Composição botânica e controle de plantas daninhas no cultivo da palma forrageira (Opuntia e Nopalea)

Forage cactus (Opuntia and Nopalea) responds positively to cultural treatments such as weeding and weed cutting. However, the scarce labor and the high cost of labor is a challenge that producers, the scientific community and the government have to solve. The objective of this work was to evaluate 9 (nine) commercial herbicides and some mixtures of them in the control of weeds in the culture of forage cactus varieties Miúda (N. cochenillifera) and Orelha de Elefante Mexicana (O. stricta) in the municipality of Caruaru, Pernambuco, Brazil. Two experiments were carried out at the Experimental Station of the Agronomic Institute of Pernambuco (IPA) in Caruaru-PE. The designs used were in randomized blocks with three replications. The treatments evaluated were: 1. No weed control, 2. Hand weeding, 3. Mowing, 4. DMA®806BR (2,4-D), 5. GLYPHOSATE ATAR 48® (glyphosate)+DIURON NORTOX 500 SC ® (diuron), 6. GLYPHOSATE ATAR 48® (glyphosate)+AMERIS® (tebuthiurom), 7. HEXAZINONE-D NORTOX (hexazinone+diuron), 8. VOLCANE® (MSMA), 9. GOAL®BR (oxyfluorfen), 10. TARGA®50 BR (kizalofop-p-ethyl), 11. FUSILADE® 250 EW (fluasifop-p-butyl), 12. AMERIS® (tebutiuron), 13. GLYPHOSATE ATAR 48® (glyphosate)+DIURON NORTOX 500 SC ® (diuron)+AMERIS® (tebuthiuron). The botanical composition of the invasive plants, bare soil, survival, toxicity and productivity of fresh and dry matter of cactus were evaluated in the two years of cultivation. Among the identified species, those with the highest densities were: Ageratum conyzoides, Nicandra physalodes, Scoparia dulcis, Conyza bonariensis, Amaranthus viridis, Acanthospermum hispidum, Alternanthera tenella, Senegalia tenuifolia, Cordia goeldiana, Senegalia tenuifolia, Turnera subulata and Poaceae. The herbicides GLYPHOSATE ATAR 48®+AMERIS®; AMERIS®; and GLYPHOSATE ATAR 48®+DIURON NORTOX 500 SC®+AMERIS® were the most efficient in controlling weeds, due to high percentages of bare soil (75 to 99.67%), low toxicity (<8.33%) and high productivity of fresh (120.69 to 167.05 t.ha-1) and dry (21.75 to 24.40 t.ha-1) matter. Dry and fresh matter productivity was positively correlated with each other, and between bare soil and plant survival. Complementary studies are needed to support the Ministry of Agriculture, Livestock and Supply in the registration of products.A palma forrageira (Opuntia e Nopalea) responde positivamente aos tratos culturais como capina e roço das plantas daninhas. No entanto, a mão de obra escassa e o custo elevado da mão de obra é um desafio que os produtores, comunidade científica e governo tem que solucionar. O objetivo do trabalho foi avaliar 9 (nove) herbicidas comerciais e algumas misturas deles no controle de plantas daninhas na cultura da palma forrageira variedades Miúda (N. cochenillifera) e Orelha de Elefante Mexicana (O. stricta) no município de Caruaru, Pernambuco, Brasil. Foram realizados dois experimentos na Estação Experimental do Instituto Agronômico de Pernambuco (IPA) em Caruaru-PE. Os delineamentos utilizados foram em blocos ao acaso com três repetições. Os tratamentos avaliados foram: 1. Ausência de controle de plantas daninhas, 2. Capina manual, 3. Roçagem, 4. DMA®806BR (2,4-D), 5. GLIFOSATO ATAR 48® (glifosato)+DIURON NORTOX 500 SC® (diurom), 6. GLIFOSATO ATAR 48® (glifosato)+AMERIS® (tebutiurom), 7. HEXAZINONA-D NORTOX (hexazinona+diurom), 8. VOLCANE® (MSMA), 9. GOAL®BR (oxifluorfem), 10. TARGA®50 BR (quizalofope-p-etílico), 11. FUSILADE® 250 EW (fluasifope-p-butílico), 12. AMERIS® (tebutiurom), 13. GLIFOSATO ATAR 48® (glifosato)+DIURON NORTOX 500 SC® (diurom)+AMERIS® (tebutiurom). A composição botânica das plantas invasoras, solo descoberto, sobrevivência, toxicidade e produtividade de matéria fresca e seca da palma foram avaliadas nos dois anos de cultivo. Dentre as espécies identificadas as que tiveram as maiores densidades foram: Ageratum conyzoides, Nicandra physalodes, Scoparia dulcis, Conyza bonariensis, Amaranthus viridis, Acanthospermum hispidum, Alternanthera tenella, Senegalia tenuifolia, Cordia goeldiana, Senegalia tenuifolia, Turnera subulata e Poaceae. Os herbicidas GLIFOSATO ATAR 48®+AMERIS®; AMERIS®; e GLIFOSATO ATAR 48®+DIURON NORTOX 500 SC®+AMERIS® foram os mais eficientes no controle das plantas daninhas, devido a altas percentagens de solo descoberto (75 a 99,67%), baixa toxicidade (<8,33%) e elevada produtividade de matéria fresca (120,69 a 167,05 t.ha-1) e seca (21,75 a 24,40 t.ha-1). A produtividade de matéria seca e fresca foi correlacionada positivamente entre si, e entre o solo descoberto e a sobrevivência das plantas. Estudos complementares são necessários para subsidiar o Ministério da Agricultura, Pecuária e Abastecimento no registro de produtos

Cattle Fecal Decomposition on \u3cem\u3ePennisetum purpureum\u3c/em\u3e Schum. Pastures Managed under Different Post-Grazing Stubble Heights

Pasture management may affect cattle diet. Post-grazing stubble height is a pasture structural characteristic intrinsically linked to forage quantity and quality. Stubble height also indicates forage utilization rate, and as a result, affects nutrient pathway return (excreta or litter) and ultimately, nutrient cycling. Cattle excreta deposition affects soil chemical and physical characteristics (Carran and Theobald 2000). Slow release of nutrients from cattle dung, however, delays nutrient bioavailability for subsequent forage growth (Haynes and Williams 1993). This study evaluated how different post-grazing stubble heights on elephant grass (Pennisetum purpureum Schum.) pastures may affect cattle dung decomposition and nutrient release

Fertilidade do solo em sistemas silvipastoris integrando leguminosas arbóreas com capim-braquiária (Urochloa decumbens Stapf. R. Webster)

Silvopastoral Systems (SPS) can increase overall productivity and generate continuous income in order to stimulate simultaneous growth and development of trees, forage and livestock. Moreover, the SPS with tree legumes would be important for add nutrients to the system, mainly N, and ensure the soil health and quality. Soil properties were assessed in two SPS, implanted in 2011, using tree legumes and Urochloa decumbens Stapf. R. Webster (Signalgrass). Treatments were Signalgrass + Mimosa caesalpiniifolia Benth (Sabia) and Signalgrass + Gliricidia sepium (Jacq.) Kunth ex Walp. (Gliricidia), and they were allocated in a randomized complete block design, with three replications. Soil was sampled in 2013, 2017, and 2018, at 0, 4, and 8 m along transects perpendicular to tree double rows, from 0- to 20- and 20- to 40-cm layers. Soil chemical properties included pH, P, K+, Ca2+, Mg2+, Al3+, H++Al3+, cation exchange capacity (CEC), and base saturation. In addition, light fraction of soil organic matter (LF-SOM), soil basal respiration (SBR), and natural abundance of 13C of the respired CO2 (δ13C-CO2) were analyzed. Soil pH (5.3, 5.2, 5.1), P (11.3, 7.2, 3.6 mg dm-3), and CECeffective (5.8, 5.1, 5.0 cmolc dm-3) decreased (P < 0.05) along the years 2013, 2017, and 2018, respectively. In 2018, the LF-SOM and δ13C-CO2 was greater in Sabia (1.1 g kg-1 and -16.4‰) compared to Gliricidia (0.7 g kg-1 and -18.2‰). Silvopastoral systems reduced soil fertility regardless of the tree legume species used as result of biomass nutrient stock, without maintenance fertilization. Sabia had greater deposition of LF-SOM, without increasing SBR, providing potential for microbial C use efficiency. Enriched C-CO2 isotope composition shows an efficient SOM oxidize in SPS with Gliricidia or Sabia. This information can contribute to the assessments related to CO2 balance and C retention. Both SPS contribute to C sequestration.Los Sistemas Silvopastoriles (SSP) pueden aumentar la productividad general y generar ingresos. Además, SSP con leguminosas arbóreas adicionan nutrientes al sistema, principalmente N, asegurando la salud y calidad del suelo. Propiedades del suelo fueron evaluadas en dos SSP utilizando leguminosas arbóreas en asociación con Urochloa decumbens Stapf. R. Webster (Barrera). Los tratamientos fueron Barrera + Mimosa caesalpiniifolia Benth (Sabiá) y Barrera + Gliricidia sepium (Jacq.) Kunth ex Walp. (Gliricidia), distribuidos en un diseño de bloques aleatorizados (tres repeticiones). Se realizaron colectas de suelo en los años 2013, 2017 y 2018, a 0, 4 y 8 m en transectos perpendiculares a las hileras de árboles, en las profundidades de 0-20 y 20-40 cm. Propiedades químicas del suelo evaluadas incluyeron pH, P, K+, Ca2+, Mg2+, Al3+, H++Al3+, capacidad de intercambio catiónico (CIC) y saturación de bases. Se analizaron la fracción activa de la materia orgánica (FA-MOS), respiración basal (RBS) y abundancia natural de 13C del CO2 respirado (δ13C-CO2). El pH (5.3, 5.2, 5.1), P (11.3, 7.2, 3.6 mg dm-3) y la CICefectiva (5.8, 5.1, 5.0 cmolc dm-3) disminuyeron (P < 0.05) a través de los años 2013, 2017 y 2018, respectivamente. En 2018, la FA-MOS y δ13C-CO2 fue mayor en Sabiá (1,1 g kg-1 y -16,4‰) comparada con Gliricidia (0,7 g kg-1 y -18,2‰). Los SSP redujeron la fertilidad del suelo independientemente de las especies arbóreas utilizadas como resultado de la reserva de nutrientes de la biomasa, sin fertilización de mantenimiento. Sabiá tuvo mayor deposición de FA-MOS, sin aumentar RBS, favoreciendo potencialmente la eficiencia del uso de C microbiano. La composición isotópica de C-CO2 enriquecida muestra una oxidación eficiente de la MOS en SSP con Gliricidia o Sabiá. Esta información puede contribuir a las evaluaciones relacionadas con el balance de CO2 y retención de C. Ambos SSP contribuyen al secuestro de C.Os Sistemas Silvipastoris (SSP) podem aumentar a produtividade e gerar renda. Também, SSP com leguminosas arbóreas adicionam nutrientes ao sistema, principalmente N, garantindo a saúde e qualidade do solo. Propriedades do solo foram avaliadas em dois SSP utilizando leguminosas arbóreas em consorcio com Urochloa decumbens Stapf. R. Webster (capim-braquiaria). Os tratamentos foram capim-braquiária + Mimosa caesalpiniifolia Benth (Sabiá) e capim-braquiária + Gliricidia sepium (Jacq.) Kunth ex Walp. (Gliricídia), sendo distribuídos em delineamento casualizado em blocos (três repetições). Coletas de solo foram realizadas nos anos 2013, 2017 e 2018, a 0, 4 e 8 m ao longo de transectos perpendiculares às fileiras duplas de árvores, nas profundidades de 0-20 e 20-40 cm. As propriedades químicas do solo avaliadas incluíram pH, P, K+, Ca2+, Mg2+, Al3+, H++Al3+, capacidade de troca de cátions (CTC) e saturação por bases. Foram analisadas a fração leve da matéria orgânica (FL-MOS), a respiração basal (RBS) e a abundância natural do 13C do CO2 respirado (δ13C-CO2). O pH (5,3; 5,2; 5,1), P (11,3; 7,2; 3,6 mg dm-3) e CTCefetiva (5,8; 5,1; 5,0 cmolc dm-3) diminuíram (P < 0,05) ao longo dos anos 2013, 2017 e 2018, respectivamente. No 2018, a FL-MOS e δ13C-CO2 foi maior em Sabiá (1,1 g kg-1 e -16,4‰) em comparação com Gliricídia (0,7 g kg-1 e -18,2‰). Os SSP reduziram a fertilidade do solo independentemente das espécies arbóreas utilizadas em decorrência do estoque de nutrientes da biomassa, sem adubação de manutenção. Sabiá teve maior deposição de FL-MOS, sem aumentar a RBS, proporcionando potencial para a eficiência do uso do C microbiano. A composição enriquecida de isótopos de C-CO2 mostra uma eficiente oxidação da MOS em SSP com Gliricídia ou Sabiá. Essas informações podem contribuir para as avaliações relacionadas ao balanço de CO2 e retenção de C. Ambos SSP contribuem para o sequestro de C

Root Decomposition of Elephant Grass Pastures Grazed at Different Management Intensities

Grazing management may alter chemical composition of plant components affecting nutrient cycling. Among pasture management tools, adjustment of stocking rate (SR) and N fertilization have potential to affect nutrient cycling in the grassland ecosystem (Dubeux et al. 2007). Excreta from grazing animal and litter are the two major pathways of nutrient return on grazed pastures (Thomas 1992). Fertilization and SR may alter these pathways by different forms. Increasing fertilization generally increases pasture net primary productivity. Stocking rate affects different pasture and animal responses. Regarding nutrient cycling, increasing SR will likely increase proportion of nutrient returned through excreta as opposed to litter, increasing as a result nutrient losses (Dubeux et al. 2006). Root system may also be affected by management intensity. Frequent defoliation and low plant nutrition level may reduce root biomass (Richards 1993) and affect its decomposition. This study evaluated the effect of different SR´s and N fertilization levels on the decomposition of elephant grass roots

Isolation of Root Endophytic Bacteria in Elephant Grass (\u3cem\u3ePennisetum purpureum\u3c/em\u3e Schum.) Cultivars

Elephant grass (Pennisetum purpureum Schum.) is one of the most productive warm-season grasses. Farmers utilize elephant grass in different forms, such as cut-and-carry operations, grazing, conserved forage (silage, hay), and as an energy source (Lira et al. 2010). Nitrogen (N) is an essential element for plant growth and development and it is usually a limiting factor for forage production in the tropics (Boddey et al. 2004). Biological N fixation (BNF) may occur in warm-season grasses by their association with diazotrophic bacteria. These bacteria colonize different niches in the host plant. Endophytic bacteria form colonies inside the plant tissue whereas epiphytic bacteria colonize plant external surfaces (Compant et al. 2010). Both types of bacteria may benefit host plants (Badri et al. 2009). This study evaluated endophytic diazotrophic bacteria density associated to the roots of different elephant grass cultivars (cvs. ‘Elefante B’, ‘Venezuela’, and ‘Pioneiro’) using two N-free growth media, at different evaluation periods

Decomposition of Cattle Dung on Mixed Grass-Legume Pastures

Animal excreta contribute positively to nutrient cycling and can improve the quality of soil (Dubeux et al. 2009, Carvalho et al. 2010). Cattle excrement, when evenly distributed over a pasture, can help to maintain plant nutrition without the application of fertilizers. The introduction of legumes intercropped with grasses benefits the soil by means of nitrogen fixation. Also, when ruminant animals eat legumes, the excrement produced may have lower C:N, C:P, lignin:N and lignin:P ratios promoting better nutrient return to the soil compared to when cattle eat only grass. Given the importance of nutrient return and decomposition time of cattle excreta on pastures, the objective of this study was to evaluate the decomposition of excrement of heifers managed in mixed grass-shrubby legume pastures and grass-only pastures

Animal Performance in Signalgrass Monoculture or in Silvopastoral Systems

Silvopastoral systems (SPS) can increase overall productivity and long-term income due to the simultaneous production of trees, forage, and livestock. This 2-yr study evaluated animal performance and herbage responses in C4-grass monoculture or in SPS in the sub-humid tropical region of Brazil. The experimental design was randomized complete block with three replications. Treatments were: Urochloa decumbens (Stapf.) R. Webster (Signalgrass) + Mimosa caesalpiniifolia Benth (SPS-Mimosa); Signalgrass + Gliricidia sepium (Jacq.) Kunth ex Walp (SPS-Gliricidia); and Signalgrass monoculture (SM). Response variables included herbage and livestock responses. Cattle were managed under continuous stocking with variable stocking rate. There was interaction between treatment × month for herbage mass. Green herbage accumulation rate ranged from 20 to 80 kg DM ha-1d-1 across months, with SPS-Mimosa presenting lower rates. Average daily gain was greater in SPS-Gliricidia, followed by SM, and SPS-Mimosa, respectively (0.77; 0.56; 0.23 kg d-1), varying across months. Stocking rate ranged from 0.86 to 1.6 AU ha-1. Total gain per area during the experimental period was greater for SPS-Gliricidia (423 kg BW ha-1), followed by signalgrass in monoculture (347 kg BW ha-1), and SPS-Mimosa (50 kg BW ha-1). Silvopasture systems using signalgrass and gliricidia enhanced livestock gains compared with signalgrass in monoculture, and mimosa trees outcompeted signalgrass, reducing livestock gains. Silvopasture systems with tree legumes have potential to provide numerous ecosystem services and reduce C footprint of livestock systems in the tropics, however, the choice of tree species is key and determined by which ecosystem service is prioritized