Phosphorus Needs of Some Australian Plants

Kevin Handreck

Over the past several years a number of SGAP members (listed below) assisted me with a CSIRO trial that tested the phosphorus-sensitivity of a considerable number of Australian plants. The plants were grown from seed in small tubes, each of 200 ml capacity. The potting mix was composted bark and sand to which had been added single superphosphate at rates of zero, 0.06, 0.25, 0.40 and 0.90 grams per litre of mix. The mix contained ample supplies of all trace elements. Nitrogen and potassium were supplied via a zero-phosphorus Osmocote. Sowing was direct onto the surface of the mix in the tubes. The seed was covered with washed 3 mm gravel. Seedlings were thinned to one per tube and grown until the largest were considered to be ready for planting out. Deaths of seedlings were noted and the growth and quality of survivors was recorded.

We started off with seeds of nearly 2000 species, but lack of germination reduced the number of species for which data were collected to 810. Eucalypts were deliberately not included in the trial, because most are quite tolerant of phosphorus. Results with them would have been similar to those obtained with melaleucas. The species were assigned scores according to their growth, the appearance of toxicity symptoms and general pattern of response to phosphorus.

Score 1
Plants were healthy at all levels of phosphorus addition, with a grading from essentially no growth without phosphorus addition to the greatest growth at the highest rate of phosphorus addition.
Score 2
Plants were healthy at all levels of phosphorus addition, but there was some growth in the mix that had not received any phosphorus. Growth was greatest at the highest rate of P addition.
Score 3
All plants were healthy, with some growth without added phosphorus. The largest plants tended to be in the mix with the second-highest phosphorus addition rate, with those in mix with the highest rate of addition being somewhat smaller, but without any unusual foliar symptoms.
Score 4
There were slight toxicity symptoms at the highest P addition rate. The largest healthy plants were at the second-highest rate.
Score 5
There were severe symptoms of P toxicity at the highest rate of addition, and some toxicity at the second-highest rate.
Score 6
There was considerable P toxicity at the two highest rates. The best plants were in the mixes with the two lowest rates of amendment with superphosphate. Plants were smaller in the mix without added phosphorus.
Score 7
Plants in the mix without added phosphorus were the only ones that grew well.

An obvious thing about the list in that the majority of the species were assigned to the first three score categories. In fact, of the 810 species for which data were eventually collected, about 82% did not show any of the symptoms that are typical of phosphorus toxicity. They grew best at the two highest rates of single superphosphate addition (0.4 to 0.9 kg/m3).

The amount of phosphorus in a 200 ml tube from an addition of 0.25 and 0.4 kg/m3 of single superphosphate was 4.3 and 6.8 mg, respectively. The lower amount is not quite enough to produce a seedling of planting-out size, but the higher amount is sufficient as long as little of it is lost by being leached from the container.

The more usual method of supplying phosphorus to plants in containers is via a controlled-release fertiliser (CRF) such as Nutricote, Osmocote, Green Jacket or Apex. At its simplest, no superphosphate is added to the mix and the CRF supplies all that is needed. The following table lists a few controlled-release fertilisers of low water-soluble phosphorus content that will provide enough phosphorus for a whole production period for most Australian plants.


Phosphorus Release of Some Controlled Release Fertilisers
Note: these products may have been superseded since this trial was carried out
or may now have different specifications
FertiliserWater-
soluble
phosphorus
(%)
When added
at 3kg/m3,
phosphorus
released per
200ml tube
(mg)
When added
at 3kg/m3,
phosphorus
released per
130mm pot
(mg)
Nutricote Blue or Red
(140 day)
1.37.839
Nutricote Total N18
(140 day)
0.95.427
Osmocote Plus 17:1.6:8.7
(8-9 month)
1.37.839

While these CRFs can provide all the P requirements of Australian plants that are being grown in a mix that has essentially no soluble phosphorus, there is one situation that makes it desirable to include some soluble phosphorus in the mix. This is in the production of seedlings of myrtaceous species (eucalypts, melaleucas, callistemons, etc). Phosphorus reserves in the often tiny seeds of these species are very low. In mixes with essentially no soluble phosphorus, growth will be very slow until seedling roots make contact with CRF prills. Early slow growth is avoided if the mix contains about 0.2 kg/m3 of single superphosphate.

Healthy phosphorus-sensitive plants typically have much lower phosphorus concentrations than do plants of less sensitive species. Such plants are successfully produced in tubes that contain any of CRFs listed above. However, if such a plant were being produced in a 130 mm pot with low-phosphorus CRFs as listed above, the 30-40 mg phosphorus being released could be enough to cause toxicity. The larger the pot, the lower should be the actual percentage of phosphorus in the CRF used. Blends of zero-phosphorus and low-phosphorus products should be used. This is likely to apply to all species that are listed in the 6-7 score categories in the table, and possibly to some of those in the score 5 category.


Phosphorus Sensitivity Lists - Least Sensitive (Score 1) to Most Sensitive (Score 7)

Score 1
Abutilonindicum, leucopetalum, oxycarpum
Acaciaamblyphylla, ampliceps, aphanoclada, bivenosa, brachystachya, calcigera, chrysella, colletioides, delibrata, dentifera, dictyoneura, elata, estrophiolata, extensa, floribunda, gracilifolia, graffiana, gregorii, guinetii, hakeoides, harveyi, holosericea, horridula, howittii, inaequilatera, iodomorpha, jibberdingensis, juncifolia, lanigera, lasiocalyx, lasiocarpa, leiophylla, leptocarpa, linophylla, littorea, longifolia, meissneri, microbotrya, o'shanessii, oncinophylla, oxycedrus, paraneura, pendula, polybotrya, prainii, pulchella, quadrimarginea, quornensis, ramulosa, retinoides, rigens, rostellifera, rotundifolia, sclerophylla, sclerosperma, spathulata, stenophylla, subcaerulea, subtessaragona, tetragonophylla, translucens, tysonii, venulosa, verniciflua, verticillata, wiseana
Agonisflexuosa, grandiflora, juniperina, marginata
Allocasuarinacorniculata, decaisneana, dielsiana, huegeliana, lehmanniana, meulleriana, pusilla, scleroclada, striata, verticillata
Alternantheranodiflora
Alyogynecuneiformis, hakeifolia
Anigozanthosbicolor, humilis, manglesii
Aotusericoides
Atriplexacutibracta, amnicola, leptocarpa, lindleyi, nummularia, rhagodioides, semibaccata, stipitata, suberecta, undulata
Banksiaaudax, elderana, laevigata, lanata, littoralis, menziesii, petiolaris, speciosa
Beaufortiamicrantha, orbifolia
Beyerialechenaultii
Billardieracymosa
Bonamiarosea
Boroniadenticulata
Bossiaeaericocarpa, foliosa, heterophylla, pulchella, rhombifolia
Brachychitonacerifolius, diversifolia
Brachysemaaphyllum, lanceolatum, latifolium
Callistemonbrachyandrus, citrinus, glaucus, phoenicius, pinifolius, pungens, rigidus, rugulosus, sieberi, speciosus, viminalis
Callitriscolumnellaris, preissii
Calocephalusbrownii, citreus
Calothamnusasper, chrysantherus, quadrifidus, sanguineus, tuberosus, validus, villosus
Canavaliapapuana
Casuarinacristata, glauca
Chorizemacordatum, dicksonii, diversifolium, ilicifolium
Conostylisaculeata, candicans
Convolvuluserubescens, remotus
Crotalariaretusa, novae-hollandiae
Daviesiabenthamii, corymbosa, flexuosa, latifolia, longifolia
Diplolaenagrandiflora
Diplopeltiseriocarpa
Dodonaeaaperta, ceratocarpa, hackettiana, inaequifolia, lobulata, microzyga, ptarmicifolia, stenozyga, viscosa
Dryandrabaxteri, ferruginea, fraseri, nobilis, serratuloides, sessilis, shuttlworthiana, stuposa
Enchylaenatomentosa
Eremaeaebracteata, pauciflora
Gastrolobiumspinosum
Goodeniastapfiana
Goodialotifolia
Gossypiumsturtianum
Grevilleacrithmifolia, robusta
Hakeaarborescens, brooksiana, commutata, coriacea, dactyloides, eriantha, falcata, macraeana, nodosa, suaveolens, verrucosa, vittata
Hannafordiaquadrivalvis
Hardenbergiacomptoniana
Hibiscusfarragei
Hoveacrispa, trisperma
Hypocalymmaangustifolium
Indigoferaaustralis
Isopogonceratophyllus
Isotropisatropurpurea, divergens
Jacksoniasternbergiana
Kennediabeckxiana, eximea, prorepens, rubicunda, stirlingii
Keraudreniahermanniifolia
Kunzeaambigua, baxteri, ericifolia, pomifera, teretifolius
Labichealanceolata
Lamarcheahakeifolia
Lambertiapropinqua
Lasiopetalumbaueri
Lavateraplebia
Lawrenciadensiflora, glomerata, repens, spicata, virid-grisea
Leptospermumcontinentale, coriaceum, flavescens, juniperinum, laevigatum, lanigerum, myrsinoides
Linummarginale
Lobeliaheterophylla, tenuior
Lotusaustralis, cruentus
Lysiphyllumcunninghamii
Maireanabrevifolia, sedifolia
Melaleucaacerosa, acuminata, armillaris, brevifolia, cardiophylla, citrina, cliffortioides, coccinea, concreta, cordata, cucullata, cuticularis, decussata, densa, depressa, diosmifolia, dissitiflora, elliptica, ericifolia, filifolia, fulgens, gibbosa, glaberrima, globifera, glomerata, halmaturorum, hamulosa, huegelii, holosericea, hypericifolia, incana, lanceolata, lateralis, lateriflora, lateritia, laxiflora, leiocarpa, leucadendra, microphylla, nesophylla, pentagona, pulchella, radula, rhaphiophylla, sheathiana, spathulata, spicigera, squamea, squarrosa, steedmanii, striata, stypheloides, suberosa, subfalcata, thymoides, thyoides, trichophylla, uncinata, undulata, urceolaris, viminea, viridiflora, wilsonii
Mirbeliaspinosa
Myoporumacuminatum
Myriocephalusstuartii
Neptuniamonosperma
Oleariateretifolia
Orthrosanthusmultifrorus
Oxylobiumatropurpurea, cuneatum, lanceolatum, racemosum
Pandoreapandorana
Pavoniahastata
Petalostylislabicheoides, millefolium
Petrophilecanescens, carduacea, diversifolia, heterofolia, longifolia, serruriae
Phymatocarpusporphyrocephalus
Pittosporumphylliraeiodes
Plantagovaria
Podolepisrugata
Psoraleacinerea, martinii, plumosa
Pultenaeareticulata
Radyerafarragei
Regeliaciliata
Rhagodiacandolleana, crassifolia, parabolica, preissii, spinescens
Samolusjunceus
Sennaartemisioides, helmsii, odorata, pleurocarpa, venusta
Sesbaniacannabina, simpliciuscula
Sidacalyxhymenia, rholenae
Solanumlinearifolium, simile, symonii
Stylidiumadnatum
Swainsonacanescens, colutoides, formosus, tephrotricha, villosa
Templetoniaegena, sulcata
Thomasiapetalocalyx
Thryptomeneaustralis
Velleiacycnopotamica, panduriformis, trinervis
Villarsiacapitata
Viminariajuncea
Wahlenbergiapreissii
Waitziaacuminata
Xanthorrhoeaquadrangulata, semiplana
Zygophyllumaurantiacum

Score 2
Acaciacomplanata, cuthbertsonii, fasciculifera, pyrifolia, validinevia, viscidula
Actinostrubuspyramidalis
Banksiaashbyi, brownii, caleyi, lemanniana, nutans, occidentalis, pilostylis, prionotes, pulchella, repens, violacea
Dodonaeahexandra
Dryandraarborea, carduacea, formosa, obtusa
Flindersiaaustralis
Hakeacycloptera, gibbosa, muelleriana
Isopogondubius
Platylobiumobtusangulum

Score 3
Abutilonlepidum
Acaciaamoena, blakelyi, deanei, difformis, dodonaeifolia, eremaea, exocarpoides, fauntleroyi, hemignosta, leptospermoides, maitlandii, megalantha, monticola, murrayana, neriifolia, orthocarpa, oxyclada, pachyacra, parramattensis, pellita, perangusta, pruinocarpa, pubicosta, pyrifolia, rubida, semilunata, siculiformis, torulosa, trachycarpa, triptera, uncinata, vestita, wildenowiana, xanthina, xylocarpa
Allocasuarinacampestris, lehmanniana
Alternantheranana
Amaranthuspallidiflorus
Anigozanthosviridis
Banksiaaemula, candolleana, coccinea, leptophylla, marginata, robur
Bossiaeaensata, scolopendria
Canavaliamaritima
Casuarinaobesa
Crotalariacunninghamii
Daviesiaacicularis, decurrens, physodes, revoluta, rhombifolia, teretifolia, umbellata
Dillwyniabrunioides, dillwynioides
Dryandracalophylla, carduacea, carlenoides, mucronulata, polycephala, quercifolia, tenuiifolia, vestita
Gastrolobiumbilobum
Gomphrenaaffinis
Hakeaadnata, baxteri, cristata, epiglottis, ferruginea, flabellifolia, platysperma, sericea, stenophylla
Jacksoniasericea
Kennediacoccinea
Lotuscruentus
Melochiapyramidata
Mirbeliadilatata, ramulosa
Oxylobiumcapitatum, ellipticum, parviflorum
Patersoniaoccidentalis
Petrophilefastigiata
Santalumacuminatum
Sennaluerssenii, oligophylla, planitiicola

Score 4
Abrusprecatorius
Acaciachincillensis, declinata, erinacea, glaucoptera, havilandii, iteaphylla, lineata, longispinea, lysiphloia, melliodora, merinthopora, papyricarpa, paradoxa, patagiata, rhodophloia, saligna, sessilispica, sibina, stereophylla, subcaerulea, terminalis, triptycha, uncinella, williamsonii
Adansoniagregorii
Banksiaattenuata, burdettii, ericifolia, integrifolia, laricina, media, oblonga, ornata, tricuspis
Bossiaeaaquifolium, webbii
Brachysemaaphyllum
Calothamnuspinifolius, rupestris
Conospermumtaxifolium
Crotalariacunninghamii, verrucosa
Darwiniadiosmoides
Daviesiaangulata, cordata, divaricata, horrida
Diplopeltishuegelii
Dryandrapulchella
Gastrolobiumlaytonii
Goodeniacorynocarpa, redacta
Gossypiumrobinsonii
Grevilleabiternata, pterosperma
Hakeabrachyptera, crassifolia, leucoptera, oleifolia, orthorrhyncha, petiolaris, rostrata, salicifolia
Isopogonanethifolius
Leptospermumlaevigatum
Melaleucaeleutherostachya, leptospermioides, leucodendron
Oleariafloribunda
Plantagodrummondii
Psoraleabadocana, lachnostachys
Pultenaeadasyphylla
Sennapruinosa
Sesbaniaerubescens
Sollyaheterophylla
Sphaerolobiumfornicatum
Swainsonadecurrens
Tephrosiaflammea

Score 5
Acaciaancistrocarpa, citrinoviridis, dawsonii, denticulosa, dictyopyhleba, fauntleroyi, fragilis, gillii, granitica, hilliana, imbricata, latipes, leioderma, lycopodifolia, mollifolia, nodiflora, pachycarpa, phlebopetala, pilligaensis, pinguifolia, pruinosa, pubifolia, pustula, quadrisulcata, retivenia, rossei, rupicoIa, saliciformis, shirleyi, signata, stricta, tenuissima, tetragonocarpa, trachyphloia, urophylla, wanyu
Amaranthusmitchellii
Banksiaaculeata, canei, cunninghamii, grandis, victoriae
Bossiaeapreissii
Calothamnusaffinis, blepharospermus
Daviesiaincrassata, mimosioides, polyphylla, wyattiana
Dodonaeacaespitosa, microzyga, petiolaris, viscosa ssp.spathulata
Dryandraashbyi, cuneata, falcata, foliosissima, nivea, pteridifolia
Gastrolobiumspinosum v.grandiflorum
Glycirrhizaacanthocarpa
Gompholobiummarginatum, tomentosum
Gomphrenacanescens
Gossypiumaustrale
Hakeacorymbosa, costata, eyreana,minyma, nitida, undulata
Indigoferaboviperda, colutea, georgei, hirsuta
Isopogonalicornis
Jacksoniafloribunda
Pultenaeacapitata
Sidacorrugata
Stylidiumscandens
Thespesiapopulneoides

Score 6
Acaciaalata, anaticeps, aphylla, aspera, auriculiformis, boormanii, cochlearis, cultriformis, drepanocarpa, dunnii,gilbertii, gladiiformis, hemiteles, hilliana, kempeana, ligustrina, minutifolia, multispicata, nervosa, neurophylla, nitidula, notabilis, rhigiophylla, sessilis, siculiformis, spectabilis, unifissilis, victoriae, wattsiana, wilhemiana
Achyranthesaspera
Actinostrobusarenarius
Agonisacutivalvis, obtusissima
Alyogynehuegelii
Banksiaattenuata, baueri, baxteri, benthamiana, blechnifolia, hookeriana, incana, lemanniana, leptophylla, oblongifolia, paludosa, quercifolia, scabrella, sceptrum, seminuda, telmatiaea
Bossiaealaidlawiana, linophylla
Brachichitondiversifolius
Burtoniapolyzyga, scabra
Daviesialeptophylla, ulicifolia
Dichrostachysspicata
Dodonaealobulata, peduncularis, physocarpa
Dryandraarmata, comosa, hewardiana
Gompholobiumlatifolium
Gomphrenacunninghamii, fusiformis
Grevilleabanksii, thelemanniana
Hakeabrownii, cinerea, decurrens, erecta, gilbertii, incrassata, lasianthoides, marginata, obtusa, pandanicarpa, prostrata, pycnoneura, scoparia
Hardenbergiaviolacea
Hibiscusmeraukensis
Isopogonaxillaris, formosus
Jacksoniafurcellata, lehmannii
Kennediaprostrata
Lysiphyllumcalycina, gilvum, sparsiflora
Nitrariabillardierei
Oleariapimeleiodes
Oxylobiumreticulatum
Petrophiledrummmondii, ericifolia
Poranasericea
Sennanotabilis
Sidacardiophylla, echinocarpa
Swainsonacyclocarpa
Templetoniaretusa
Tephrosiacoriacea
Xylomelumangustifolium

Score 7
Acaciapolystachya
Bossiaeadentata
Petrophilesessilis

I would like to sincerely thank the following SGAP members for the considerable amount time and effort they put into this project: Lloyd and Lorraine Carman, John and Tracy Early, Wendy and Brian Fopp, Mick Freeborn, Barbara Godfrey, Ian Graham, Karen Lane, Ben Lethbridge, John Maddern, Jamie Mugridge, Karen Parry, Arthur Pratt, Warrick Pybus (and his employees Eddie Bos, Mark Castine, Martin Giles and John Rievel), Jeff Read, Dean Reid, Jeff Reid, Ian Roberts and Diedre Stewart.




This article is reproduced from the February 1997 issue of the "SGAP Journal", the newsletter of the South Australian Region of the Society for Growing Australian Plants.

At the time of this trial, Kevin Handreck was Senior Research Chemist with the CSIRO (Commonwealth Scientific and Industrial Research Organisation) Division of Soils, Adelaide.


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