Nitrogen status in maize grown at different row spacings and nitrogen availability

Barbieri, P. A., Echeverría, H. E., Sainz Rozas, H. R. and Andrade, F. H. 2013. Nitrogen status in maize grown at differentrow spacings and nitrogen availability. Can. J. Plant Sci. 93: 10491058. Improving nitrogen use efficiency (NUE) isimperative to sustainable agriculture. To attain this goal in maize crops (Zea mays L.) there are nitrogen (N) diagnosismethods that enable determination of a crop?s nutritional status by analysis of plant parts. Maize planted in narrow rows(NR) can have increased dry matter (DM), grain yield and accumulated N. However, no reports have been found on theeffect of NR of N in plant diagnosis methods. An experiment was performed over 3 yr to evaluate NR and N fertilizer rateson the N dilution curve, N concentration in grain and chlorophyll content in maize. Treatments consisted of a factorialcombination of row width (70, 52 and 35 cm) and N rate (0 to 180 kg N ha1). The N dilution curves adjusted for fertilizedor control treatments were similar among row spacing. Nitrogen concentration in grain was correlated with relative yield(RY), and similar critical values for N response were similar between row spacings. Leaf chlorophyll content increasedwith N and NR; however, green index (GI) and N sufficiency index (NSI) values were not different between row spacingwhen correlated to RY. These results indicate that response thresholds to N fertilization determined on plant tissue for NRtreatments were similar among row spacings. Thus, there is no need to adjust the response thresholds to N applicationbased on row spacing, as NR did not cause any changes in physiological efficiency (PE) due to the determined proportionalincreases, both in accumulated N in DM and grain yield.Fil: Barbieri, Pablo Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Área de Investigación en Agronomía; ArgentinaFil: Echeverria, Hernan Eduardo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Área de Investigación en Agronomía; ArgentinaFil: Sainz Rozas, Hernan Rene. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Área de Investigación en Agronomía; ArgentinaFil: Andrade, Fernando Héctor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Área de Investigación en Agronomía; Argentin

Nitrogen recovery efficiency from urea treated with NSN co-polymer applied to no-till corn

Nitrogen (N) rate increases used by many farmers produce a reduced or null effect on N recovery efficiency (RE) by crops. Therefore, management practices to reduce N losses and increase RE are necessary. Co-polymer maleic itaconic acid (NSN) have become available for use with urea and has shown potential in reducing N losses. The objective of this study was to evaluate the effectiveness of urea treated with NSN on grain yield and RE in a no-till corn. A field experiment was carried out at Balcarce, Argentina over three years, evaluated treatments were urea and urea + NSN at 120 N kg ha− 1, and additional 0 N treatment was included. Urea + NSN was effective to reduce total ammonia volatilization losses, and the average of two years were 1.4 (1.1% to N applied) and 8.7 kg ha− 1 (7.2% to N applied) for urea + NSN and urea, respectively. However, while grain yield and N grain removal were not affected by urea + NSN, the N rate significantly increased grain yield and N grain removal. Nitrogen recovery efficiency was not affected by urea + NSN, RE (average of three years) was 29.0% and 27.8% for urea and urea + NSN, respectively. In conclusion, there was no advantage of using urea treated with NSN in no-till corn overgrain yield, N grain removal, or RE.Fil: Barbieri, Pablo Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Sainz Rozas, Hernan Rene. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Echeverria, Hernan Eduardo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentin

Alternatives for Nitrogen Diagnosis for Wheat with Different Yield Potentials in the Humid Pampas of Argentina

A correct determination of nitrogen (N) fertilization thresholds in wheat that is based on objective yield produces efficient use of this nutrient. Nitrogen fertilization recommendations for traditional wheat require determination of nitrate (NO3-)-N availability at 60 cm deep at planting time. However, this methodology is complicated, expensive, and time-consuming; thus, the determination of NO3--N level at a lesser depth and at a different time would be desirable. The goals of this work were to determine available N in soil thresholds for traditional and French germplasm wheats and the feasibility of diagnosing N requirements by measuring NO3--N at 40 cm deep, at planting or tillering times, in the southeastern Pampas. The experiments were factorial combinations of N rates and fertilization times (planting and tillering) at different sites and years during 2002-2006. Nitrogen fertilization significantly increased grain yield and protein content. French varieties presented greater grain yield (23%), lower protein content (11%), and greater yield per N unit, indicating greater N-use efficiency (NUE) than traditional varieties. A similar relationship was determined between grain yield and available N at both sampling depths. This might be explained by the strong association between NO3--N content at 60 and 40 cm deep at both sampling dates. Maximum yield and available N determined at 60 or 40 cm soil deep showed that thresholds were lower for tillering than for planting, regardless of the genotype (152 and 174 kg of available N, respectively). Available N thresholds for 95% of maximum yield were less at 0-40 cm deep than at 0-60 cm deep (10 and 14 kg N ha-1 for traditional and French genotypes, respectively). The results of this experiment suggest the possibility of diagnosing N requirements for wheat by measuring NO3--N content at 40 cm deep, instead of the usual 60 cm, for both traditional and French genotypes.Fil: Barbieri, Pablo Andres. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Echeverria, Hernan Eduardo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Sainz Rozas, Hernan Rene. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentin

Inclusion of Cover Crops in Cropping Sequences with Soybean Predominance in the Southeast of the Humid Argentine Pampa

Abstract: The incorporation of a cover crop (CC) may be an alternative to increase soil carbon (C) and nitrogen (N) supply in crop sequences with a high frequency of soybean. The aims of this study were (i) to determine shoot biomass production, C and N contents in the CC under two N additions, (ii) to evaluate the effect on soybean grain yield of including a CC, and (iii) to evaluate the water productivity of the crop sequences. Crops were evaluated during three growing seasons of a long-term field trial under no tillage on Typic Argiudoll in Balcarce, Buenos Aires, Argentina. Mean CC shoot biomass was 6.6 Mg ha-1 yr-1 for N-fertilized and 5.2 Mg ha-1 yr-1 for non-fertilized treatments. Mean C and N accumulation in the CC shoot biomass were 2.8 Mg C ha-1 yr-1 and 131 kg N ha-1 yr-1 in N-fertilized treatments, and 2.3 Mg C ha-1 yr-1 and 67 kg N ha-1 yr-1 in nonfertilized treatments. Soybean grain yield ranged from 2.4 to 4.3 Mg ha-1. In two out of the three growing seasons, soybean grain yield was greater (p<0.05) for crop sequences that included a CC. Water productivity was higher (p<0.05) in crop sequences with a CC and even higher when they were N-fertilized. The inclusion of a CC preceding soybean in crop sequences is an alternative to improve soil C and N budgets and would be a promising strategy to increase productivity and cropping system sustainability in this region.Fil: Martínez, Juan Pablo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Barbieri, Pablo Andres. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Sainz Rozas, Hernan Rene. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Echeverria, Hernan Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentin

Indigenous arbuscular mycorrhiza and Trichoderma from systems with soybean predominance can improve tomato growth

In the last decades, there has been a tendency towards sustainable agriculture. Following this trend, edaphic fungi as Trichoderma and arbuscular mycorrhizal fungi (AMF) could increase plant growth contributing to diminish agricultural chemical supply. However, little information exists in current research regarding the possible effects of alternative practices to soybean monoculture systems on fungal groups that could contribute to plant health and/or productivity. Thus, our objective was to assess changes in the abundance and diversity of indigenous AMF and Trichoderma from a long-term field experiment located in the Argentinean Pampas, in order to test the effect of alternative practices to soybean monoculture. The fungal ability to promote the growth of crops, such us tomato plant was also tested. Soil samples were collected from a soybean monoculture system (Sb), a system including cover crop (Avena sativa) followed by soybean (CC/Sb) and a system including rotations (rot) of Soybean-Maize-Wheat crops CC/Sb-rot, M-rot and W-rot, respectively. Highest AMF and Trichoderma abundance was found at W-rot and M-rot systems, and highest AMF diversity was found at W-rot and CC systems. Furthermore, highest mycorrhizal colonization was found at CC/Sb and W-rot systems. Inoculated plants with single AMF consortium or with Trichoderma strains showed significant increases in comparison with the control. Dual inoculation increased tomato plant growth as compared to the control, and evidence of synergism was found by increases in shoot and root growth. Our results show that dual inoculation with indigenous AMF and Trichoderma from alternative crop systems to soybean monoculture could play an important role in tomato plant growth. This information could be useful to decrease production costs and environmental impacts.Fil: Commatteo, Jacqueline Giselle. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Agencia de Extensión Rural Balcarce; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Consolo, Verónica Fabiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; ArgentinaFil: Barbieri, Pablo Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible - Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce. Instituto de Innovación para la Producción Agropecuaria y el Desarrollo Sostenible; ArgentinaFil: Covacevich, Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; Argentin

Comparison of methods for determining soil organic carbon

El carbono orgánico total (COT) del suelo por su efecto benéfico sobre las propiedades físicas, químicas y biológicas, es considerado como uno de los principales indicadores de calidad de suelo, por lo que es necesario determinarlo con suficiente exactitud. Para algunos suelos de la Región pampeana y extrapampeana se compararon las técnicas de determinación de COT de Walkley & Black, Walkley & Black modificado y calcinación (LOI) con respecto al método de combustión seca de Dumas, tomado como referencia. Se obtuvo una alta correlación entre las técnicas de determinación de COT (r2 =0,98-0,99). Se verificó el factor de corrección de 1,32, usado habitualmente en la metodología de Walkley & Black para convertir el carbono fácilmente oxidable (CFO) en COT. Se observó que la pendiente de la relación entre la MO determinada por LOI y el COT determinado por el método de Dumas (1,697) no difirió del valor de 1,724 habitualmente empleado para la conversión de COT a MO. La metodología de Dumas mostró mayor veracidad y precisión respecto de las demás técnicas de determinación de COT.Beneficial effects of soil organic carbon (COT) on physical, chemical and biological properties, is considered an indicator of soil quality, so it is necessary to determine it accurately. Walkley & Black, modified Walkley & Black and ignition (LOI) with respect to the dry combustion method of Dumas were compared for some soils of the Pampean and extrapampean region. A high correlation between COT determination techniques (r2 = 0.98-0.99) was obtained. Correction factor of 1.32, commonly used in the methodology of Walkley & Black to convert readily oxidizable carbon (CFO) in COT was verified. It was observed that the slope of the relationship between the COT determined by LOI and COT determined by the Dumas method (1.697) did not differ in value from 1,724, routinely used for the conversion of COT a MO. Dumas methodology showed greater accuracy and precision with respect to other techniques for determination of COT.Fil: Eyherabide, Mercedes. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Sainz Rozas, Hernan Rene. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Barbieri, Pablo Andres. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Echeverria, Hernan Eduardo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Phosphorus placement effects on phosphorous recovery efficiency and grain yield of wheat under no-tillage in the Humid Pampas of Argentina

No-till (NT) affects dynamics of phosphorus (P) applied. Wheat response to P fertilization can be affected by available soil P, grain yield, placement, rate, and timing of fertilization. Furthermore, mycorrhizal associations could contribute to improving plant P uptake. Three experiments were used to evaluate P rate (0, 25, and 50 kg P ha−1) and fertilizer placement (broadcasted or deep-banded) effects in NT wheat on P recovery efficiency (PRE) yield and arbuscular mycorrhizal colonization (AMC) which was assessed in one experiment. Fertilization increased dry matter (DM) and accumulated P. Broadcasted P produced lower P accumulation than deep-banded P only at tillering. Phosphorus rate decreased PRE, and placement method did not affect it. Grain yield response was increased by P rate (857 and 1805 kg ha−1 for 25 and 50 kg P ha−1, resp.) and was not affected by placement method (4774 and 5333 kg ha−1 for broadcasted and deep-banded, resp.). Deep-banded P depressed root AMC compared with broadcast applications. Highest AMC in P broadcasted treatments could help to explain the lack of differences between placement methods. These results indicate that Mollisol have low P retention capacity. Therefore, broadcasted P could be used as an alternative of fertilizer management for NT wheat.Fil: Barbieri, Pablo Andres. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires. Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Sainz Rozas, Hernan Rene. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires. Estación Experimental Agropecuaria Balcarce; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Covacevich, Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigaciones en Biodiversidad y Biotecnología; Argentina. Fundación para Investigaciones Biológicas Aplicadas; ArgentinaFil: Echeverría, Hernán Eduardo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires. Estación Experimental Agropecuaria Balcarce; Argentin

Tillage and fertilization as modulators of the dynamics of microbial communities associated with a wheat crop of southeast of Buenos Aires (Argentina)

El objetivo del trabajo fue evaluar a campo el efecto de la labranza y la fertilización con macro y micronutrientes, sobre el crecimiento y la colonización de raíces por hongos micorrícicos arbusculares y la abundancia de microorganismos solubilizadores de P en la rizósfera del cultivo de trigo. Para ello, se realizó el monitoreo del crecimiento y la colonización micorrícica de un cultivo de trigo (&quot;Buck SY 300&quot;) durante dos campañas en Balcarce (Pcia. Buenos Aires). Se evaluó el crecimiento, la colonización micorrícica del cultivo y las características químicas del suelo de un ensayo dispuesto en tres bloques completamente aleatorizados con arreglo de tratamientos en parcelas divididas. La parcela principal correspondió a los tratamientos de labranza: siembra directa y labranza convencional y las subparcelas a los siguientes tratamientos: Sin Fertilizar (Testigo); Fertilizado con N, P y S (NPS); y Fertilizado con N, P, S; y los micronutrientes Cu y Zn (NPS+Mi). Durante el segundo año se cuantificó además la abundancia de microorganismos cultivables totales y de solubilizadores de P. La fertilización incrementó el crecimiento y rendimiento del cultivo; sin embargo, la labranza no tuvo efectos significativos. La fertilización (NPS y NPS+Micronutrientes) afectó negativamente la colonización micorrícica nativa, mientras que la labranza deprimió la micorrización solo en macollaje. Ni la labranza ni la fertilización afectaron significativamente la abundancia de bacterias totales. Independientemente de la labranza, la fertilización con macro y micronutrientes ocasionó una reducción en los recuentos de solubilizadores de P (solP). En este estudio, se confirma la falta de efecto de la labranza, aunque es evidente el efecto depresivo de la fertilización sobre la colonización micorrícica y la abundancia de solubilizadores deP asociados a un cultivo de trigo. Los resultados muestran que aun en sistemas productivos intensivos, los hongos micorrícicos arbusculares y las bacterias solubilizadoras de P se asocian al cultivo de trigo y que estrategias de fertilización son requeridas para lograr mantener alta productividad sin deprimir las poblaciones microbianas nativas del suelo.The objective was to evaluate under field conditions, the effect of tillage and fertilization with macro and micronutrients on growth of wheat crop, root colonization by arbuscular mycorrhizal fungi and the abundance of P solubilizing microorganisms in the rhizosphere. Wheat crop (cv. &quot;Buck SY 300&quot;) growth, root mycorrhizal colonization and soil chemical characteristics were assessed during two growing seasons (two years) in Balcarce (Buenos Aires province) of a trial arranged in three completely randomized blocks with treatments arranged in split plot. The main plot treatments were tillage: non-tillage and conventional tillage and subplots following treatments: unfertilized (control); fertilized with N, P and S (NPS); and fertilized with N, P, S; Cu and Zn and micronutrients (NPS + Mi). During the second year abundance of total bacteria and P solubilizer (solP) were also assessed. Fertilization increased growth and yield of the wheat crop; however, tillage had no significant effect. Fertilization (NPS and NPS+Micronutrients) negatively affected mycorrhizal colonization, while tillage depressed root colonization only in tillering. Tillage and fertilization did not affect the abundance of total cultivable bacteria. Instead, tillage and fertilization with macro and micronutrients reduced solP abundance. We confirmed lack of tillage effect but depressive fertilization effect on mycorrhizal colonization and solP associated of wheat crop of Balcarce (Buenos Aires Province). Furthermore, this results shown that even in intensive production systems, arbuscular mycorrhizal fungi and soil P solubilizer bacteria are associated to the wheat crop and fertilization strategies are required in order to maintain high productivity without depressing the native soil microbial populations.Fil: Pérez, Germán Ricardo. Universidad Nacional de Mar del Plata. Facultad de Ciencias AgrariasFil: Barbieri, Pablo Andres. Universidad Nacional de Mar del Plata. Facultad de Ciencias AgrariasFil: Hernandez Guijarro, Keren. Universidad Nacional de Mar del Plata. Facultad de Ciencias AgrariasFil: Echeverría, Hernán Eduardo. Universidad Nacional de Mar del Plata. Facultad de Ciencias AgrariasFil: Covacevich, Fernanda. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agraria

Incorporación de cultivos de cobertura previos a soja en el sudeste bonaerense

En la zona del sudeste bonaerense existe escasa información sobre las eventuales ventajas de la incorporación de los CC en los planteos productivos actuales, la cual sería de suma utilidad para evaluar la factibilidad de dicha alternativa. El objetivo de este trabajo fue determinar la acumulación de biomasa aérea, C y N en CC con y sin fertilización con N y evaluar el efecto de su incorporación sobre el rendimiento del cultivo de soja, en un suelo Argiudol Típico de Balcarce (Buenos Aires, Argentina).Fil: Martinez, Juan Pablo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce. Unidad Integrada. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Barbieri, Pablo Andres. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce. Unidad Integrada. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sainz Rozas, Hernan Rene. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce. Unidad Integrada. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Echeverria, Hernan Eduardo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce. Unidad Integrada. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentin

Cover crops: effect on sulfur availability in soybean

La elección de la especie de cultivo de cobertura (CC) a emplear puede afectar la disponibilidad de azufre (S) para el cultivo de soja (Glycine max (L.) Merr.) posterior. Así, el objetivo de este trabajo fue evaluar el efecto de avena (Avena sativa L.) y vicia (Vicia villosa Roth.) como CC y la fertilización azufrada sobre algunos parámetros que definen la disponibilidad de S y el rendimiento en el cultivo de soja posterior. Se realizaron tres ensayos de campo en distintas zonas del sudeste bonaerense donde se evaluó la combinación de tres niveles de CC (avena, vicia y un testigo sin CC) con dos niveles de fertilización azufrada en la soja (0 y 15 kg S ha-1). Se determinó el contenido de S-SO4-2 (0-60 cm) en el suelo a la siembra de la soja, el índice de verdor (IV) a inicio de floración (R1) y el rendimiento en grano. Los principales resultados del trabajo son: i) los CC acumularon entre 7 y 17 kg S ha-1, logrando reducir las pérdidas de S por lixiviación durante el barbecho invernal, ii) la vicia incrementó en promedio 28 kg S ha-1 su disponibilidad en el suelo a la siembra de la soja, respecto a la avena y al testigo, iii) el IV de la soja fue menor con antecesor avena que con vicia y el testigo, iv) no hubo respuesta en rendimiento a la fertilización con S, v) en dos de los tres sitios el CC de vicia redujo el rendimiento en grano de la soja, posiblemente por un efecto negativo sobre la nodulación y fijación biológica de nitrógeno, lo cual deberá ser corroborado en futuros trabajos.Selecting the cover crop (CC) specie may affect sulfur (S) availability for the succeeding soybean (Glycine max (L.) Merr.) crop. Thus, the objective of this work was to evaluate the effect of oat (Avena sativa L.) and vetch (Vicia villosa Roth.) as CC and S fertilization on some parameters that define S availability and yield in the succeeding soybean. Three field experiments were conducted in different areas of southeastern Buenos Aires province, where the combination of three levels of CC (oats, vetch, and a control without CC) with two levels of S fertilization (0 and 15 kg S ha-1) was evaluated in soybean. Determinations included: SO4 -2-S content in soil (0-60 cm) at soybean sowing, greenness index (IV) at the beginning of flowering (R1), and seed yield. The main results were: i) CC accumulated between 7 and 17 kg S ha-1, allowing reductions of S losses by leaching during the winter fallow, ii) vetch increased S availability in the soil at soybean planting by 28 kg S ha-1, compared to oat and the control, iii) soybean IV was lower when preceded by oat compared to vetch and the control, iv) there was no yield response to S fertilization, v) in two of the three sites vetch reduced soybean seed yield, possibly due to a negative effect on nodulation and biological nitrogen fixation, which should be tested in future works.Fil: Carciochi, Walter Daniel. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Contreras, Lucas E.. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; ArgentinaFil: Crespo, Cecilia. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Barbieri, Pablo Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentin