RESUMO -Neste estudo avaliou-se a influência da adubação com doses combinadas de nitrogênio e cálcio na emissão de folhas e perfilhos, a área foliar e a produção de massa seca da parte aérea do capim-tanzânia. O capim-tanzânia foi cultivado em solução nutritiva, utilizando-se sílica como substrato, em experimento em casa de vegetação. O experimento foi conduzido em delineamento estatístico de blocos ao acaso, com quatro repetições, utilizando-se um esquema fatorial 5 2 fracionado, com combinações de cinco doses de nitrogênio (2; 9; 16; 23 e 30 mmol L -1 ) e cinco doses de cálcio (0,50; 1,75; 3,00; 4,25 e 5,50 mmol L -1 ). Foram realizados três cortes nas plantas, o primeiro aos 39 dias após o transplantio, o segundo aos 30 dias após o primeiro corte e o terceiro aos 28 dias após o segundo corte. As doses de cálcio não interagiram com as de nitrogênio para as variáveis testadas no primeiro corte do capim-tanzânia. O número de perfilhos e de folhas dependeu apenas do suprimento de nitrogênio. A combinação entre doses de nitrogênio e de cálcio foi determinante para a área foliar no terceiro corte e para a produção de massa seca da parte aérea no segundo e terceiro cortes do capim-tanzânia. As máximas respostas produtivas da gramínea ocorreram com suprimento mínimo de nitrogênio de 23 mmol L -1 . A utilização de cálcio em dose não inferior a 2 mmol L -1 na solução nutritiva não restringiu as respostas produtivas desse capim, mesmo na presença de elevadas doses de nitrogênio.Palavras-chave: área foliar, folhas, massa seca, Panicum maximum, perfilhos Nitrogen and calcium fertilization on tanzaniagrass morphogenesis and yieldABSTRACT -The objective of this study was to evaluate grass responses to combined rates of nitrogen and calcium. Measured response variables included leaf number, tiller number, leaf area, and DM yield. Tanzaniagrass was grown in nutrient solution with ground quartz as substrate, in a greenhouse experiment. The experiment was carried out in randomized block design, with four replications. A fractionated 5 2 factorial was used, with combinations of five nitrogen rates (2, 9, 16, 23, and 30 mmol L -1 ) and five calcium rates (0.50, 1.75, 3.00, 4.25, and 5.50 mmol L -1 ). Three harvests were performed, the first one 39 days after seedlings transplanting, the second one 30 days after the first harvest, and the third one 28 days after the second harvest. Calcium rates did not interact with the nitrogen rates for the productive variables in the first growth of this grass. The number of tillers and leaves depended only on nitrogen rates. Combination of nitrogen and calcium rates was necessary for tanzaniagrass leaf area at the third growth, and for the shoot biomass at the second and third growths. Maximum productive responses of this forage were reached with the minimum supply of nitrogen of 23 mmol L -1 . The use of calcium at rate not inferior to 2 mmol L -1 did not reduce productive variables of this grass, even with the supply of high nitrogen rate.Key Words: dry mass, leaf area, leaves, Panicum maxi...

Phosphorus transport is an environmental concern, particularly in coarse‐textured soils with minimal P‐sorbing capability. This 2‐yr study evaluated the impact of an Al water treatment residual (Al‐WTR) application on soil P responses, leachate P concentrations, and bahiagrass (Paspalum notatum Flüggé) yield and nutritive value. Treatments were a factorial combination of three Al‐WTR levels (0, 35, and 70 Mg ha–1) and two methods of application (surface vs. incorporated), replicated four times in a randomized complete block design. Forage was harvested at 28‐d intervals from May to November 2007 and 2008 and analyzed for neutral detergent fiber and tissue mineral concentrations. Soil samples were collected in August 2006, before the Al‐WTR application, and in November 2007 and 2008. Shallow groundwater P was monitored using a piezometer installed at the 60‐cm depth. Soil water‐extractable P and leachate P concentrations decreased as Al‐WTR application level increased. Mehlich‐1 Al and soil P storage capacity values increased linearly as Al‐WTR application level increased. Soil disturbance due to incorporation of Al‐WTR resulted in horizontal P transport in the soil. Incorporation of Al‐WTR caused a yield suppression in Year 1 (∼11% compared with surface application), but no negative effect was observed in Year 2. Neutral detergent fiber and crude protein were not affected by Al‐WTR application level or method. Data indicate that Al‐WTR reduced P mobility in a Spodosol with no impact on forage responses except for a light reduction in yield in the first year if Al‐WTR was incorporated.

The Diagnosis and Recommendation Integrated System (DRIS) allows the interpretation of results of leaf analysis through relationships among nutrients, instead of the absolute and isolated concentration of each one, as it is used by the criterion of sufficiency range. The objective was to evaluate three procedures of calculation of DRIS indices, and to verify the efficiency of DRIS as interpretation method for the results of Brachiaria decumbens (Signal grass). The study was developed with the results of six experiments carried out in a greenhouse at Piracicaba, SP, with nutrient solution. Concentrations of N, P, K, Ca, Mg, S, Cu, Fe, Mn, and Zn were used in the samples of recently expanded leaf laminae of the grass. The validation of the DRIS method used results from an experiment with nitrogen and sulfur rates applied to the same grass from the Mundo Novo farm, Brotas, SP. DRIS indices were calculated according to two criteria to choose the ratio order of nutrients (F value and R value) and three ways to calculate the nutrient functions (methods of Beaufils, Jones, and Elwali & Gascho). Nutritional Balance Index (NBI), calculated according to the generated norms, presented negative and significant correlation coefficients with the productivity in the combinations of methods tested and DRIS methods proposed by Beaufils, Jones and Elwali & Gascho were efficient in detecting concentrations that show nutrients deficiency or excess.

The Diagnosis and Recommendation Integrated System (DRIS) has been proved efficient as a method for nutritional diagnosis in several crops. However there is a lack of information on the use of DRIS for tropical forage grass. The aim of this paper was to establish norms for interpretation of results of analysis from recently expanded leaf laminae of Brachiaria decumbens Stapf. (Signal grass), through the DRIS method. To establish DRIS norms, concentrations of N, P, K, Ca, Mg, S, Cu, Fe, Mn, and Zn and the relative production obtained in six experiments conducted in greenhouse using nutrient solution and silica as substrate were considered. DRIS indices were calculated using two criteria in order to choose the ratio order of nutrients: F value -ratio of variance for the relationships among nutrients between the reference group and the low productivity group; and R value -correlation coefficients between the productivity values and the relationship among the pairs of nutrients, and three forms of calculation for the functions of nutrients (methods of Beaufils, of Jones, and of Elwali & Gascho). The two criteria to choose the ratio order of nutrients selected different ratios between pairs of nutrients; the nutrient concentrations were positively and significantly correlated with the respective DRIS indices, except for N; and DRIS norms are useful for the nutritional diagnosis of the ten studied nutrients in leaf laminae of Signal grass.

-The objective of this research was to evaluate the effect of combinations of nitrogen and sulfur rates in degraded signal grass (Brachiaria decumbens) pasture on their productive, morphological and nutritional attributes in the root system at four soil depths. The pasture used in the experiment was established over eight years ago in Entisol. Five nitrogen rates (0; 150; 300; 450 and 600 kg/ha/year) and five sulfur rates (0; 15; 30; 45 and 60 kg/ha/year) were combined in a fractionated factorial in a randomized block design, with three replications. Nitrogen was supplied as ammonium nitrate and sulfur as gypsum, and the rates were split into three times in the rainy season. The evaluations occurred at intervals of 35 days during the rainy season and 56 days in the dry season, in two consecutive years. Roots were collected with a 4-cm diameter auger at 0-10; 10-20; 20-30 and 30-40 cm soil depths. It was determined root dry matter, length and surface of the root system and nitrogen and sulfur concentrations in roots. Nitrogen rates applied in two consecutive years in the pasture affected dry mass, length, surface and nitrogen concentration in signal grass root system. Rates of sulfur by themselves or combined with nitrogen rates do not affect attributes of root system. Key Words: Brachiaria decumbens, dry mass, length, nitrogen concentration, surface Adubações com nitrogênio e enxofre durante dois anos em pastagem de capim-braquiária em degradação: alterações no sistema radicular RESUMO -Objetivou-se avaliar os efeitos das combinações de doses de nitrogênio e de enxofre em pastagem de capimbraquiária (Brachiaria decumbens) em degradação nos atributos produtivos, morfológicos e nutricionais do sistema radicular em quatro profundidades do solo. A pastagem utilizada no experimento foi estabelecida há mais de oito anos em solo Neossolo Quartzarênico. Cinco doses de nitrogênio (0; 150; 300; 450 e 600 kg/ha/ano) e cinco doses de enxofre (0; 15; 30; 45 e 60 kg/ha/ano) foram combinadas em fatorial fracionado, em delineamento de blocos ao acaso, com três repetições. O nitrogênio foi fornecido por meio de aplicação de nitrato de amônio e o enxofre por gesso, em doses parceladas em três vezes no período chuvoso. As avaliações ocorreram em intervalos de 35 dias no período chuvoso e de 56 dias no período seco, em dois anos consecutivos. As raízes foram coletadas por meio de trado de 4 cm de diâmetro nas profundidades de 0-10; 10-20; 20-30 e 30-40 cm do solo. Foram determinados a massa seca de raízes, o comprimento e a superfície radicular e as concentrações de nitrogênio e enxofre nas raízes. As doses de nitrogênio aplicadas em dois anos consecutivos na pastagem promoveram alterações nas raízes, em termos de massa seca, comprimento, superfície e concentração de nitrogênio no capim-braquiária. As doses de enxofre, isoladamente ou combinadas com as de nitrogênio, não promovem alterações nos atributos do sistema radicular.Palavras-chave: Brachiaria decumbens, comprimento, concentração de nitrogênio, massa seca, superfíc...