DM Ha-1 Research Articles

<b>Productivity of Tifton 85 grass irrigated and overseeded with winter forages

Intercropping with cool season species has been used as an alternative to increase productivity off-season (fall/winter) of irrigated pastures. This study was conducted from May to October 2009 in Icaraima, Parana State, to evaluate the productivity and morphological composition of the Tifton 85 grass overseeded with winter forage in irrigated system. The experiment was a randomized block design with four replicates and repeated measures over time. The experimental plots consisted of five treatments, three as oats overseeding using the genotypes IAPAR 61, IPR 126, and FMS2 on Tifton 85 pasture and one as overseeding of oats combined with rye (IPR 126 + IPR 89) also on Tifton 85 grass and, finally, a control with only Tifton 85 without overseeding. The overseeding of IPR 126 oats achieved the highest cumulative productivity, 4102 kg DM ha-1, with leaf/stem ratio higher than that of exclusive Tifton 85 exclusive, 1.77 and 1.08, respectively. However, overseeding of winter forages did not increase the overall productivity of the pasture.

Long-term response of forest plantation productivity and soils to a single application of municipal biosolids

Ouimet, R., Pion, A.-P. and Hebert, M. 2015. Long-term response of forest plantation productivity and soils to a single application of municipal biosolids. Can. J. Soil Sci. 95: 187-199. After 16 to 19 yr, we revisited four experimental trials set up in the early 1990s to evaluate the long-term impact of municipal biosolids applied in forest plantations. Tree growth and the soil were sampled to determine the effects of a single application of biosolids applied at (liquid equivalent) rates of 0, 130, 200, and 400 m3 ha-1. Tree radial growth responded markedly to biosolids in the young plantations, increasing from 18 % for Pinus resinosa to 62 % for Picea glauca, and up to 700 % for Quercus sp. Increases in phosphorus (P) concentrations in the tree foliage in response to biosolids could still be detected in the conifer trials. In the top 0-5 cm soil layer, organic carbon (C), total nitrogen (N), P, and copper (Cu) concentrations and pools increased, while soil compaction and bulk density decreased. In the deepest soil layer sampled (20-40 cm depth), the total N and calcium (Ca) pools were reduced by the biosolids treatments, while the pool of exchangeable acidity increased. Our observations indicate that a single application of liquid biosolids up to 400 m3 ha-1 (30 t ha-1 DM) in young forest plantations is a sustainable practice without undue risk to such podzolic soils.

Características agronômicas, estruturais e bromatológicas do capim Piatã em lotação intermitente com período de descanso variável em função da altura do pasto

<p>Objetivo-se avaliar a influência das diferentes alturas de pastejo sobre as características agronômicas, estruturais e bromatológicas da Brachiaria brizantha cv. Piatã manejada sob lotação intermitente. Avaliou-se três alturas do dossel forrageiro (30, 45 e 60 cm) ao longo de duas estações de crescimento (Meio e Final da estação). Adotou-se o delineamento em blocos ao acaso, com parcelas subdivididas, onde as parcelas foram alocadas as alturas e nas subparcelas as estações de crescimento. Os valores de altura atenderam o protocolo experimental apresentando médias de 35,2; 43,5 e 59,4, respectivamente para 30, 45 e 60cm de altura. O período de descanso foi variável no decorrer das alturas e proporcionou diferentes ciclos de pastejo, com PD médio de 34, 39 e 54 dias, respectivamente, para as alturas estudadas. A maior produtividade de MST obtida por ciclo foi na altura de 60cm, com média de 4612,51 kg ha-1 e, 3566 kg ha-1 para altura de 30 cm. No entanto nas alturas de 30 e 45 cm foram obtidos três ciclos de pastejo e somente dois para a altura de 60 cm, totalizando com isso, 12,4, 10,7 e 9,2 t MS ha-1 no período. Na relação folha/colmo não houve diferença nas alturas estudadas. O número de perfilho não sofreu alteração com as diferentes alturas, sendo observada a superioridade do número de perfilhos no meio da estação de crescimento. O aumento na altura do pasto não proporcionou alteração no teor de PB e na digestibilidade e aumento nos teores de FDA, apenas foi alterado FDN na altura de 60 cm.</p>

Frequency and intensity of grazing in winter: their effects on herbage accumulation and nutritive value of Lolium perenne L. dominant swards

A study was conducted in southern Chile with the objective of determining the effect of two frequencies and two intensities of grazing, measured as herbage mass, on production and nutritive value of a permanent sward dominated by Lolium perenne L. during winter season. Additionally the residual effect of the treatments applied in winter was evaluated on the same variables in the following spring. Two pre-grazing herbage mass (kg DM ha-1): low frequency (1,800), high frequency (1,500) and two post-grazing herbage mass: low intensity (1,300), high intensity (1,000), were evaluated. Plots of 145.7 m2 were grazed by dairy cows. The same plots were grazed in the subsequent spring to a frequency of 2,400 kg DM ha-1 and intensity of 1,400 kg DM ha-1. There was no significant effect of the frequency of grazing on herbage mass and growth rate during the first winter. However, in the second winter a greater production with low frequency was obtained. In the two winter seasons, a significant effect of the intensity was obtained, with greater production in high intensity. The most frequently grazed treatments showed higher crude protein and lower soluble carbohydrates. Also, there was a residual effect in the spring generated by frequency and intensity of grazing in the first year, and only for the intensity the second year. It can be concluded that frequency and intensity of grazing applied in winter generate changes in herbage mass production and nutritive value of the sward and also a residual effect in the following spring.

Temporal evolution of litterfall and potential bio-element return in a successional forest sequence of the Espinal Ecoregion, Argentina

Aim of study: The aim of this work was to assess the litterfall contribution and the return of bioelements of a successional forest sequence from the Mesopotamian Espinal (Argentina) which was associated with livestock production.Area of study: Mesopotamian Espinal, Argentina.Material and methods: Litterfall samples were taken and a chemical characterization of their fractions was determined in three stages: a) in the initial successional stage (IF); b) in an intermediate secondary forest (SF); and c) in a mature forest (MF).Main results: The litterfall contribution of the three forests was 1140 ±98, 2947 ±154, and 2911 ±57 kg DM ha-1 yr-1; respectively. The IF showed a seasonal pattern of contribution with a peak occurring during summer (528 ±85 kg DM ha-1 yr-1), then decreasing during autumn, winter, and spring (241 ±30, 165 ±27, and 207 ±29 kg DM ha-1 season-1,respectively). The SF showed a rather constant seasonal pattern (about 750 kg DM season-1). The MF showed significant differences among seasons, the maximum and minimum contributions ranging between 846 ±29 and 598 ±33 kg DM ha-1 season-1 in summer and spring, respectively. The litterfall leaves/branch ratio decreased as ecological succession advanced, being lower as the forest gets more mature. As a consequence, this ratio can be used as an indicator of maturity in the sequence. The potential return of bio-elements of the successional forest sequence was proportional to the litterfall input, with a maximum amount of N in the Fabaceae species. Research highlights: The litterfall assessment and the leaves/branch ratio allowed the characterization of the successional stages in Xerophytic forest used for livestock production. Keywords: Semi-xerophytic trees; tree production pattern; plant organ contribution; leaf/branch ratio; return of bio-elements; tree nutrients.

Swine manure application methods effects on ammonia volatilization, forage quality, and yield in the Pre-Amazon Region of Brazil

The use of swine manure (SM) as a nutrient source for pastures is increasingly common in Brazil, due to its low cost. However, this practice can cause N losses in agricultural soil, where ammonia (NH3) volatilization may be the main drawback, generating undesirable economic and environmental consequences. The objective of this study was to evaluate SM application methods that retain N within the system and determine how these methods affect forage yield and quality. The study was conducted in the municipality of Chapadinha, Maranhao, Brazil, and the following SM application methods were evaluated: (1) surface application, (2) incorporation at 5-cm soil depth, (3) incorporation at 10-cm soil depth, and (4) control when SM was not applied. Lower N losses due to NH3 volatilization and higher pasture yield and quality were found when SM was incorporated at 10-cm soil depth (83 kg N-NH3 ha-1 and 6.3 Mg DM ha-1, respectively, compared to 86 kg N-NH3 ha-1 and 1.5 Mg DM ha-1 for the control), whereas higher N-NH3 losses and lower pasture yield were observed when SM was applied to the soil surface (143 kg N-NH3 ha-1 and 2.6 Mg ha-1, respectively). Higher quality forage in terms of chemical composition was also observed when SM was incorporated at greater soil depth. Incorporating SM at 10-cm depth represents an efficient management to mitigate N-NH3 volatilization, and this application method is associated with significantly increased in DM yield and improved chemical composition.

Fatty acid intake and rumen fatty acid composition is affected by pre-grazing herbage mass and daily herbage allowance in Holstein dairy cows

The objective of this study was to investigate the effect of level of pre-grazing herbage mass (HM) and daily herbage allowance (DHA) on the fatty acid (FA) intake and composition of ruminal content of grazing dairy cows. Four rumen fistulated Holstein-Friesian dairy cows were allocated to either a high or low HM (1700 vs 2600 kg DM ha-1) and within herbage mass treatment further allocated to a high or low DHA (20 vs 16 kg of DM cow-1 day-1) in a 4 × 4 Latin square design. Total FA intake and linolenic acid (LNA) intake was higher for cows on high DHA (p<0.05). Ruminal oleic acid, linoleic and LNA were not affected by treatments. Ruminal stearic acid (C18:0) and vaccenic acid (VA) concentrations were higher at low HM (43.6 and 14.8 g/100 gof FA respectively; p<0.01) compared to high HM (42.0 and 12.5 g/100 gof FA respectively for C18:0 and VA). Cows grazing high DHA had higher ruminal concentration of VA (15.3 g/100 gof FA; p<0.01) than low DHA (12.1 g/100 gof FA). Regarding milk FA composition, only some of the milk FA varied across treatments, being the VA and LNA concentrations higher at low HM (p<0.05). These data suggest that low HM and high DHA, at least within the range studied here, promotes the accumulation of ruminal VA which could be available for subsequent conversion within the mammary gland to the human health promoting c9,t11 isomer of conjugated linoleic acid.

Aveia preta e azevém anual colhidos por interceptação de luz ou intervalo fixo de tempo em sistemas integrados de agricultura e pecuária no Estado de São Paulo

Objetivou-se caracterizar o potencial produtivo, a distribuição mensal, a composição morfológica e botânica da forragem de aveia preta e de azevém anual submetidos a estratégias de manejo de corte no estado de São Paulo. O delineamento experimental foi inteiramente casualizado, com tratamentos correspondendo a combinações entre formas de cultivo (aveia e azevém exclusivos ou combinados) e estratégias de colheita (cortes com 95% de interceptação de luz (IL) ou intervalo FIXO de 30 dias de rebrotação), em arranjo fatorial com três repetições. Os estandes colhidos por IL acumularam 1580kg MS ha-1 corte-1, e os por FIXO 2020kg de MS ha-1 corte-1. A proporção de folhas foi maior no azevém (70%), seguido do cultivo combinado (64%) e depois pela aveia (52%). Entre os manejos, a IL resultou em maiores proporções de folha e menor proporção de colmos que o FIXO. A proporção de azevém foi de 64%, sob o manejo por IL, e 70% no manejo por descanso FIXO. Ao longo do tempo, ocorreu a substituição da aveia pelo azevém na composição do dossel combinado. Ambas as estratégias de manejo podem ser adotadas para essas forrageiras de inverno em sistemas de integração agricultura e pecuária, com vantagem para o azevém.

Características agronômicas e eficiência do uso da chuva em cultivares de sorgo no semiárido

Objetivou-se quantificar o rendimento forrageiro, o percentual de componentes da planta, as características morfométricas e a eficiência do uso da chuva de cinco genótipos de sorgo para silagem no semiárido paraibano. O experimento foi conduzido na Estação Experimental Pendência, no município de Soledade-PB. O delineamento experimental utilizado foi em blocos casualizados, com quatro repetições, sendo os tratamentos experimentais representados por cinco genótipos de sorgo: Ponta Negra, SF 15 IPA 1011, IPA 2502 e IPA 46742. Não foram observadas diferenças entre os genótipos para a produção de matéria natural e produção de matéria seca e para o percentual de lâmina foliar. Entretanto, para o percentual de colmo foram observados maiores valores (P<0,05) para os genótipos Ponta Negra e IPA 46742. O percentual de panícula foi superior (P<0,05) para as cultivares 'IPA 1011' e 'IPA 2502'. As cultivares 'IPA 1011' e 'IPA 2502' apresentaram percentual de panícula acima de 38% da MS. Não houve diferença (P<0,05) para eficiência no uso da água de chuva entre os genótipos estudados, com valores variando de 94,37 a 126,25kg de MS ha-1 mm-1. Os genótipos avaliados apresentam elevada eficiência no uso da chuva e produtividade. Recomenda-se o IPA 1011 pela maior participação de panícula.

Efecto sobre la producción de carne de la aplicación de tecnologías de renovación de praderas de Bothriochloa pertusa (L.) A. Camus en la Costa Norte Colombiana

Uno de los factores que limitan de manera importante la competitividad y sostenibilidad del sector ganadero de la región Caribe es la degradación de suelos y praderas. El objetivo del estudio fue evaluar en fincas del departamento del Atlántico y dedicadas a la de producción de carne, el efecto de las tecnologías de renovación de praderas como la intervención mecánica con labranza vertical, establecimiento de una nueva gramínea, aplicación de un plan de fertilización y pastoreo rotacional, sobre la producción de carne. Se seleccionaron tres fincas en las cuales se estableció una línea base en el año 2007 y posteriormente en los años 2008 y 2009 se evaluó el efecto de la renovación sobre la producción de forraje y carne. Se determinó la disponibilidad de forraje tanto en la pradera renovada como en la pradera sin renovación y cada mes se registró el peso de los animales. Los datos se analizaron empleando un diseño de bloques completos al azar con arreglo factorial. Los resultados mostraron un efecto significativo de la renovación de praderas en la producción de forraje, tanto en época seca como lluviosa (P < 0.05). El efecto fue mayor en la época lluviosa que en la época seca (P < 0.05). Las praderas renovadas tuvieron en promedio 1,5 veces más forraje que la pradera testigo (21,9 vs. 8,9 t de MS ha-1). Durante el período seco, la tecnología de renovación disminuyó el efecto negativo del estrés hídrico, manteniendo una producción promedio de forraje que duplicó la registrada durante el mismo período en la pradera sin intervención (5,2 vs. 2,5 t de MS ha-1). En la producción total de carne también se observó un efecto de renovación de praderas tanto en época seca como lluviosa. El efecto de la tecnología en producción de carne fue mayor en la época de lluvias que en la época seca (353 vs. 163 kg ha-1). El promedio general indicó que la producción de carne por unidad de área fue 4 veces mayor en la pradera renovada que en la pradera testigo (859 vs. 171 kg ha-1).Los resultados mostraron que la aplicación de tecnologías de renovación de praderas a nivel de finca en el departamento del Atlántico se logra aumentos significativos en producción de forraje y producción de carne por unidad de área lo cual tendría repercusiones en los ingresos de los productores. 
 

SUSTAINABLE LIVESTOCK PRODUCTION IN FORESTRY SYSTEMS SUSTAINABLE LIVESTOCK PRODUCTION IN FORESTRY SYSTEMS

Forest systems, both natural and cultivated, have a very high potential for livestock production. The fodder for feed could be obtained from forestry systems. This biomass can easily be converted to cash generating products through animals. Therefore, 'GOAT' is an ideal livestock species, best suited for these systems.In the Dry Zone under natural browsing in scrub jungles live-weight gains up to 50 - 75 g d-1 have been achieved. The rumen ammonia levels were higher (400 mg N l-1 SRF) than those where grazing was in pure Brachiria pastures. The blood urea levels were satisfactory (10.3 m moll-1). In cultivated forests such as Eucalyptus and Pinus, similar potentials exist. Under Pinus forests in the Mid-Country, goats on natural pastures gained 45 g d-1 and with Gliricidia this increased to 55 gd-1.They are also efficient "Biological Weeders". Removal of weeds reduces weeding costs, competition and fire hazards. A single goat will remove nearly 0.5 mt. of weed dry matter per year and convert this to 25 Kg of meat. Five goats can keep a hectare of moderately weedy land clean (2500 Kg Dm ha-1 y-1), while returning 28 Kg N, 18 Kg P2O5 and 11 Kg K2O as nutrients to the system. Livestock fit well into agroforestry systems, where tree/ shrub species are grown as hedgerow and more biomass is produced than is needed. Therefore, the specified 'SALT-2' system is well suited to improve the family budget and sustain the soil productivity for Mid-Country farmers.

Establishment of lucerne (Medicago sativa) sown on five dates with four inoculation treatments

The establishment and growth of 'Stamina 5' lucerne (Medicago sativa) seed sown with three inoculant carriers (ALOSCA®, coated, and peat slurry treated) or as bare seed (control) on five dates (21 October 2010, 9 November 2010, 8 December 2010, 13 January 2011 and 3 February 2011) was investigated on a Lismore stony silt loam soil at Ashley Dene dryland research farm in Canterbury. Initial lucerne populations were 300 plants m-2 from coated seed and on average 200 ± 11.2 plants m-2 from bare seed, ALOSCA® and the peat slurry inoculated seed. The higher population from coated seed treatments did not confer a herbage yield advantage. In the establishment year, yield was lowest (0.59 t DM ha-1) from the last sowing (3 February 2012) and highest from sowing dates (SD) 2 and 3 (2.6 ± 0.12 t DM ha-1). Yields were restricted by the low volumetric soil moisture content from November until March. The declining autumn photoperiod (14.9 to 14.1 hours) probably increased the partitioning priority of assimilates to the roots, reducing the above ground DM in the later sowing dates. In most cases, DM yields in Year1 were unaffected by seed inoculant treatments. In Year 2, DM production from the peat slurry treated seed (8.0 t ha-1) was highest, while coated seed crops were lowest (6.0 t ha-1). The effects of sowing date carried through to the second year with lower DM yields from SD4 and SD5 (6.0 ± 0.18 t ha-1) compared with 7.3 ± 0.18 t ha-1 from the earlier sowing dates. Keywords: alfalfa, ALOSCA®, bare seed, coated seed, Ensifer meliloti, peat slurry treated seed, rhizobia, sowing date

Which way forward in the quest for drought tolerance in perennial ryegrass?

Pasture moisture stress for "summer" (November to March) was calculated for five main pastoral regions of New Zealand, and 9 or 10 years' weather data were modelled in each case. Amelioration of water deficit with deeper rooting, stronger plant tissue osmotic potential for greater water extraction, or increased photosynthetic water use efficiency (WUE) was also modelled. Regional mean summer moisture deficits ranged from 34 mm in Taranaki to 447 mm in Canterbury. For a 10-cm increase in rooting depth, the model predicted an additional 16 mm water extraction. Increased plant osmotic potential was predicted to only slightly increase water extraction and paradoxically reduce yield. The assumed increase in photosynthetic WUE improved production by 240 kg DM ha-1 for the same water use. Drought tolerance traits exhibited by a range of ryegrass cultivars were measured in a series of glasshouse experiments and the potential to improve New Zealand ryegrass drought tolerance by introgression with germplasm originating from North Africa was assessed. North African germplasm possesses a trait of deep rootedness but has low summer productivity as a soil moisture conservation strategy and a high percentage of tillers flowering, so initial evaluations of this material for suitability for use in New Zealand are not promising. Ryegrass cultivars incorporating germplasm of Spanish origin appear to maintain summer production with enhanced WUE. Keywords: drought tolerance, root depth, Lolium perenne, perennial ryegrass, water deficit

Producción de forraje y composición morfológica del pasto mulato (Brachiaria híbrido 36061) sometido a diferentes regímenes de pastoreo

Three grazing frequencies (14, 21 and 28 d) and two grazing intensities (9-11 and 13-15 cm cutting height) were assessed in Mulato grass (Brachiaria hybrid 36061) in a completely randomized block design with a 3*2 factorial arrangement and three replicates. The following attributes were taken into account, herbage yield, growth rate (GR), botanic composition and leaf:stem ratio. No significant interaction (P>0.05) was found between frequency*intensity for herbage yield. Herbage yield distribution was 55, 28 and 17 % respectively for the rainy, north and dry seasons in 2007-2008, evaluation period. The highest annual herbage yield (12,310 kg DM ha-1) was recorded with 28 d grazing interval at 13-15 cm of grazing intensity. Herbage yield increased progressively when grazing frequency lengthened from 14 to 28 d (P<0.05). A similar herbage yield pattern was observed in 2008-2009. The greater growth rate (GR) was obtained in the rainy season, 36, 44 and 47 kg DM ha-1 d-1 at 14, 21 and 28 d grazing frequency, respectively. The lowest GR was found in the dry season. Relative to morphological components, the greater leaf mass yield was found in the rainy season, followed by the north and dry seasons at 28 d grazing frequency and 13-15 cm grazing height. As a conclusion, the greater herbage yield, growth rate, leaf mass and leaf:stem ratio were found in the rainy season at 13-15 cm grazing height and 28 d grazing frequency.

Seedling Establishment and Forage Accumulation of ‘Ceres Tonic’ Plantain in Pure Stands and in Grass Mixtures

This study evaluates the balance of species 2 mo after sowing, its effects on seasonal and annual dry matter accumulation of Plantago lanceolata L. �Ceres Tonic� sown in pure stands, in binary mixtures with three grasses, and different initial growth rates: annual ryegrass (Lolium multiflorum Lam.), tall fescue (Festuca arundinacea Schreb.), and orchard grass (Dactylis glomerata L.). Plantain monocultures were sown at three densities (4, 8, and 12 kg seed ha-1), while halved densities were used in the mixtures. Each grass was sown at the density that is typical for the region (annual ryegrass = 30, tall fescue = 15, and orchard grass = 6 kg seed ha-1). The trial was carried out in Balcarce (37o45� S, 58o18� W; 130 m a.s.l.), Argentina in 1.4 × 5 m plots sown in April 2005 with a randomized complete block design, a factorial arrangement of pasture type and plantain sowing density, and seasons as a measurement repeated over time. Plant density 2 mo after sowing was not a good estimator of the balance between species for all pasture types at the end of the first year. Total forage accumulation throughout the experimental period was affected by pasture type (p = 0.08) and plantain sowing density (p < 0.05), but not by their interaction (p > 0.05). The plantain and annual ryegrass mixture accumulated 28% more biomass than the mean biomass of all the other pastures (7948 ± 647 vs. 6204 ± 502 kg DM ha-1) mainly because of its higher yield in fall and winter. Total precipitation during the year under study was 15% lower than the historic average so that higher accumulations could be expected in years with higher precipitation.

English

A field experiment was conducted on an infertile red soil under a hairy vetch (Vicia villosa&nbsp;Roth) and corn (Zea mays&nbsp;L.) rotation system in a highland area of Yunnan Province, China. Effects of phosphate (P) fertilization, combined with hairy vetch returned to the soil, on crop yield and soil fertility were studied, and the balances of nitrogen (N), phosphorus (P) and potassium (K) in the rotation system were estimated. As P application increased from 135 to 315 kg ha-1, the dry matter yield of hairy vetch increased by 900.6 to 1283.86 kg DM ha-1, and also promoted P absorption by hairy vetch. When compared with CK, the corn and corn straw yield increased by 16.64 and 33.48%, respectively, from the crop rotation system, while it increased by 18.36 and 34.96% and 32.58 and 66.5%, from the integrated use of green manure and P fertilizer, respectively. Simple crop rotation proceeding could improve soil N content in the 0 to 20 cm soil layer, while the combined P application improved soil P content. After corn harvest, soil Olsen-P content under the different treatments increased by 35.31 and 122.15% and 19.70 and 63.63% in the 0 to 10 and 10 to 20 cm soil layers, respectively. The optimum P fertilizer rate for the hairy vetch-corn rotation system in Yunnan Province was 135 kg P2O5&nbsp;ha-1. At this P rate, the nutrient balance surpluses for N, P and K were 84.9, 18.9 and 26.4%, respectively. &nbsp; Keywords:&nbsp;Rotation system, crop yield, green manure, NPK balance, P fertilizer, soil physical and chemical properties.

Produtividade e composição estrutural de aveia e azevém submetidos a épocas de corte e adubação nitrogenada

A atividade leiteira é fundamental para a pequena propriedade do sudoeste do Paraná. Este estudo teve como objetivo avaliar o efeito de épocas de corte de pastagem de aveia e azevém, com e sem adubação nitrogenada, sobre a produção de matéria seca e a qualidade da pastagem. O experimento foi conduzido em Pato Branco, PR, num delineamento de blocos ao acaso, com parcelas subdivididas e quatro repetições. Nas parcelas, fez-se uso de adubação nitrogenada de cobertura (0 e 100 Kg de N ha-1), na forma de ureia, e, nas subparcelas, foram avaliadas três épocas de corte de pastagem de aveia e azevém (30, 45 e 60 dias após a emergência). A aplicação de nitrogênio proporcionou um acúmulo de massa de 1133 Kg de MS ha-1, aos 45 dias após a emergência, próximo daquele considerado ideal para início de pastejo. O primeiro corte nessa época, combinado com o uso de nitrogênio, também favoreceu a capacidade de rebrota da pastagem, pois 30 dias após esse corte, o acúmulo de massa alcançou 2398 Kg de MS ha- 1. A adubação nitrogenada aumentou a quantidade de folhas de aveia na pastagem, fato que contribuiu para que o teor de proteína bruta fosse de 27%, indicando alta qualidade do material.

Respuesta productiva de la alfalfa a diferentes frecuencias de corte

The present study was performed with the objective of assessing the effect of cutting frequency on herbage yield, botanical and morphological composition, leaf area per tiller and intercepted radiation in alfalfa (Medicago sativa L.) cv. San Miguelito. The study was carried out from August 2006 to August 2007 at the Colegio de Postgraduados research station, Montecillo, Estado de Mexico. The treatments consisted in four cutting frequencies, 3, 4, 5 and 6 wk in spring-summer and 4, 5, 6 and 7 wk in fall-winter, distributed in a completely randomized block design with four replicates. Seasonal and annual herbage yield showed differences between cutting frequencies (P<0.05). The greatest total accumulated dry matter yield (34,454 kg DM ha-1) was recorded at the 6 and 7 wk cutting frequencies, showing a 31, 26, 23 and 20 % distribution for summer, spring, fall and winter,respectively. Leaf area per tiller increased as the cutting frequency decreased (P<0.05) and its greater value was recorded during summer with 5 wk frequency (108 cm2 tiller-1), similar to the one found at the summer 6 wk frequency (105 cm2 tiller-1),but significantly different and higher to those observed in all the other treatments (P<0.05). Relative to intercepted radiation, regardless of season (P<0.05) its greater values were found at the 6 and 7 wk cutting frequencies, averaging 90 %. As a conclusion, it can be stated that the greatest herbage yield was observed when the alfalfa was harvested at 6 and 7 wk cutting frequency in spring-summer and in fall-winter.

Valor nutricional, cinética de fermentación y producción estimada de leche en ensilajes de maíz cortado a diferentes alturas

The dry matter production DM (ton ha-1), nutritional value, estimated milk yield and fermentation kinetics of corn silage cut at 20, 40 and 60 cm over the soil surface were evaluated. The corn hybrid PIONEER 33G66 was planted at a density of 125,000 seeds ha-1, with a row distance of 0.80 m, and harvested at half milk line (115 d of age), and ensiled in laboratory mini silos of 5 kg (n=3). After 45 d, the silos were opened and analyzed by triplicate for pH, DM, OM, Ash, CP, EE, NDF, ADF, ADL, in vitro DM and NDF digestibility (IVDMD and IVNDFD), and fermentation kinetics. Milk yield and NEL were estimatedusing the MILK2000 model. Data were analyzed using PROC GLM of SAS, adjusting a model in which height of cut was the fixed effect. Production of DM ha-1 decreased by 12.7% by rising cutting height to 60 cm. The NDF and CP concentration were linearly reduced (P &lt; 0.05). NEL tended (P &lt; 0.07) to improve when the height of cutting was raised from 20 to 60 cm (1.2 vs 1.4 Mcal kg-1 DM). Estimated milk yield was not different among treatments. The asymptotic gas production was increased (P &lt; 0.05) by rising cutting height to 60 cm; the gas production rate at 72 h was higher (P &lt; 0.05) in corn silagecut at 60 cm. The fermentation parameter B was decreased linearly (P &lt; 0.05) by rising cutting height. The parameter C was high in corn silage cut at 20 cm vs corn silage cut at 40 and 60 cm.

Effect of bradyrhizobial inoculation and n fertilization on promiscuous soybean and subsequent maize yield grown in degraded “terre de barre” in Benin

Poor adoption of green manure and agro forestry systems for sustainable intensification of agricultural production in the moist savannah of West-Africa, as well as the low contribution of traditional grain legumes such as groundnuts, cowpea and common bean have prompted the search for alternative socio-economic solutions for smallholders. One of them is the development of N2 fixation by promiscuous soybean to increase food production and to improve soil fertility, in particular on degraded lands. Fifteen farmers’ fields were selected for soybean trials in 2001 and 2002, and again in 2002 and 2003 for the maize trials. Each farmer’s field represented one replication. The 15N isotope dilution method was used to assess symbiotic N2 fixation of the International Institute for Tropical Agriculture (IITA) promiscuous soybean variety TGX 1448 2E and its response to inoculation and fertilization. In both 2001 and 2002, the application of 20 kg N did not affect nodulation, biomass production and N accumulation of soybean uninoculated in 2001, or inoculated in 2002. However, inoculation produced the highest soybean nodule number and nodule weight in 2002. The highest values of biomass production and N accumulation were found with soybean that received poultry manure in 2001 and 100 kg N ha-1 as urea in 2002. The highest biomass and N accumulation in 2001 was 1600 kg DM ha-1 and 41 kg N ha-1 with soybean amended with poultry manure. Shoot N content in 2002 averaged only 25 kg N ha- 1, while the average N accumulation in soybean seed was 64 kg N ha-1. The best percentage of N derived from atmosphere (Ndfa) (54 %), amounting to only 13 kg N ha-1, was obtained with soybean fertilized with 20 kg N ha-1 and inoculated. These values are very low indicating that soybean cultivated in the study area was far from satisfying its requirements through N fixation. The N balance calculated on the basis of the amount of N fixed removed in the grain is negative (-48 kg ha-1). Significant increase occurred only when plots were previously grown to soybean and fertilized with poultry manure being 5124 and 3211 kg DM ha-1 compared to the previous soybean plot without N, for maize shoot and grain, respectively. Total N yield in shoots was significantly higher in plots previously cropped to soybean than to maize. The contribution of soybean to maize yield was not significantly different from the contribution of maize-to-maize in 2003. Soybean growing in West-Africa is a promising technology that has multiple benefits.Keys words : Benin Republic ; promiscuous soybean ; symbiotic N fixation ; 15N isotope dilution; N accumulation ; N Balance ; % Ndfa.