ABSTRACT
Hay una creciente preocupación, a nivel mundial, por la declinación de la calidad de los suelos. Numerosos reportes sugieren la adición de biochar, para incrementar la fertilidad del suelo y la productividad de los cultivos. Se evaluó el efecto de la aplicación de diferentes niveles de biochar, en un oxisol representativo de la Altillanura Colombiana y su efecto en el crecimiento del maíz. Las muestras de suelo fueron recolectadas y tratadas con biochar de cuesco de palma africana procesado, en un reactor termoquímico cilíndrico de lecho fijo; se manejó régimen de flujo concurrente y diferentes temperaturas, para priorizar la obtención de biochar. Se utilizaron dosis de biochar (masa/masa) de 0, 2, 5 y 10% y se compararon con tratamiento con cal. Después de incubación por 45 días bajo condiciones ambientales exteriores, cuatro semillas de maíz (Zea maíz L.) variedad Guacavía fueron sembradas en cada recipiente, sin adición de fertilizante o enmienda. Las unidades experimentales fueron contenedores plásticos de 5kg. El material vegetal, aunque se recolectó a los 90 días después de la siembra, presentaba una fase vegetativa V5. Se analizó absorción de nutrientes por el maíz en planta entera. Independiente, se analizaron muestras del biochar, encontrándose que predominaron las cargas negativas. En la mezcla suelo-biochar, se observó incremento de P, Ca, Mg y K, pero el Na no tuvo incremento; se redujo el Al+3 proporcional a la aplicación de biochar. La absorción de Zn y Mg aumentó notablemente en el maíz, pero también la absorción de Fe se incrementó, a niveles tóxicos.
There is growing concern worldwide for the decline of soil quality. Numerous reports suggest the addition of biochar to increase soil fertility and crop productivity. The effect of applying different levels of biochar in a representative oxisol of Colombian Altillanura and its effect on corn growth was evaluated. Soil samples were collected and treated with African palm shell biochar, thermochemically obtained in a cylindrical fixed bed reactor, in a concurrent flow regime. Different temperatures were handled to prioritize obtaining biochar. Doses of biochar (m/m) of 0, 2, 5 and 10% were used and compared with treatment with lime. After 45 days incubation, under external environmental conditions, seeds of maize (Zea mays L.), Guacavía variety were planted in each container, without addition of fertilizer or amendment. The experimental units were plastic containers of 5kg. Although the plant material was collected 90 days after planting, it presented a vegetative phase V5. Nutrient uptake by corn was analyzed in whole plant. Independent biochar samples were analyzed and found predominance negative charges. In the mix biochar-soil increased P, Ca, Mg and K was observed, but did not increase Na. Al+ 3 proportional to the application of biochar was reduced. The Zn and Mg absorption increased significantly in maize, but also Fe uptake increased to toxic levels.
ABSTRACT
Sugarcane is an important crop for sugar and biofuel production in Brazil. Growers depend greatly on herbicides to produce it. This experiment used herbicide physical-chemical and sugarcane plant physiological properties to simulate herbicide uptake and estimate the bioconcentration factor (BCF). The (BCF) was calculated for the steady state chemical equilibrium between the plant herbicide concentration and soil solution. Plant-water partition coefficient (sugarcane bagasse-water partition coefficient), herbicide dilution rate, metabolism and dissipation in the soil-plant system, as well as total plant biomass factors were used. In addition, we added Tebuthiuron at rate of 5.0kg a.i. ha-1 to physically test the model. In conclusion, the model showed the following ranking of herbicide uptake: sulfentrazone > picloram >tebuthiuron > hexazinone > metribuzin > simazine > ametryn > diuron > clomazone > acetochlor. Furthermore, the highest BCF herbicides showed higher Groundwater Ubiquity Score (GUS) index indicating high leaching potential. We did not find tebuthiuron in plants after three months of herbicide application.
A cana de açúcar é uma cultura importante para produção de açúcar e biocombustíveis no Brasil e exige elevada utilização de herbicidas. Utilizamos modelo matemático para ajudar na compreensão da absorção de herbicida dessa cultura. Propriedades físico-químicas dos herbicidas e propriedades fisiológicas das plantas de cana foram usados para estimar a absorção e também o fator de bioconcentração, bioconcentration factor (BCF), calculado para o equilíbrio químico entre a concentração do herbicida na planta e na solução do solo. O coeficiente de partição planta/água, a taxa de diluição de herbicida, o metabolismo e a dissipação no sistema solo-planta e biomassa total das plantas foram adicionados ao modelo. O herbicida tebuthiuron aplicado ao solo na dose de 5,0kg ha-1 i.a. foi utilizado para testar o modelo. A absorção dos herbicidas mostrada pelo modelo indicou em ordem o seguinte: sulfentrazone> picloram> tebuthiuron> hexazinone> metribuzin> simazina> ametryn> diuron> clomazone> acetochlor. Esses herbicidas com alto índice (BCF) também apresentaram alto índice de potencial de lixiviação para água subterrânea "Groundwater Ubiquity Score" (GUS). Tebuthiuron não foi encontrado nas plantas após três meses de aplicação.