Diurnal and seasonal variations on soil CO2 fluxes in tropical silvopastoral systems

This study aimed to quantify the dynamics of soil CO₂ fluxes in two silvopastoral systems based on Leucaena leucocephala, one associated with Panicum maximum (L + P) and another with Cynodon plectostachyus (L + C). We measured CO₂ fluxes fortnightly during the dry and rainy seasons in the morning and the afternoon, with an infrared gas analyzer. Simultaneously, we measured soil temperature, soil moisture, ambient temperature, and relative humidity. Soil CO₂ fluxes ranged from 6.0 ± 0.14 to 6.1 ± 0.12 µmol CO₂/m²/s but no statistical differences were observed between systems. Soil CO₂ flux in the L + P was 12.5% higher in the rainy season compared with the dry season but the season did not affect the fluxes in L + C. Regarding the diurnal variation, CO₂ fluxes were 17.6%–34.8% higher in the morning compared with afternoon measurements. Soil moisture and temperature were higher in L + C, but the ambient temperature and relative humidity showed no statistical differences between systems. In both systems, soil temperature was greater in the afternoon, while the soil moisture and relative humidity were greater in the morning. The diurnal variation of soil CO₂ fluxes in silvopastoral systems correlated positively with soil temperature and ambient temperature, but negatively with relative humidity. We concluded that soil CO₂ fluxes did not vary between silvopastoral systems but respond differently to the seasons. The results have important implications on the establishment and management of Leucaena-based silvopastoral systems for the mitigation of soil CO₂ fluxes from extensive livestock production lands.     

Forage yield and quality of Leucaena leucocephala and Guazuma ulmifolia in mixed and pure fodder banks systems in Yucatan,Mexico

In tropical areas of Mexico, Leucaena leucocephala is widely used in silvopastoral systems. However, little information exists on other native woody species of high forage potential, such as Guazuma ulmifolia. The aim of this study was to evaluate the components of biomass, forage yield and quality, and availability of N in fodder banks of L. leucocephala, G. ulmifolia, and a mixture of both species during dry and rainy seasons, under sub-humid tropical conditions. The experimental unit was a 5 × 10 m plot, containing three rows with 2 m between rows; each row had 20 plant positions with 0.50 m between plants. Within each plant position there was either a single plant, in the case of pure-crop, or two plants, in the case of mixed of both species. A complete randomized block design with three repetitions was used. In both seasons, there were a significantly greater proportion of leaves in the G. ulmifolia fodder banks (71 %) and in mixed fodder banks (69 %) than in L. leucocephala fodder banks (64 %). Consequently, these systems had leaf-to-stem ratios of 2.4, 2.2 and 1.9, respectively. The forage yield of fodder banks was not influenced by season. The mixed fodder bank had greater forage yield (5.1 t DM ha^?1) than the L. leucocephala fodder bank (3.4 t DM ha^?1) in each season. Additionally, the mixed fodder bank accumulated more forage yield during the experimental period (10.2 t DM ha^?1 year^?1) than G. ulmifolia (9.0 t DM ha^?1 year^?1) or L. leucocephala (6.9 t DM ha^?1 year^?1). The concentrations of CP, C and C:N were not influenced by season. Forage NDF and ADF concentrations were greater in the rainy season (476 g kg^?1 DM) compared with the dry season (325 g kg^?1 DM). Mixed fodder banks had the greatest N yield (185.9 kg ha^?1) and consequently the greatest availability of N (371.8 kg N ha^?1 year^?1). We conclude that mixed fodder banks of L. leucocephala and G. ulmifolia are a better option for improving productivity and forage quality in comparison with pure fodder banks in Yucatan, Mexico.     

Estimation of body weight in hair ewes using an indirect measurement method

Tropical Animal Health and Production - The aim of the present study was to develop and evaluate an equation to predict body weight (BW) using hip width (HW) in Pelibuey ewe lambs and ewes. Five...     

Silvopastoral systems improve carbon stocks at livestock ranches in Tabasco,Mexico

Silvopastoral systems have great potential for storing carbon because of carbon assimilation in tree woody biomass, carbon input through litterfall and below-ground carbon turnover. In this study, we quantified and compared the carbon stocks at livestock ranches in Tabasco, Mexico, containing either scattered trees in grazing pastures (STP) or grass monocultures. Sampling plots were randomly established at each ranch where the above- and below-ground carbon stocks, carbon input from litterfall, grass production and arboreal biomass growth were measured. We found that silvopastoral systems stored an average of 257.45 Mg ha⁻¹ of soil organic carbon (SOC) compared to 119.17 Mg SOC ha⁻¹ at grass monoculture ranches (to 30 cm depth); silvopastoral systems also stored 44.64 Mg C ha⁻¹ in wood biomass; and, grass monocultures had greater cumulative grass biomass production. Overall, it is concluded that livestock ranches in Tabasco, Mexico, with scattered trees in grazing pastures stored 58.8% more carbon than those grass monocultures, with carbon stocks of 327.01 Mg C ha⁻¹and 134.47 Mg C ha⁻¹, respectively. The results are useful for land management decision making for sustainable livestock systems framed in the Sustainable Development Goals (SDGs).