Erinevate haljasväetiskultuuride bioproduktsioon ja mõju järgnevate kultuuride saagile

As green manure crops and green manure undersows haven’t been comparatively studied in Estonia, the current research is focused on comparing different green manure crops and their cultivation in Estonia – both when pure sown or when undersown with cereals. Hypotheses of present thesis are: (i) when organic matter from green manure reaches the soil, its mineralization rate and its effect on succeeding crops is influenced by the way it was sown (pure or undersown), the amount of biomass, its chemical composition and weather conditions; (ii) the decomposition rate of organic matter and its release of nutrients to the soil varies with plant species; it also differs between roots and above-ground biomass; (iii)it is possible to influence succeeding crop yields by different ploughing times of green manures; the duration of the effect of the ploughed biomass depends on the plant species; (iv) the biomass formation and nutrient binding capacities of catch crops depend on the plant species, the climatic conditions and the length of the growing period. The objectives of the present study were as follows: (i) to determine the amount of the aboveground biomass and root system of various green manure crops, as well as their decomposition rate and amount of nutrients (N, P, K) introduced to soil; (ii) to investigate the duration of the effect of, and the efficiency of, biologically bound nitrogen based on the yield and yield quality of succeeding crops; (iii) to investigate the decomposition rate of organic matter at different C:N ratios; (iv) to determine catch crop biomass amount, nutrient binding capacity and effect on soil plant available nitrogen content and succeeding crop yield, and to identify catch crops most suitable for Estonian conditions. The formation of legume crop biomass varied with legume species, trial year weather and herbage use duration. Of the pure crop legumes studied by us, red clover, hybrid lucerne and white melilot produced the greatest biomass. When under sown, the amounts of biomass, N and C returned to the soil depended on aftermath formation. The amounts of nutrients returned to the soil were mostly influenced by biomass size and its nutrient content. Of the legumes used in the trials, bird’s foot trefoil was not suitable as a green manure crop when under-sown, and even when pure sown its efficiency on succeeding crop yield was the lowest. Westerwold ryegrass use reduced succeeding crop yield. The biomass of bird’s foot trefoil and red clover decomposed faster and their effect materialised in the succeeding crop yield. The effect of the lucernes and white melilot, which decompose more slowly, on succeeding crop yield materialised also in the second and third years. Another major conclusion is that it is important for the N effect of green manures to be utilised by subsequent crops. Red clover, white melilot and hybrid lucerne pure sowing biomass effect was roughly equal to that of the N100 treatment. The effect of bird’s foot trefoil was smaller than that of other leguminous green manure crops, with following cereal yield approximately equal to that after N50. Cereal yield was similar after under-sowings biomass incorporation into soil. After spring ploughing of green manure, the succeeding crop yield increased more than with spring ploughing alone, but this effect was not evident in all trial years. Where legumes were grown as under-sowings the C:N ratio of incorporated organic matter improved, which creates better conditions for organic matter decomposition in soil and reduces microbiological soil nitrogen binding. The effectiveness of catch crops depended on the choice of species, sowing time and main crop harvesting time, as well as on weather conditions during the autumn and winter. The optimal catch crops in Estonian weather conditions were fodder radish and white mustard.Käesolev doktoritöö keskendub erinevate haljasväetiskultuuride uurimisele põhjamaistes tingimustes nii katteviljata- ja katteviljaga- kui ka vahekultuuridena kasvatamisel. Doktoritöö raames uuriti millistes kogustes kasutavad ja seovad need taimed toitaineid ning bioloogiliselt seotud lämmastiku mõju kestvust ja efektiivsust järelkultuuride saagile ja selle kvaliteedile. Doktoritöö hüpoteesideks on et, (i) haljasväetiste orgaanilise aine mineralisatsiooni kestus mullas ja mõju järgnevate kultuuride saagile sõltub erinevate haljasväetiskultuuride katteviljata ja katteviljaga külvidest, biomassi suurusest, selle keemilisest koostisest ning ilmastikutingimustest; (ii) orgaanilise aine lagunemisdünaamika ja toitainete vabanemise kiirus mulda sõltub taimeliigist ning on erinev juurtes ja maapealses massis; (iii) haljasväetiste mõju järgnevate kultuuride saagile ja selle kvaliteedile oleneb biomassi sissekünniajast, (iv) vahekultuuride bioproduktsioon ja toitainete sidumine sõltub taimeliigist, ilmastikutingimustest ja kasvuperioodi pikkusest. Tulenevalt püstitatud hüpoteesidest oli uurimustöö eesmärkideks: (i) selgitada erinevate haljasväetiskultuuride bioproduktsiooni, maapealse biomassi ja juurte koguseid, keemilist koostist, erineva koostisega orgaanilise aine lagunemise kiirust mullas ja haljasväetistega mulda viidavaid toiteelementide (N, P, K) koguseid; (ii) uurida bioloogiliselt seotud lämmastiku efektiivsust ja mõju kestust järgnevate kultuuride saagikusele ja saagi kvaliteedile; (iii) uurida, kuidas laguneb erineva C:N suhtega orgaaniline aine mullas; (iv) selgitada, millised on Eesti tingimustesse kõige sobivamad vahekultuurid, kui suur on nende bioproduktsioon, millisel hulgal seovad nad toitaineid ja milline on nende mõju mulla liikuva mineraaliseerunud lämmastiku sisaldusele ja järgneva kultuuri saagile. Haljasväetiskultuuride biomassi kogus ja selle keemiline koostis sõltus kasvatavast taimeliigist. Katteviljaga külvidel sõltus biomassi suurus ja mulda tagastatava C ja N kogus ädala moodustumisest, kasvuajast ja taimede konkurentsivõimest. Uuritud liblikõielistest ei sobi harilik nõiahammas haljasväetiskultuuriks katteviljaga kasvatades, kuid ka katteviljata külvi korral oli selle mõju järelkultuuride saagile kõige väiksem. Itaalia raiheina kasvatamine haljasväetiseks vähendas järgnevate kultuuride saaki. Lämmastiku vabanemine orgaanilise aine mineraliseerumisel toimus kiiremini nende liblikõieliste biomassist, mille C:N suhe oli kitsam ja lämmastiku sisaldus suurem. Kiiremini lagunes nõiahamba ja punase ristiku biomass ning nende mõju realiseerus järgneva kultuuri saagikuses. Aeglasema biomassi lagunemisega lutsernide ja valge mesika mõju järgnevate kultuuride saagile realiseerus veel ka teisel ja kolmandal järelmõju aastal. Katteviljata külvatud punase ristiku, valge mesika ja hübriidlutserni biomassi mõju oli esimesel järelmõju aastal ligikaudu võrdne mineraalse lämmastikväetisnormiga N100. N50 tasemele jäi katteviljaga külvatud liblikõieliste biomassi muldaviimise järgse teravilja saak. Võrreldes sügisese künniga suurenes haljasväetiste kevadise sissekünni järgselt järelkultuuri saak, kuid kevadkünni efekt ei ilmnenud kõikidel katseaastatel. Liblikõieliste kasvatamisel allakülvidena paranes muldaviidava orgaanilise aine C:N suhe, mis loob paremad tingimused orgaanilise aine lagunemiseks mullas ja vähendab lämmastiku sidumist mullast mikroorganismide poolt. Vahekultuuride efektiivsus sõltub kasvatatavast kultuurist, kasvuperioodi pikkusest ja efektiivsete temperatuuride summast kasvuperioodil. Kõige sobivamad vahekultuurid Eesti tingimustesse on õlirõigas ja valge sinep

Maheviljelus koos vahekultuuridega parandab mullaomadusi

Eesti Maaülikoolis on viimasel kümnendil 5-väljalises külvikorrakatses uuritud mullaomaduste ja talitlusliku elurikkuse muutumist talviste vahekultuuride toimel maheviljelussüsteemides võrreldes mineraalväetamisega tavaviljelussüsteemidega. Aastatel 2012–2014 oli katse osa ERA Net Core Organic TILMAN-ORG ja 2015–2017 FertilCrop projektist

Pestitsiidid suruvad alla mulla mikroobide hüdrolüütilist aktiivsust

Mulla kvaliteet on mulla võime toetada bioloogilist aktiivsust, säilitada keskkonna kvaliteeti ning soodustada mullaelustikku

Diversified cropping systems for promoting the beneficial insects - ground beetles (Coleoptera: Carabidae)

Received: January 31st, 2023 ; Accepted: April 10th, 2023 ; Published: April 27th, 2023 ; Correspondence: [email protected] agro-ecosystems ground beetles - carabids (Coleoptera: Carabidae) are important as generalist predators of invertebrate pests and weed seeds and as prey for larger animals. This way they contribute to biodiversity and influence the most important ecological processes. Impacts of crop management practices on the carabids are not well described. Carabids were studied in winter wheat which is one crop in the rotation experiment (barley undersown with clover-clover-winter wheat-pea-potato). Carabids were collected with pitfall trap during one week at the end of June 2022. In laboratory, their species was identified. Trapping of carabids during the spiking phase of winter wheat has shown significant differences in carabids activitydensity and diversity depending on five different cropping systems. In two conventional systems where pesticides were used the number of carabids was two times smaller in comparison with three organic systems. Activity-density and diversity of carabids was significantly higher in all organic systems and especially in Org II system where winter cover crops and composted manure where used for rotation diversification. The Shannon–Wiener index values, which takes into account the number of species and their relative abundance were 1.24–1.53 in conventional systems, but higher in diversified organic systems (1.60–1.78). Only in organic systems Org I and Org II there were very rare species present, like Acupalpus meridianus (Linnaeus) and Microlestes minutulus (Goeze). In diversified organic systems the higher activity-density and abundance of carabids could be explained by the diverse plant community as possible source for better food and microclimatic conditions

Haljasväetistest vahekultuuride kasvatamine külvikorras vähendab umbrohtumust

Mahepõllumajanduses seab saagikusele tihti piiri umbrohtumus, kuivõrd konkureeritakse kultuurtaimedega vee, päikesevalguse ja toitainete pärast ning sageli ollakse vaheperemeesteks ka kahjuritele ning haigustele (Hole jt., 2005). Samas suurendavad umbrohud elurikkust ja toetavad põllukoosluse ökoloogilist talitluskindlust, luues toidubaasi taimekahjustajate looduslikele vaenlastele. Seetõttu tuleb taimekasvatusele kasuks nende mõningane olemasolu põllul, ent liigse konkurentsi vältimiseks tuleb nende arvukust siiski reguleerida, kuid loodushoidlikul moel. Selles on üheks olulisemaks meetmeks läbimõeldult kavandatud külvikord. Kultuuride mitmekesisus parandab kultuurtaimede võimet võidelda kahjurite ja haigustega ja vähendab umbrohtumust (Altieri, 1999; Pretty, 2008). Üheks võimaluseks selle saavutamisel on vahekultuuride kasvatamine külvikorras. Nimelt põhikultuuri kasvuaja vahepealsel ajal vahekultuurid kaitsevad ja rikastavad mulda toitainetega ning suruvad alla umbrohtumust. Vahekultuure ei kasvatata müügikasu eesmärgil, vaid sissekündmisel muutub see haljasväetiseks (Fageria jt., 2005). Vahekultuuride kasvatamine on eriti oluline teraviljarohkes külvikorras, vähendades teraviljade negatiivset mõju järgnevatele kultuuridele. Käesoleva uurimustöö eesmärgiks oli uurida viieväljalises külvikorras kolmes erinevas maheviljelussüsteemis vahekultuuridena kasvatatavate talviste haljasväetistest kattekultuuride ning nende ja sõnniku koostoimet umbrohtumusele

Punase ristiku kasvatamise mõju mulla üldlämmastiku sisaldusele erinevates viljelusviisides

Maheviljelussüsteemide (Mahe I ja Mahe II) mullas olid üldlämmastiku sisalduse näitajad võrreldes tavaviljeluse süsteemiga Tava I odra alla külvatud ristiku järgselt vastavalt 17,4% ja 18,5%, ristiku järgselt 10,6% ja 17,1% ning talinisu järgselt 14,3% ja 13,5% võrra suuremad. Samas usutav erinevus kasvatatud kultuuride vahel puudus. Tava 0 mullas olid üldlämmastiku sisalduse näitajad ristiku allakülviga odra järgselt 24,0%, ristiku järgselt 10,6% ja talinisu järgselt 14,8% võrra väiksemad kui Mahe 0 süsteemis. Ristiku kasvatamine tõstis Tava 0 ala Nüld sisaldust, kuid ilmnes tendents, kus pärast talinisu kasvatamist hakkab mullas üldlämmastiku sisaldus jälle vähenema

Nitrogen and carbon release during decomposition of roots and shoots of leguminous green manure crops

In Nordic conditions, soils are frozen during winter, affecting the decomposition rates of crop residues. Hence, the decomposition rates of above- and underground biomass and the dynamics of the N and C released into the soil were studied in trials focused on green manure crops. The decomposition of the residue and N release from the residue varied among the five species of legume tested. There was a marked difference in decomposition rates between shoots and roots, which may also be explained by the differences in the chemical composition of the residue. The shoot residue decomposes rapidly and it serves as a source of N for the subsequent crop. The root residue decomposes more slowly and this had a positive effect in a crop rotation in the second year. The green manure crops play an important role in managing N for organic crop production. Through efficient utilization of symbiotically fixed N by legumes in green manure, it is possible to achieve higher yields of subsequent crops

The advantage of Decision Support System for managing spring barley disease in Estonia

ArticleA Decision Support System (DSS) I - Taimekaitse focusing on use of timely applied and reduced fungicide rates in control of cereal diseases has been tested in field trials since 2003 . We compared the conventional treatment and the DSS - based spray practices in 18 field trials in five agricultural locations over 7 - year period. Efficacy of the control of net blotch caused by Pyrenophora teres (Drechsler, am Drechlera teres Sacc. Shoem), the main fungal disease in spring barley has been tested to determine the economic advantage of DSS use. Compared with the conventional spray practices, the advantage I - Taimekaitse resulted in reduction of application doses by 30 to 60% of the registered rate. According to I - Taimekaitse , the fungicides were applied mainly between heading and flowering growth stages (GS 55 – 65), whereas traditional routine spraying is commonly made at booting (GS 37 – 49) . The experiment clarifies the cost - benefit of using DSS - based approach in barley disease management with average yield increase above the control in 12.8% and above the conventional treatment in 14.1%. I - Taimekaitse gave competitive disease control and average yield output reduction compared with conventional practice by 9%. In general the Treatment Frequency Index applied in conventional treatment was 0.65 and in DSS 0.41. Although the cost of treatment expense in DSS was 20% less compared with conv entional practice, the performance of conventional used spray practices was outstanding in economic return

Finding new cover crops for Estonian conditions

Cover crops are essential in fallow periods of cropping systems to protect the soil from erosion and loss of plant nutrients through leaching and runoff (especially in winter). Experiments with potential cover crop species were carried out to evaluate their suitability to the local climate. The biomass production of tested cover crops in the experiment that lasted for two years was different depending on the length of the growing seasons

Winter cover crops impact on plant nutrients in an organic crop rotation

In crop rotations winter cover crops (WCC) can play a certain role in organic matter and plant nutrient formation. Under Nordic conditions the selection of crops for winter cover crops is quite limited. The aim of the present research was to explain the biomass and nutrients (N, P and K) formation by certain winter cover crops in an organic crop rotation. The effects of WCC on the following main crop yields were monitored