Método de interrupción (químico o rolado) de cultivos de cobertura y la influencia en la dinámica del agua, nitratos y malezas
No Thumbnail Available
Date
2022
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
FCA-UNR
Abstract
La masiva adopción del sistema de siembra directa y la utilización de cultivares
de soja tolerantes a glifosato, generó una alta dependencia de herbicidas de amplio
espectro para el control de malezas. Los cultivos de cobertura (CC) constituyen una
práctica con potencial para reducir el uso de herbicidas en postemergencia de soja y a su
vez minimizar el impacto ambiental.
Se evaluó el efecto del método de secado en CC de invierno sobre la composición
y dinámica de la comunidad de malezas, la dinámica del agua, el impacto ambiental y la
productividad del cultivo de soja en el Departamento Marcos Juárez, provincia de
Córdoba. Se establecieron dos experimentos, en el primero se estudiaron durante tres
campañas el efecto del método de secado (químico vs rolado) en triticale (x Tritico secale
Wittm. ex A. Camus) utilizado como CC sobre la dinámica del agua útil (AU) disponible
en el suelo, la supresión de malezas a la cosecha del cultivo de la soja y la productividad
de la misma y el efecto sobre el impacto ambiental de los diferentes manejos a través del
coeficiente de impacto ambiental (EIQ). Los tratamientos fueron triticale secado con rolo
(TR) y secado con herbicida (TH), vs un tratamiento barbecho (B) sin CC.
En el segundo experimento se evaluó el efecto de triticale, centeno (Secale cereale
(L.) y vicia (Vicia villosa Roth) utilizados como CC, dos métodos de secado y diferentes
estrategias de control químico de malezas sobre la dinámica del agua y los nitratos, la
dinámica poblacional de las malezas, impacto ambiental y la productividad del cultivo de
soja. Los tratamientos fueron: secado mediante el rolado (R), secado con herbicida (H) y
secado con herbicida más un herbicida residual (HM). Paralelamente a cada repetición se
agregó una parcela principal, barbecho sin CC (B) con dos programas de manejo de
malezas, con glifosato solo (BH) y con herbicidas residuales (BHM). Además, la
dinámica poblacional de malezas de estos tratamientos se comparó con un testigo sin CC
y sin herbicidas.
En el primer experimento, en el tratamiento B, el AU en todos los momentos de
muestreo y en las tres campañas se diferenció significativamente de los CC. El método
de secado de los CC no mostró influencia significativa en el AU, esto implica que el
rebrote de TR las dos primeras campañas no disminuyó el AU al momento de la siembra
de soja.
Tanto en el análisis por campaña como en el conjunto, los CC presentaron valores
significativamente menores de MS de malezas a la cosecha de la soja respecto al
tratamiento B, mientras que el método de secado no tuvo incidencia. Al analizarlos en
forma conjunta se observa que en los tratamientos con CC hay una tendencia a reducir el
número de aplicaciones y la cantidad de principio activo comparado con el tratamiento
B. No se comprobaron diferencias significativas en el rendimiento de la soja por utilizar
CC y método de secado comparado con el tratamiento B. Los valores de EIQ presentaron
la misma tendencia en las tres campañas TR<TH<B. En el promedio de las tres campañas
el EIQ en TR se redujo 55,9% respecto a B mientras que en TH la reducción fue de 32,9%,
respectivamente.
En el segundo experimento al momento de secado los CC tuvieron un 35% menos
de AU, mientras que a la siembra de la soja el contenido de AU fue un 16% mayor
respecto de BH. La reducción de la densidad de malezas otoño-invernales como Conyza
spp. y Gamochaeta spicata fue superior al 90% en los CC con respecto a los barbechos.
En cuanto a las malezas primavero-estivales en la mayor parte del periodo
considerado, la densidad total de malezas fue mayor en el tratamiento testigo. En todos
los censos realizados la densidad en ambos tratamientos de barbecho fue
significativamente mayor que la observada en los CC. En BH la emergencia fue siempre
mayor o igual a BHM durante todo el ciclo. En los tratamientos con CC la emergencia de
las malezas se retrasó aproximadamente 60 días respecto a los tratamientos de barbecho.
Del grupo de las malezas primavero-estivales la especie más abundante en el tratamiento
testigo fue Amaranthus hybridus L. La reducción en la emergencia de yuyo colorado en
los CC fue del 98,8% con respecto al testigo y del 93,9% con respecto a los barbechos.
Considerando las tres especies utilizadas como CC, la biomasa total de malezas
fue, en promedio, 0,8 g MS m-2, mientras que en los barbechos fue, en promedio, 47,6 g
MS m-2 esto representa una reducción del 98% asociada con la presencia de los CC. Por
la inclusión de CC y el secado mediante el rolado el valor de EIQ se redujo más de un
70% respecto del barbecho sin reducir el rendimiento de soja.
El sistema de CC y secado mecánico mediante rolado, permiten reducir
considerablemente las dosis y el número de aplicaciones de herbicidas, sin afectar la
disponibilidad hídrica ni el rendimiento del cultivo de soja. Este tipo de práctica se
constituye en una herramienta promisoria para áreas con restricciones en la aplicación de
herbicidas.
The massive adoption of the direct seeding system and the use of glyphosatetolerant soybean cultivars, caused a high dependence on broad-spectrum herbicides for weed control. Cover crops (CC) are a practice with potential to reduce the use of herbicides in post- emergence of soybean crop and at the same time to minimize environmental impact. The effect of the termination method in winter CC on the composition and dynamics of the weed community, water dynamics, environmental impact and productivity of soybean cultivation were evaluated in the Marcos Juárez Department, Córdoba province. Two experiments were established, in the first one, was studied during three farm years the effect of the termination method (chemical vs rolling) in triticale (x Tritico secale Wittm. ex A. Camus) used as CC on the dynamics of the available water (AU) in the soil, the suppression of weeds at the soybean harvest time and the productivity of the same and the effect on the environmental impact of the different management through the coefficient of environmental impact (EIQ). The treatments were: triticale with roller crimper termination (TR) and herbicide termination (TH), vs a fallow treatment (B) without CC. The second experiment evaluated the effect of triticale, rye (Secale cereale (L.) and (Vicia villosa Roth) used as CC, two termination methods and different strategies of chemical weed control on water dynamics, weed population dynamics and nitrates, environmental impact and soybean productivity. The treatments were roller crimper termination (R), herbicide termination (H) and herbicide termination plus a residual herbicide (HM). Parallel to each repetition was added a main plot, fallow without CC (B) with two weed management programs, with glyphosate alone (BH) and with residual herbicides (BHM). In addition, the weed population dynamics of these treatments were compared with a control without CC and without herbicides. In the first experiment, in the B treatment, available water (UA) at all sampling times and in the three farm years differed significantly from the CC. The termination method of the CC did not showed significant influence on the UA, this implies that the regrowth of TR the first two seasons did not decrease the UA at the time of soybean sowing. Both in the analysis by farm year and in the whole, the CC showed significantly lower values of MS of weeds at soybean harvest with respect to treatment B, while the termination method had no incidence. When analyzing them together, it is observed that in treatments with CC there is a tendency to reduce the number of sprays and the amount of active ingredient compared to treatment B. No significant differences were found in the yield of soybean by using CC and termination method compared with B. EIQ values showed the same trend in the three farm years TR<TH<B. In the average of the three farm years EIQ in TR was reduced 55,9% compared to B while in TH the reduction was 32,9% respectively. In the second experiment at the time of termination the CC had 35% less AU, while at the time of soybean sowing the AU content was 16% higher than BH. The autumn-winter weeds density reduction such as Conyza spp. and Gamochaeta spicata was higher than 90% in CC with respect to fallow. For spring-summer weeds most of the period considered, the total density of weeds was higher in the control treatment. In all the censuses performed the density in both fallow treatments was significantly higher than that observed in the CC. In BH the emergency was always greater than or equal to BHM throughout the cycle. In CC treatments the emergence of weeds was delayed by about 60 days with respect to fallow treatments. From the group of spring-summer weeds the most abundant species in the control treatment was the Amaranthus hybridus L. The reduction in the emergency of smooth pigweed in the CC was 98,8% with respect to the control and 93,9% with respect to fallows. Considering the three species used as CC, the total weed biomass was, on average, 0,8 g MS m-2, while in fallow plots it was, on average, 47,6 g MS m-2 this represents a reduction of 98% associated with the presence of CC. Due to the inclusion of CC and roller-crimper termination the EIQ value was reduced by more than 70% compared to fallow plot without reducing soybean yield. The CC system and the mechanical termination by roller-crimper, can considerably reduce the doses and the number of herbicide sprays, without affecting the water availability or the yield of soybean crop. This type of practice is a promising tool for areas with restrictions on the sprays of herbicides.
The massive adoption of the direct seeding system and the use of glyphosatetolerant soybean cultivars, caused a high dependence on broad-spectrum herbicides for weed control. Cover crops (CC) are a practice with potential to reduce the use of herbicides in post- emergence of soybean crop and at the same time to minimize environmental impact. The effect of the termination method in winter CC on the composition and dynamics of the weed community, water dynamics, environmental impact and productivity of soybean cultivation were evaluated in the Marcos Juárez Department, Córdoba province. Two experiments were established, in the first one, was studied during three farm years the effect of the termination method (chemical vs rolling) in triticale (x Tritico secale Wittm. ex A. Camus) used as CC on the dynamics of the available water (AU) in the soil, the suppression of weeds at the soybean harvest time and the productivity of the same and the effect on the environmental impact of the different management through the coefficient of environmental impact (EIQ). The treatments were: triticale with roller crimper termination (TR) and herbicide termination (TH), vs a fallow treatment (B) without CC. The second experiment evaluated the effect of triticale, rye (Secale cereale (L.) and (Vicia villosa Roth) used as CC, two termination methods and different strategies of chemical weed control on water dynamics, weed population dynamics and nitrates, environmental impact and soybean productivity. The treatments were roller crimper termination (R), herbicide termination (H) and herbicide termination plus a residual herbicide (HM). Parallel to each repetition was added a main plot, fallow without CC (B) with two weed management programs, with glyphosate alone (BH) and with residual herbicides (BHM). In addition, the weed population dynamics of these treatments were compared with a control without CC and without herbicides. In the first experiment, in the B treatment, available water (UA) at all sampling times and in the three farm years differed significantly from the CC. The termination method of the CC did not showed significant influence on the UA, this implies that the regrowth of TR the first two seasons did not decrease the UA at the time of soybean sowing. Both in the analysis by farm year and in the whole, the CC showed significantly lower values of MS of weeds at soybean harvest with respect to treatment B, while the termination method had no incidence. When analyzing them together, it is observed that in treatments with CC there is a tendency to reduce the number of sprays and the amount of active ingredient compared to treatment B. No significant differences were found in the yield of soybean by using CC and termination method compared with B. EIQ values showed the same trend in the three farm years TR<TH<B. In the average of the three farm years EIQ in TR was reduced 55,9% compared to B while in TH the reduction was 32,9% respectively. In the second experiment at the time of termination the CC had 35% less AU, while at the time of soybean sowing the AU content was 16% higher than BH. The autumn-winter weeds density reduction such as Conyza spp. and Gamochaeta spicata was higher than 90% in CC with respect to fallow. For spring-summer weeds most of the period considered, the total density of weeds was higher in the control treatment. In all the censuses performed the density in both fallow treatments was significantly higher than that observed in the CC. In BH the emergency was always greater than or equal to BHM throughout the cycle. In CC treatments the emergence of weeds was delayed by about 60 days with respect to fallow treatments. From the group of spring-summer weeds the most abundant species in the control treatment was the Amaranthus hybridus L. The reduction in the emergency of smooth pigweed in the CC was 98,8% with respect to the control and 93,9% with respect to fallows. Considering the three species used as CC, the total weed biomass was, on average, 0,8 g MS m-2, while in fallow plots it was, on average, 47,6 g MS m-2 this represents a reduction of 98% associated with the presence of CC. Due to the inclusion of CC and roller-crimper termination the EIQ value was reduced by more than 70% compared to fallow plot without reducing soybean yield. The CC system and the mechanical termination by roller-crimper, can considerably reduce the doses and the number of herbicide sprays, without affecting the water availability or the yield of soybean crop. This type of practice is a promising tool for areas with restrictions on the sprays of herbicides.
Description
Keywords
Uso de herbicidas, Control químico de malezas, Dinámica del agua, Impacto ambiental, Productividad, Cultivos de cobertura, Nitratos