03469naa a2200289 a 450000100080000000500110000800800410001902400540006010000200011424501630013426000090029752025960030665000140290265000120291665000190292865000190294765000220296665000170298865000220300565000140302765000220304165300120306370000190307570000170309470000140311177300540312515237852023-05-24       1979    bl uuuu     u00u1 u    #d7 ahttps://doi.org/10.1016/0304-3746(79)90024-62DOI1 aPEAKE, D. C. I.  aSimulation of changes in herbage biomass and drought response of a buffel grass (Cenchrus ciliaris cv. biloela) in Southern Queensland.h[electronic resource]  c1979  aAbstract: Changes of herbage biomass on ungrazed Biloela buffel grass swards at the Narayen Research Station were investigated in field experiments and by means of computer simulation. The daily rate of change of herbage biomass was calculated by an empiricial model consisting of two equations. The first, used when the ration of estimated actual to potential transpiration (transpiration ratio) was &gt 0.26, computed the daily of increase in herbage dry weight (DW) as the product of the potential net production of herbage multiplied by temperature and moisture factors, and by a factor that allowed for delayed regrowth when effective rain fell after drought. The second equation, used when the transpiration ratio was &lt 0.26, computed the daily loss of DW as a function of the standing weight of herbage multiplied by the same moisture factor. Transpiration was estimated with a water-balance model. The herbage model was used to simulate the biomass of Biloela buffel grass on an ungrazed field experiment on a duplex soil (similar to the solodic and eutric planosols of the ?FAO Soil Map of the World?). The plots were mown three times a year, in spring, summer and autumn, and they received sufficient nitrogen and other nutrients for near-maximum production. The linear regression of measured on simulated DW's of herbage for the two years' data from which the values of the models' constants and functions were derived had a coefficient of determination (R2) of 0.955; two additional years' results from the same experiment were estimated with an R2 of 0.913. Using the same model but different soil constants, in another experiment at Narayen on a gradational clay soil (related to the eutric nitosols) the biomass of Biloela buffel grass was simulated with an R2 of 0.823. The model was then used with historical rainfall records to simulate the biomass of Biloela buffell grass herbage in the Narayen environment for the period 1887 to 1973. Frequencies were calculated for: (a) in the case of swards with optimum nitrogen supply ? estimated mean daily transpiration ratios, estimated daily rates of herbage production (or reduction), and estimated herbage yields from three harvests a year, and (b) in the case of swards dependent on soil nitrogen ? potential nitrogen fertilizer responses of at least 200 or 2000 kg DW ha?1 at the spring, summer and autumn harvests. The reduction in standing crop of herbage during drought, delay in regrowth after drought, evapotranspiration models, and nitrogen responses in dry climates are discussed with reference to previous results.  aAustralia  aBiomass  aForage grasses  aGrowing season  aVegetable growing  aCapim Buffel  aCenchrus ciliaris  aGramínea  aPlanta Forrageira  aWeights1 aHENZELL, E. F.1 aSTIRK, G. B.1 aPEAKE, A.  tAgro-Ecosystemsgv. 5, n. 1, p. 23-40, Jan. 1979.