Promocijas darbs

Promocijas darbā pētītas augsnes virskārtas morfoloģiskās īpašības (atbilstoši EHFRB humusa formu klasifikācijai), organisko vielu saturs, padziļināti pētīts augsnes humusvielu sastāvs un ķīmiskās īpašības. Pētījuma rezultāti liecina, ka sausieņu mežos Latvijā organiskajām vielām relatīvi bagātu augšņu (mull humusa formas) telpisko izplatību nosaka glacigēnie un glaciolimniskie nogulumi. Lauksaimniecības zemju apmežošanās procesā organisko vielu uzkrāšanās augsnes virskārtā sākas 30 gadus pēc apmežošanās, augstākā C krāja ir 60 līdz 100 gadus vecu meža zemju augsnēs. Palielināts koku nobiru īpatsvars meža attīstības gaitā augsnē veicina fulvoskābju īpatsvara pieaugumu, kā arī augsnes humīnskābju humifikācijas, aromatizācijas pakāpes un molekulmasas pieaugumu. Atslēgas vārdi: augsne, humusa forma, apmežošanās, organiskais ogleklis, humusvielasThe doctoral thesis presents a research on the topsoil, its morphological properties (according to the EHFRB humus form classification), and organic matter, focusing on the composition and the chemical properties of the soil humic substances. The results indicate that in forests formed on dry mineral soils in Latvia the spatial distribution of soils which are relatively rich in organic matter (mull humus form) is related to glacigenic and glaciolimnic deposits. The afforestation of agricultural lands leads to the accumulation of organic matter in the topsoil which starts 30 years after the establishment of the forest. The highest organic carbon stock can be observed in 60- to 100-year-old forest land soils. An increased amount of woody debris in the process of forest growth produces an increase in the proportion of fulvic acid, humification rate, aromaticity and molecule weight of the soil humic acids. Key words: soil, humus forms, afforestation, organic carbon, humic substancesDarba izstrādāšanai saņemts Eiropas Sociālā fonda projekta “Atbalsts doktora studijām Latvijas Universitātē” Nr. 2009/0138/1DP/1.1.2.1.2/09/IPIA/ VIAA/004 finansiāls atbalsts. Promocijas darbs izstrādāts arī ar ES Sociālā fonda un Latvijas Universitātes snieguma finansējuma projekta “Klimata pārmaiņas un dabas resursu ilgtspējīga izmantošana” (ZD2016/AZ03) finansiālu atbalstu

A global perspective on soil science education at third educational level; knowledge, practice, skills and challenges

The pivotal role of soil as a resource is not fully appreciated by the general public. Improving education in soil science represents a challenge in a world where soil resources are under serious threat. Today’s high school students, the world’s future landowners, agriculturalists, and decision makers, have the potential to change society’s apathy towards soils issues. This research aimed to compare the level of soil education in high and/or secondary schools in forty-three countries worldwide, together comprising 62% of the world's population. Comparisons were made between soil science content discussed in educationally appropriate textbooks via a newly proposed soil information coefficient (SIC). Interviews with teachers were undertaken to better understand how soil science education is implemented in the classroom. Statistical analyses were investigated using clustering. Results showed that gaps in soil science education were most commonly observed in countries where soil science is a non-compulsory or optional subject. Soil science concepts are predominantly a part of geography or environmental science curricula. Consequently, considerable variability in soil science education systems among investigated countries exists. Soil information coefficient‘s outcomes demonstrated that a methodological approach combining textbooks and the use of modern digitally based strategies in the educational process significantly improved soil education performances. Overall, soil science education is under-represented in schools worldwide. Dynamic new approaches are needed to improve pivotal issues such as: i) promoting collaborations and agreements between high school and universities; ii) encouraging workshops and practical exercises such as field activities; and, iii) implementing technology tools. This, in turn, will prepare the next generation to contribute meaningfully towards solving present and future soil problems

Farmland afforestation effects on soil humus

Šajā pētījumā ir aplūkots augsnes organiskā oglekļa daudzums dažādās lauksaimniecības zemju ainavu aizaugšanas sukcesijas stadijās un dažāda vecuma meža, bijušajās lauksaimniecības zemēs Latvijā. Pētījumā ir noskaidrota lauksaimniecības zemju apmežošanas, kā arī citu faktoru ietekme uz augsnes organisko vielu saturu un humifikāciju. Pētījuma gaitā konstatēts, apmežošanai ir būtiska ietekme uz organisko vielu saturu augsnes minerālslānī līdz 10 cm dziļumam. Tāpat veicot augsnes paraugu analīzi konstatēts arī, ka Apmežošana būtiski ietekmē arī organisko vielu humifikācijas pakāpi augsnes A horizontā. Atslēgas vārdi: augsnes organiskās vielas, apmežošana, humifikācija.In this research work is examined the amount of organic carbon in soil in the agricultural landscape in different phases of overgrowing successions and of different ages in forest soil – in former farmlands in: Latvia. In the research is found out the influence of farmland’s afforestation as well as the influence of other factors on the content of soil’s organic substances and humification. During the researh was made a conclusion that afforestation has a significant influence on the content of soil’s organic substances in soil mineral layer in the depth of 10 cm. As well as analysing the samples of soil was found out that afforestation substantially influences the level of humification of organic substances in the A horizon of the soil. Keywords: soil organic matter, afforestation, himificatio

Changing character of the organic matter in a raised bog peat

Darbā ir aplūkoti humifikācijas procesi Eipuru, Dzelves, Augstā Kalna un Buļļu purvu kūdrā. Bakalaura darbā pētīts kūdras humifikācijas process atkarībā no kūdras kolonas atrašanās vietas, kūdras sastāva un cilvēka ietekmes. Humifikācijas procesa raksturošanai ir izmantoti šādi rādītāji: humīnskābju/fulvoskābju attiecība, fluorescences intensitātes attiecība I460/I510 un E4/E6 attiecība. Pētījumā konstatēts, ka humifikācijas procesi kūdrā ir intensīvāki kūdras aerācijas zonā, tos stipri ietekmē cilvēka darbība, kā arī tas, ka humifikācijas procesus vienlīdz labi raksturo gan humīnskābju/fulvoskābju attiecība, gan I460/I510 attiecība. Atslēgas vārdi: augstais purvs, humifikācija, humīnskābes, fulvoskābes, fluorescences intensitāte, E4/E6 attiecība.Paper covers questions about the humification proceses in Eipuru, Dzelves, Augstā Kalna and Buļļu rised bogs, related with sampling state position, peat composition and effect of human activities. To describe humification proceses, was used: humic acid/fulvic acid ratio, fluorescence intensity ratio I460/I510 and E4/E6 ratio. In study was find out, that humification intenses in aeration zone, it has effect on human activities, and that both humic acid/fulvic acid ratio and I460/I510 ratio are good humification indices. Keywords: raised bog, humification, humic substances, fluorescence intensity, E4/E6 ratio

Effects of afforestation of agricultural land with grey alder (Alnus incana (L.) Moench) on soil chemical properties, comparing two contrasting soil groups

Abstract Background Natural afforestation of former agricultural lands with alder species is common in Europe. Symbiotic nitrogen fixation by actinomycetes associated with alder species has been widely used for improvement of soil properties of abandoned agricultural lands, but relatively little is known of the interactions of these processes with soil type and chemical composition. We conducted a space-for time study with soil sampling under and outside grey alder tree canopies on two different soil groups to explore effects of colonisation of former agricultural lands by alder on soil properties. Results The results were analysed using analysis of variance. During the first 25 years after afforestation of former agricultural lands there was a significant increase in content of Ctot, Ntot, K+, Fe3+, Mn2+ and available P in the topsoil (0–10 cm and 11–20 cm) of Dystric Arenosols soils, which are deficient in organic matter. Such trends were not evident in organic matter rich Endostagnic Umbrisols soils, in which exchangeable K+ concentration decreased and exchangeable Fe3+ and Al3+ concentration increased. Conclusions The results show that the effects of grey alder on soil chemical properties depend on initial soil properties. The invasion of agricultural land by grey alder leads to spatial variability of soil chemical properties creating a mosaic pattern