Reference evapotranspiration of Brazil modeled with machine learning techniques and remote sensing.

Reference evapotranspiration (ETo) is a fundamental parameter for hydrological studies and irrigation management. The Penman-Monteith method is the standard to estimate ETo and requires several meteorological elements. In developing countries, the number of weather stations is insufficient. Thus, free products of remote sensing with evapotranspiration information must be used for this purpose. In this context, the objective of this study was to estimate monthly ETo from potential evapotranspiration (PET) made available by MOD16 product. In this study, the monthly ETo estimated by Penman-Monteith method was considered as the standard. For this, data from 265 weather station of the National Institute of Meteorology (INMET), spread all over the Brazilian territory, were acquired for the period from 2000 to 2014 (15 years). For these months, monthly PET values from MOD16 product for all Brazil were also downloaded. By using machine learning algorithms and information from WorldClim as covariates, ETo was estimated through images from the MOD16 product. To perform the modeling of ETo, eight regression algorithms were tested: multiple linear regression; random forest; cubist; partial least squares; principal components regression; adaptive forward-backward greedy; generalized boosted regression and generalized linear model by likelihood-based boosting. Data from 2000 to 2012 (13 years) were used for training and data of 2013 and 2014 (2 years) were used to test the models. The PET made available by the MOD16 product showed higher values than those of ETo for different periods and climatic regions of Brazil. However, the MOD16 product showed good correlation with ETo, indicating that it can be used in ETo estimation. All models of machine learning were effective in improving the performance of the metrics evaluated. Cubist was the model that presented the best metrics for r2 (0.91), NSE (0.90) and nRMSE (8.54%) and should be preferred for ETo prediction. MOD16 product is recommended to be used to predict monthly ETo, which opens possibilities for its use in several other studies.

Impact of drought associated with high temperatures on Coffea canephora plantations: a case study in Espírito Santo State, Brazil.

Droughts are major natural disasters that affect many parts of the world all years and recently affected one of the major conilon coffee-producing regions of the world in state of Espírito Santo, which caused a huge crisis in the sector. Therefore, the objective of this study was to conduct an analysis with technical-scientific basis of the real impact of drought associated with high temperatures and irradiances on the conilon coffee (Coffea canephora Pierre ex Froehner) plantations located in the north, northwest, and northeast regions of the state of Espírito Santo, Brazil. Data from 2010 to 2016 of rainfall, air temperature, production, yield, planted area and surface remote sensing were obtained from different sources, statistically analyzed, and correlated. The 2015/2016 season was the most affected by the drought and high temperatures (mean annual above 26 °C) because, in addition to the adverse weather conditions, coffee plants were already damaged by the climatic conditions of the previous season. The increase in air temperature has higher impact (negative) on production than the decrease in annual precipitation. The average annual air temperatures in the two harvest seasons that stood out for the lowest yields (i.e. 2012/2013 and 2015/2016) were approximately 1 °C higher than in the previous seasons. In addition, in the 2015/2016 season, the average annual air temperature was the highest in the entire series. The spatial and temporal distribution of Enhanced Vegetation Index values enabled the detection and perception of droughts in the conilon coffee-producing regions of Espírito Santo. The rainfall volume accumulated in the periods from September to December and from April to August are the ones that most affect coffee yield. The conilon coffee plantations in these regions are susceptible to new climate extremes, as they continue to be managed under irrigation and full sun. The adoption of agroforestry systems and construction of small reservoirs can be useful to alleviate these climate effects, reducing the risk of coffee production losses and contributing to the sustainability of crops in Espírito Santo.

Mapping within­field variability of soybean evapotranspiration and crop coefficient using the Earth Engine Evaporation Flux (EEFlux) application.

Accurate information about the spatiotemporal variability of actual crop evapotranspiration (ETa), crop coefficient (Kc) and water productivity (WP) is crucial for water efficient management in the agriculture. The Earth Engine Evapotranspiration Flux (EEFlux) application has become a popular approach for providing spatiotemporal information on ETa and Kc worldwide. The aim of this study was to quantify the variability of water consumption (ETa) and the Kc for an irrigated commercial planting of soybeans based on the EEFlux application in the western region of the state of Bahia, Brazil. The water productivity (WP) for the fields was also obtained. Six cloud-free images from Landsat 7 and 8 satellites, acquired during the 2016/17 soybean growing season were used and processed on the EEFlux platform. The ETa from EEFlux was compared to that of the modified FAO (MFAO) approach using the following statistical metrics: Willmot's index of agreement (d-index), root mean square error (RMSE), mean absolute error (MAE) and mean bias error (MBE). The Kc from EEFlux was compared to the Kc used in the soybean field (Kc FAO-based) and to the Kc values obtained in different scientific studies using the d-index. A similar procedure was performed for WP. Our results reveal that EEFlux is able to provide accurate information about the variability of ETa and the Kc of soybean fields. The comparison between ETa EEFlux and ETa MFAO showed good agreement based on the d-index, with values of 0.85, 0.83 and 0.89 for central pivots 1, 2 and 3, respectively. However, EEFlux tends to slightly underestimate ETa. The Kc EEFlux showed good accordance with the Kc values considered in this study, except in phase II, where a larger difference was observed; the average WP of the three fields (1.14 kg m-3) was higher than that in the majority of the previous studies, which is a strong indicator of the efficient use of water in the studied soybean fields. The study showed that EEFlux, an innovative and free tool for access spatiotemporal variability of ETa and Kc at global scale is very efficient to estimate the ETa and Kc on different growth stages of soybean crop.

Controlled water stress in agricultural crops in brazilian cerrado / Estresse hídrico controlado em lavouras agrícolas no cerrado brasileiro

Considering the scenarios with reduction of water availability, the need to increase water use efficiency and crop yield, the objective of this study was to evaluate the effect of reducing the evapotranspiration of the main irrigated crops on productivity. Data from the years 2005 to 2016 for carrot, garlic, potato, sugarcane, bean, maize, soybean, wheat, coffee and cotton crops grown in the Brazilian states of Bahia, Minas Gerais, São Paulo, Goiás, Distrito Federal and Mato Grosso were collected. The crops were irrigated by central-pivot irrigation and drip irrigation systems, and irrigation management was performed using IRRIGER® software. With the information on potential crop evapotranspiration (ETpc) and crop evapotranspiration (ETc), it was possible to obtain a reduction of ETpc (%) for all crops. For all scenarios, these data were confronted with crop productivity and regression models were fitted. It was concluded that the maximum reductions of ETpc (%) without affecting productivity are 5% for garlic and potato, 12% for maize, 13% for bean, 15% for wheat, 20% for soybean and cotton, 25% for sugarcane and 30% for coffee.

Diante dos cenários com redução da disponibilidade hídrica, necessidade de aumento da eficiência no uso da água e da produtividade das culturas agrícolas, objetivou-se neste trabalho avaliar o efeito da redução da evapotranspiração na produtividade das principais culturas irrigadas. Informações foram coletadas nas safras dos anos de 2005 à 2016 para as culturas da cenoura, alho, batata, cana-de-açúcar, feijão, milho, soja, trigo, café e algodão cultivadas nos estados da Bahia (BA), Minas Gerais (MG), São Paulo (SP), Goiás (GO), Distrito Federal (DF) e Mato Grosso (MT). As culturas foram irrigadas por sistemas de irrigação por pivô central e gotejamento, sendo que os manejos de irrigação foram realizados por meio do software IRRIGER®. Com as informações de evapotranspiração potencial da cultura (ETpc) e evapotranspiração da cultura (ETc) foi possível obter a redução da ETpc (%) para todos os cultivos. Para todos os cenários, estes dados foram confrontados com a produtividade das culturas e modelos de regressão foram ajustados. Concluiu-se que a redução máxima de ETpc (%) sem afetar a produtividade é 5% para o alho e batata, 12% para o milho, 13% para o feijão, 15% para o trigo, 20% para a soja e algodão, 25% para a cana-de-açúcar e 30% para o café.

Precision tools for irrigation management of tomato seedlings / Ferramentas de precisão para manejo de irrigação de mudas de tomate

Seedling production is important to vegetable productions, however, irrigation planning for seedling production is usually inefficient due to the lack of information about water consumption by the seedlings, which decreases the quality of the seedlings. The objective of this work was to evaluate the use of hydrogel in the substrate and determine the appropriate irrigation management for the production of tomato seedlings (Solanum lycopersicom), using an automated irrigation system. The experiment was conducted in a protected environment at the Federal University of Viçosa, Brazil. Tomato seedlings were grown in polyethylene trays on substrates with, and without hydrogel. The seedlings were irrigated using an automated micro sprinkler system. Irrigation treatments were chosen considering different crop evapotranspiration (ETc) and reference evapotranspiration (ETo), and the use of timer. The height, root length, stem base diameter, root and shoot dry weights, seedlings were evaluated. The use of the hydrogel for the production of tomato seedlings resulted in seedlings with higher final heights, larger stem base diameter, greater shoot dry weight, larger crown area projection, and greater shoot relative growth rate.

A produção de mudas é um ponto crítico do sistema de produção de hortaliças. Devido a informações sobre o consumo de água pelas mudas, o planejamento da irrigação se torna ineficiente, fato que provoca perdas na qualidade das mudas. O objetivo do experimento foi testar o uso de hidrogel no substrato e determinar o manejo de irrigação adequado através de ferramentas de automatização do sistema de irrigação. O experimento foi conduzido em ambiente protegido na Universidade Federal de Viçosa. Foram produzidas mudas de tomate (Solanum lycopersicom) em bandejas de polietileno, preenchidas com substrato com e sem a presença de hidrogel. As mudas foram irrigadas com sistema de microaspersão, acionado a partir de um sistema automatizado. Os tratamentos de manejo de irrigação foram através da evapotranspiração da cultura (ETc), timer, 0.50 ETo e 1,00 ETo. Foram avaliados componentes de qualidade das mudas como altura, comprimento de raiz, diâmetro de colo, massa seca de raiz e parte aérea. O uso do hidrogel foi um diferencial para produção de mudas de tomate mais precoces, com maior altura final, maior diâmetro de colo, maior acúmulo de massa seca de parte aérea, maior área de projeção da copa e maior a taxa de crescimento relativo de parte aérea. Na presença do hidrogel o manejo 0.50 ETo favoreceu maiores plantas, com colo mais fino e menor massa seca de parte aérea.

Agronomic performance of lettuce cultivars submitted to different irrigation depths.

The use of cultivars adapted to the climate and soil conditions associated with adequate irrigation supply maximizes lettuce agronomic performance. The aim of this work was to evaluate the agronomic performance of four lettuce cultivars submitted to five different drip irrigation depths under a protected environment in Viçosa-MG, Brazil. A randomized block design was applied in a split plot scheme with four replications, and several agronomic characteristics were evaluated by analysis of variance, Tukey range tests, regression and principal component analysis. A higher chlorophyll concentration in the Raider Plus cultivar promoted the production of more leaves, leading to a higher phytomass. The Luara cultivar presented a higher number of commercial leaves per plant than the other cultivars, regardless of the irrigation depth, reflected in a larger diameter and volume of the aerial part of the plants. The Raider Plus and Luara cultivars presented better root development than that of the other cultivars, reducing the effect of plant water stress even under lower irrigation depth conditions. Although higher water productivity (WP) was observed for the lowest irrigation depth (50% of ETc), important variables reached the maximum values at depths higher than 100% water replenishment. Therefore, Raider Plus and Luara cultivars with an irrigation depth of 110% of crop evapotranspiration provided better commercial lettuce quality and are recommended for lettuce cultivation in the research region and under conditions similar to those of the present study.

Spacial distribution of fertigated coffee root system / Distribuição espacial do sistema radicular do cafeeiro fertirrigado

ABSTRACT The development of coffee plant root system changes when subjected to drip irrigation and fertigation. This work aimed to evaluate the effects of different levels of fertigation on the development of coffee root system by drip irrigation in western Bahia. The experiment was carried out with Catuaí Vermelho IAC 144 coffee plants, of about 3.5 years of age, in the "Café do Rio Branco" farm, located in Barreiras - BA, and consisted of a complete randomized blocks design with 3 replicates. Treatments consisted of three levels of nitrogen and potassium fertilization (900/800, 600/500 and 300/250 kg ha-1 year-1 N and K2O), weekly distributed, by means of fertigation, throughout the process. After the fourth harvest, coffee root system was evaluated, and root length density (RLD) and root density (RD) were determined at different sampled layers. The highest root concentration, root length density (RLD), and root density (RD) were observed in the superficial layers of soil (0-20 cm), and under the dripline (30 and 70 cm from the orthotropic branch). Results showed that the lower the N and K2O levels, the higher was the development (RLD and RD) of the coffee root system.

RESUMO O desenvolvimento do sistema radicular do cafeeiro é alterado quando submetido à irrigação localizada e fertirrigação. Este trabalho foi desenvolvido com o objetivo de avaliar os efeitos de diferentes doses de fertirrigação sobre o desenvolvimento do sistema radicular do cafeeiro irrigado por gotejamento na região Oeste da Bahia. Realizou-se o trabalho na fazenda Café do Rio Branco, localizada em Barreiras - BA, em cafeeiros de aproximadamente 3,5 anos de idade, da variedade Catuaí IAC 144. O experimento foi montado em um esquema fatorial 3 x 3, sendo três níveis de adubação nitrogenada e potássica (900/800, 600/500 e 300/250 kg ha-1 ano-1 de N e K2O), em 3 parcelamentos mensais de fertirrigação (2, 4 e 8 vezes). Após a quarta safra, o sistema radicular do cafeeiro foi avaliado e a densidade de comprimento radicular (DCR) e densidade radicular (DR) em diferentes camadas amostradas foram determinadas. A maior concentração de raízes, densidade de comprimento radicular (DCR) e densidade radicular (DR) foi obtida nas camadas superficiais (0-20 cm) e sob a linha lateral (30 e 70 cm de distância do ramo ortotrópico). As menores doses de N e K2O propiciaram maior desenvolvimento (DCR e DR) do sistema radicular do cafeeiro.

Produtividade e rendimento industrial da cana-de-açúcar em função de lâminas de irrigação / Productivity and industrial yield of sugarcane as a function of irrigation depths

O presente trabalho foi desenvolvido com o objetivo de determinar as lâminas de irrigação que resultem na máxima produtividade, no máximo rendimento econômico e no máximo rendimento industrial da cana-deaçúcar e a relação existente entre a lâmina de água e a formação de dextrana. O experimento foi instalado em outubro de 2010 em Jaíba/MG, em uma área irrigada por pivô central, com cana-de-açúcar no quarto ciclo de produção. Para a aplicação dos tratamentos, trocaram-se os bocais dos emissores, em cada vão entre torres do pivô central, de modo que fossem aplicadas as lâminas referentes a 25, 50, 75, 100, 125 e 150% da evapotranspiração da cultura, com o manejo da irrigação realizado para atender a demanda de 100%. Determinou-se a produtividade de colmos e o rendimento industrial da cana-de-açúcar, expressos em açúcares totais recuperáveis (ATR) e os teores de dextrana. Com os dados de produtividade e os custos relacionados à irrigação, calculou-se as lâminas para obtenção da máxima produtividade física (Lmpf) e do máximo rendimento econômico (Lmre), considerando-se a produtividade de colmos e de açúcares. Analisando-se os resultados obtidos, concluiu-se que: a lâmina que proporcionou a maior produtividade de colmos foi de 1.537 mm, para a produtividade de 112,3 t ha-1, ou seja, são necessários 136,9 m3 de água para se produzir uma tonelada de colmos. A lâmina de maior rendimento econômico foi de 1.334 mm para uma produtividade de 108,5 t ha-1. O maior rendimento de açúcares (158,1 kg t-1) foi obtido com lâmina de 1.373 mm. A lâmina que proporcionou a maior produtividade de açúcares (17,56 t ha-1) foi de 1.508,4 mm. O melhor rendimento econômico, em termos de açúcares por unidade de área, foi de 17,4 t ha-1(lâmina recomendada), com fornecimento de 1.406 mm de água, resultando na necessidade de 808 m3 de água para se produzir uma tonelada de açúcar. Lâminas acima de 1.000 mm no ciclo da cultura promoveram teores de dextrana acima dos limites estabelecidos para produção de açúcar. Recomenda-se para as indústrias de etanol e, principalmente de açúcar, introduzirem as análises de dextrana na rotina laboratorial.

The present work was developed due to determine the irrigation depths that result in the maximum productivity, maximum economic yield and the maximum industrial yield of sugarcane, and the relationship between water depth and the formation of dextran. The experiment was installed in October 2010 in Jaíba/MG, Brazil, in an area irrigated by a center pivot with sugarcane in the fourth cycle. For the application treatments the emitter nozzles were exchanged so that the depths were applied referring to 25, 50, 75, 100, 125 and 150% of crop evapotranspiration with irrigation management performed to meet the 100% of the demand. Stalk productivity and industrial yield of sugarcane were determined, as well as levels of ATR and dextran. With productivity data and irrigation costs, the maximum productivity (Lmpf), and maximum economic yield (Lmre) were calculated considering the stalk and sugar yields. The values obtained were subjected to analysis of variance and subsequently developed regressions. Analyzing the results, it was concluded that: the depth that provided the highest stalk yield was 1,537 mm, for a yield of 112.3 t ha-1, i.e. 136,9 m3 of water are necessary do produce one ton of stalks. The depth resulting in greatest economic yield was 1,334 mm for a yield of 108.5 t ha-1. The greatest sugar yield (158.1 kg t-1) was obtained with the depth of 1,373.1 mm. Highest sugar yield (17.56 t ha-1) was obtained from the depth of 1,508 mm. The best economic performance, in terms of sugar per unit area was 17.4 t ha-1, with supply of 1,405.9 mm of water, resulting in a water demand of 808 m3 to produce one ton of sugar. The best economic performance, in terms of sugar per unit area was 17.4 t ha-1 with the supply of 1,406 mm of water (recommended depth). Irrigation depths up to 1,000 mm in the crop cycle promoted dextran levels above the limits established for sugar production. It is recommended that the ethanol industries, and especially sugar industries, utilize dextran analyses in the laboratorial routine.

Indicadores morfo-fisiológicos do estresse hídrico para a cultura da cana-de-açúcar em função de lâminas de irrigação / Morpho-physiological indicators of water stress on sugarcane as a function of irrigation depths

O presente trabalho foi desenvolvido, objetivando-se encontrar as relações entre lâmina de água (chuva e irrigação) e indicadores morfológico (índice de área foliar) e fisiológicos do estresse hídrico (temperatura foliar, potencial hídrico foliar e índice de clorofila nas folhas) na cana-de-açúcar submetida a diferentes lâminas de irrigação. O experimento foi instalado em outubro de 2010 em Jaíba/MG, em uma área irrigada por pivô central, com cana-de-açúcar no quarto ciclo. Para a aplicação dos tratamentos, trocaram-se os bocais dos emissores, em cada vão entre torres, de modo que fossem aplicadas as lâminas referentes a 25, 50, 75, 100, 125 e 150% da evapotranspiração da cultura, com o manejo da irrigação realizado para atender a demanda de 100%. Foram medidos o índice de área foliar, o potencial hídrico foliar, a temperatura foliar e o índice de clorofila nas folhas. Os valores obtidos foram submetidos a análises de variância e, posteriormente, elaboradas regressões. Diante dos resultados, foi possível concluir que houve tendência de aumento do índice de área foliar (IAF) da cana-de-açúcar à medida que se aumentou a lâmina de irrigação no ciclo da cultura; o aumento do IAF foi mais acentuado nos tratamentos que receberam mais água; o potencial hídrico foliar foi menor para menores lâminas de irrigação, com destaque para o tratamento que recebeu menos água (25%); a temperatura foliar foi próxima à temperatura do ar nos tratamentos que receberam as maiores lâminas (100 a 150%), com tendência de aumento da diferença entre a temperatura das folhas, à medida que se reduziu o suprimento hídrico; houve tendência de aumento do índice de clorofila (ICF) à medida que se aumentou as lâminas, com leve queda nos tratamentos que receberam lâminas maiores que 100% da ETc.

The present study was developed to evaluate relationships between the water depths (rain and irrigation) and morphological (leaf area index) and physiological indicators (leaf temperature, leaf water potential and chlorophyll content in leaves) of water stress on sugarcane subject to different irrigation levels. The experiment was installed in October 2010 in Jaíba/MG, Brazil, in an area irrigated by a center pivot system with sugarcane in the fourth cycle. For the treatments, emitter nozzles were exchanged in each vain between pivots so that the depths applied related to 25, 50, 75, 100, 125 and 150% of evapotranspiration, with the irrigation management performed to meet 100% of the demand. The factors of leaf area index, leaf water potential, leaf temperature and leaf chlorophyll index were measured. The values obtained were subjected to analysis of variance and subsequently developed regressions. From the results, it was concluded that there was a trend of increased leaf area index (LAI) for sugarcane as increasing the water depth in the crop cycle; the increase in LAI was more pronounced in treatments that received more water; leaf water potential was lesser for smaller irrigation depths, with emphasis on the treatment that received less water (25%); leaf temperature was close to the air temperature in the treatment receiving the highest depths (100 and 150%) with a trend for an increased difference between the temperature of the leaves as reducing the water supply; the chlorophyll index (ICF) tended to increase as increasing the depths, with a slight drop in treatments receiving depths greater than 100% of the ETc.

Manejo da irrigação na cafeicultura irrigada por pivô central nas regiões norte do Espírito Santo e extremo sul da Bahia / Irrigation management of coffee crop irrigated by center pivot in the north of Espírito Santo and south of Bahia states

O objetivo desse trabalho foi avaliar as formas de analisar o manejo de irrigação na cafeicultura irrigada por pivô central na região Norte do Espírito Santo e Extremo Sul da Bahia. Em uma primeira etapa, três propriedades foram utilizadas para estudar o manejo de irrigação adotado, analisando-se a lâmina aplicada e o momento da irrigação. Para isso, foram feitas três avaliações consecutivas de manejo em cada uma das propriedades, determinando-se a umidade do solo antes da irrigação e a lâmina aplicada pelo sistema. Em todas as propriedades avaliadas nessa etapa foram detectadas falhas no manejo de irrigação adotado, com atraso nas irrigações e lâminas aplicadas inferiores às lâminas requeridas, proporcionando elevados valores de déficit. Na segunda etapa, fez-se um acompanhamento do manejo de irrigação em outras três propriedades selecionadas, durante o período de um ano, utilizando-se dados meteorológicos de estações locais e o aplicativo Irriplus. Foram detectadas falhas no manejo de irrigação nas três propriedades avaliadas, com déficits hídricos acentuados em importantes fases da cultura.

This study was carried out to analyze the irrigation management in coffee growing irrigated by center-pivots in the South of Bahia and North of the Espírito Santo States. In a first step, three farms were used to study the irrigation management adopted, analyzing the applied depth and the timing of irrigation. It were made three consecutive assessments of management in each of that farms, determining the soil moisture before irrigation and irrigation depth applied by the system. On all farms assessed at this stage were observed failures in the irrigation management, with late in the irrigation and water depths below the required, providing high deficit levels. In the second stage it was made up an irrigation management in three other farms, during the period of one year, with meteorological data from local automatic stations using the software Irriplus. Failures were detected in irrigation management in the three properties examined, with pronounced water deficits at important culture stages.

Composição bromatológica e digestibilidade "in vitro" da matéria seca do capim tanzânia irrigado / Bromatological composition

Objetivou-se estudar o efeito de diferentes turnos de rega e níveis de irrigação sobre a composição bromatológica e a digestibilidade "in vitro' da matéria seca (DIVMS) de Panicum maximum Jacq. cv. Tanzânia-1. Uma bancada experimental foi montada sob ambiente protegido, onde foram colocados recipientes cultivados com a gramínea. As irrigações foram realizadas com turnos de rega de um, quatro e sete dias e lâminas d'água para restabelecer 50, 75 e 100% da disponibilidade total de água no solo. Foram avaliados os teores de proteína bruta (PB), fibra em detergente neutro (FDN), fibra em detergente ácido (FDA) e DIVMS após o último corte. Foi verificado que o teor de PB foi maior quanto menor foi a quantidade de água aplicada. Os valores de DIVMS foram inversamente proporcionais aos teores de FDA. Conclui-se que o turno de rega pouco influencia nos fatores estudados e que a irrigação elevando o teor de água do solo próximo a capacidade de campo, diminui e aumenta os teores de PB e FDA, respectivamente.

The aim of this work was to study the effect of different frequency and levels of irrigation on chemical composition and ?in vitro? dry matter digestibility (IVDMD) of tanz?nia grass (Panicum maximum Jacq. Cv Tanzania-1). The experiment was carried out under greenhouse conditions where drums were filled with soil and cultivated with tanzania grass. The irrigations were performed with a frequency of one, four and seven days, in order to reestablish soil water content to 50, 75 and 100% of the total available water in the soil. During the experiment were evaluated the crude protein (CD), neutral detergent fiber (NDF), acid detergent fiber (ADF) and IVDMD after the last cut. The CD increased as the irrigation depth decreased. The values of IVDMD of were inversely proportional to that of the ADF. The results show that irrigation frequency does not influency in the monitored variables and the irrigation could be.