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The aim of this research was to evaluate the spatial distribution of bedding variables in a climate-controlled compost bedded pack barn (CBP) equipped with an evaporative cooling system associated with a tunnel ventilation mode. The study was conducted on a farm in the West Mesoregion of Minas, MG, Brazil. The interior of the animal facility was divided into a mesh of 120 equidistant points, where the bedding surface temperature (t b-sur ), the bedding temperature at 0.20 m depth (t b-20 ) and the bedding penetration resistance (PR b ) of layer 0 to 0.20 m depth were measured. Bedding samples were collected to obtain the moisture (M b ) and pH in the surface and at 0.20 m depth. Geostatistics technique was used to evaluate the dependence and spatial distribution. Through the bedding area, the t b-sur presented low variability, with 6 ºC of amplitude, and t b-20 presented highest values (up to 55 °C). The spatial distribution of M b-20 was similar to that observed on the surface and its highest levels occurred in the region near the feed alley (> 40%). The distribution of pH was similar in both layers. The tendency of high PR b occurred in the layer between 0.15 and 0.20 m (0 and 1500 kPa).

The objective of this study was to characterize the dependence and spatial distribution of bedding attributes in an open compost-bedded pack barn (CBP) system with positive pressure ventilation during the winter period in Brazil. The study was conducted in July 2021, in the Zona da Mata region, Minas Gerais, Brazil. The bedding area (shavings and wood sawdust) was divided into a mesh with 44 equidistant points. At each point, the bedding temperature at the surface (tB-sur) and at a depth of 0.2 m (tB-20) and the air velocity at bedding level (vair,B) were measured, and bedding samples were collected. The bedding samples were used to determine the moisture level and pH at the surface (MB-sur e pHB-sur) and at a depth of 0.2 m (MB-20 and pHB-20). The spatial behavior of the variables was evaluated using geostatistics techniques. For all variables, the occurrence of strong spatial dependence was verified. Through the maps, it was observed that tB-sur, tB-20, MB-sur, MB-20, and vair,B showed high spatial variability, whereas pHB-sur and pHB-20 demonstrated low variation. On the surface, values of tB-sur < 20 °C and MB-sur > 60% were observed. At the subsurface, there was a predominance of tB-20 < 40 °C, MB-20 > 60%, and pH > 9, which are indications of low bedding composting activity.

In this study, we aimed to assess the spatial variability of microclimate inside a closed compost-bedded pack barn (CBP) with a negative ventilation system during summer and winter. The research was carried out in a CBP located in the Zona da Mata region, Minas Gerais, Brazil. For each of the stations analyzed, the following environmental mean variables observed inside a CBP were measured: air dry-bulb temperature (t db ), air relative humidity (RH), and windspeed, Temperature-Humidity index, and specific enthalpy. The kriging maps showed that the most critical housing conditions in the thermal environment were found, mainly, from the central part of the CBP, close to the exhaust fans. The analyses also pointed out that the system presented temperature gradients along the length, up to 3°C. During the summer afternoon, the entire region of the CBP was in a discomfort situation (t db >26°C; RH>75%). During the winter, the measured environmental data remained within the comfort zone throughout the facility. However, probably due to the lack of thermal insulation of the material used to close the sides of the CBP, it did not allow spatial thermal uniformity for both seasons.It was also inefficient to keep the animals within the comfort zone for lactating cattle during the critical summer period.

For drip irrigation design and management, it is necessary to know the relation between flow and pressure acting on emitters. In the case of subsurface drip irrigation, the backpressure phenomenon may change the hydraulic characteristics of emitters. Thus, this study aimed at determining such relationship between flow and pressure of different driplines in surface and subsurface conditions; aiming to find possible differences in hydraulic behavior. We tested four emitter types; two pressure compensating (D5000 and Hydro PCND) and two non-pressure compensating (TalDrip and Jardiline). Emitter flow rates were attained in atmospheric conditions and submerged in water, in which submergence levels represented backpressure. Assays were performed using inlet pressures of 80, 100, 120, and 150 kPa for the Hydro PCND dripline and 25, 50, 100, and 150 kPa for the other ones; the backpressures were of 0.49, 1.47, 2.45, 4.41 and 6.37 kPa with four replications. The emitters had their proportionality constants and discharge exponents changed in submerged applications, representing backpressure effect. Non-pressure compensating emitters had their discharge exponent decreased, while in pressure compensating ones, it was increased. Backpressure reduced emitter flow rates at all evaluated pressures.KEYWORDS: discharge exponent, proportionality constant, trickle irrigation. EFEITOS DA CONTRAPRESSÃO SOBRE A RELAÇÃO VAZÃO-PRESSÃO DE TUBOGOTEJADORESRESUMO: Para o projeto e o manejo da irrigação por gotejamento, é necessário o conhecimento da relação entre vazão e pressão atuante sobre os emissores. Porém, o fenômeno da contrapressão, no caso do gotejamento subsuperficial, pode alterar as características hidráulicas dos emissores. Assim, o objetivo deste trabalho foi determinar a relação entre a vazão e a pressão de diferentes tubogotejadores em condições superficiais e subsuperficiais, e as possíveis diferenças no comportamento hidráulico dos emissores nessas duas condições. Foram utilizados nos ensaios quatro emissores: dois autocompensantes (D5000 e Hydro PCND) e dois não autocompensantes (TalDrip e Jardiline). A vazão destes foi obtida em condição atmosférica e submersa em água, em que os níveis de submersão representaram a contrapressão. Os ensaios foram realizados utilizando as pressões de entrada de 80; 100; 120 e 150 kPa para o tubo gotejador Hydro PCND e 25; 50; 100 e 150 kPa, para os demais, e contrapressões de 0,49; 1,47; 2,45; 4,41 e 6,37 kPa, com quatro repetições. Os emissores tiveram suas constantes de proporcionalidade e expoentes de descarga alterados em aplicação submersa. Emissores não autocompe nsantes tiveram seu expoente de descarga diminuído, enquanto nos autocompensantes, este aumentou. A vazão de emissores foi reduzida pelo efeito da contrapressão, em todas as pressões avaliadas.