706 research outputs found
Aspetti agronomici della produttività dei pascoli
Nel corso dell'annata 1984-85 nelle stazioni ubicate in areali rappresentativi delle superfici a pascolo della VIII Comunità Montana Marghine-Planargia sono stati raccolti i primi dati per la costruzione delle curve di produzione del pascolo naturale.
I primi risultati confermano la discreta produttività naturale dei pascoli della Comunità soprattutto se paragonati a quelli di altre aree pascolative su terreni granitici. Si tratta di dati parziali in quanto coprono una sola annata e quindi non consentono di trarre conclusioni definitive. Infatti l'andamento della stagione in corso (1985-86) per la carenza di piogge non ha consentito alcuna valutazione della produzione autunnale contrariamente a quanto verificato nell'annata precedente.
Nell'annata 1985-86 proseguiranno i rilievi nelle stazioni già impiantate e verranno seguiti anche nuovi areali. Nella stazione di Macomer, in collaborazione con l'Istituto Zootecnico Caseario, i dati agronomici saranno integrati da alcuni rilievi zootecnici grazie all'uso di animali fistolati
Impact of soil management on the functional activity of microbial communities associated to cork oak rhizosphere
The microbial ecology of cork oak rhizosphere was investigated using the Biolog community level physiological profile (CLPP) that provides a unique metabolic fingerprint helpful for the characterization of complex microbial communities. Microbial populations from the rhizosphere of cork oak plants growing at three different sites within the same area were characterized using CLPP and compared. The sites were distinguished by a different soil management under the tree cover and, in general terms, by a different anthropogenic impact. The comparison of metabolic fingerprints of the different microbial populations showed the existence of a relationship between general microbial activity and functional biodiversity in the rhizosphere and the level of anthropogenic impact. Particularly the presence of grazing animals, soil tillage and fire could be identified as the main factors affecting both the general microbial activity and the structure of microbial populations from cork oak rhizospheres
The Use of the grassmeter as a simplified method to estimate dry matter yield on annual self-reseeding medics and clovers
BACKGROUND. The grassmeter non-destructive
method was used to estimate dry matter yield (DMY)
of 24 annual self-reseeding legumes. The possibility
was evaluated of using the grassmeter as an alternative
to conventional destructive quadrats for large
field plot experiments.
METHODS. The linear regressions between sward
height measured by the grassmeter and DMY were
analysed. Three types of regression equations were
calculated: (i) ‘general’, a single equation including
the three-year set of height/DMY pairs of data; (ii)
‘specific’, one regression equation for each species;
(iii) ‘preliminary’, calculated from the data collected
in the spring and autumn cuts of the first year.
RESULTS. The ‘general’ calibration gave a satisfactory
estimate of DMY (R2=0.55). The ‘specific’ calibration
was particularly accurate for Trifolium
brachycalicynum “Osilo” (R2=0.88), T. squarrosum
“Chilivani” (R2=0.81) and Medicago polymorpha
“Circle Valley” (R2=0.81), but not for M. rugosa
“Sapo” (R2=0.22) and “Paraponto” (R2=0.26). The
‘preliminary’ calibration, which was based only on the
destructive assessment of DMY at the first cut, provided
reliable estimates of DMY until the sward conditions,
namely cover rate and weeds, were comparable
to those of the calibration period. The coefficient
of variation of the DMY estimate based on the
grassmeter ‘general’ calibration was about 10% lower
than that of the DMY measured with conventional
quadrats.
CONCLUSIONS. Results suggest that the grassmeter
could effectively replace destructive measurements
for estimating the DMY of annual self-reseeding
legumes, thus reducing labour requirements and
number of samples to be processed, or increasing,
when needed, the number of accessions to compare
and hence the inference of the experiment
Reattività alla concimazione fosfo-azotata dei pascoli naturali di alta collina
Over the 4 years from 1975 to 1979 a trial on N - P fertilization was carried out on natural
pastures with shallow granitic soils.
Fertilizing with 100 Kg/ha of P2O5 every four years and 100 Kg/ha of N every year tripled the
yield (1,9 t/ha of dry matter as against the 0,6 t/ha of test).
Climatic limitations do not allow notable increases in yield even with greater applications of P
Reattività del pascolo naturale alla somministrazione frazionata di diverse dosi di azoto
In the year 1981-82 a N-fertilization pasture trial was begun on Sardinian granitic hill soil. 4 N levels (0,40,
80 e 120 kg/ha divided into four dressings) combined with 100 kg/ha of P2O5 and a test without fertilization
were compared.
NP fertilization reactivity was high. The highest N level achieved the best production: 6.2 t/ha of DM in the
total of 4 utilizations against 1.8 t/ha of the test. The efficency of N DM or F.U. increase for each kg of N
dressed) was 30 kg of DM e 22 F.U. using 40 kg/ha of N and 27 kg/ha of DM and 21 F.U. using 120 kg/ha of
N
Esperienze di concimazione dei pascoli: risultati consegulti su terreni trachitici della Sardegna Centro-Occidentale
In the biennum 1972-'74, a factorial trial on N, P, K, fertilization was
carried aut on trachytic permanent pastures of Central-western Sardinia.
Nitrogen, at the dose of 100 kg/ha, brought about greatest production
increases of dry matter and U.F.. Phosphorus - still working beneficially
on the production, even if in a slighter manner - has its macroscopic effects
on plant population, with a remarkable leguminosae increase.
In the absolute, the best results are attained by binary N + P fertlization
(about 50 kg/ha of dry matter). K shows to have no effect
Introduzione in coltura di nuove specie foraggere: produttività e composizione bromatologica di <i>Chrysanthemum coronarium</i> L. (crisantemo) sottoposto a pascolamento simulato
Crysanthemum coronarium L. is a weed of grain cereals also grazed by sheep. A research, aimed at the productive and
qualitative characterization of C. coronarium, was carried out in North Sardinia (Italy) during 1993-96 in order to evaluate its
introduction and role, as pasture species, within forage systems for dairy ewes. A sowed sward of C. coronarium has been
evaluated both according to the «Corrall» method, with cutting every 28 days, and under undisturbated herbage accumulation.
“Corrall” seasonal yield trends were different between years due to the meteorological conditions and number of cuts. The forage
yields were 3,5, 2,5 e 1,9 t ha-1 ( respectively in the three years with high dry matter availability in winter and favourable crude
protein and NDF contents, particularly in late spring. Under undisturbated accumulation forage production were from twice to
six times higher than those obtained using the “Corrall” method. First data about seed production and re-establishment have
shown the self-reseeding capacity of this species. On the basis of the results obtained, C. coronarium appears very interesting as
forage species and its introduction in forage chains is desiderable.
Chrysanthemum coronarium L. (crisantemo) è una composita diffusa negli incolti ed infestante di colture a ciclo
autunno-vernino che, sulla base di numerose osservazioni, è appetita dagli ovini. Al fine di valutare il suo possibile inserimento
e ruolo, come specie da pascolo, all'interno di sistemi foraggeri asciutti mediterranei è stata effettuata una ricerca volta alla
caratterizzazione produttiva e qualitativa di una popolazione naturale di crisantemo. Nel Nord-Sardegna una cotica artificiale di
C. coronarium è stata valutata sia secondo la metodologia “Corrall”, con sfalci ripetuti ogni 28 giorni, sia sotto accrescimento
indisturbato, durante il triennio 1993-96. Le curve stagionali di produzione relative alle tre annate sono risultate diverse tra loro
per effetto dell'andamento meteorologico e della frequenza degli sfalci. Le produzioni complessive accertate con la prima
metodologia sono state pari a 3,5, 2,5 e 1,9 t ha-1 di sostanza secca rispettivamente nelle tre annate, con elevate disponibilità
invernali e favorevoli tenori in proteina grezza e NDF soprattutto nelle utilizzazioni di tarda primavera. Le produzione massime
conseguite sotto accrescimento indisturbato sono risultate pari a 8,8, 10 e 12 t ha-1 nelle tre annate e da 2 a 6 volte superiori
rispetto a quelle stimate con la metodologia “Corrall”.
I primi dati sulla produzione degli acheni ed il reinsediamento spontaneo delle plantule nell'autunno successivo hanno
messo in evidenza la spiccata capacità autoriseminante del crisantemo.
Sulla base delle caratteristiche produttive e qualitative riscontrate nel triennio, C. coronarium appare di sicuro interesse dal punto
di vista foraggero; pertanto è auspicabile la sua introduzione in coltura ed il suo inserimento come specie da pascolo in sistemi
foraggeri asciutti
Itinerari tecnici per la raccolta meccanica di seme di <i>Medicago polymorpha</i> : sintesi dei risultati del secondo anno di attività
Sintesi dei risultati della raccolta meccanica di seme di Medicago polymorpha, effettuata nel mese di giugno 2006 presso l'azienda "Ottava" dell'Università degli studi di Sassari
A Static Hybrid Renewable Energy System for Off-Grid Supply
The electrification of the rural areas of the planet has become one of the greatest challenges for sustainability. In fact, it would be the key to guaranteeing development for the poorest areas of the planet from which most of the raw material for the food market derives. The paradigm of centralized production is not applicable in these territories, because the distribution network would involve unjustifiable costs. For this reason, many studies have been carried out to ensure that the energy supply (specifically electricity) for off-grid utilities is maintained, in order to guarantee energy autonomy while reducing dependence on specialist assistance for the management of the system. In this work, a hybrid system (HRES) is proposed that combines the exploitation of solar radiation, wind power, and biomass using static devices, in order to improve the system’s availability and limit the cost of operation and maintenance. The aim of the study is to define promising lines of research, which can improve the sustainability of renewable harvesting systems to supply off-grids users
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