Long-term crop rotation effects on winter and spring cereals productivity

A long-term field experiment was carried out at the Experimental Station of the VDU Agriculture Academy (formerly Aleksandras Stulginskis University), Institute of Agroecosystems crop rotation collection (equipped in 1967), during 2015–2017. The soil of the Experimental site is moderately fine textured Calc(ar)i-Endohypogleyic Luvisol. The research was carried out on winter rye (Secale cereale L.) ‘Matador’, winter wheat (Triticum aestivum L.) ‘Skagen’ and 71 spring barley (Hordeum vulgare L.) ‘Orphelija’, which were sown in 8 different crop rotations after different preceding crops and rye monoculture. The aim of the experiment was to investigate the effect of long-term crop rotation combinations on testing crops yield and productivity indicators. In many cases, rye productivity indicators were lower during 50-year monocropping. The best productivity indicators were obtained by growing rye in them in grass and fallow crop sequences, and for winter wheat in fallow with vetch–oat mixture for fodder and after manure application. In rye these indicators were more dependent on the precipitation amount and the amount of the sum of temperature during the period of generative organ formation. Among these indicators and the number of productive stems, a statistically strong and medium strength correlation interaction was identified: r = 0.83, P ≤ 0.01; r = 0.90, P ≤ 0.05; r = 0.58, P ≤ 0.05; r = 0.85, P ≤ 0.01; and winter weat r = 0.87, P ≤ 0.01; r = 0.89, P ≤ 0.01. The highest winter wheat productivity was established in crop rotation after perennial grasses and leguminous crops. Crop yield in monoculture decreases, but the optimal amount of mineral fertilizers saves lower but stable yields. Spring barley is less dependent on preceding crop, so it can be grown after winter cereals. However, they are more productive when sown after row crops and in crop rotations where one of the rotation members is fertilized with organic fertilizers.