Microclimate and the thermal comfort during the implementation of silvopastoral systems: the windbreak countereffect.

Little has been studied about microclimate and the thermal comfort during the implementation of silvopastoral systems. This study aimed to evaluate the microclimate and thermal comfort during the implementation of High Biodiversity Silvopastoral System with Nuclei (SPSnu). Three treatments were investigated, SPSnu with 5 and 10% of the pasture area with nuclei, (SPSnu5 and SPSnu10, respectively), and treeless pasture (TLP). Each treatment was subdivided into 4 areas: within the nuclei, around the nuclei, around the nuclei with shade and internuclei. The analyzed variables were soil surface temperature, air temperature, wind speed, relative humidity, black globe temperature and the Heat Load Index (HLI) at 20 and 120 cm height. We hypothesized that the wind speed reduction associated with insufficient shade projection typical of the first years of SPSs may interfere in microclimate and thermal comfort during the hot seasons. SPSnu5 and SPSnu10 had a reduction in wind speed of 51.58% and 68.47% respectively when compared to TLP at 20 cm. Soil surface temperature and air temperature at 120 cm were higher for SPSnu than TLP. The same effect was observed for the HLI. At 20 cm, HLI indicated better thermal comfort in TLP than in the SPSnu treatments. The lack of shade projection from young nuclei in conjunction with the decrease of wind speed between the nuclei caused a higher air temperature and HLI in the SPSnu treatments, we called this conditions, windbreak countereffect. Farmers must knowledge this effect when implementing SPSs, and when necessary, mitigate with the proper management decisions.

Applied nucleation under high biodiversity silvopastoral system as an adaptive strategy against microclimate extremes in pasture areas.

This study aimed to assess the influence of the high biodiversity silvopastoral system (SPSnu) on the microclimate, pasture production, and pasture chemical composition. Microclimate variables and pasture production and chemical composition were measured in pared paddocks under SPSnu and treeless pasture (TLP) in a commercial farm during four seasons in Southern Brazil. SPSnu measurements were subdivided into two areas: around the nuclei (AN) and area inter-nuclei (IN). In the TLP paddocks, we plotted fictitious nuclei with the same areas and distributions of SPSnu, however without trees. For the microclimate measurements, these areas were noted when shaded or unshaded by the nuclei trees. In each season, the microclimate variables air temperature (AT, °C), relative humidity (RH, %), illuminance (Ilu, lux), wind speed (WS, m/s), and soil surface temperature (SST, °C) were measured. In addition, botanical composition (%), pasture production (kg/DM/ ha), and pasture chemical composition were evaluated. The SPSnu provided the lowest values of microclimate variables in all seasons (p < 0.05), except for the relative humidity. Winter had the highest thermal amplitude in the systems. The highest difference between SPSnu and TLP for AT (4.3 °C) and SST (5.2 °C) was measured during the hot seasons (spring and summer). In contrast, during cold seasons (autumn and winter) it observed highest thermal amplitude between SPSnu and TLP. Overall, the highest annual pasture production was observed in the SPSnu (p < 0.05). During the summer, the SPSnu areas showed the highest values of crude protein and dry matter (p < 0.05). During the winter, the TLP showed the lowest values (p < 0.05) of pasture production and dry matter. It was observed that SPSnu improved the microclimate at the pasture level, influencing pasture production and pasture chemical composition. The enhanced microclimate can partially mitigate some of the effects of climate change on pastoral agroecosystems, creating conditions for ecological rehabilitation of ecosystem processes and services. These conditions could be amplified to a biome level through a payment for ecosystem services program.

Discrimination of soils managed with different sources of fertilization and plant species in organic and conventional farming through near-infrared spectroscopy and chemometrics.

BACKGROUND: The combination of near-infrared (NIR) spectroscopy and chemometrics can be used to group or discriminate soils based on spectral response. In this study, we conducted discrimination and classification analyses on soils managed with different sources of fertilization and plant species grown in organic and conventional farming systems. RESULTS: Principal component analysis explained 96% (PC1) and 3% (PC2) of the data variability and separated the soil samples of organic and conventional management systems. The wavenumbers that contributed most to the separation of the management systems were in the range of 3600 and 7300 cm-1 , especially the absorption peaks of 3700 and 4600 cm-1 (characteristic of CH and NH combinations), and 5200 and 7000 cm-1 (typical of OH combinations). Machine learning analysis using k-nearest neighbor and random forest algorithms was efficient in classifying soil samples according to management system with an accuracy of 97.8% and can therefore be used for future classification studies. CONCLUSION: Based on the results, we strongly recommend the use of NIR spectroscopy associated with chemometrics for discriminating soils grown with Malus domestica, Musa spp., Oryza sativa and Solanum tuberosum L. under organic and conventional management systems through spectral response. © 2021 Society of Chemical Industry.

Ruminal fermentation characteristics and fatty acid profile of ruminal fluid and milk of dairy cows fed flaxseed hulls supplemented with monensin.

Flaxseed hull, a co-product obtained from flax processing, is a rich source of n-3 fatty acids (FA) but there is little information on its value for dairy production. Monensin supplementation is known to modify biohydrogenation of FA by rumen microbes. Therefore, the main objective of the experiment was to determine the effect of feeding a combination of monensin and flaxseed hulls on ruminal fermentation characteristics and FA profile of ruminal fluid and milk. Four ruminally fistulated multiparous Holstein cows averaging 665 ± 21 kg body weight and 190 ± 5 d in milk were assigned to a 4×4 Latin square design (28-d experimental periods) with a 2×2 factorial arrangement of treatments. Treatments were: 1) control, neither flaxseed hulls nor monensin; 2) diet containing (dry matter basis) 19·8% flaxseed hulls; 3) diet with monensin (16 mg/kg dry matter); 4) diet containing 19·8% (dry matter basis) flaxseed hulls and 16 mg monensin/kg. Flaxseed hull supplementation decreased the acetate to propionate ratio in ruminal fluid and monensin had no effect. Concentrations of trans-18:1 isomers (trans9,trans11,trans13/14+6/8) and cis9,12,15-18:3 in ruminal fluid and milk fat were higher and those of cis9,12-18:2 in milk fat tended (P=0·07) to be higher for cows supplemented with flaxseed hulls than for cows fed no flaxseed hulls. Monensin had little effect on milk fatty acid profile. A combination of flaxseed hulls and monensin did not result in better milk fatty acid profile than when feeding only flaxseed hulls.