WATER USE IN IRRIGATED AGRICULTURE: AN APPROACH TO WATER PRODUCTIVITY IN DRIP AND SPRINKLER SYSTEMS

Irrigation plays an important role in agriculture and the increase in the irrigated area and scarce water resources have encouraged the use of irrigation systems and management systems that increase the efficiency of water use. Thus, maximize water productivity has been one of the most important challenges in agriculture. The present study aimed to relate information on water productivity for two irrigation systems, drip and sprinkler systems, with the purpose of understanding the characteristics of these systems and contributing to the advancement of studies and research carried out in the area. Technological innovations aimed at reducing consumption and increasing water productivity through improved water management practices have had limited impact and still need to be adopted on a large scale. It should be emphasized that future research and studies should focus on strengthening the relationships between yield and water consumption to improve productivity. In addition, the techniques and technologies to be deployed in the field must be preceded by a cost analysis for each specific situation in order to verify the economic viability of its adoption

Crop coefficient estimated by degree-days for ‘Marandu’ palisadegrass and mixed forage

Considering profitability in pasture-based systems, investigating parameters affecting crop coefficients for irrigation management becomes important. In this experiment, we determined the crop coefficient of ‘Marandu’ palisadegrass based on accumulated degree-days and estimated plant water consumption under single (‘Marandu’ alisadegrass) and mixed (‘Marandu’ palisadegrass + black oats + Italian ryegrass) cropping regimes. The research was conducted at the Luiz de Queiroz College of Agriculture in Piracicaba, São Paulo, Brazil, between 2016 and 2017. Evapotranspiration was assessed using weighing lysimeters while crop evapotranspiration was calculated using mean weight variation. Reference evapotranspiration and degree-days were estimated. Data were obtained from an automated weather station. Equations and regression models relating crop coefficient with accumulated degree-days were generated for two seasons (spring/summer and autumn/winter) and evaluated for two year-cycles, from 2015 to 2018. The results showed better prediction accuracy for the single cropping system in spring/summer 2017–18. Highlights The model for determinating crop coefficient (Kc) by accumulated degree-days showed efficient for use in determination local. The use of the degree days for determination Kc is more vantage because only necessary to measure the air temperature (maximum and minimum). The equations for determining crop coefficient by accumulated degree days for the spring/summer season in Marandu palisade grass cultive show more precision that in mixture forage system.Considering profitability in pasture-based systems, investigating parameters affecting crop coefficients for irrigation management becomes important. In this experiment, we determined the crop coefficient of ‘Marandu’ palisadegrass based on accumulated degree-days and estimated plant water consumption under single (‘Marandu’ alisadegrass) and mixed (‘Marandu’ palisadegrass + black oats + Italian ryegrass) cropping regimes. The research was conducted at the Luiz de Queiroz College of Agriculture in Piracicaba, São Paulo, Brazil, between 2016 and 2017. Evapotranspiration was assessed using weighing lysimeters while crop evapotranspiration was calculated using mean weight variation. Reference evapotranspiration and degree-days were estimated. Data were obtained from an automated weather station. Equations and regression models relating crop coefficient with accumulated degree-days were generated for two seasons (spring/summer and autumn/winter) and evaluated for two year-cycles, from 2015 to 2018. The results showed better prediction accuracy for the single cropping system in spring/summer 2017–18. Highlights The model for determinating crop coefficient (Kc) by accumulated degree-days showed efficient for use in determination local. The use of the degree days for determination Kc is more vantage because only necessary to measure the air temperature (maximum and minimum). The equations for determining crop coefficient by accumulated degree days for the spring/summer season in Marandu palisade grass cultive show more precision that in mixture forage system

Yield parameters and water productivity of tropical and overseeded winter forages

Intensive pasture exploitation with tropical forages is one of the most efficient forms ruminant production. However, the results depends on the knowledge about these forages and the experience in its management. The objective of this work was to evaluate water productivity (WP) and yield parameters of Megathyrsus maximum cv. Mombaça “Guinea grass” and Cynodon spp. “Bermuda grass”, in single culture and overseeded with oats + ryegrass in autumn/winter period. Irrigation management was done considering a depletion factor of 0.3 (70% of the humidity the field capacity). The experimental design was a randomized complete block design with four replications, in which the forages are the treatments with evaluation at the time of the cycles. For all evaluated parameters, the best results were obtained with the Guinea grass in exclusive cultivation. The TFP (Total Forage Productivity) of Guinea grass was superior to Bermuda grass (59.3 and 30.2 Mg ha-1, respectively), in accordance with its average LAI (Leaf area index) values of 4.8 and 2.5, respectively. The most efficient use of water occurred for Guinea grass in exclusive cultivation, and the intercropped crops did not present increases in the WP. In the autumn/winter period, the accumulated TFP of the exclusive crop of Guinea grass was higher than the other crops. However, the SDM of Bermuda grass was higher than the other crops. In winter, the highest LAI occurred in Guinea grass in exclusive cultivation, followed by the overseeded Guinea grass, 4.8 and 4.5, respectively. Consortia did not increase forage yield during the winter. The consortiums did not increase forage yield during the winter

Performance and influence of Tifton 85 (Cynodon sp.) and vetiver (Chrysopogon zizanioides) grasses in the treatment of sanitary sewage in constructed wetlands

No presente trabalho, procurou-se avaliar o desempenho de uma espécie de raízes fasciculadas (capim-vetiver) e outra estolonífera (capim-tifton 85), quando cultivadas em sistemas alagados construídos de escoamento horizontal subsuperficial (SAC- EHSS), no tratamento do efluente primário de esgoto sanitário. Para avaliação da influência da presença e do sistema radicular das plantas, foram utilizados três leitos, um plantado com capim-tifton 85 (SAC-EHSST), outro com capim-vetiver (SAC- EHSSV), com 12,5 propágulos por m², sendo o terceiro mantido sem plantas. Os SACs-EHSS foram construídos em paralelo, com fundo concretado e laterais em alvenaria, cobertos com lona de 2 mm de espessura. Como substrato, foi utilizada a brita gnáissica # 0, de diâmetro D60 igual a 7,0 mm, Coeficiente de Uniformidade (D60 /D10) de 1,6 e volume de vazios de 48,4 %, preenchido até a altura de 0,25 m. Cada SACs-EHSS, de área superficial de 4 m² e volume molhado (volume do substrato de preenchimento dos SACs-EHSS em contato com o esgoto sanitário em tratamento) de 1 m³, foi alimentado com vazão na faixa de 0,53 a 0,80 m³ d^-1, correspondente à de uma taxa de carregamento orgânico (TCO) de, aproximadamente, 350 kg ha^-1 d^-1 de DBO. Essa vazão proporcionou um tempo de detenção hidráulica (TDH) teórico entre 0,6 e 0,9 dias. Para avaliar o desempenho dos sistemas, foram efetuadas dez amostragens da água residuária afluente e efluente de cada SAC, no decorrer do período experimental, medindo-se a condutividade elétrica (CE), turbidez e o pH e quantificando-se as concentrações de DBO, DQO, SST, N-total, P-total, K e Na. Os valores foram corrigidos considerando-se as perdas de água por evaporação/evapotranspiração nos SACs-EHSS. Para a quantificação da produtividade de matéria seca e dos teores de N-total, P-total, K e Na no tecido vegetal, foram efetuados seis cortes da biomassa aérea das espécies vegetais cultivadas nos SACs-EHSS. No final do período de monitoramento, foram feitas escavações no meio suporte, para medição da profundidade atingida pelas raízes das plantas no substrato de preenchimento dos SACs-EHSS, além de serem quantificadas a massa e o volume ocupado pelas raízes das plantas, bem como seus teores de N-total, P-total, K e Na. De modo geral, as espécies avaliadas se adaptaram bem ao cultivo em SACs-EHSS utilizados no tratamento de esgoto sanitário, considerando- se a TCO aplicada. No substrato, foi observado maior volume, massa e profundidade das raízes do capim-vetiver, dando indícios de sua melhor adaptação e adequação a esse SAC-EHSS, comparativamente ao cultivado com o capim-tifton 85. O capim-tifton 85 mostrou-se capaz de remover mais Na em sua biomassa aérea que o capim-vetiver (p > 0,05), no entanto, em função de sua maior produtividade, houve tendência de maior remoção de N, P e K pelo capim-vetiver. A estação climática da primavera proporcionou maior remoção de nutrientes/poluentes pelas espécies vegetais avaliadas. Os SACs-EHSS cultivados e o não cultivado se mostraram eficientes na remoção da turbidez, SST, DBO, DQO e N-total o, apresentando, no entanto, relativamente baixas remoções de P, K e Na do esgoto sanitário. A unidade não cultivada apresentou desempenho semelhante (p 0.05), however, due to its higher productivity, a trend towards greater removal of N, P and K by vetiver grass. The spring weather station provided greater removal of nutrients/pollutants by plant species evaluated. Cultivated CW-HSSF and uncultivated were efficient in the removal of turbidity, TSS, BOD, COD, Total-N, presenting, however, relatively low removal of P, K and Na of the sanitary sewage. The unit uncultivated showed similar performance (p < 0,05) to the CWs-HSSF planted as regards the removal of COD, total-N, and K, but was less efficient than CW-HSSFV retention TSS, BOD and turbidity. The results obtained in this study indicated that the vetiver grass, representative group of fasciculated plant species system performed that have better performance in removing sewage polluting the Tifton 85, representative of stoloniferous species. Perhaps the greatest volume and range, in terms of depth, of fasciculate roots is that explain the largest removals observed by CW-HSSFV.Fundação de Amparo à Pesquisa do Estado de Minas Gerai

WATER USE IN IRRIGATED AGRICULTURE: AN APPROACH TO WATER PRODUCTIVITY IN DRIP AND SPRINKLER SYSTEMS

Irrigation plays an important role in agriculture and the increase in the irrigated area and scarce water resources have encouraged the use of irrigation systems and management systems that increase the efficiency of water use. Thus, maximize water productivity has been one of the most important challenges in agriculture. The present study aimed to relate information on water productivity for two irrigation systems, drip and sprinkler systems, with the purpose of understanding the characteristics of these systems and contributing to the advancement of studies and research carried out in the area. Technological innovations aimed at reducing consumption and increasing water productivity through improved water management practices have had limited impact and still need to be adopted on a large scale. It should be emphasized that future research and studies should focus on strengthening the relationships between yield and water consumption to improve productivity. In addition, the techniques and technologies to be deployed in the field must be preceded by a cost analysis for each specific situation in order to verify the economic viability of its adoption

Crop coefficients of tropical forage crops, single cropped and overseeded with black oat and ryegrass

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)

Consumo de água em forrageiras tropicais e de inverno obtido por sonda FDR e lisímetros de pesagem

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.A determinação da umidade do solo é preponderante para o bom uso dos recursos hídricos disponíveis. Neste aspecto, as sondas de Reflectometria no Domínio da Frequência (FDR) tem a vantagem da mobilidade e praticidade em relação aos lisímetros. O experimento foi conduzido entre abril e junho de 2016 na Escola Superior de Agricultura “Luiz de Queiroz” (ESALQ/USP), localizada em Piracicaba, SP nas coordenadas geográficas 22°42?14.6? S e 47°37?24.1? O e altitude de 546 m. O objetivo desse trabalho foi avaliar o uso de sonda FDR para estimativa do consumo de água em relação a medidas obtidas através de lisímetros de pesagem (ETcLis) e da evapotranspiração de referência (ETo) em pastagens de capim Mombaça e Cynodon em cultivos exclusivos e sobressemeados com aveia e azevém. A umidade de solo foi diariamente avaliada pela sonda FDR estimando a evapotranspiração de cultura (ETcsonda FDR), a partir do cálculo de balanço hídrico no solo, que foi correlacionada com a ETcLis e a ETo (Penman-Monteith - FAO 56). A sonda FDR apresentou para todos os tratamentos os maiores consumos em relação aos outros dois métodos de evapotranspiração, com acúmulos durante o ciclo de 126,5 mm e 125,6 mm, no Mombaça exclusivo e sobressemeado, respectivamente. No Cynodon spp., o consumo foi de 123,4 mm no cultivo exclusivo e 128,5 mm no sobressemeado. O método de estimativa de evapotranspiração pela sonda FDR apresentou boas correlações com a ETo e ETcLis

Seasonality of biomass production of irrigated Mombaça ‘Guinea grass’

Seasonality in tropical forage production is common in tropical and subtropical regions and should be identified for decision making on the stocking rate for each period. This study aimed to evaluate the variability of dry matter production of Megathyrsus maximum cv. Mombaça ‘Guinea grass’ over two years. The experiment was carried out from February 2016 to August 2018, under a randomised block design in a 2 × 4 factorial scheme, with four replications. Treatments consisted of (i) two growing years (2016/2017 and 2017/2018) and (ii) four seasons (spring, summer, fall, and winter). The grass was fertilised with 1,000 kg N ha−1 year−1 and sprinkler irrigated, with soil moisture monitored by tensiometry. The evaluated parameters consisted of leaf dry matter, stem dry matter and total dry matter production. The results showed that the irrigated Guinea grass reached an elevated production of dry matter (DM), with the highest yields occurring in the spring/summer period, evidencing the yiel gap in the autumn/winter. The grass showed high daily forage accumulation, expressing high productive potential, demonstrating a good indicator for animal production in intensive systems with irrigated and fertilised pastures for regions of tropical climate. Thus, Guinea grass showed great potential for use in livestock