Grasslands may act as a carbon (C) sink or C source depending on how they are managed. Soil C stocks, root biomass, root length, root length density and soil organic C concentrations were assessed on pastures of elephant grass (Pennisetum purpureum) managed under different post-grazing stubble heights and signal grass (Brachiaria decumbens) managed under different stocking rates. Soil samples were collected in 20-cm layers down to 1-m soil depth. Neither stubble height nor stocking rate had any significant effects on root parameters. Both the root system and C stocks declined in both pastures with increasing soil depth. Root biomass in the 0-20 cm layer contained 2.84 and 2.04 t C/ha, declining to 0.39 and 0.64 t C/ha at 80-100 cm for elephant grass and signal grass, respectively. Signal grass had greater root development deeper in the soil than elephant grass pastures, possibly due to its greater tolerance of Al toxicity and acidity. Total soil C stocks were greater for signal grass than for elephant grass (358 vs. 214 t C/ha, respectively). ResumenLas pasturas pueden actuar como reservorio o fuente de carbono (C), dependiendo de la forma de manejo. En el trabajo se evaluaron las reservas de C y la concentración de C orgánico en el suelo, la biomasa y longitud radiculares y la densidad de la longitud de las raíces en pasturas de pasto elefante (Pennisetum purpureum) pastoreado a diferentes alturas y de pasto braquiaria (Brachiaria decumbens) manejado con diferentes cargas animal. Las muestras de suelo fueron tomadas cada 20 cm hasta 1 m de profundidad. La altura del pasto elefante ni la carga animal en braquiaria afectaron los parámetros de raíz y suelo evaluados. En ambas pasturas, tanto el sistema radicular como la reserva de C disminuyeron con el incremento de la profundidad en el suelo. En pasto elefante la biomasa radicular entre 0 y 20 cm contenía 2.84 t/ha de C y entre 80 y 100 cm contenía 0.39 t/ha. En pasto braquiaria estos contenidos eran, respectivamente, 2.04 t/ha y 0.64 t/ha. Este último pasto presentó un mayor desarrollo radicular a través del perfil del suelo que el pasto elefante, posiblemente por su mayor tolerancia a acidez del suelo y toxicidad por aluminio. La reserva total de C en el suelo fue mayor en pasto braquiaria (358 t C/ha) que en pasto elefante (214 t C/ha).

The aim of this work was to evaluate the agronomic and bromatologic aspects of nine herbaceous forage legumes. Legumes studied included C. ternatea L., D. heterocarpon (L.) DC. subsp. ovalifolium (Prain) Ohashi cv. Itabela, A. pintoi Krap and Greg. cv. Amarillo, Pueraria phaseoloides (Roxb.) Benth, S. guianensis (Aubl.) Sw. cv. Bandeirante, cv. Cook and cv. Mineirão and Stylosanthes macrocephala Ferreira e Sousa Costa cv. Pioneiro. The following response variables were measured: soil cover, plant height, fresh matter production, stand, seed production, FDN, FDA, hemicellulose, lignin, PB and MM concentrations of leaves and stems. Four cuts were performed during the experimental period. Cutting intensities were at the ground level for the first cut and 5 cm for the following cuts. It was used a complete randomized block design with *Trabalho realizado através do convênio IPA/ UFRPE.

SUMMARYThe aim of this work was to evaluate the agronomic and bromatologic aspects of nine herbaceous forage legumes. Legumes studied included C. ternatea L., D. heterocarpon (L.) DC. subsp. ovalifolium (Prain) Ohashi cv. Itabela, A. pintoi Krap and Greg. cv. Amarillo, Pueraria phaseoloides (Roxb.) Benth, S. guianensis (Aubl.) Sw. cv. Bandeirante, cv. Cook and cv. Mineirão and Stylosanthes macrocephala Ferreira e Sousa Costa cv. Pioneiro. The following response variables were measured: soil cover, plant height, fresh matter production, stand, seed production, FDN, FDA, hemicellulose, lignin, PB and MM concentrations of leaves and stems. Four cuts were performed during the experimental period. Cutting intensities were at the ground level for the first cut and 5 cm for the following cuts. It was used a complete randomized block design with *Trabalho realizado através do convênio IPA/ UFRPE.

No abstract

Nutrients from fecal return may improve herbage growth and chemical composition, but herbage rejection may occur around dung pads. Rejected herbage increases in maturity and might be rejected in future grazing cycles. The aim of this study was to determine the influence of dung pad on soil and herbage characteristics of signalgrass [Urochloa decumbens (Stapf) R. D. Webster (syn. Brachiaria decumbens Stapf.)] pastures managed under three stocking rates (1.9, 3.2, and 4.2 animal units (Alls) ha^''; 1 AU = 450 kg of cattle live weight). Herbage and soil responses were measured at different distances from the dung pad border (0 to 20, 20 to 40, and 40 to 60 cm). A rotational stocking was applied with 3 d of grazing and 32 or 67 d of resting for the dry and rainy seasons, respectively. Herbage mass increased near the dung pad by 40% compared to the surrounding areas but was not affected by stocking rate. Herbage rejection was greater near the dung pad and rejection was greater at lower stocking rate. Plants distant from the dung pad presented lower P concentration. Regardless of stocking rate, K, N, and P fecal and herbage concentrations were affected by the grazing cycle, and there was a higher nutrient concentration during the rainy season. Soil beneath dung pad had higher pH value (5.6 vs. 5.2), Mehlich-I P (22.4 vs. 12.5 g m-^), and K concentration (9 vs. 5 mol m"^) compared to soil from the surrounding areas. Grazing management practices should improve fecal distribution in pastures to maximize nutrient return via this pathway.