Ultisols

Abstract The environmental availability of trace radiocesium (137 Cs) was studied in soils devoid of weathered micas. The soils were developed from basaltic ash, within a sequence Udand→ Tropept→ Udalf→ Udult from Cameroon. Tropepts and Udalfs are halloysite-rich ...

Se evaluo el efecto del encalado en el rendimiento de naranja Valencia y en la fertilidad de un Ultisol de la Zona Norte de Costa Rica. Se utilizo 3 materiales de encalado: CaCO3 de granulometria gruesa; CaCO3 de granulometria fina; y una mezcla fisica de 85% de CaCO3 y 15% de oxido de magnesio, cada uno de ellos en dosis de 1, 2 y 3 t ha-1, y un testigo sin cal, en un diseno de Bloques Completos al Azar y 4 repeticiones. Se hicieron 4 cosechas de fruta entre 1994 y 1998, y 3 muestreos de suelo y tejido foliar (6, 12 y 24 meses despues de aplicar la cal). La aplicacion de cal tuvo un efecto significativo en la fertilidad del suelo; al aumentar la dosis se incremento el contenido de Ca intercambiable, y se redujo la acidez del suelo y la saturacion de acidez. La mezcla de CaCO3 + MgO aumento significativamente el contenido de Mg intercambiable, siendo el efecto mas marcado con la dosis de 3 t ha-1. La respuesta de la cal se presento en forma lineal en los 4 anos de cosecha evaluados,...

O uso de fertilização mineral e de leguminosas são as principais alternativas para fornecimento, em larga escala, de nitrogênio (N) a culturas exigentes deste nutriente. Os riscos de poluição ambiental decorrentes da adubação nitrogenada podem ser elevados; portanto, em uma agricultura sustentável, torna-se necessário aprimorar a recomendação desta adubação. Este trabalho objetivou desenvolver uma estimativa da necessidade de adubação nitrogenada que considere o sistema de preparo e o uso de culturas de cobertura. Utilizou-se um experimento de longa duração, localizado na Depressão Central do Rio Grande do Sul, em Argissolo Vermelho Distrófico típico. O delineamento foi o de blocos casualizados com parcelas subsubdivididas e três repetições. As parcelas principais foram três sistemas de preparo: convencional, reduzido e direto; as subparcelas foram três sistemas de cultura: aveia/milho, ervilhaca/milho e aveia + ervilhaca/milho + caupi; as subsubparcelas foram: solo descoberto/milho...

Se evaluó el efecto del encalado en el ren-dimiento de naranja Valencia y en la fertilidad de un Ultisol de la Zona Norte de Costa Rica. Se utilizó 3 materiales de encalado: CaCO3 de granulometría gruesa; CaCO3 de granulometría fina; y una mezcla física de 85% de CaCO3 y 15% de ...

O nitrogênio, na maioria das situações, é o nutriente que mais influencia o rendimento do milho. O manejo da adubação nitrogenada deve satisfazer o requerimento da cultura com o mínimo de risco ambiental. Para tanto, é necessário que a recomendação da dose de adubo nitrogenado seja a mais exata possível. A generalização do uso do sistema de plantio direto e culturas de cobertura, no Sul do Brasil, criou a necessidade de ser a recomendação da adubação nitrogenada adaptada a este novo cenário agrícola. O presente trabalho, além de considerar o teor de MO e a expectativa do rendimento de grãos de milho na recomendação da adubação nitrogenada conforme preconiza a CFS-RS/SC (1995), propõe a introdução de um terceiro parâmetro que é a contribuição em N das culturas de cobertura antecedente. O efeito das culturas de cobertura foi considerado em três situações: leguminosas em cultivo solteiro, gramíneas em cultivo solteiro e consorciações. No caso de leguminosas e gramíneas em cultivo solte...

Abstract A field experiment was conducted in 2016 and 2017 cropping seasons to determine the effects of tillage practice alone and tillage practices amended with woodash on soil physicochemical properties and soil concentration, shoot and seed uptake of heavy metals (Fe,Zn,Cu,B,Pb). The experiment was laid out as split plot in Randomized Complete Block Design with six treatments and three replications. The treatments were: Flat tillage alone (FO) Mound tillage alone (MO), Ridge tillage alone (RO) Flat tillage +4 t ha- 1 woodash, Mound tillage +4 t ha- 1 and Ridge tillage +4 t ha- 1 . Results of the study showed significant (p = 0.05) increase in soil hydraulic conductivity and total porosity (%) in tillage practices relative to woodash amended tillage practices. Results of the study also showed significant (p = 0.05) increase in soil base saturation, organic carbon, available P, soil total N, effective cation exchange capacity, pH and decrease in exchangeable acidity in wood ash amended tillage practices relative to tillage practices alone. Significant (p = 0.05) increases in heavy metals concentration in soil, shoot and seed of castor but to non-toxic level except Fe concentration in soil were observed in tillage practices amended with woodash and tillage practices alone. On the average RW was observed to have the highest improvement in the studied parameters. Use of woodash as soil amendment at applied rate improved soil properties and did not have any negative effect on soil and crops.

Equilibrium adsorption experiments on zinc(Zn), cadmium(Cd), copper(Cu), and lead(Pb) were conducted in three horizons of two Ultisols and one Oxisol with and without liming, from Viçosa-MG(Brazil). Equilibrium solutions were applied as a cocktail containing 700 mg ...

The nutritive quality of ten grasses harvested at 3, 6, 9 and 12 weeks of regrowth was assessed during the rainy season (August-October) 2008, in the humid tropics of Veracruz, Mexico. Grasses tested included four Brachiaria spp.: “insurgente”–B. brizantha, “signal”–B. decumbens, Chetumal–B. humidicola, “mulato I”–B. brizantha x B. ruziziensis; three Panicum maximum: Mombasa, “privilegio”, Tanzania; and three Pennisetum spp.: TaiwAin, and the hybrids P. purpureum x P. glaucum “Cuban” king grass and “purple” king grass. Means for crude protein by grass group were: Pennisetum spp. (9.9 %) = P. maximum (8.7 %) > Brachiaria spp. (7.6 %), whereas means for in situ dry matter disappearance (ISD) were: Pennisetum spp. (69.7 %) > Brachiaria spp. (65.1 %) > P. maximum (59.7 %). Crude protein and ISD significantly decreased by 0.42 % and 1.50 % per week. Neutral detergent fiber was not affected by model effects (mean 71.4 %). Means for acid detergent f...

Se evaluó el efecto de la aplicación de una enmienda calcárea líquida sobre el rendimiento del arroz y la fertilidad del suelo. El ensayo se realizó en un Ultisol de Los Chiles, Alajuela. Se utilizó una enmienda líquida que contiene 40% de Ca en forma de CaCO3 y 6,9% de N en forma de urea (Cal 56®). Los tratamientos fueron: testigo sin cal; Cal 56 8 l.ha-1; Cal 56 10 l.ha-1; y Cal 56 6 l.ha-1 + Nitro LL 4 l.ha-1. El Nitro LL es un fertilizante líquido de liberación controlada, que contiene 33% de N. Los produc tos fueron aplicados con bomba de espalda, con un volumen de caldo de 200 l.ha-1, en forma de aspersión al suelo 8 días después de germinado el arroz. Se utilizaron parcelas de 10x10 m, con un diseño experimental de Bloques Completos al Azar, con 4 tratamientos y 4 repeticiones. No hubo diferencias significativas con las variables tamaño de panícula en cm, número de espigas por panícula, número total de granos por panícula, número de granos llenos, número de granos vanos y pes...

High rates of potassium (K) are often applied in an attempt to increase stress tolerance of hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy] turfs. Two field-grown bermudagrass cultivars, `Tifdwarf' and `Tifway', were used to determine the influence of applied K on plant nutrient content and nutrient retention in two soils. Six rates of K ranging from 0 to 390 kg·ha-1 were applied twice per month each growing season from 1992 to 1994. The cultivars were established on both a sand-peat (9:1 by volume) and loamy sand. Potassium chloride and K2SO4 were compared as sources of K, and were applied simultaneously with N applications. Extractable soil K and leaf tissue K concentrations increased with increasing K rates. There was a critical K fertilization level (74 to 84 kg·ha-1) for each cultivar and medium combination beyond which no increase in tissue concentration was observed. Increasing K fertilization resulted in a decrease in extractable Ca a...

A field experiment was conducted in 2016 and 2017 cropping seasons to determine the effects of tillage practice alone and tillage practices amended with woodash on soil physicochemical properties and soil concentration, shoot and seed uptake of heavy metals (Fe,Zn,Cu,B,Pb). The experiment was laid out as split plot in Randomized Complete Block Design with six treatments and three replications. The treatments were: Flat tillage alone (FO) Mound tillage alone (MO), Ridge tillage alone (RO) Flat tillage +4 t ha-1 woodash, Mound tillage +4 t ha-1 and Ridge tillage +4 t ha-1. Results of the study showed significant (p = 0.05) increase in soil hydraulic conductivity and total porosity (%) in tillage practices relative to woodash amended tillage practices. Results of the study also showed significant (p = 0.05) increase in soil base saturation, organic carbon, available P, soil total N, effective cation exchange capacity, pH and decrease in exchangeable acidity in wood ash amended tillage practices relative to tillage practices alone. Significant (p = 0.05) increases in heavy metals concentration in soil, shoot and seed of castor but to non-toxic level except Fe concentration in soil were observed in tillage practices amended with woodash and tillage practices alone. On the average RW was observed to have the highest improvement in the studied parameters. Use of woodash as soil amendment at applied rate improved soil properties and did not have any negative effect on soil and crops.