Mears, P.T. and Humphreys, L.R. (1974) Nitrogen response and stocking rate of Pennisetum clandestinum pastures. 1. Pasture nitrogen requirement and concentration, distribution of dry matter and botanical composition. Journal of Agricultural Science, 81 (3). pp. 451-467.
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Abstract
Ammonium nitrate was applied to a Kikuyu grass dominant pasture at annual rates of 0, 134, 336 or 672 kg N/ha. Each N treatment was continuously grazed at 3 stocking rates (SR) designed to apply similar grazing pressures at each N level and covering a range from 2.2 to 16.6 Angus weaner cattle/ha. The N status of these pastures was periodically assessed 8-10 weeks after seasonal N applications by temporarily excluding stock and measuring DM and N response to additional ammonium nitrate application. Pasture growth response to additional N was constant and independent of SR and of annual N rate over the range 0-336 kg N/ha, despite wide variation in pasture availability. N concentration of plant shoots was increased by high SR, and the rate of N uptake was not significantly affected by SR. Pasture growth rate was positively related to annual N rate. Herbage yield of leaf, stem and litter on offer was negatively related to SR, but weight of underground organs was unaffected. Increasing SR increased the proportion of leaf and the rate of tillering. Pasture availability was positively and linearly related to N rate over the range 0 to 336 kg N/ha. The size of the litter fractions and underground organs was generally independent of N rate. N content in leaf and stem was reduced at low SR; N content of leaf, stem, litter, rhizome and root was positively related to N rate, which was more influential than SR. The effect of SR on the size and relative distribution of the N in plant tops and litter fraction is discussed. Kikuyu grass dominance was positively related to N rate and was independent of SR. There was invasion by white clover with 0 and 134 kg N/ha, especially at a high SR
| Item Type: | Article |
|---|---|
| Author Affiliation: | Research Station, Department of Agriculture, Grafton, New South Wales 2460, Australia |
| Subjects: | Plant Protection Plant Physiology and Biochemistry > Biochemistry |
| Divisions: | Millet |
| Depositing User: | Mr B Krishnamurthy |
| Date Deposited: | 12 May 2012 04:34 |
| Last Modified: | 12 May 2012 04:35 |
| URI: | http://eprints.icrisat.ac.in/id/eprint/5252 |
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