Thesis (MScFor)--Stellenbosch University 2002. / ENGLISH ABSTRACT: One of the greatest .limitations to the productivity of a plantation forest is poor nutrient status of the soil. Empirical application of corrective treatments are marginally successful in some cases, but because of limited understanding of the soiltree system, most nutritional problems go unnoticed or are accepted as a conceivable growth constraint. The aim of this investigation was to identify nutrient growth problems through field observations and to determine means of confirming these nutrient imbalances. Poor and abnormal growth of pine trees in the following areas were investigated: (i) The North Eastern Cape: Ugie and Maclear Districts (ii) The Natal Midlands: Mooi River area (iii) Mpumalanga: .Graskop and Kaapsche Hoop areas (iv) Southwestern Cape: Jonkershoek Plantation The study was conducted as nursery trials at the University of Stellenbosch and field trials at the various locations. Soils from the different regions were collected and used as growing media to test the growth response of five timber species (Pinus patula, P. elliottii, P. taeda, P. greggii and Eucalyptus nitens) under controlled conditions to various nutrient treatments. Indicator plants (cauliflower and soya) were included in these bio-assays. In the field trials nutrients were applied to seedlings and established stands of various ages by means of foliar and soil application. In the nursery trials and the trials where seedlings were planted in the field, plant performance was measured by quantitative means. The reaction of established stands to nutrient treatments were however less vigorous and qualitative means (e.g. colour changes) were used for assessment. Field observations in the North Eastern Cape and the Natal Midlands indicated possible boron, iron and molybdenum deficiencies and thus the work concentrates on these elements. Foliar and soil analyses reinforced these observations with marginal to deficient levels for boron and molybdenum being detected. The yellowing of foliage during the dry season was symptomatic of ineffective nitrogen assimilation and pointed to a molybdenum deficiency while seasonal growth tip dieback, resm exudation, sinuous tree limbs and bushy trees were classical boron deficiency symptoms. Potted trials indicated positive reaction to the application of boron and molybdenum deficiency symptoms were observed on indicator plants. Conclusive evidence of a boron deficiency in some of the pot trials, the planted field trials and the tree evaluation field trials remain elusive due to toxicity experienced as a result of an over-application of the nutrient. The occurrence of multiple deficiencies (phosphorous and calcium) further complicated the findings. The Mpumalanga observations indicated severe nutrient imbalance due to manganese toxicity (strong iron antagonism). The discolouring of the foliage on some sites towards the end of the winter was thought to be an induced molybdenum deficiency on the weathered and acidic red soils. Positive reaction to molybdenum application occurred in a single. tree evaluation trial, but because of soil oxidisation during collection, the effect of manganese toxicity was diluted in the pot trials. Foliar analyses indicated that foliar application of iron was unsuccessful and that other means should be considered to ensure uptake of this nutrient. / AFRIKAANSE OPSOMMING: Die lae vrugbaarheid van grond is een van die grootste beperkings tot die produktiwiteit van plantasie bosbou. Empiriese toedienings van kunsmisstowwe is in sekere gevalle suksesvol tot die bekamping van onvrugbaarheid. Weens gebrekkige kennis t.o.v die grond-boom sisteem word baie van die voedingstof probleme egter onkundig oorgeslaan' of word dit as natuurlike beperking in die produksie konteks aanvaar. Die doel van hierdie ondersoek was om swak boomgroei in die veld waar te neem en om bevestigende metodes te vind waarmee hierdie probleme as voedingstoftekorte geëien kan word. Swak en abnormale boomgroei van denne is in die volgende gebiede ondersoek: (i) Die Noordoos Kaap: Ugie- en Maclear Distrikte (ii) Die Natal Middelande: Mooirivier area (iii) Mpumalanga: Graskop- en Kaapsche Hoop areas (iv) Suidwes Kaap: Jonkershoek Plantasie Die ondersoek is uitgevoer as kwekery proewe by die Universiteit van Stellenbosch en as veldproewe in die onderskeie areas. Grond is uit die verskilende gebiede versamel en as groeimeduim gebruik om die groei-reaksie van vyf verskillende houtspesies (Pinus patula, P. elliottii, P. taeda, P. greggii en Eucalyptus nitens) onder beheerde klimaatsomstandighede te ondersoek. Daar is ook gebruik gemaak van indikator spesies (blomkool en soya) vir diagnose van visuele tekort simptome. Beide saailinge en reeds gevestigde bome is in die veldproewe gebruik. Voedingstowwe is by aanplanting toegedien, of in die geval van groter bome, as blaar- of grondtoedienings. Waar dit moontlik was (meestal in die geval van die saailinge) is die reaksie op die toegediende voedingstowwe met kwantitatiewe metodes bepaal. Daar moes egter van alternatiewe kwalitatiewe metodes gebruik gemaak word om die reaksie by die ouer en groter bome te bepaal. Gevolglik is verandering in bladkleur t.o.v. 'n basiskleur onder andere as maatstaf gebruik. Waarnemings van swak boomgroei in die Noordoos Kaap en die Natal Middelande het gedui op moontlike boor, yster en/of molibdeen tekorte. Lae vlakke van hierdie elemente in blaar- en grondanalises het hierdie waarnemings bevestig. Die geel verkleuring van die naalde gedurende die droë seisoen is simptomaties van oneffektiewe stikstof assimilasie en dui op 'n molibdeen tekort. Die waarneming van seisoenale terugsterwing van groeipunte, gebuigde stamme en takke, gomuitskeiding en bome met bosagtige voorkoms is eienskappe van 'n boor tekort. In die potproewe was daar positiewe reaksie op die toediening van boor en tekort simptome van molibdeen is in die indikator plante waargeneem. In van die potproewe, die saailing veldproewe en ander veldproewe kon daar egter nie uitsluitsel tot die effektiwiteit van boor gevind word nie aangesien toedienings te heftig was en toksisiteit ervaar is. Diagnose van enkel element voedingstof tekorte word bemoeilik deur van die proewe wat ook dui op veelvoudige voedingstoftekorte (veral fosfaat en kalsium). In Mpumalanga is daar waargeneem dat drastiese voedingstof wanbalanse a.g.v. mangaan toksisiteit aanwesig is (veral 'n sterk Fe antagonisme). Die bladverkleuring op sekere proefopstande aan die einde van die winter is ook 'n aanduiding van geïnduseerde molibdeen tekorte wat op die verweerde en suur rooi gronde van die omgewing verwag kan word. Daar was dan ook positiewe reaksie op die toediening van molibdeen, hoewel slegs byeen proefopstand. Die inherente nadeel van potproewe is op die mangaanryk gronde geopenbaar deurdat belugting (gedurende grond versameling) die effek van mangaan toksisiteit verminder het. Die gebruik van blaaranalises is ook voordelig aangewend om te bepaal dat die toediening van yster as blaartoediening onsuksesvol was en dat ander metodes ondersoek moet word om opname van die element te verseker.

Thesis (MScFor)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: In South Africa fertilizer applications at establishment is a common practice in the forestry industry. Recommendations are based on past research with conventional sources (CV) and as a result there have only been slight improvements in additional plantation production over recent years. The objective of this study was to investigate initial stand responses in terms of leaf are index (LAI), foliar nutrient content, biomass index (BI) and volume growth to the application of controlled release fertilizers (CRF) at re-establishment. Nitrogen (N), phosphorus (P) and potassium (K) were applied in a three way factorial combination to Pinus radiata at planting on a site in the Western Cape. The design was replicated five times across the study area. N (CRF) and P (CV) were applied in a two way factorial combination at planting to two Eucalyptus grandis x urophylla hybrids and Eucalyptus dunnii across three sites, one ex-agricultural and two re-establishment sites, on the Zululand coastal plain and the Midlands region. The design was replicated nine times on each study site. Harvesting residues were burnt on the eucalypt sites prior to establishment and may have had an impact on the responses found. An outbreak of Fusarium circinatum on the P. radiata site resulted in unexpected and extremely variable responses. An attempt to quantify the effect of the disease had limited success. The mean BI of the control treatment reached 25. The best CV and CRF treatments yielded improvements of 42 % and 83 % in BI over the control respectively, with only the CRF treatment difference being significant. Foliar analysis results revealed marginal to deficient concentrations of P and Mg being alleviated by the treatments in question. On the KZN Zululand sites there was a marked response of the hybrids to N with P having an additive effect on volume growth, LAI and foliar N content. Application of 120 g N and 20 g P per tree on the ex-agriculture site produced a volume of 8 m3 ha-1 at one year of age, a significant increase of 118 % and 80 % over the control and best CV treatment respectively. Application of 80 g N and 20 g P per tree, on the re-establishment site, yielded a volume of 24.6 m3 ha-1 at one year which equates to a significant 39 % and insignificant 7 % additional volume at one year over the control and best CV treatment respectively. A non-significant suppressive effect was found with 20 g CV P application only. At the KZN Midlands site, the major early response in height were to P application. Applications of 20 g CV P per tree, resulted in a mean height of 162.6 cm at seven months of age, a significant 28 % higher than the control. There was no significant effect of 80 g CRF N and 20 g CV P per tree respectively. CRF N applications up to 120 g per tree provide additional growth over recommended CV applications on coastal Zululand sites with low organic carbon (OC) content. On the KZN Midlands site with higher OC and clay content, early responses were limited to P fertilization only regardless of the fertilizer source. / AFRIKAANSE OPSOMMING: Dit is algemene praktyk in die Suid Afrikaanse bosbou industrie om kunsmis tydens aanplanting toe te dien. Hierdie aanbeveling is gebasseer op navorsing resultate met konvensionele bronne (CV), gevolglik was slegs ‘n klein toename in bykomende plantasie produksie gemeet die afgelope paar jaar. Die doelwit tydens hierdie studie is om die aanvanklike reaksie van die bome in terme van blaar oppervlak indeks (LAI), blaar-voedingstof inhoud, biomassa indeks (BI) en volume op die toediening van beheerde vrylating kunsmis (CRF) tydens aanplanting vas te stel. Stikstof (N), fosfor (P) en kalium (K) is in drie-ledige kombinasie aan Pinus radiata op ’n plantasie in die Weskaap toegedien. Die ontwerp is vyf keer in die studiegebied herhaal. N en P is in twee-ledige kombinasie aan twee Eucalyptus grandis x urophylla hibriede en Eucalyptus dunnii op drie groeiplekke, een eks-landbou en twee eks-bosbou, op die Zoeloeland kusvlakte en in die Natalse Middellande toegedien. Die ontwerp is nege keer in elke studiegebied herhaal. Oesreste is voor aanplanting op die Eucalyptus groeiplekke verbrand. Die voorkoms van Fusarium circinatum op die P. radiata groeiplek het onverwagte en hoogs uiteenlopende reaksies tot gevolg gehad. ’n Poging om die effek van die siekte te kwantifiseer, was slegs gedeeltelik suksesvol. Die gemiddelde BI van die kontrole behandeling, was 25. Die beste CV en CRF behandeling het onderskeidelik 42 % en 83 % hoër BI as die kontrole groep gehad, waarvan slegs die CRF behandeling beduidend was. Blaarontleding het gewys dat daar marginale of ontoereikende konsentrasies van P en Mg was. In Zoeloeland het die Eucalyptus hibriede ’n beduidende reaksie op N en P getoon met meer volume groei, LAI en N inhoud. Die toediening van 120 g N en 20 g P per boom op die eks-landbou groeiplek het ’n volume van 8 m3 ha-1 op eenjarige ouderdom tot gevolg gehad. Dis beduidend beter met 118 % en 80 % onderskeidelik vir die kontrole en beste CV behandeling. Die toediening van 80 g N en 20 g P per boom op die hervestigde eks-bosbou groeiplek, het ’n volume van 24.6 m3 ha-1 op eenjarige ouderdom tot gevolg gehad. Dit is 39 % beduidend en 7 % onbeduidend addisionele volume op eenjarige ouderdom vir onderskeidelik die kontrole groep en beste CV behandeling. ’n Onbeduidende depressie effek is met die alleen toediening van 20 g CV P gevind. In die Natalse Middellande groeiplek het die toediening van P ‘n vroeë reaksie in hoogte groei veroorsaak. Die toediening van 20 g CV P per boom, het ’n gemiddelde hoogte van 162.6 cm op die ouderdom van sewe maande tot gevolg gehad. Dit is 28 % beduidend hoër as die kontrole. Die toediening van 80 g CRF N en 20 g CV P per boom was onbeduidend. Toedienings van CRF N tot en met 120 g per boom het in die kusgebiede van Zoeloeland met ‘n lae organiese koolstof (OC) inhoud, groter groei as die aanbevole CV toedienings gehad. Die Middellande groeiplek met ’n hoër OC en klei inhoud, was die vroeë reaksie alleenlik beperk tot P bemesting.

The increased demand for wood and fiber from a continually shrinking land base has resulted in the use of intensively managed forest plantations. The concentration of timber production on the most suitable sites allows the world's demand for forest products to be met on less land and enable native forests to be conserved. Because much of the water flowing in rivers in the U.S. originates as precipitation in forests, there is a justified concern about the impacts of forest management on water quality. Nutrient concentrations were measured in eight streams from October 2002 to September 2011 to assess nutrient response to contemporary forest practices at the Hinkle Creek Paired Watershed Study in the Oregon Cascades. This period of time included a two-year pre-treatment calibration between control and treatment watersheds, a fertilization treatment of both basins in October 2004, and a post-treatment period from 2005 to 2011. A treatment schedule comprised of two temporally explicit harvest entries was used to assess the effects of clearcutting at the non-fish-bearing headwater scale and the fish-bearing watershed scale. Stream water samples were analyzed for nitrogen, phosphorus, calcium, sodium, potassium, magnesium, sulfate, chloride, and silicon as well as specific conductance, pH, and alkalinity. Programmable water samplers were used to take water samples during fall freshets in November 2009 to assess the stream water discharge versus NO₃ + NO₂ concentration relationship. All treatment watersheds showed a statistically significant increase in NO₃ + NO₂ concentrations after clearcutting (p < 0.001). The slope of the streambed through the disturbance was a stronger predictor of the magnitude of the response than was the magnitude of disturbance. Ammonia and organic nitrogen displayed notable increases after harvest treatment, but these increases were attributed to increases in the control watersheds. Phosphorus showed a response to timber harvest in one headwater stream. The remaining nutrients showed a small decrease in the control and treatment watersheds for the period after harvest. There was some evidence to suggest that the addition of urea nitrogen to both basins may have caused an increase in in-stream biota uptake of these nutrients. The storm response results showed that NO₃ + NO₂ concentrations in stream water increase with discharge during small storms that occur after periods of negligible precipitation. Concentrations of NO₃ + NO₂ observed during the calibration period were similar to concentrations observed in an old-growth forest in the H.J. Andrews, suggesting that nutrient processing within the Hinkle Creek watershed had returned to levels that existed prior to its initial harvest sixty years ago. This finding helps to assess long-term impacts of shorter rotation timber harvest of regenerated Douglas-fir stands characteristic of industrialized timber harvest in Oregon. / Graduation date: 2012

Thesis (MScFor)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: A field trial of six replications was established to test the effect of various wood ash and fertilisers application rates on soil chemistry, tree nutrition and early growth rate of a clonal Eucalyptus grandis x urophylla stand. Wood ash from pulpmills is currently disposed of in landfills. Increasing costs and potential environmental risks have driven companies to investigate alternative disposal methods. Ash consists of a combination of carbonates, hydroxides and other calcium containing minerals that induce the liming effect if ash is applied to a soil. The trial was established near Richards Bay in October 2013 on a sandy soil with a low buffer capacity and a pH of approximately 5.5. The trial consists of four wood ash application rates in combination with three levels of fertiliser, viz. no fertiliser, 150 g conventional NPK fertiliser mixture, or 320g NPK controlled release mixture. Fertiliser mixtures and application levels were based on previous fertiliser trials in the region. Ash application rates for the field trial were based on a lab incubation study done with soil samples from Richards Bay, to which increasing amounts of lime were added. The study tested wood ash application rates of 0, 300, 600 and 1200 kg/ha. Field measurements were taken at 4 and 8 months after trial establishment. The primary objective was to investigate which application levels in combination with the type of fertiliser could be applied to soils without negatively affecting the stand nutrition or increase the levels of potentially harmful elements in the soil; thus investigating the feasibility of safely disposing wood ash on plantation soils as an alternative disposal method. Soil nutrient concentrations were not affected by individual wood ash treatments, but more a product of the time interval after the ash additions were made. Soil C, P, K+ and Mg2+ showed decreased concentrations from 4-8 months after establishment. Ca2+ concentrations increased in the same time interval. In addition, Na+ and B concentrations decreased from 4-8 months. Soil heavy metal concentrations for Cd, Hg, Cr and Pb, analysed for 0-1200 kg/ha ash rates, were well below toxic levels at both time intervals. Wood ash induced a temporary liming effect. Mean soil pH increased with 0.6 units for the period 0 - 4 months and decreased with 0.4 units at 4 - 8 months after trial establishment. Foliar nutrient analyses and assessment techniques revealed sub-optimal nutrient concentrations for P, K and Zn at 4 and 8 months of age. Concentrations were defined as sub-optimal, as none of the nutrients were below critical levels. Foliar heavy metal concentrations for Cd, Hg, Cr and Pb, measured at both time intervals, were less than 1mg/kg. The small concentrations found in this project were attributed to the low bioavailability of all four elements and were likely a product of the edaphic factors at Richards Bay, which was representative of a large greater portion of the Zululand coastal plain sites. The response in biomass index ranged between 13 % and 683 % relative to the control treatment (A0F0). Results showed that application of purely wood ash, or in combination with a supplementary N and P source increased growth up to 8 months after trial establishment for wood ash applications up to 1200 kg/ha. This project demonstrated that 1200 kg/ha wood ash can safely be disposed of on a typical Zululand coastal sand with little environmental risk and no supressed growth, provided that it is balanced with an appropriate NP fertiliser. / AFRIKAANSE OPSOMMING: ‘n Veldproef met ses herhalings is in Oktober 2013 uitgelê met die doel om die uitwerking van verskillende vlakke hout as en kunsmis toedienings op die grond-voedingstof status, boom-voedingstof status en die groei-tempo van ‘n Eucalyptus grandis x urophylla hibried plantasie te bestudeer. Hout as by pulpmeulens word tans weggegooi op stortingsterreine. Toenemende onkostes vir storting en die omgewingsrisiko’s gebonde aan stortingsterreine, dryf maatskappye om verbeterde en meer omgewingsvriendelike metodes te ondersoek om van die as ontslae te raak. Hout as bestaan uit ‘n reeks karbonate, hidroksiede en kalsium bevattende minerale en is verantwoordelik vir die bekalkingseffek op die grond na toediening. Die veldproef is geleë naby Richardsbaai op ‘n sanderige grond met n lae bufferkapasiteit en pH van ongeveer 5.5. Die proef het vier hout as vlakke getoets, gekombineer met drie vlakke van bemesting: geen, 150g konvensionele landbou kunsmis (CV) óf 320g beheerd-vrystellende kunmis (CRF). Die kunsmismengsels en vlakke van bemesting is gebaseer op bestaande of voltooide bemestingseksperimente in die streek. Hout as vlakke was bereken in gekontroleerde laboratorium toestande en gebaseer op ‘n inkubasie studie met grond monsters verkry vanaf Richardsbaai, waarby toenemende vlakke suiwer landboukalk gevoeg is. Die veldproef het hout as vlakke van 0, 300, 600 en 1200 kg/ha getoets. Veld metings is op 4 en 8 maande na behandeling geneem. Die primêre doelwit van die studie was om te bepaal watter vlak hout as en kunmis kombinasie toegedien kan word, sonder om die grond-voedingstof status negatief te beïnvloed of ‘n potensiële skadelike uitwerking op die plantasie groei te veroorsaak. Die uiteinde van die studie was om die haalbaarheid van hout as toedienings op plantasie gronde te bestudeer relatief tot die huidige praktyk van storting, insluitend die risiko van moontlike skadelike newe-effekte. Grondvoedingstatus was nie beduidend beïnvloed deur individuele hout as toevoegings nie, maar was eerder ‘n funksie van die tydsduur sedert behandeling. Grond koolstof, P anione, K+ en Mg2+ konsentrasies het beduidend afgeneem in die periode van 4 - 8 maande na behandling. Die Ca2+ konsentrasies het toegeneem tussen 4 en 8 maande en terselfdertyd het Na+ en B konsentrasies afgeneem. Die swaarmetaal status, spesifiek vir Cd, Hg, Cr en Pb, vir toevoegings van 0-1200 kg/ha hout as was beduidend laer as toelaatbare vlakke in gronde op albei tydsintervalle. Die hout as het ‘n tydelike toename in grond pH veroorsaak. Die gemiddelde pH het tussen 0 - 4 maande toegeneem met 0.6 eenhede en gedurende 4 - 8 maande afgeem met 0.4 eenhede. Blaarontledings en voedingstof assesseringsmetodes het sub-optimale konsentrasies vir P, K en Zn getoon op die ouderdom van 4 en 8 maande. Voedingstof konsentrasies is as sub-optimaal geklassifiseer, omdat konsentrasies nooit laer as kritieke waardes vir gebreksimptome was nie. Die inhoud van Cd, Hg, Cr en Pb in blare was aansienlik kleiner as 1 mg/kg op albei tydsintervalle. Die merkwaardige lae konsentrasies wat in die projek aangeteken is, word toegekryf aan die lae bio-beskikbaarheid van al vier elemente as gevolg van die edafiese faktore eie aan die Richardsbaai omgewing (en ook aan groot dele van die Zoeloelandse kusvlakte). Die groeireaksie (bepaal as biomassa indeks op ouderdom 8 maande) het gewissel van 13 % - 683 % groter as die kontrole behandeling (A0F0). Resultate het bewys dat toedienings van suiwer hout as, of hout as gekombineer met ‘n addisionele N en P kunsmisbron die groei postief beïnvloed tot op die ouderdom van 8 maande. Die studie het bewys dat 1200 kg/ha hout as veilig toegedien kan word op die sandgronde van die kusgebiede in Zululand, met minimale omgewingsrisiko en geen tekens onderdrukte groei nie, mits dit gebalanseer word met ‘n geskikte NP kunsmisbron.