Métodos indiretos para estimar a massa de forragem em pastos de Cynodon spp

Silva, Sila Carneiro da; Cunha, Waldeliza Fernandes da

doi:10.1590/s0100-204x2003000800011

Cited by 8 publications

(1 citation statement)

References 16 publications

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“…1993). These were determined using calibration curves between sward height and herbage mass, produced in a concomitant set of measurements being made in the same experimental area (Da Silva et al 2013) following the procedure described by Da Silva & Cunha (2003). Estimates of sward herbage mass were made on a monthly basis using data from the measurements of sward height and the calibration equations.…”

Section: Methodsmentioning

confidence: 99%

Carbon and nitrogen reserves in marandu palisade grass subjected to intensities of continuous stocking management

et al. 2014

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SUMMARYPlant organic reserves and sward leaf area index (LAI) influence plant growth, persistency and herbage accumulation in grazed swards. The present study was conducted to describe patterns of variation in herbage accumulation and carbohydrate and nitrogen (N) reserves in shoot and root of marandu palisade grass subjected to intensities of continuous stocking management throughout the year. Treatments corresponded to four levels of grazing intensity – severe (S), severe/moderate (S/M), moderate (M) and lenient (L) – and were implemented in the field using bands of sward surface height (SSH – 10, 20, 30 and 40 cm ± 10%, respectively) maintained through continuous stocking and variable stocking rate. Total N concentration was higher in the shoot relative to the root compartment during autumn, early and late spring. On the other hand, the concentration of non-structural carbohydrates (NSC) and soluble N was higher in the root compartment, regardless of grazing intensity and season of the year. When taking into account the pool of C and N reserves, the shoot compartment represented the main storage organ, since it corresponded to the largest pool of NSC (averages of 0·102 ± 0·0038 and 0·201 ± 0·0088 kg/m2 for root and shoot, respectively) and soluble N (averages of 2·7 ± 0·26 and 5·3 ± 0·59 kg/m2 for root and shoot, respectively). During late spring, the time of active plant growth, there was a clear contrast in herbage accumulation and sward LAI among grazing intensities, particularly between the severe and lenient grazing treatments. The results show that even with larger pools of soluble N and NSC in the shoot compartment, herbage accumulation was limited by the reduced leaf area of swards subjected to the severe grazing treatment, indicating that under continuous stocking growth seems to be sustained by current assimilates instead of organic reserves. Therefore, targets of grazing management for maximizing herbage accumulation throughout the year should provide adequate combinations between quantity and quality of sward leaf area. This condition was obtained in the severe/moderate and moderate grazing intensities, and corresponded to sward heights between 20 and 30 cm for marandu palisade grass.

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Section: Methodsmentioning

confidence: 99%

Carbon and nitrogen reserves in marandu palisade grass subjected to intensities of continuous stocking management

et al. 2014

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Calibration of a capacitance probe for measurement and mapping of dry matter yield in Mediterranean pastures

et al. 2011

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The main objective of this study was to calibrate a commercial capacitance probe for measuring pasture dry matter yields under Mediterranean conditions. The standard method of assessing pasture biomass is based on cutting all the forage within a specified area and requires great effort and expense to collect enough samples to accurately represent a pasture. The field tests were carried out in 2007, 2008 and 2009 on different dates (phenological stages), and on five dairy farms, representing typical pastures in the region (grasses; legumes; and bio-diverse flora, mixture of grasses, legumes and others species). The linear regression techniques used in 2007 to relate the weight of the herbage (direct measurements) to the meter reading of capacitance (indirect measurements) led to high regression coefficients in grasses (R 2 = 0.90; P \ 0.01) and heterogeneous botanical composition (R 2 = 0.87; P \ 0.001) and moderate regression coefficient in legumes species (R 2 = 0.48; P \ 0.05). The validation of the calibration equations in 2008 and 2009 in two sites showed RSME values of 130 kg ha -1 in heterogeneous botanical composition and 456 kg ha -1 in legumes. The results indicated that the capacitance probe together with a GPS receiver might support site-specific management of pastures which would be useful in large areas.

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Calibration of GrassMaster II to estimate green and dry matter yield in Mediterranean pastures: effect of pasture moisture content

2016

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Accurate assessment of standing pasture biomass in livestock production systems is a major factor for improving feed planning. Several tools are available to achieve this, including the GrassMaster II capacitance meter. This tool relies on an electrical signal, which is modified by the surrounding pasture. There is limited knowledge on how this capacitance meter performs in Mediterranean pastures. Therefore, we evaluated the GrassMaster II under Mediterranean conditions to determine (i) the effect of pasture moisture content (PMC) on the meter’s ability to estimate pasture green matter (GM) and dry matter (DM) yields, and (ii) the spatial variability and temporal stability of corrected meter readings (CMR) and DM in a bio-diverse pasture. Field tests were carried out with typical pastures of the southern region of Portugal (grasses, legumes, mixture and volunteer annual species) and at different phenological stages (and different PMC). There were significant positive linear relations between CMR and GM (r2 = 0.60, P < 0.01) and CMR and DM (r2 = 0.35, P < 0.05) for all locations (n = 347). Weak relationships were found for PMC (%) v. slope and coefficient of determination for both GM and DM. A significant linear relation existed for CMR v. GM and DM for PMC >80% (r2 = 0.57, P < 0.01, RMSE = 2856.7 kg ha–1, CVRMSE = 17.1% to GM; and r2 = 0.51, P < 0.01, RMSE = 353.7 kg ha–1, CVRMSE = 14.3% to DM). Therefore, under the conditions of this current study there exists an optimum PMC (%) for estimating both GM and DM with the GrassMaster II. Repeated-measurements taken at the same location on different dates and conditions in a bio-diverse pasture showed similar and stable patterns between CMR and DM (r2 = 0.67, P < 0.01, RMSE = 136.1 kg ha–1, CVRMSE = 6.5%). The results indicate that the GrassMaster II in-situ technique could play a crucial role in assessing pasture mass to improve feed planning under Mediterranean conditions.

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Métodos indiretos para estimar a massa de forragem em pastos de Cynodon spp

Cited by 8 publications

References 16 publications

Carbon and nitrogen reserves in marandu palisade grass subjected to intensities of continuous stocking management

Carbon and nitrogen reserves in marandu palisade grass subjected to intensities of continuous stocking management

Calibration of a capacitance probe for measurement and mapping of dry matter yield in Mediterranean pastures

Calibration of GrassMaster II to estimate green and dry matter yield in Mediterranean pastures: effect of pasture moisture content

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