Nitrogen supplementation has been an important means for increasing yield in tropical gramineous forage plants in Brazil because, in most growing areas, the levels of this nutrient in the soil do not adequately meet crop needs. We assessed the effect of different sources and application rates of N on the chemical properties of an Oxisol (Latossolo Amarelo) and the production of Panicum maximum cv. Mombaça. The experiment was carried out at the Instituto Federal do Espírito Santo (State of Espirito […]

The greatest limitation to the sustainability of no-till systems in Cerrado environments is the low quantity and rapid decomposition of straw left on the soil surface between fall and spring, due to water deficit and high temperatures. In the 2008/2009 growing season, in an area under center pivot irrigation in Selvíria, State of Mato Grosso do Sul, Brazil, this study evaluated the lignin/total N ratio of grass dry matter , and N, P and K deposition on the soil surface […]

The nutrient use efficiency, expressed by the ratio between the produced biomass and nutrient content, is an important adaptive characteristic of plants, particularly of those cultivated in low-fertility soils. A high P-use efficiency (PUE) is conferred by high P remobilization rates, i.e., P transport to regions of greater metabolic demand in the plant. High P remobilization rates have been associated with high acid phosphatase (APase) and ribonuclease (RNase) enzyme activities. In our study, we evaluated the activity of these enzymes […]

Aruana grass (Panicum maximum cv. Aruana) is well adapted to pastures, especially those grazed by sheeps, but knowledge on mineral nutrition of this grass is scant. In order to evaluate the nutritional status of this forage in relation to nitrogen, Aruana grass was grown in a nutrient solution with N six rates (14; 112; 210; 294; 378 and 462 mg L-1). The experiment was carried out in a greenhouse in the Spring, from October to December 2000. Each experimental unit consisted of […]

The behavior of glyphosate in a Rhodic Oxisol, collected from fields under no-till and conventional management systems in Ponta Grossa, Parana state (Brazil) was investigated. Both agricultural systems had been in production for 23 years. Glyphosate mineralization, soil-bound forms, sorption and desorption kinetics, sorption/desorption batch experiments, and soil glyphosate phythoavailability (to Panicum maximum) were determined. The mineralization experiment was set up in a completely randomized design with a 2 x 2 factorial scheme (two management systems and two 14C radiolabelled positions in the […]

Two experiments were carried out simultaneously in a greenhouse to evaluate the effects of plant age and regrowth periods on soil and plant phosphorus critical levels for two tropical forage grasses. Treatments corresponded to the 2x5x5 factorial arrangement in the initial growth study, and the 2x2x5 factorial in the regrowth study.Those factorials consisted of two species (Brachiaria decumbens cv. Basilisk and Panicum maximum cv. Mombaça); five plant ages (14, 28, 42, 56, and 70days after emergence) in the initial growth […]