para neutralizar 1,5 veces el hidrógeno intercambiable. En cuanto al magnesio, las enmiendas dolomita y mezcla aumentaron significativamente el contenido independientemente de la dosis. La información aquí presentada es de utilidad para la prescripción de enmiendas calcáreo- magnésica en los suelos de la Pampa llana santafesina

Morphological characteristics of soybean root apexes as indicators of soil compaction

Plant soil compaction poses a serious problem to agriculture because it produces different types of changes in plant characteristics. No method has been implemented to date to use root morphological changes as indicators of soil compaction levels. Therefore, the aim of the present study was to evaluate whether or not the morphological changes in root apexes of soybean (Glycine max (L.) Merrill) can be used as indicators of soil compaction levels. To this end, a silt-loamy soil material (from a Typic Argiudoll, Esperanza series), sieved through a 2 mm mesh was used and the following soil bulk density levels were determined: 1.1, 1.3 and 1.5 g cm³ for which the corresponding mechanical resistances were < 0.1, 0.5 and 3.5 MPa, respectively. The distance from the apex to the first tertiary root and the root diameter at 1.5 cm from the apex were measured on the secondary root apexes. A form factor equal to the quotient between these two variables was subsequently calculated. An inverse relationship between soil mechanical impedance and secondary root length and form factor as well as a direct relationship with the secondary root diameter were observed. Changes in rhizodermis cells were also recorded. The following morphological characteristics were found to evidence the highest sensitivity to soil compaction: i) the form factor, ii) rhizodermis papillose cells, iii) apical malformations in root hairs, and iv) root diameter in expansion areas. Taken together, the morphological characteristics of root apexes could be considered to be indicative of soil compaction

Soil physical quality of Mollisols quantified by a global index

Indicators synthesizing the state of the structural quality and the function of the porous system are useful for assessing soil production capacity as well as the way it may serve natural ecosystems. This research aimed (i) to determine indicators of the state and function of the porous system, (ii) to use them to derive a global index to characterize the soil physical quality, and iii) to establish a reference pore-size distribution curve for Mollisols from the province of Santa Fe (Argentina). Sixty water retention curves (WRC) of A and B horizons of Mollisols, with clay varying between 119 and 538 g kg&#8722;1, organic matter between 5 and 40 g kg&#8722;1, and soil bulk density between 1.09 and 1.49 Mg m&#8722;3, were used. The indicators measured were: pore size distribution, macroporosity (PORp), air capacity (ACt) and plant-available water capacity (PAWC) among others. Soils were classified into four groups according to their physical properties and a reference WRC was determined. From this WRC and considering a total porosity of 0.514 m3 m&#8722;3, PORp was 0.035 m3 m&#8722;3, ACt 0.153 m3 m&#8722;3, field capacity 0.361 m3 m&#8722;3, permanent wilting point 0.136 m3 m&#8722;3 and PAWC 0.225 m3 m&#8722;3. Both the high silt content and low organic matter content confer on the soil characteristics with low stability, excess of small pores and low porosity of the macropore domain. Consequently, the capacity to quickly drain the water excess and allow root proliferation was not optimal, possibly due to the high silt or clay content and the low sand content, characteristic of the soil matrix of these Mollisols