ABSTRACT The use of tools such as process capability index for irrigation aims to observe how this irrigation is adequate in terms of quality. The aim of the study was analyzing the Christiansen uniformity coefficient and the flow of a drip irrigation system with self-compensating emitters under water different salt concentrations, using the process capability index. The research was conducted in a greenhouse at the Federal University of Campina Grande (UFCG). The experimental design was a randomized block in a factorial 5 x 2 with three replications, the factors consisted of five levels of irrigation water salinity (CEw) (0.6, 1.5, 2.5, 3.5 and 4.5 dS m−1 at 25°C) and two running times (0 and 350 hours of operation). The Christiansen uniformity coefficient (CUC) for new and used emitters was greater than 90%, in different salt concentrations studied. The flow of emitters is maintained within the statistical quality control, since management and maintenance operations are made after 350 hours of operation. The potential process capability index for the Christiansen uniformity coefficient was higher than recommended for new and used emitters, being the process within the required specifications.

RESUMO Os elevados preços e a escassez de madeiras nobres tornam necessário o uso de fontes alternativas de madeira, como guapuruvu (Schizolobium parahybae), espécie arbórea nativa da Mata Atlântica a qual apresenta rápido crescimento e alto potencial mercadológico; todavia, não há informações sobre seu cultivo no cerrado do Brasil; objetivou-se, neste sentido, analisar a contribuição da adubação mineral e da calagem no solo do cerrado sobre o crescimento inicial de Schizolobium parahybae. O delineamento foi em blocos casualizados, com 4 tratamentos (solo do cerrado; solo + calagem; solo + adubo; solo + adubo + calagem) e 15 repetições. As variáveis analisadas foram: altura de planta, diâmetro do caule, número de folhas, massas secas totais da parte aérea, das folhas, da raiz e do caule e relação raiz/parte aérea. Os dados obtidos foram submetidos à análise de variância, ao teste de Tukey e à análise de regressão. Observou-se, durante o crescimento inicial, que o Schizolobium parahybae pode ser cultivado em solo do cerrado brasileiro apenas com adubação mineral sem a necessidade de calagem do solo.

ABSTRACT High prices and the scarcity of hardwoods require the use of alternative wood sources, such as the Guapuruvu (Schizolobium parahybae), an arboreal species native to the Atlantic Forest, which has fast growth and high market potential. However, there is no information on its cultivation in the Brazilian Cerrado. Thus, this study aimed to analyze the contribution of mineral fertilization and liming in a Cerrado soil on the initial growth of Schizolobium parahybae. The experiment was set in a randomized block design, with 4 treatments (Cerrado soil; soil + liming; soil + fertilizer; and soil + fertilizer + liming) and 15 replicates. The following variables were analyzed: plant height, stem diameter, number of leaves, total, shoot, leaf, root and stem dry matter, and root/shoot ratio. The obtained data were subjected to the analysis of variance, Tukey test and regression analysis. During the initial growth, Schizolobium parahybae can be cultivated in a Brazilian Cerrado soil only under mineral fertilization, with no need for soil liming.

Na irrigação localizada com gotejadores posicionados de modo subsuperficial há o risco potencial de partículas de solo serem succionadas através do orifício de saída de água, em virtude da ocorrência de vácuo podendo resultar no entupimento dos mesmos. Objetivou-se, com este trabalho, avaliar o efeito da aplicação de vácuo no desempenho de diferentes modelos de gotejadores sob duas condições de textura de solo e posicionados de modo subsuperficial. Os tratamentos consistiram da aplicação dos níveis de sucção de -10, -15, -20 e -40 kPa, em solos de textura arenosa e argilosa, em 23 modelos de gotejadores usados com mais de 1 ano de funcionamento. O desempenho dos emissores no gotejamento subsuperficial foi influenciado pela textura do solo. De modo geral, em 80% dos emissores o vácuo de -40 kPa proporcionou obstrução nos emissores e redução da vazão, em ambas as texturas de solo. A maior redução de uniformidade de aplicação de água ocorreu com o modelo Irrimon Irridrip Plus 2,5 L h-1 na condição de solo arenoso e aplicação de 40 kPa de sucção.

In drip irrigation with emitters positioned subsurfacely there is the potential risk of soil particles being suctioned through the water outlet port, due to the occurrence of vacuum which may result in clogging of drippers. The objective of this study was to evaluate the effect of vacuum on the performance of different models of subsurface positioned drippers under two conditions of soil texture. The treatments consisted of applying suction levels of -10, -15, -20 and -40 kPa in sandy and clayey soils in 23 models of used drippers with more than 1 year of operation. The performance of the subsurface drip emitters was influenced by soil texture. Overall, in 80% of drippers , -40 kPa vacuum caused the obstruction of emitter and reduced flow in both soils. The largest reduction of uniformity of water application was observed in model Irrimon Irridrip Plus 2.5 L h-1 in sandy soil and application of 40 kPa suction.