Search

In this study, our investigated hypothesis was that different pre-crops would have different effects on earthworm activity and soil CO2 emissions. We also hypothesized that a pre-crop clover–timothy mixture would perform best in terms of increasing the share of organic carbon in soil and, in this way, contribute to improving the sustainability of agroecosystems. The aim of this study was to explore the residual effects of using a 50-year-term of three different crop rotations and a continuous bare fallow period on soil CO2 emissions by investigating the soil earthworm populations, soil agrochemical properties, and winter wheat yields. A field experiment was carried out from 2016 to 2017 at Vytautas Magnus University in Lithuania (54°53′ N, 23°50′ E). The experiment was conducted in crop stands of winter wheat cv. 'Skagen', which were sown in three crop rotations with different pre-crops and a continuous bare fallow period. The pre-crop used for winter wheat in the cereal crop rotation (CE) was a vetch and oat mixture for green forage, LEG-CER; the pre-crop used for winter wheat in the field with row crops (FWR) crop rotation was black fallow, FAL-CER; the pre-crop used for winter wheat in the Norfolk (NOR) crop rotation was a clover–timothy mixture, GRS-CER; and finally, continuous bare fallow, FAL-CONTROL, was used as well. The highest soil CO2 emission intensity was determined after the pre-crops that left a large amount of plant residues (clover and timothy mixture) in the soil. Plant residues remaining after the pre-crop had the greatest effect on the number of earthworms in the soil after the harvesting of winter wheat. Winter wheat had the best yield when grown in grass and legume sequences. Crop rotation sequences that included perennial grasses accumulated higher contents of total nitrogen and organic carbon. The best values for the productivity indicators of wheat were obtained when it was grown after a fallow crop fertilized with cattle manure. An appropriate crop rotation that promotes the steady long-term contribution of organic matter and increases the content of organic carbon in the soil will have a positive effect on the agrochemical, biological, and physical properties of soil and agroecosystem sustainability; moreover, these effects cannot be achieved by technological means alone. [ABSTRACT FROM AUTHOR]

One of the main goals of the 21st century's developing society is to produce the necessary amount of food while protecting the environment. Globally, particularly in Lithuania and other northern regions with similar climatic and soil conditions, there is a lack of data on the long-term effects of crop rotation under the current conditions of intensive farming and climate change. It has long been recognized that monocultures cause soil degradation compared to crop rotation. Research hypothesis: the long-term implementation of crop rotation makes a positive influence on the soil environment. The aim of our investigation was to compare the effects of a 50-year-long application of different crop rotations and monocultures on soil CO2 emissions, earthworms, and productivity of winter rye. Long-term stationary field experiments were established in 1966 at Vytautas Magnus University Experimental Station (54°53′ N, 23°50′ E). The study was conducted using intensive field rotation with row crops, green manure crop rotations, three-course rotation, and rye monoculture. Pre-crop had the largest impact on soil CO2 emissions, and more intensive soil CO2 emissions occurred at the beginning of winter rye growing season. Rye appeared not to be demanding in terms of pre-crops. However, its productivity decreased when grown in monoculture, and the optimal mineral fertilization remained lower than with crop rotation, but productivity remained stable. [ABSTRACT FROM AUTHOR]

Equally effective way to achieve sustainable farming and the challenge set by the European Commission on 20 May 2020: proper crop rotation and thus reduction of the quantity of on-farm chemicals. Long-term stationary field experiments were established in 1966 at Vytautas Magnus University Experimental Station (54°53′ N, 23°50′ E). The study was conducted with intensive, three-course, field rotation with row crops, for green manure crop rotations, and rye monoculture as well during the last 5-year period of a 50-year investigation to determine the effect of crop rotation combinations and rye monoculture on weed density and seed bank and grain yield. In cereal crops, weed counting was performed twice: weed density was determined before the application of herbicides, and weed counting was done before the harvest. Weed seedlings were counted, their botanical species were determined, annual and perennial weed number was estimated. Weed seed bank was established before primary tillage in soil. The results obtained confirmed the hypothesis that with climate change and intensive farming, long-term crop rotations are likely to increase crop productivity, reduce weeds and weed seed banks in the soil, and thus contribute to maintaining agroecosystem sustainability. The winter rye 1000 grain weight and yield decreases as weed mass increases showing strong negative correlations: y = 475.56 − 11.93x, r = −0.91, p ≤ 0.05; y = 82.97 −14.82x, r = −0.97, p ≤ 0.01. Reseeding of rye crops leads to a growing prevalence of weeds such as Equisetum arvense L. and Mentha arvensis. Crop structures these days are dominated by cereals, which inevitably increase the spread of weeds, and therefore, the importance of crop rotations increases in the context of intensive farming. [ABSTRACT FROM AUTHOR]