Crop coefficient (Kc) is the ratio between crop evapotranspiration (ETc) and reference evapotranspiration (ETo), representing the phenological effects on crop water consumption. Kc is fundamental to estimating ETc by agrometeorological methods. This research study aimed to determine Kc and ETc values for Guinea grass (Megathyrsus maximus cv. Mombaça) and Bermuda grass (Cynodon spp.), both single cropped for one year and overseeded with black oat (Avena strigosa) and ryegrass (Lolium multiflorum) during fall/winter. The experiment in the field comprised four plots, two for each tropical forage, with and without overseeding. At the center of each plot, there was a weighing lysimeter with an automated system for data collection. ETc was measured daily over four seasons following the lysimetric method; ETo was calculated using the Penman-Monteith equation. ETc and ETo values were used to estimate Kc values. The single cropped Guinea grass showed the highest values for ETc, with mean ETc and Kc of 3.99 mm d-1 and 1.07, respectively. The single cropped Bermuda grass showed ETc and Kc values of 3.57 mm d-1 and 0.96, respectively. The results of paired t-testing for Kc showed no significant differences (p = 0.05) between single cropped and intercropped for both Guinea grass and Cynodon spp. During winter, intercropped Guinea grass did not show an ETc significantly higher than single cropped Guinea grass, with mean Kc values 0.98 for intercropped and 1.10 for single cropped. Similarly, Bermuda grass did not show significant differences between mean Kc values for intercropped (1.02) and single cropped (1.00).

One of the limitations to producing irrigated forages is setting suitable biometric parameters to establish the entrance of animals to grazing areas. Such parameters can be measured or even estimated. Estimates are advantageous for being practical and able to be used for grazing optimization. This study aimed to evaluate the correlation among growing degree-days (GDD), canopy height (CH), leaf area index (LAI), and number of cycle days (NCD) of Guinea grass (Panicum maximum cv. Mombaça) and Bermuda grass (Cynodon spp. Tifton 85) single cropped for one year and overseeded with black oat and ryegrass in the autumn-winter season. The study was carried out from February 2016 to February 2017, and forage crops were sprinkle irrigated. LAI and CH were measured twice a week, at intervals of 3 and 4 days. These parameters were correlated to GDD accumulation at each cutting cycle (CC). All the correlations showed high coefficients in linear fits. For spring-summer cycles, Guinea grass in exclusive cultivation showed the highest averages for CH and LAI, being 102.3 cm and 5.93, respectively. For autumnwinter cycles, when this grass was overseeded, it showed an LAI value similar to that when single cropped, which was of about 5.6. Yet single Bermuda grass presented lower values of LAI (one unit lower) and CH (16.4 cm lower) in the autumn-winter season when compared to that overseeded. The spring-summer cycles of Guinea grass had a duration of 24 days, after which no increase in leaf production was registered.

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Tropical forage crops present different productive behavior during climatic seasons, because meteorological elements significantly influence the increase or decrease of their forage production and some plant biometric parameters. This work aimed to characterize productive and phytotechnical parameters of palisadegrass under two cultivation systems, single cropped and intercropped (black oats plus ryegrass) during four seasons of one-year period. The experiment was carried out at ESALQ/USP, under a completely randomized statistical design, in two experimental plots with individual area of 144 m². Irrigation was applied by a sprinkler system with a spacing of 12×12 m. The parameters evaluated were: total forage yield, leaf-stem ratio, final leaf area index (LAI final), leaves yield, stems yield, dead material yield, and the mass percentages of leaf, stem and dead material. All over the cycle, the leaf area index (LAI) and canopy height (CH) parameters were measured and correlated with degree-days. The statistical analysis was performed using ASSISTAT 7.7 software. The results showed that the maximum forage yield of single cropped palisadegrass (summer and winter) was 4951.5 and 1318.7 kg DM ha-1. The comparison between the sum of yield in all overseeded cropping cycles (4th IS to 8th IS) and the sum of yield in all the single cropping cycles showed a higher yield in the first ones. The LAI final also presented similar behavior to the crop yield in the single cropped system all over the year. The estimates for CH and LAI from daily air temperature data (degree-days) improve the management of irrigated pastures.

Knowing the soil moisture available to plants is important for adequate management of water use in agricultural farms, with automated methods being the most accurate. However, acquisition costs are high and most of the commercially available irrigation controllers still work using pre-set times. This study aimed to develop and calibrate a low-cost automated tensiometer with high efficiency in irrigation control, based on real-time monitoring. The research was conducted at the Laboratories of Hydraulics and of Water Soil Plant and Atmosphere Relationship, which belong to the Federal University of Grande Dourados (UFGD), in Dourados, MS, Brazil, with soil classified as an Oxisol. Pressure transducers and a microcontroller were used to assimilate the pressure inside tensiometers and transform it into readings of soil water matric potential (Ψm). Thus, the calibration was carried out by comparing the different readings of the transducer and digital tension meter. Different tensions were applied to obtain a soil moisture curve, starting from the most humid point (saturated) to the driest one (oven-dried soil), collecting 20 valid points. Subsequently, the data were subjected to the normality test, with subsequent statistical analysis and regression curve models. Linear adjustments with a high coefficient of determination (R2 = 0.99) were observed, with the automated system built in this study being capable of monitoring soil water tension in real-time.

Soil moisture determination is essential for a good use of available water resources. In this regard, the use of frequency domain reflectometry (FDR) probes has as advantages mobility and practicality in relation to lysimeters. The experiment was carried out between April and June 2016 at the Luiz de Queiroz College of Agriculture (ESALQ/USP), located in Piracicaba, SP at the geographical coordinates 22°42?14.6? S and 47°37?24.1? W and altitude of 546 m. This study aimed to assess these FDR probes to estimate water consumption in comparison to measurements by weighing lysimeters (ETcLys) and reference evapotranspiration (ETo) in Mombaça and Bermuda grass pastures under single cultivation and overseeded with oat and ryegrass. Soil moisture was assessed daily by FDR probes by estimating crop evapotranspiration (ETcFDR probe) from soil water balance calculation, which was correlated with ETcLys and ETo (Penman-Monteith, FAO 56). For all treatments, FDR probes presented the highest water consumptions when compared to the other two evapotranspiration methods, with accumulations of 126.5 and 125.6 mm for single and overseeded Mombaça grass, respectively. For Bermuda grass, water consumption was 123.4 mm in the single cultivation and 128.5 mm when overseeded. The method of estimating evapotranspiration by FDR probes showed good correlations with ETo and ETcLys.

ÁGUAS RESIDUÁRIAS PARA IRRIGAÇÃO NO BRASIL: UMA ABORDAGEM QUÍMICA, FÍSICA E MICROBIOLÓGICA     FERNANDA LAMEDE FERREIRA DE JESUS1; OTÁVIO NETO ALMEIDA SANTOS2; MARCUS VINICIUS TALAMINI JUNIOR3; TAMARA MARIA GOMES4; FABRÍCIO ROSSI5 E RODRIGO MÁXIMO SÁNCHEZ ROMÁN6   1 Departamento de Engenharia Agrícola, Universidade Federal Rural da Amazônia, Rod. PA 140, CEP. 68680-000 Tomé-Açu, Pará, Brasil, fernanda.lamede@ufra.edu.br 2 Departamento de Engenharia de Biossistemas, Escola Superior de Agricultura “Luiz de Queiroz”, Universidade de São Paulo, Av. Pádua Dias, 235, CEP 13418-900, Piracicaba, São Paulo, Brasil, otaneto@alumni.usp.br 3 Department of Agriculture and Life Sciences, Lincoln University, 85084 Ellesmere Junction Road, Lincoln, POBOX 7647, Canterbury, New Zealand, marcus.talaminijunior@lincolnuni.ac.nz 4 Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo, R. Duque de Caxias, 225 - Jardim Elite, CEP. 13635-900, Pirassununga, São Paulo, Brasil, tamaragomes@usp.br 5 Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de São Paulo, R. Duque de Caxias, 225 - Jardim Elite, CEP. 13635-900, Pirassununga, São Paulo, Brasil, fabrício.rossi@usp.br 6 Departamento de Engenharia Rural e Socioeconomia, Faculdade de Ciências Agronômicas, Universidade Estadual Paulista “Júlio de Mesquita Filho”, Av. Universitária, nº 3780 - Altos do Paraíso, CEP. 18610-034, Botucatu, São Paulo, Brasil, msanchezr@gmail.com     1 RESUMO   Os principais atributos a serem avaliados na qualidade da água residuária para irrigação contemplam os parâmetros físicos, químicos e biológicos, que definem o potencial para uso. As águas residuárias podem conter contaminantes, os quais podem ocasionar efeitos adversos no solo, nas plantas e nas águas subterrâneas se estiverem presentes em concentrações elevadas. O objetivo deste trabalho foi discutir as principais características que influenciam na qualidade da água residuária destinada à irrigação por meio de levantamento de informações disponíveis na literatura específica. O uso de efluentes para fins de irrigação requer uma abordagem mais cautelosa e o estudo sobre o mesmo ainda é incipiente. Os resultados obtidos nas pesquisas revelam que diversas culturas podem ser irrigadas com águas residuárias, quando devidamente tratadas. Este fato, ratifica a importância de se adotar uma política de reuso ainda mais específica no que diz respeito à utilização de águas residuárias em diversas atividades agrícolas, principalmente pela irrigação. Todavia, ainda existem diversos problemas relacionados a essa prática, sendo necessários mais estudos que contribuam para desenvolvimento da agricultura, visando à conservação dos recursos naturais, produção das culturas e segurança a saúde.   Palavras chave: Recurso hídrico, efluente, agricultura, contaminação, reuso.     JESUS, F. L. F.; SANTOS, O. N. A.; TALAMINI JUNIOR, M. V; GOMES, T. M.; ROSSI, F.; SÁNCHEZ-ROMÁN, R. M. WASTEWATER FOR IRRIGATION IN BRAZIL: A CHEMICAL, PHYSICAL AND MICROBIOLOGICAL APPROACH     2 ABSTRACT   The main attributes to be evaluated in irrigation water quality include  physical, chemical and biological parameters that define the potential for use. Wastewater may contain contaminants, which may cause adverse effects on the soil, plants and groundwater if they are present at high concentrations. The objective of this work was to discuss the main characteristics that influence the quality of the wastewater destined to  irrigation by means of information gathering available in the specific literature. The use of effluents for irrigation requires a more cautious approach and its study of is still incipient. The results obtained in the surveys reveal that several crops can be irrigated with wastewater when properly treated. This fact confirms the importance of adopting an even more specific reuse policy regarding the use of wastewater in various agricultural activities, mainly through irrigation. However, there are still several problems related to this practice, and further studies are needed that contribute to the development of agriculture, aiming at the conservation of natural resources, crop production and health security.   Keywords: Water resource, effluent, agriculture, contamination, reuse.

The use of swine wastewater (SW) for irrigation can be an excellent alternative to increase productivity and quality of pastures. This work was carried out from October 2013 to September 2014 in Dourados -MS. The objectives were evaluation of the productivity and nutritional quality of Tifton 85 grass (Cynodon spp.) under different doses of SW in the presence and absence of normal water irrigation. The experiment was set in a randomized block with split plots design, including water irrigated and non-irrigated in the main plots and four doses of SW in the subplots (75, 150, 225 and 300 m 3 ha -1 cut -1 ), with four replicates. The total forage yield and the bromatological value (crude protein, neutral and fibre detergent acid and dry matter digestibility) were evaluated. There was a significant effect of irrigation and SW doses on total dry matter yield, reaching 41.4 Mg ha -1 year -1 using the highest dose of SW (300 m 3 ha -1) and irrigation use. Irrigation also provided higher crude protein levels, increasing with linear adjustment to SW doses, reaching 17.9% in the annual average. The neutral detergent fibre and the acid detergent fibre presented lower results under irrigation, reaching 65.4 and 32.6% in the annual average, respectively, and linearly decreased using SW doses. Inverse behavior was observed in the in vitro digestibility of dry matter, which was higher under irrigation, reaching 69.5% in the annual average and presenting linear growth according to doses of SW.