The effect of later underseeding of clover on the yield of barley cereals in organic and conventional crops

Bakalaureusetöö Põllumajandussaaduste tootmise ja turustamise õppekavalTöö põhineb 2008. a. Eesti Maaülikooli Põllumajandus- ja keskkonnainstituudi Eerikal asuvale põllule rajatud pikaajalisel katsel. Antud uurimustöös on kasutatud 2013‒2016 aasta keskmisi ja 2017 aasta andmeid ning võrreldud tava- ja maheviljelusviisi ja ristiku külviaja mõju ristiku allakülviga odra terasaagile, selle kujunemisele ja saagi kvaliteedile. Maheviljeluses olid väetisvariandid Org 0, Org I ja Org II, kus lämmastiku allikateks olid vastavalt eelnevalt külvikorras kasvatatud liblikõieliste poolt seotud õhulämmastik, lisaks seotud õhulämmastikule veel ka talvised vahekultuurid ning lisaks eelnevatele veel sõnnik. Tavasüsteemis väetisvariandid olid N0, mis oli kontrollvariant ja ei saanud mineraalset lämmastikku ning N40, N80 ja N120, mis said vastavalt lämmastikku 40, 80 ja 120 kgN/ha. Ristiku hilisem allakülv on mahesüsteemis ja tavasüsteemis suurendanud odra tera saaki usutavalt. Varasemalt, kui ristik külvati koos odraga, on allakülvatud ristik mahesüsteemis odra terasaaki tunduvalt vähendanud, kuid hilisem allakülv mahesüsteemis aastal 2017 on odra terasaaki tõstnud 49‒79%. Ka 1000 tera mass on mahe- ja tavasüsteemis hilisema allakülvi korral vastavalt 5,3– 8,7% ja 9,3–14,4% tõusnud. Vastupidiselt on ristiku biomass hilisema allakülvi korral mahesüsteemis vähenenud 47,1–56,5% ja tavasüsteemi väetatud variantidel praktiliselt puudub.This thesis is based on a long-term experiment conducted in 2008 on a field of the Institute of Agricultural and Environmental Sciences in the Estonian University of Life Sciences. In this thesis the data from 2013‒2016 as an average of these years and additionally the data from 2017 were used to study the influence of later sowing of red clover on the grain yield formation and quality of barley in conventional and organic farming. The trial variants in organic farming were Org 0, Org I and Org II, where the nitrogen sources were the atmospheric nitrogen fixed by legumes grown in the croprotation, as well as winter catch crops and maure, respectively. In the convnentional system, the trial variants were N0, which was a test selection and could not obtain mineral nitrogen, N40, N80 and N120, which obtained nitrogen 40, 80 and 120 kgN/ha respectively. The later undersowing of clover has significantly increased barley grain yield in organic and conventional systems. Undersowing of red clover at the same time with barley seeds caused the vigorous growth of red clover and decrease of barley grain yield in the organic system significantly. The later undersowing of red clover in 2017 increased the barley grain yield by about 49‒79% in the organic system. The 1000 kernel weight with later undersowing has increased in organic and conventional systems by 5,3‒8,7% and 9,3‒14,4% respectively. On the contrary the clover biomass with later undersowing, has decreased by 47,1 % in the organic system and was absent in the treatments with higher amount of nitrogen in the conventional system