Produção de milheto em consórcio com gramíneas forrageiras no semiárido cearense.

Resumo: Objetivou-se avaliar gramíneas com reconhecida tolerância a períodos de estresse hídrico em consórcio com a cultura do milheto e doses de nitrogênio. O ensaio foi realizado em Sobral-CE, em delineamento em blocos casualizados com os tratamentos sendo o consórcio da cultura do milheto com o capim-buffel ou capim-massai, com 3 doses de adubação em cobertura para o milheto, sendo: 0, 50 e 100 kg ha-1 de nitrogênio, e o tratamento testemunha sendo o plantio do milheto solteiro sem adubação de cobertura; com 3 blocos. Avaliaram-se os dados biométricos e produtividade de massa seca. O consórcio de culturas anuais com gramíneas forrageiras é alternativa interessante para produção de volumoso em região semiárida. O consórcio de milheto e capim-massai mostrou-se superior para dados biométricos e produtividade. O emprego de 100 kg ha-1 de N em cobertura na cultura do milheto propiciou maior produtividade de massa seca. [Millet production with forage consortium in semiarid region of State of Ceará]. Abstract: This study aimed to evaluate grasses with recognized tolerance to periods of water stress in partnership with millet cultivation and doses of nitrogen. The test was conducted in Sobral-CE, at a randomized block with treatments and millet culture consortium with buffel grass or massai grass with 3 fertilizer levels at coverage for millet, as follows: 50 and 100 kg ha-1 of nitrogen, and the control treatment being the planting millet single without cover fertilization; with 3 blocks. Evaluated were the biometric data and dry matter productivity. The consortium of annual crops with grasses is interesting alternative to massive production for semi-arid region. The consortium millet and massai grass was superior to biometric data and productivity. The use of 100 kg ha-1 of N topdressing in the millet culture provided greater dry mass productivity.

Estudios básicos para el mejoramiento genético de buffelgrass (Cenchrus ciliaris L.)

El "pasto salinas" o "buffel grass" (Cenchrus ciliaris L.), forrajera introducida hace pocos años a nuestro medio, muestra buena adaptación a regiones subtropicales áridas y semiáridas (desde Córdoba hacia el norte del país), en las que la actualidad se cultivan materiales provenientes de áreas agroecológicas afines a las zonas de difusión de nuestro país. Estas introducciones manifestaron diferentes niveles de adaptación, no contando los productores con opciones en cuanto a disponibilidad de cultivares de reconocida aptitud forrajera y adecuada producción de semillas. Se plantea como objetivo general del proyecto la generación de variabilidad genética a partir del cruzamiento entre una estirpe sexual y materiales apomícticos adaptados, evaluación y selección de los mejores híbridos apomícticos y obtención a partir de estos nuevos cultivares. Como objetivos específicos se propone: 1) Caracterización morfológica, citológica y reproductiva de la estirpe sexual y materiales apomícticos a utilizarse en este proyecto. 2) Puesta a punto de una técnica de hibridación para la obtención de materiales F1. 3) Determinación de caracteres descriptores que posibiliten la diferenciación de cultivares dentro de la especie (actualmente no disponibles en el INASE).

Nitrogen symbiotically fixed by cowpea and gliricidia in traditional and agroforestry systems under semiarid conditions

The objective of this work was to estimate the amounts of N fixed by cowpea in a traditional system and by cowpea and gliricidia in an agroforestry system in the Brazilian Northeast semiarid. The experiment was carried out in a randomized complete block design, in a split-plot arrangement, with four replicates, in the semiarid region of the state of Paraíba, Brazil. Plots consisted of agroforestry and traditional systems (no trees), and split-plots of the three crops planted between the tree rows in the agroforestry system. To estimate N fixation, plant samples were collected in the fourth growth cycle of the perennial species and in the fourth planting cycle of the annual species. In the agroforestry system with buffel grass and prickly-pear cactus, gliricidia plants symbiotically fix high proportions of N (>50%) and contribute with higher N amounts (40 kg ha-1 in leaves) than in the traditional system (11 kg ha-1 in grain and 18 kg ha-1 in straw). In the agroforestry system with maize and cowpea, gliricidia plants do not fix nitrogen, and N input is limited to the fixation by cowpea (2.7 kg ha-1), which is lower than in the traditional system due to its lower biomass production.

Consumo, digestibilidade aparente de nutrientes e balanços de nitrogênio e hídrico de ovinos alimentados com silagens de cultivares de capim-búfel

The objective of this present experiment was to determine intake and apparent digestibility of dry matter and nutrients, nitrogen (NB) and water balances (WB) of sheep fed with buffel grass silages. The buffel grass cultivars used were Tanzania, Buchuma and Biloela. 21 male, castrated, crossbred Santa Ines x Non defined genotype sheep, with initial body weight of 31.8±3.16kg were used, kept in metabolic cages. The experimental design was completely randomized with seven replicates. No differences were observed in dry matter intake in g/day (919.2) and % of body weight (2.9). In general, digestibility coefficients of dry matter varied from 37.7% to 60.0%. The NB and WB were positive, with higher NB values in sheep fed with Tanzania (5.1g/day) and Biloela (3.9g/day) and higher WB in animals fed with Buchuma (1.38kg/animal/day) and Biloela (1.42kg/animal/day). All cultivars of buffel grass evaluated (Tanzania, Buchuma and Biloela) presented adequate chemical composition, where the silage of buffel grass used corresponded to 60% of the total daily water intake by sheep.

Effects of litter and fine root composition on their decomposition in a Rhodic Paleustalf under different land uses

Plant litter and fine roots are important in maintaining soil organic carbon (C) levels as well as for nutrient cycling. The decomposition of surface-placed litter and fine roots of wheat ( Triticum aestivum ), lucerne ( Medicago sativa ), buffel grass ( Cenchrus ciliaris ), and mulga ( Acacia aneura ), placed at 10-cm and 30-cm depths, was studied in the field in a Rhodic Paleustalf. After 2 years, = 60% of mulga roots and twigs remained undecomposed. The rate of decomposition varied from 4.2 year -1 for wheat roots to 0.22 year -1 for mulga twigs, which was significantly correlated with the lignin concentration of both tops and roots. Aryl+O-aryl C concentration, as measured by 13 C nuclear magnetic resonance spectroscopy, was also significantly correlated with the decomposition parameters, although with a lower R 2 value than the lignin concentration. Thus, lignin concentration provides a good predictor of litter and fine root decomposition in the field.

A comparison of the excretion rate of endogenous purine derivatives in the urine of Bos indicus and Bos taurus steers

Estimates of microbial crude protein (MCP) production by ruminants, using a method based on the excretion of purine derivatives in urine, require an estimate of the excretion of endogenous purine derivatives (PD) by the animal. Current methods allocate a single value to all cattle. An experiment was carried out to compare the endogenous PD excretion in Bos taurus and high-content B. indicus ( hereafter, B. indicus) cattle. Five Holstein - Friesian ( B. taurus) and 5 Brahman (> 75% B. indicus) steers ( mean liveweight 326 +/- 3.0 kg) were used in a fasting study. Steers were fed a low-quality buffel grass (Cenchrus ciliaris; 59.4 g crude protein/kg dry matter) hay at estimated maintenance requirements for 19 days, after which hay intake was incrementally reduced for 2 days and the steers were fasted for 7 days. The excretion of PD in urine was measured daily for the last 6 days of the fasting period and the mean represented the daily endogenous PD excretion. Excretion of endogenous PD in the urine of B. indicus steers was less than half that of the B. taurus steers ( 190 mu mol/kg W-0.75. day v. 414 mu mol/kg W-0.75. day; combined s.e. 37.2 mu mol/kg W-0.75. day; P< 0.001). It was concluded that the use of a single value for endogenous PD excretion is inappropriate for use in MCP estimations and that subspecies-specific values would improve precision.

Ecological stoichiometry controls the transformation and retention of plant-derived organic matter to humus in response to nitrogen fertilisation

Carbon (C) sequestration in soils is a means for increasing soil organic carbon (SOC) stocks and is a potential tool for climate change mitigation. One recommended management practice to increase SOC stocks is nitrogen (N) fertilisation, however examples of positive, negative or null SOC effects in response to N addition exist. We evaluated the relative importance of plant molecular structure, soil physical properties and soil ecological stoichiometry in explaining the retention of SOC with and without N addition. We tracked the transformation of 13C pulse-labelled buffel grass (Cenchrus ciliaris L.), wheat (Triticum aestivum L.) and lucerne (Medicago sativa L.) material to the <53 μm silt + clay soil organic C fraction, hereafter named “humus”, over 365-days of incubation in four contrasting agricultural soils, with and without urea-N addition. We hypothesised that: a) humus retention would be soil and litter dependent; b) humus retention would be litter independent once litter C:N ratios were standardised with urea-N addition; and c) humus retention would be improved by urea-N addition. Two and three-way factorial analysis of variance indicated that 13C humus was consistently soil and litter dependent, even when litter C:N ratios were standardised, and that the effect of urea-N addition on 13C humus was also soil and litter dependent. A boosted regression analysis of the effect of 44 plant and soil explanatory variables demonstrated that soil biological and chemical properties had the greatest relative influence on 13C humus. Regression tree analyses demonstrated that the greatest gains in 13C humus occurred in soils of relatively low total organic C, dissolved organic C and microbial biomass C (MBC), or with a combination of relatively high MBC and low C:N ratio. The greatest losses in 13C humus occurred in soils with a combination of relatively high MBC and low total N or increasing C:N ratio. We conclude that soil variables involved in soil ecological stoichiometry exert a greater relative influence on incorporating organic matter as humus compared to plant molecular structure and soil physical properties. Furthermore, we conclude that the effect of N fertilisation on humus retention is dependent upon soil ecological stoichiometry.

Productive performance and parasitological control of kids supplemented with umbu fruits (Spondias tuberosa Arruda).

Native fruits from Caatinga vegetation can be an important alternative to improve the productive performance of kids in the semi-arid region of Brazil. This work aimed to evaluate the effect of supplementation with Umbuzeiro fruits in natura over the weight gain and anthelmintic control of kids kept in Buffel grass pasture in the semi-arid zone of Pernambuco, Brazil. Twenty-four castrated, crossbreed kids were allocated into three treatments: 1) Control (n = 8) fed exclusively with Buffel grass; 2) Umbu 1x (n = 8) fed with fruits once a week and 3) Umbu 3x (n = 8) fed with fruits for three times a week. The following parameters were evaluated: variation of body weight, faecal egg counts (FEC) and coproculture. Overall, the average consumption of Umbu fruits in natura was 1.48 kg/animal/day, which corresponded to 133.5 g daily dry matter intake (DMI/animal/day). There were no significant difference (P>0.05) for any parameters evaluated. During the experimental period, the overall daily weight gain was variable between 108.75 to 116.70 g/animal/day and the average FEC was 436 eggs. In the present study, the goat kids supplemented with fresh umbu fruits showed a good productive performance, however the supplementation with umbu did not control the infestation of gastrointestinal nematodes in kids.

Avaliacao da produtividade de treze cultivares de campim buffel, na regiao semi-arida de Peranmbuco.

Para identificar as cultivares de capim buffel (Cenchrus ciliaris L.), melhor adaptadas a regiao semi-arida do Nordeste, foi conduzido um experimento no periodo de 1979/1983, no Campo Experimental de Manejo da Caatinga, do Centro de Pesquisa Agropecuaria do Tropico Semi-Arido (CPATSA-EMBRAPA), localizado em Petrolina, PE. Foram avaliadas treze cultivares de capim buffel, estabelecidas vegetativamente em parcelas de 4 m x 2,5 m. O delineamento experimental adotado foi o de blocos ao acaso com cinco repeticoes. Entre as cultivares de porte alto, destacou-se o Molopo com maiores produtividades (6.750 kg de materia seca/ha-ano), relacao colmo/folha e altura (106 cm). Comparativamente, a Biloela, que e atualmente a mais utilizada no CPATSA, apresentou menor altura (97 cm) e produtividade (5.455 kg de materia seca/ha-ano). Entre as cultivares de porte medio, observou-se a Gayndah com menor altura (77 cm) e a F1 Hibrido 171, com menor produtividade (3.745 kg de materia seca/ha-ano). Com relacao ao valor nutritivo, temos a Gayndah (12,43%) e o Molopo (9,51%), com maior e menor teor de proteina bruta, na materia seca, respectivamente.

Effect of silicate fertilization on soil and on palisade grass plants under grazing intensities

Application of calcium silicate (SiCa) as soil acidity corrective was evaluated in a Rhodic Hapludox soil with palisade grass conducted under pasture rotation system with different grazing intensities. Experimental design was complete randomized blocks with four grazing intensities - grazing intensities were imposed by forage supply (50, 100, 150 and 200 kg t-1 of DM per LW) - in experimental plots with four replicates and, in the subplots, with seven doses of calcium silicate combined with lime: 0+0, 2+0, 4+0, 6+0, 2+4, 4+2 and 0+6 t ha-1, respectively. In the soil, it was evaluated the effect of four levels of calcium silicate (0, 2, 4 and 6 t ha-1) at 45, 90, and 365 days at three depths (0-10, 10-20 and 20-40 cm) and at 365 days, it was included one level of lime (6 t ha-1). For determination of leaf chemical composition and silicate content in the soil, four levels of calcium silicate (0, 2, 4 and 6 t ha-1) were evaluated at 45 and 365 days and at 45 days only for leaf silicate, whereas for dry matter production, all corrective treatments applied were evaluated in evaluation seasons. Application of calcium silicate was positive for soil chemical traits related to acidity correction (pH(CaCl2), Ca, Mg, K, H+Al and V), but the limestone promoted better results at 365 days. Leaf mineral contents were not influenced by application of calcium silicate, but there was an increase on silicate contents in leaves and in the soil. Dry matter yield and chemical composition of palisade grass improved with the application of correctives.

Seasonal variation of soluble carbohydrates and starch in Echinolaena inflexa, a native grass species from the Brazilian savanna, and in the invasive grass Melinis minutiflora

Echinolaena inflexa (Poir.) Chase is an abundant C3 grass species with high biomass production in the Brazilian savanna (cerrado); Melinis minutiflora Beauv. is an African C4 forage grass widespread in cerrado and probably displacing some native herbaceous species. In the present work, we analysed seasonally the content and composition of soluble carbohydrates, the starch amounts and the above-ground biomass (phytomass) of E. inflexa and M. minutiflora plants harvested in two transects at 5 and 130 m from the border in a restrict area of cerrado at the Biological Reserve and Experimental Station of Mogi-Guaçu (SP, Brazil). Results showed that water soluble carbohydrates and starch amounts from the shoots of both species varied according to the time of the year, whilst in the underground organs, variations were observed mainly in relation to the transects. Marked differences in the pattern of the above-ground biomass production between these two grasses relative to their location in the Reserve were also observed, with two peaks of the invasive species (July and January) at the Reserve border. The differences in carbohydrate accumulation, partitioning and composition of individual sugars concerning time of the year and location in the Reserve were more related to the annual growth cycle of both grasses and possibly to specific physiological responses of M. minutiflora to disturbed environments in the Reserve border.

Evaluation of elephant grass silage with the addition of cassava scrapings

The objective of this experiment was to evaluate the effects of adding cassava scrapings on gas and effluent losses, dry matter recovery, pH, contents of N-NH3, organic acids and volatile fatty acids and the bromatological composition of elephant grass silages. It was used a randomized complete design, with four levels of cassava scrapings (0, 7, 15 or 30% natural matter) each one with four replications per level. The grass was cut at 50 days of regrowth and ensiled in 15-L silos, equipped with a Bunsen valve to allow gas outflow. The gas losses decreased quadratically with the addition of cassava scrapings, whereas effluent losses decreased linearly. Dry matter recovery increased quadratically with the addition of cassava scrapings. Dry matter (DM) concentration increased but crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and hemicellulose (HEM) decreased linearly with the addition of cassava scrapings. The pH value and lactic acid concentration increased quadratically with the addition of cassava scrapings. Contents of N-NH3 and butyric acid decreased quadratically with the addition of cassava scrapings, whereas acetic acid content decreased linearly. Addition of cassava scrapings reduced gas and effluent losses and improved the fermentation profile of elephant grass silages and the level of 7% already ensures this improvement.

Herbage accumulation, growth and structural characteristics of Mombasa grass (Panicum maximum Jacq.) harvested at different cutting intervals

The objective of the present study was to evaluate herbage accumulation, morphological composition, growth rate and structural characteristics in Mombasa grass swards subject to different cutting intervals (3, 5 and 7 wk) during the rainy and dry seasons of the year. Treatments were assigned to experimental units (17.5 m(2)) according to a complete randomised block design, with four replicates. Herbage accumulation was greater in the rainy than in the dry season (83 and 17%, respectively). Herbage accumulation (24,300 kg DM ha(-1)), average growth rate (140 kg DM ha(-1) d(-1)) and sward height (111 cm) were highest in the 7 wk cutting interval, but leaf proportion (56%), leaf:stem (1.6) and leaf:non leaf (1.3) ratios decreased. Herbage accumulation, morphological composition and sward structure of Mombasa grass sward may be manipulated through defoliation frequency. The highest leaf proportion was recorded in the 3-wk cutting interval. Longer cutting intervals affected negatively sward structure, with potential negative effects on utilization efficiency, animal intake and performance.

Macronutrients in Marandu Palisade Grass as Influenced by Lime, Slag, and Nitrogen Fertilization

Soil acidity is one of the main limiting factors for the growth of pasture grasses in Brazilian soils. In addition to lime, slag can be used to correct soil acidity and help plants to absorb nutrients in adequate amounts. The objective of this experiment was to evaluate, under greenhouse conditions, the effects of slag and lime plus nitrogen (N) on marandu palisade grass plants` nutritional status as well as the absorption of macronutrients submitted to two cuts. The treatments consisted of two corrective materials (slag and lime), three corrective material rates (0.81, 1.61, and 3.22 g dm-3 of ECaCO3), three N rates (75, 150, and 300 mg dm-3) plus a control treatment, with four replications. Macronutrient contents in the forage plants were found to be present in adequate levels. The mean value of N accumulated in the shoot was 40.1 mg per plant, phosphorus (P) was 4.6 mg per plant, potassium (K) was 38.6 mg per plant, calcium (Ca) was 7.3 mg per plant, magnesium (Mg) was 6.7 mg per plant, and sulfur (S) was 3.5 mg per plant at the first cut. At the second cut, the nutrient accumulations values were N 50.8 mg per plant, P 6.3 mg per plant, K 20.7 mg per plant, Ca 21.6 mg per plant, Mg 24.0 mg per plant, and S 4.7 mg per plant. Macronutrients accumulation in the shoot of grass increased with the addition of both the correctives as well as the N rates.

Spatio-temporal variability behavior of land surface soil water content in shrub- and grass-land

The knowledge of the relationship between spatial variability of the surface soil water content (theta) and its mean across a spatial domain (theta(m)) is crucial for hydrological modeling and understanding soil water dynamics at different scales. With the aim to compare the soil moisture dynamics and variability between the two land uses and to explore the relationship between the spatial variability of theta and theta(m), this study analyzed sets of surface theta measurements performed with an impedance soil moisture probe, collected 136 times during a period of one year in two transects covering different land uses, i.e., korshinsk peashrub transect (KPT) and bunge needlegrass transect (BNT), in a watershed of the Loess Plateau, China. Results showed that the temporal pattern of theta behaved similarly for the two land uses, with both relative wetter soils during wet period and relative drier soils during dry period recognized in BNT. Soil moisture tended to be temporally stable among different dates, and more stable patterns could be observed for dates with more similar soil water conditions. The magnitude of the spatial variation of theta in KPT was greater than that in ENT. For both land uses, the standard deviation (SD) of theta in general increased as theta(m) increased, a behavior that could be well described with a natural logarithmic function. Convex relationship of CV and theta(m) and the maximum CV for both land uses (43.5% in KPT and 41.0% in BNT) can, therefore, be ascertained. Geostatistical analysis showed that the range in KPT (9.1 m) was shorter than that in BNT (15.1 m). The nugget effects, the structured variability, hence the total variability increased as theta(m) increased. For both land uses, the spatial dependency in general increased with increasing theta(m). 2011 Elsevier B.V. All rights reserved.