Vahekultuuride biomassi moodustamise ja lämmastiku sidumise võime ja mõju järelkultuuri saagile

A Thesis for applying for the degree of Doctor of Philosophy in Agriculture.The aims of the thesis were to evaluate the biomass and N accumulation of winter cover crop species (winter rye, winter turnip rape, forage radish, berseem clover and hairy vetch), winter hardiness of hairy vetch, the effect of sowing date on biomass and N accumulation and the effect of CCs on the yield of subsequent spring barley. The results showed that CC biomass and N accumulation depended on species and growing conditions, especially the sum of effective temperatures. Frost sensitive forage radish accumulated the highest amount of biomass and N in autumn, whereas berseem clover accumulated low amount of biomass and N, especially in the year with drought conditions before the establishment. Hairy vetch over-wintered similarly to winter turnip rape and winter rye in all trial years. Hairy vetch and winter turnip rape accumulated higher amount of biomass and N in the spring than winter rye, which may be partly related to characteristics of the used winter rye variety. Cover crop biomass and N accumulation decreased with delayed sowing dates, while the influence of sowing date on cover crop species was different. Forage radish produced the highest amount of biomass and N at all sowing dates. Although the biomass of rye was relatively low, the reduction at delayed sowing dates was lowest compared to other species. Among over-wintering CCs, hairy vetch as a legume species accumulated the highest amount of N in the spring. It can be concluded that in Estonia, CCs require sowing in early August to enable maximum biomass and N accumulation. It is possible to delay the sowing of over-wintering species if the following cash crop is sown later. As an average over the three years, only forage radish and hairy vetch significantly increased the yield of subsequent barley, probably because of the N contribution. None of the CCs had negative effect on barley, as the yield level following winter turnip rape, winter rye, and berseem clover were similar to the control.Doktoritöö eesmärkideks oli hinnata erinevate sügistalvisel perioodil kasvatatavate vahekultuuride (talirukis, talirüps, kesaredis, aleksandria ristik ja talivikk) biomassi moodustamise ja N sidumise võimet, taliviki sobivust talvekindlaks vahekultuuriks, külviaja mõju vahekultuuride biomassile ja N sidumisele ja vahekultuuride mõju järgneva suviodra saagile. Uurimistöö tulemusel selgus, et vahekultuuride biomass ja N sidumine nii sügisel kui ka kevadel sõltusid liigist, kasvuperioodi pikkusest ja ilmastikutingimustest, eelkõige efektiivsete temperatuuride summast. Kesaredis ei talvitunud, kuid moodustas sügisel nii suurima maapealse kui ka juurte biomassi ja sidus kõige rohkem lämmastikku. Aleksandria ristik, mis samuti ei talvitunud, moodustas aga väikseima biomassi ja sidus väikseima koguse N. Aleksandria ristik oli ka põuatundlik, moodustades väikseima biomassi 2018. aastal, kui vahekultuuride külvile eelnes kuiv periood. Lisaks talirukkile ja talirüpsile talvitus mõlemal aastal ka talivikk, mis oli suurima biomassi ja N sidumise võimega kevadel. Vahekultuuride biomass ja N kogus vähenesid külviaja hilinemisel ning vähenemine sõltus vahekultuuri liigist. Kõikidel külviaegadel oli suurima biomassi ja N sidumise võimega kesaredis. Kuigi talirukki biomass oli katses küllaltki madal, oli külviaja hilinedes biomassi vähenemine kõige väiksem. Aastate keskmisena suurendasid vaid kesaredis ja talivikk usutavalt järgneva suviodra saaki. Teiste vahekultuuride puhul oli suviodra saak sarnane kontrollvariandile

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

The effect of sowing date on cover crop biomass and nitrogen accumulation

ArticleCover crops are important tools for reducing nitrogen (N) leaching from the soil and improving the nutrition of cash crops. In northern regions with short autumns it is important to maximise the growing season of cover crops to achieve sufficient biomass and N accumulation. The objective of the study was to evaluate the biomass and N accumulation of cover crops at different sowing dates in August. Field experiment at Estonian Crop Research Institute was conducted in 2017 and 2018 with white mustard (Sinapis alba L.), phacelia (Phacelia tanacetifolia Benth), buckwheat (Fagopyrum esculentum Moench), berseem clover (Trifolium alexandrinum L.), field pea (Pisum sativum L.) and faba bean (Vicia faba L.). Cover crops were sown on August 3, 8, 14 and 18 in 2017 and August 3, 8, 13, 17 and 23 in 2018. The two year experiment showed that biomass and N accumulation of cover crops were reduced with delayed sowings, but the reduction mainly depended on cover crop species. White mustard, field pea and faba bean accumulated significantly higher amount of biomass and N than phacelia, buckwheat and berseem clover at all sowing dates in both years. Because of a rapid decrease in biomass, the optimum sowing time for phacelia and buckwheat should not be later than middle of August. In both year berseem clover produced the modest amount of biomass and therefore more suited as spring sown cover crop in Estonian conditions

Soil weed seed bank and factors influencing the number of weeds at the end of conversion period to organic production

In 2008 an experiment was set up on the field in Eerika experimental station (Estonian University of Life Sciences) as a 5-field crop rotation: red clover, winter wheat, pea, potato and barley undersown with red clover. The objective of the study was to measure the content of weed seeds in the soil and to evaluate the diversity of the species at the end of the period of converting to organic production. In conventional farming systems without fertilizer (Conv I) and conventional farming with mineral fertilizer (Conv II) herbicides were used for weed control. All the crops in Conv II system received P 25 kg ha-1 and K 95 kg ha-1, but the application rates of mineral nitrogen fertilizer differed. In organic systems (Org I – organic farming based on winter cover crop and Org II - organic farming based on winter cover crop and manure), the winter cover crops (ryegrass after winter wheat, winter oilseed rape after pea, winter rye after potato) were sown after the harvest and were ploughed into the soil as green manure in spring. The content of annual weed seeds was the lowest in red clover that had 17.7% less weed seeds in the soil of Org II system compared to control (Conv I). In winter wheat the content of winter annual weed seeds was 50–76% higher compared to other crops. By the end of 2009 the content of organic carbon (Corg %) in the soil had increased significantly in both organic systems which results in higher activity of organisms that decrease the viability of weed seeds

The content of weed seeds in the soil based on the management system

ArticleIn 2008 an experiment was set up on the field in Eerika experimental station (Estonian University of Life Sciences) as a 5-field crop rotation: barley (Hordeum vulgare L.) with undersown red clover, red clover (Trifolium pratense L.), winter wheat (Triticum aestivum L.), pea (Pisum sativum L.), potato (Solanum tuberosum L.). The objective of the study was to measure the content of weed seeds in the soil and to evaluate the diversity of the species at the beginning of the period of organic production in 2011. In conventional farming systems without fertilizer (Con I) and conventional farming with mineral fertilizer (Con II) herbicides were used for weed control. All the crops in Con II system received P 25 kg ha-1 and K 95 kg ha-1 , but the application rates of mineral nitrogen fertilizer differed. In organic systems (Org I – organic farming based on winter cover crop and Org II – organic farming based on winter cover crop and manure), the winter cover crops (ryegrass after winter wheat, winter oilseed rape after pea, winter rye after potato) were sown after the harvest and were ploughed into the soil as green manure in spring. Organic farming systems (Org II) had a negative effect on the content of weed seeds in the soil (2.0–22.7% less seeds than in other variants). The seeds of Chenopodium album were the most abundant among summer annual weeds and the seeds of Viola arvensis among winter weeds in the soil. Organic farming measures increased the domination of Chenopodium album – the dominance index D’ was increased by 0.09–0.14 compared to conventional variants. The content of seeds of winter weed Viola arvensis in Org II variant was decreased by 82%. The index of species evenness J’ and Shannon Wiener diversity index H’ were lower in organic plots by 0.10– 0.18 and 0.60–0.19, respectively. Org II variants showed the best results based on the decrease of soil weed seed bank and distribution of the weed species

Saagikultuuride segukülvides kasvatamine

Segukultuuride kasvatamine monokultuuride asemel mahepõllumajanduslikus külvikorras võib olla üks viis riskide hajutamiseks ning saagikuse ja saagi kvaliteedi tõstmiseks. Kaunviljade ja eriti nisu segus kasvatamine võib tõsta terade proteiinisaldust ning vähendada ka haiguste ja kahjurite riski. Mõnede põllukultuuride, näiteks põldherne ja viki puhul võimaldab segaviljelus kergemini saaki koristada. Segukultuur, kui seda oskuslikult kombineerida, võib olla vahepealne võimalus põhikultuuride ja vahekultuuride vahepealne variant, parandades mitte ainult saagikust, vaid ka mulla viljakust. Projekti käigus katsetati mitmeid kombinatsioone kaunviljade ja teraviljadega

Paljuliigilised vahekultuuride segud haljasväetisena mahepõllukultuuride külvikorras

Mahetaimekasvatuses on vahekultuuride ehk haljasväetiste kasvatamine üks olulisemaid mullaviljakuse säilitamise meetodeid. Traditsiooniliselt on kasutatavate haljasväetiste valik väga piiratud – enamasti kasutatakse punast või valget ristikut, kas puhaskülvis või põldheina segus ühe- või kaheaastase kultuurina külvikorras. Vahekultuuride õnnestunud kasvatamisel on võimalus vähendada ka umbrohtumust, mis on hetkel üks maheviljeluse suurematest probleemidest. Vahekultuuride lagunemisel mullas muutuvad toitained järgnevatele kultuuridele kättesaadavaks, parandades nii stabiilset varustatust toitainetega. Paljuliigilised vahekultuuride segud mõjutavad mulda laiemas võtmes kui seni valdavalt üksikliigina kasvatavad liblikõielised heintaimed

The Effect of Cover Crops on the Yield of Spring Barley in Estonia

Using cover crops in fallow periods of crop production is an important management tool for reducing nitrate leaching and therefore improving nitrogen availability for subsequent crops. We estimated the short-term effect of five cover crop species on the yield of successive spring barley (Hordeum vulgare L.) for two years in Estonia. The cover crop species used in the study were winter rye (Secale cereale L.), winter turnip rape (Brassica rapa spp. oleifera L.), forage radish (Raphanus sativus L. var. longipinnatus), hairy vetch (Vicia villosa Roth), and berseem clover (Trifolium alexandrinum L.). The results indicated that out of the five tested cover crops, forage radish and hairy vetch increased the yield of subsequent spring barley, whereas the other cover crops had no effect on barley yield. All cover crop species had low C:N ratios (11–17), suggesting that nitrogen (N) was available for barley early in the spring

The effect of cover crops on biomass and nitrogen accumulation and on spring barley yield

Saabunud / Received 27.05.2023 ; Aktsepteeritud / Accepted 21.06.2023 ; Avaldatud veebis / Published online 15.08.2023 ; Vastutav autor / Corresponding author Merili Toom ; [email protected] crops play an important role in preventing nutrient loss, reducing agricultural inputs, improving soil quality and environmental sustainability. The objectives of the study were to determine the biomass and nitrogen accumulation of cover crops and their effect on the following spring barley (Hordeum vulgare L.). Field trials with cover crop species winter rye (Secale cereale L), winter turnip rape (Brassica rapa spp. oleifera L.), forage radish (Raphanus sativus L. var. longipinnatus), hairy vetch (Vicia villosa Roth), and berseem clover (Trifolium alexandrinum L.) were carried out during four growing seasons (2016/17, 2017/18, 2018/19, and 2019/20) at the Estonian Crop Research Institute (present: The Centre of Estonian Rural Research and Knowledge, METK). Cover crop biomass and N accumulation in autumn and in spring depended on species and growing conditions. The biomass and nitrogen (N) accumulation were at their lowest in the first growing season (2016/17) due to lowest level of effective temperatures. Forage radish accumulated the highest amount of biomass and N in autumn. Berseem clover accumulated lowest amount of biomass and N in the year with drought conditions (2018) before sowing. Among overwintered cover crops, hairy vetch accumulated the highest amount of N in the spring although its biomass was similar to winter turnip rape. Winter rye had the lowest biomass and N accumulation in spring. As an average over the four years, only forage radish and hairy vetch significantly increased the yield of subsequent barley. None of the cover crops had a negative effect on barley, as the yield level following other species was similar to the control without cover crop. The knowledge about cover crop selection is useful to integrate suitable species into Estonian cropping systems