Browsing by Author "Orjala, Jenni"

Long-term, one-sided cultivation of crops has become more common in farming systems in recent decades, but at the same time, it has had negative impacts on soil structure, soil carbon reserves and the biodiversity of farming systems. Pea (Pisum sativum L.) is a legume that can be used to diversify crop rotations and improve protein self-sufficiency. Pea can symbiotically fix nitrogen from the atmosphere with the help of nitrogen-fixing Rhizobium bacteria living in its root nodules, and convert it into usable forms for plants, thus reducing the need to use industrial fertilizers. The following crop may also benefit from the organic nitrogen derived from the pea crop residues and pea’s ability to reduce pest pressure on cereals. The aim of this study was to study the pre-crop effects of pea on the formation of dry matter and nitrogen yields of oat (Avena sativa L.) and rapeseed (Brassica napus L.). The study was conducted as a field experiment in Haltiala with a completely randomized block design in four replicates. The study included four oat treatments (fertilized with 90 kg (N) ha-1 and either oat, pea or pea-rapeseed mixture as a pre-crop, and unfertilized oat with a pea-rapeseed mixture as a pre-crop) and two rapeseed treatments (pea as a pre-crop, unfertilized or fertilized with 90 kg (N) ha-1). In the study, the pre-crop did not affect the amount or formation of dry matter or nitrogen yield of oats and rapeseed. The effect of fertilization on the formation of dry matter and nitrogen yield was also small, but the maximum rates of dry matter accumulation and nitrogen uptake occurred earlier in fertilized than in non-fertilized treatments. Although pea as a pre-crop did not significantly affect the amount of dry matter and nitrogen yield of the crops during the growing season, it did not either affect them negatively compared to the monoculture oat because their yields were similar. Drought in June and July limited the release of nitrogen for plant use, which explains the effect of both the pre-crop and the fertilization treatment being rather small in the dry matter and nitrogen yield of oats and rapeseed. Pea very likely has a positive effect on the growth of the following crop, but further research is needed in different soil types and in more favorable weather conditions.