This research evaluated soil properties in a silvopastoral system using double rows of tree legumes. Treatments were signalgrass (Brachiaria decumbens) in monoculture or in consortium with sabiá (Mimosa caesalpiniifolia) or gliricidia (Gliricidia sepium). Treatments were arranged in a complete randomized block design, with 4 replications. Response variables included chemical characteristics and physical attributes of the soil. Silvopastoral systems had greater (P<0.001) soil exchangeable Ca (gliricidia = 3.2 and sabiá = 3.0 mmolc/dm 3 ) than signalgrass monoculture (2.0 mmolc/dm 3 ). Water infiltration rate was greater within the tree legume double rows (366 mm/h) than in signalgrass (162 mm/h) (P = 0.02). However, soil moisture was greater in signalgrass pastures (15.9%) (P = 0.0020) than in silvopastures (14.9 and 14.8%), where soil moisture levels increased as distance from the tree rows increased. Conversely, the light fraction of soil organic matter was greater within the tree legume double rows than in the grassed area (P = 0.0019). Long-term studies are needed to determine if these benefits accumulate further and the productivity benefits which result.Keywords: Fertility, legumes, soil physics, trees. ResumenEntre enero 2012 y diciembre 2013 en Itambé, Pernambuco, Brasil, se evaluaron algunas propiedades físicas y químicas del suelo en un sistema silvopastoril, utilizando filas dobles de leguminosas arbóreas. Los tratamientos consistieron en Brachiaria decumbens sola o en asociación con sabiá (Mimosa caesalpiniifolia) o gliricidia (Gliricidia sepium) en un diseño de bloques completos al azar, con 4 repeticiones. Los sistemas silvopastoriles presentaron mayor contenido (P<0.001) de calcio intercambiable (gliricidia = 3.2 y sabiá = 3.0 mmolc/dm 3 ) comparados con la gramínea sola (2.0 mmolc/dm 3 ). La tasa de infiltración de agua fue mayor en el suelo dentro de las filas dobles de los árboles leguminosos (366 mm/h) en comparación con la gramínea sola (162 mm/h) (P = 0.02). No obstante, la humedad fue más alta en el suelo con gramínea (15.9%) (P = 0.0020) comparada con los sistemas silvopastoriles (14.9 y 14.8%, respectivamente para sabiá y gliricidia). La humedad en el suelo aumentó con la distancia a partir de la línea de árboles. Por el contrario, la fracción ligera de la materia orgánica del suelo fue mayor (P = 0.0019) dentro de las filas dobles de árboles (0.071 mg/kg) comparada con el suelo fuera de la línea de árboles. Se requieren estudios a largo plazo para determinar si estos beneficios continuan acumulándose y si resultan en mayor productividad.Palabras clave: Árboles, fertilidad, física del suelo, leguminosas.

Livestock excreta is one of the major nutrient sources in natural grasslands. Understanding how livestock diet and season affects the decomposition dynamics is critical to nutrient cycling models. We hypothesised that livestock diet and season of the year affect dung decomposition. This study evaluated the decomposition and release of N, P, K, Ca, Mg, and Na from faeces of cattle collected in dry and wet seasons. Treatments were signalgrass (Brachiaria decumbens Stapf) in monoculture or mixed with sabiá (Mimosa caesalpiniifolia Benth.) or gliricidia (Gliricidia sepium (Jacq.) Kunth ex Walp.). Excreta samples were incubated in nylon bags for 0, 2, 4, 8, 16, 32, 64, 128 and 256 d. The single negative exponential mathematical model was adequate (P < 0.0001) to explain the decomposition. The relative rate of dung decomposition (k) was greater for samples that originated from cattle grazed on signalgrass (k = 0.00284 g g −1 d −1 ), followed by sabiá (k = 0.00233 g g −1 d −1 ), and gliricidia (k = 0.00200 g g −1 d −1 ) pastures. The rate of nutrient release showed a time effect for all variables and interaction between time and season for Ca (P = 0.0042) and Mg (P = 0.0013). Faeces collected from cattle grazing/browsing intercropped pastures tended to have lower decomposition rates.

Silvopasture systems enhance the use efficiency of natural resources by diversifying vegetation structure and function. However, shading from trees may affect the production and quality of herbaceous forages and, consequently, the animal performance. The objective of this research was to evaluate regrowth and development of tree legumes as well as productivity and nutritive value of signalgrass [Brachiaria decumbens (Stapf) R.D. Webster] subjected to shading from the tree legumes gliricidia [Gliricidia sepium (Jacq.) Steud] and sabiá (Mimosa caesalpiniifolia Benth.). Herbage responses were evaluated every 56 d. Trees were evaluated every 120 d to assess morphological responses and forage nutritive value. Response variables included in vitro digestible organic matter (IVDOM), concentrations of N, and stable isotopes (δ 15 N) in grass and legume leaves. Greater herbage accumulation occurred for signalgrass submitted to full sun (57 kg ha -1 d -1 ) than under shade (27 kg ha -1 d -1 ) (p = .0006). Morphometric measurements of tree regrowth did not show differences for total leaf mass (p = .8603) and mass of thick stems (p = .6157) between tree legume species. Gliricidia leaf IVDOM was greater (504 g kg -1 ) than sabiá leaf IVDOM (315 g kg -1 ) (p < .0001).Nitrogen concentration was greater in leaves (p = .0007), fine stems (p = .0050), and thick stems (p = .0333) of gliricidia throughout the evaluated period when compared to the same fractions of sabiá. Both tree species, at the densities employed in this study, affected negatively and to a similar extent the herbage accumulation of signalgrass.Abbreviations: BD, base diameter; BHD, breast height diameter; ID, intermediate diameter; IVDOM, in vitro digestibility organic matter; TLM, total leaf mass; TMFS, total mass of fine stems; TMTS, total mass of thick stems.

This research evaluated soil properties in a silvopastoral system using double rows of tree legumes. Treatments were signalgrass (Brachiaria decumbens) in monoculture or in consortium with sabiá (Mimosa caesalpiniifolia) or gliricidia (Gliricidia sepium). Treatments were arranged in a complete randomized block design, with 4 replications. Response variables included chemical characteristics and physical attributes of the soil. Silvopastoral systems had greater (P<0.001) soil exchangeable Ca (gliricidia = 3.2 and sabiá = 3.0 mmolc/dm 3 ) than signalgrass monoculture (2.0 mmolc/dm 3 ). Water infiltration rate was greater within the tree legume double rows (366 mm/h) than in signalgrass (162 mm/h) (P = 0.02). However, soil moisture was greater in signalgrass pastures (15.9%) (P = 0.0020) than in silvopastures (14.9 and 14.8%), where soil moisture levels increased as distance from the tree rows increased. Conversely, the light fraction of soil organic matter was greater within the tree legume double rows than in the grassed area (P = 0.0019). Long-term studies are needed to determine if these benefits accumulate further and the productivity benefits which result.Keywords: Fertility, legumes, soil physics, trees. ResumenEntre enero 2012 y diciembre 2013 en Itambé, Pernambuco, Brasil, se evaluaron algunas propiedades físicas y químicas del suelo en un sistema silvopastoril, utilizando filas dobles de leguminosas arbóreas. Los tratamientos consistieron en Brachiaria decumbens sola o en asociación con sabiá (Mimosa caesalpiniifolia) o gliricidia (Gliricidia sepium) en un diseño de bloques completos al azar, con 4 repeticiones. Los sistemas silvopastoriles presentaron mayor contenido (P<0.001) de calcio intercambiable (gliricidia = 3.2 y sabiá = 3.0 mmolc/dm 3 ) comparados con la gramínea sola (2.0 mmolc/dm 3 ). La tasa de infiltración de agua fue mayor en el suelo dentro de las filas dobles de los árboles leguminosos (366 mm/h) en comparación con la gramínea sola (162 mm/h) (P = 0.02). No obstante, la humedad fue más alta en el suelo con gramínea (15.9%) (P = 0.0020) comparada con los sistemas silvopastoriles (14.9 y 14.8%, respectivamente para sabiá y gliricidia). La humedad en el suelo aumentó con la distancia a partir de la línea de árboles. Por el contrario, la fracción ligera de la materia orgánica del suelo fue mayor (P = 0.0019) dentro de las filas dobles de árboles (0.071 mg/kg) comparada con el suelo fuera de la línea de árboles. Se requieren estudios a largo plazo para determinar si estos beneficios continuan acumulándose y si resultan en mayor productividad.Palabras clave: Árboles, fertilidad, física del suelo, leguminosas.