Douglas Ramos Guelfi

Acúmulo de macronutrientes na soja influenciado pelo cultivo prévio do capim-marandu, correção e compactação do solo

O presente trabalho foi desenvolvido com o objetivo de avaliar o efeito do cultivo previo do capim-Marandu (Brachiaria brizantha cv. Marandu), da aplicacao de corretivos e da compactacao do solo no acumulo de macronutrientes pela soja cultivada em sucessao. O delineamento experimental foi inteiramente casualizado em esquema fatorial 4 x 6 x 2, com tres repeticoes. Os fatores de estudo foram quatro densidades do solo: 1,0; 1,20; 1,40 e 1,60 Mg m-3; seis tratamentos de correcao: 1) controle, sem correcao; 2) calcario; 3) silicato de calcio; 4) gesso; 5) calcario + gesso; 6) silicato de calcio + gesso; alem de dois sistemas de cultivo: com e sem cultivo previo do capim-Marandu. As unidades experimentais foram compostas por vasos de tubos de PVC de 20 cm de diâmetro, compostos por dois aneis: o anel inferior, de 40 cm de altura, recebeu o solo sob condicoes naturais e densidade de 1,0 Mg m-3; o anel superior, com 20 cm de altura representando 6,28 dm3, recebeu os tratamentos de densidades, correcao e gesso como descrito adiante. Em cada um foram conduzidas tres plantas de soja (cv. Conquista) ate o final do ciclo, quando o acumulo de macronutrientes pela cultura foi avaliado. Os resultados mostraram que o cultivo previo do capim-Marandu e o uso de corretivos amenizaram os efeitos negativos da compactacao do solo sobre a nutricao da soja. A utilizacao de corretivos do solo contribuiu para o aumento no acumulo de macronutrientes na parte aerea da soja, porem o incremento na compactacao diminuiu o acumulo de N, P, K, Ca, Mg e S. A compactacao do solo persistiu parcialmente mediante o cultivo previo com o capim marandu.

Ammonia volatilization from blends with stabilized and controlled-released urea in the coffee system

Application of stabilized and controlled-release urea blends can reduce the losses of N-NH3 as compared to conventional urea. The aim of this study was to quantify ammonia volatilization from conventional nitrogen fertilizers and blends of urea + (urea + NBPT) + controlled release urea applied in drip irrigated coffee system. The experiment was conducted under field conditions in in a Red Latosol located in Lavras-MG, Brazil. The randomized complete block design with six treatments: Urea = 450 kg ha-1 yr-1 N (100% of the recommended dose) divided in three splittings equal to 150 kg ha-1 N with an interval of 50 days; ammonium nitrate = 450 kg ha-1 yr-1 N (100% of the recommended dose) in three splittings equal to 150 kg ha-1 N with an interval of 50 days; Polyblen Extend(r)-100%= 450 kg ha-1 yr-1 (100% of the recommended dose) applied in two splittings, 315 kg ha-1 N in the 1o split and 135 kg ha-1 N in the 2o split; Polyblen Extend(r)-70% = 315 kg ha-1 yr-1 N (70% of the recommended dose) in two splittings, 220.5 kg ha-1 N in the 1o split and 94.5 kg ha-1 N in the 2o split; Polyblen Montanha(r)-100% = 450 kg ha-1 yr-1 (100% of the recommended dose) in an unique application in the 1o split and Polyblen Montanha(r)-70% = 315 kg ha-1 yr-1 N (70% of the recommended dose) at an unique application in the 1o split, with three repetitions. Total accumulated N-NH3 losses followed the decreasing order: Urea (83.2 kg ha-1 N) > Polyblen Extend(r) - 100% (60.3 kg ha-1 N) > Polyblen Montanha(r) - 100% (46.8 kg ha-1 N) > Polyblen Extend(r) - 70% (35.1 kg ha-1 N) > Polyblen Montanha(r) - 70% (24.2 kg ha-1 N) > nitrate ammonium (2.0 kg ha-1 N ). The use of Polyblen Montanha(r) decreases two splittings compared to conventional sources such as urea and ammonium nitrate, by applying only 70% of the recommended dose without affecting yield and coffee crop nutrition.

Nitrogen loss by volatilization of nitrogen fertilizers applied to coffee orchard

Ammonia volatilization (N-NH3) is one of the main pathways of Nitrogen loss reducing nitrogen use efficiency in coffee orchard. This work aimed at quantifying ammonia volatilization (N-NH3) losses from N-sources to be used in coffee plantations fertilization in Brazil. The experiment was conducted in the field on a dystrophic red latosol (Ferralsol in FAOs classification) at the Coffee Research Sector, University of Lavras, MG, Brazil. The experimental design was of complete randomized blocks with three repetitions of the following treatments: conventional urea, ammonium nitrate and urea + 0.15% Cu and 0.4% B, urea + anionic polymers, urea + elementary sulfur (S0) + polymers, and urea + plastic resin. These N sources were split into three doses of 150 kg ha-1 and band applied. The N-NH3 losses by volatilization and variations of pH (H2O) were measured, before and after N application. The N-sources contributed to reduce the soil pH, measured after the third nitrogen fertilization. The N-NH3 losses by volatilization (average from three applications) was as follows: urea + anionic polymers (35.8%) > conventional urea (31.2%) = urea + S0 + polymers (31.0%) > urea + 0.15% Cu + 0.4 % B (25.6%) > urea + plastic resin (8.6%) = ammonium nitrate (1.0%).

Agronomic efficiency of polymer-coated triple superphosphate in onion cultivated in contrasting texture soils

Information related to phosphate fertilization and coated phosphate fertilizer in onion is scarce. Thus, this study was carried out to evaluate agronomic efficiency, production and nutritional characteristics of triple superphosphate coated with polymers in onion cultivated in contrasting texture soils. Two experiments were carried out under protected conditions in pots containing 5 kg soil. The experimental design was completely randomized with treatments arranged in a 2 x 5 factorial: triple superphosphate (TSP) and polymer-coated triple superphosphate (TSP+P) applied in five phosphorus rates: Dystroferric Red Latosol (LVdf) (clayey) = 0; 100; 200; 400; 800 mg P2O5 kg-1, and Quartzarenic Neosol (sandy) = 0; 75; 150; 300; 600 mg P2O5 kg-1, with three replications. Results indicated that polymer-coated TSP showed no difference for bulb mass and agronomic efficiency for phosphorus fertilization. Agronomic efficiency of phosphorus fertilization decreased with the increase in the amount of phosphorus applied. Phosphorus accumulation for onion bulb cultivated in Dystroferric Red Latosol (LVdf) was higher with the use of polymer-coated triple superphosphate. Growth, production and nutritional characteristics in onion were affected by phosphorus. The highest bulbs mass production and phosphorus accumulation occurred at the doses of 783; 629 mg kg-1 P2O5 (Dystroferric Red Latosol - LVdf), and of 406; 600 mg kg-1 P2O5 (Quartzarenic Neosol -RQ).

Productive characteristics, nutrition and agronomic efficiency of polymer-coated MAP in lettuce crops

In contrast to enhanced-efficiency nitrogen fertilisers, principally urea, phosphate fertilisers have been little studied and the available information is limited. The aim of this work therefore was to evaluate the productive and nutritional characteristics and the agronomic efficiency of a polymer-coated MAP fertilizer on two subsequent lettuce crops. The experiment was carried out in a greenhouse, in pots with a capacity of 4 kg, filled with a dystrophic yellow Latosol of a clayey texture. The experimental design was completely randomised and the treatments arranged in a 2 x 5 factorial scheme: two sources of phosphorus (P) (MAP and polymer-coated MAP), applied to the plots in five dosages (0, 100, 200, 400, 800 mg P2O5 kg-1) with three replications. The results showed that the polymer-coated MAP increased the efficiency of the phosphate fertilizer in both lettuce crops, improving utilisation of the residual phosphorus. The agronomic efficiency of fertilization decreases with the increases in applied phosphorus. The production and nutritional characteristics of the lettuce were influenced by the levels of P2O5 and the use of MAP with polymers. Higher values for dry and fresh weight and for the accumulation of P in the first crop occurred with the use of polymer-coated MAP at dosages of 506.9, 450.1 and 522.8 mg kg-1 P2O5.

Monoammonium phosphate coated with polymers and magnesium for coffee plants

The coating of phosphate fertilizer granules with polymers and magnesium (Mg) is a technology that can improve phosphorus (P) use efficiency and mitigate problems of low Mg supply in coffee crops. The objective of this work was to evaluate the growth and nutrition characteristics of coffee seedlings and the agronomic efficiency (AE) of monoammonium phosphate (MAP) coated with anionic polymers and Mg in comparison with other phosphate fertilizer technologies. The experiment was carried out in a greenhouse in 20 L pots. Two five-month-old coffee seedlings were transplanted into each pot. The experimental design was completely randomized with three replicates. The following treatments, applied at a dose corresponding to 20 g pot-1 of P2O5, were carried out: MAP; MAP coated with anionic polymers (Policote Phós®); MAP coated with anionic polymers+Mg (Policote Phós_Mg®); Top-Phós®; and Agrocote®. A control (without P) was prepared. Plant height; leaf area; dry mass of leaves, stems, and roots; total dry mass; shoot/root ratio; specific leaf weight; P and Mg content in plants and their availability in the soil after cultivation and efficiency indicesof the phosphate fertilization treatment were evaluated. The recovery of applied P and the agronomic efficiency of phosphate fertilizers was found to increase in the following order: MAP = Top-Phós® = Agrocote®<MAP+Policote Phós® = MAP+Policote Phós_Mg®. The coating of the MAP+Policote Phós_Mg® granules increased growth, the content and accumulation of P and Mg in coffee seedlings, the availability of these nutrients in the soil after cultivation and the agronomic efficiency of phosphate fertilization.

Agronomic Characteristics of Lettuce Grown with Monoammonium Phosphate in Sandy Soil

ABSTRACT Information related to phosphate fertilization and coated phosphate fertilizer in lettuce (Lactuca sativa L.) is scarce. Thus, this study was carried out to evaluate the agronomic efficiency, production, and nutritional characteristics of coated monoammonium phosphate (MAP) in two subsequent crops with lettuce cv. Solaris. The experimental design was completely randomized (2 x 5 factorial experiment): two sources of phosphorus (P) (MAP and coated MAP), five applications (0; 75; 150; 300; and 600 mg phosphorus pentoxide (P2O5) kg−1) with four replications. In the first crop, there was a greater accumulation of P in plants shoot with the application of coated MAP until 150 mg P2O5 kg−1 dose, surpassed by MAP after this dose. On the second crop, fresh mass and the accumulation of P in the leaves were higher than the uncoated MAP. In both crops, the agronomic efficiency of P fertilization decreased with increase in the amount of phosphorus applied in lettuce cultivation.

Ammonia and carbon dioxide emissions by stabilized conventional nitrogen fertilizers and controlled release in corn crop

O consumo de fertilizantes nitrogenados estabilizados, de liberacao lenta e controlada representa 1% do total de fertilizantes utilizados no mundo. Por outro lado, um aumento na disponibilidade, inovacao e utilizacao dessas tecnologias pode levar a maior eficiencia no uso do nitrogenio (N) na agricultura com menor impacto ambiental. O objetivo deste trabalho foi quantificar as perdas de amonia (N-NH3) por volatilizacao e as emissoes de CO2 de fertilizantes nitrogenados convencionais, estabilizados e de liberacao controlada na cultura do milho. O experimento foi realizado em condicoes de campo no municipio de Lavras (MG) no ano agricola 2013/2014, sem irrigacao. Os tratamentos foram compostos por fertilizantes nitrogenados aplicadas em cobertura na dose de 150 kg ha-1 de N. A perda acumulada de N-NH3 dos fertilizantes nitrogenados convencionais, estabilizados de liberacao controlada em ordem decrescente foi: Ureia granulada (39% do N aplicado) = ureia perolada (38%) > ureia + 16% de S0 (32%) = mistura fisica de grânulos (blend) de ureia revestida com S0 e polimeros e ureia convencional (32%) > ureia perolada incorporada (24%) > ureia + 530 mg kg-1 de NBPT (8%) = hidrolisado de couro bovino (9%) > ureia + resina termoplastica (3%) = sulfato de amonio (1%) = nitrato de amonio (0,7%). O sulfato e nitrato de amonio e a ureia + resina termoplastica promovem a menor emissao de dioxido de carbono (C-CO2) em area de cultivo de milho. Enquanto que, o hidrolisado de couro promoveu a maior emissao total de C-CO2 para a atmosfera.